This article is republished from The Conversation.

Brazil’s coastal waters teem with a rich array of species that paint a living tapestry beneath the waves. This underwater world is particularly special because many of its species are endemic – they are found nowhere else on Earth. The southwestern Atlantic is home to 111 endemic reef fish species, each of which plays a crucial role in the intricate web of marine life.

An uninvited guest has arrived in these tropical waters: the Pacific red lionfish (Pterois volitans). Renowned for its stunning appearance and voracious appetite, the lionfish was first detected off of Florida in 1985 and has spread throughout the Caribbean, killing reef fish in large numbers.

Now it has breached a formidable obstacle: the Amazon-Orinoco river plume, which flows into the Atlantic from northeastern Brazil. This massive discharge of fresh water has long functioned as a barrier separating Caribbean fish species from those farther south along Brazil’s coastline.

Scientists and environmental managers widely agree that the lionfish invasion in Brazil is a potential ecological disaster. As a marine ecologist, I believe mitigating the damage will require a comprehensive approach that addresses the ecological, social and economic harms wrought by this predatory fish.

Tracing the lionfish’s spread

It’s easy to see why lionfish appeal to aquarium enthusiasts. Native to the warm waters of the Indo-Pacific ocean, they are 12 to 15 inches long, with red and white stripes and long, showy fins. They protect themselves with dorsal spines that deliver painful venomous stings.

Lionfish were first detected in the Atlantic Ocean in 1985 off Dania Beach, Florida, probably discarded by a tropical fish collector. Since then they have spread throughout the Caribbean Sea, the Gulf of Mexico and northward as far as Bermuda and North Carolina – one of the most successful marine invasions on record. A close relative, the common lionfish or devil firefish (Pterois miles), has invaded the Mediterranean Sea and is spreading rapidly there.

Lionfish can be eaten safely if they are properly prepared to remove their venomous spines. In Florida and the Caribbean, lionfish hunting tournaments have become popular as a control method. However, lionfish move to deeper waters as they grow, so hunting alone can’t prevent them from spreading.

Marine scientists have anticipated for years that lionfish would someday arrive along the eastern coast of South America. A single sighting in 2014, far removed from the Amazon-Orinoco plume, was likely a result of an aquarium release rather than a natural migration.

Then in December 2020, local fishermen caught a pair of lionfish on coral reefs in the mesophotic, or “twilight,” zone several hundred feet below the mighty Amazon River plume. A scuba diver also encountered a lionfish in the oceanic archipelago of Fernando de Noronha, 220 miles (350 kilometers) off Brazil’s tropical coast.

New invasion fronts have quickly opened along Brazil’s north and northeast coasts, covering eight states and diverse marine habitats. More than 350 lionfish have been tallied along a 1,720-mile (2,765-kilometer) swath of coastline.

Aggressive predators without natural enemies

Like many introduced species, lionfish in the Atlantic don’t face natural population control mechanisms such as predation, disease and parasitism that limit their numbers in the Indo-Pacific. A 2011 study found that lionfish on reefs in the Bahamas were larger and more abundant than their Pacific counterparts.

Lionfish thrive in many marine habitats, from mangroves and seagrass beds to deepwater reefs and shipwrecks. They are aggressive, persistent hunters that feed on smaller fish, including species that keep coral reefs clean and others that are food for important commercial species like snappers and groupers. In a 2008 study, when lionfish appeared on reefs in the Bahamas, populations of small juvenile reef fish declined by 80% within five weeks.

Brazil’s northeast coast, with its rich artisanal fishing activity, stands on the front line of this invasive threat. Lionfish are present in coastal mangrove forests and estuaries – brackish water bodies where rivers meet the sea. These areas serve as nurseries for important commercial fish species. Losing them would increase the risk of hunger in a region that is already grappling with substantial social inequality.

Fishers also face the threat of lionfish stings, which are not lethal to humans but can cause painful wounds that may require medical treatment.

Facing the invasion: Brazil’s challenges

Biological invasions are easiest to control in early stages, when the invader population is still growing slowly. However, Brazil has been slow to react to the lionfish incursion.

The equatorial southwestern Atlantic, where the invasion is taking place, has been less thoroughly surveyed than the Caribbean. There has been little high-resolution seabed mapping, which would help scientists identifying potential lionfish habitats and anticipate where lionfish might spread next or concentrate their populations. Understanding of the scale of the invasion is largely based on estimates, which likely underrepresent its true extent.

Moreover, turbid waters along much of Brazil’s coast make it hard for scientists to monitor and document the invasion. Despite their distinctive appearance, lionfish are difficult to spot and record in murky water, which makes it challenging for scientists, divers and fishers to keep an accurate record of their spread.

Still another factor is that from 2018 through 2022, under former President Jair Bolsonaro, Brazil’s government sharply cut the national science budget, reducing funding for field surveys. The COVID-19 pandemic further reduced field research because of lockdowns and social distancing measures.

Making up for lost time

Brazil has a history of inadequately monitoring for early detection of marine invasions. The lionfish is no exception. Actions thus far have been reactive and often initiated too late to be fully effective.

As one of many Brazilian scientists who warned repeatedly about a potential lionfish invasion over the past decade, I’m disheartened that my country missed the window to take early action. Now, however, marine researchers and local communities are stepping up.

Given the length of Brazil’s coast, traditional monitoring methods are often insufficient. So we’ve turned to citizen science and information technology to fill the gaps in our knowledge.

In April 2022, a group of academic researchers spearheaded the launch of an online dashboard, which is updated continuously with data from scientific surveys and local community self-reports. This interactive platform is maintained by a research group led by marine scientists Marcelo Soares and Tommaso Giarrizzo from the Federal University of Ceará.

The dashboard allows anyone, from fishers to recreational divers and tourists, to upload data on lionfish observations. This information supports rapid response efforts, strategic planning for preventive measures in areas still free from lionfish, and the development of localized lionfish removal programs.

I believe lionfish are here to stay and will integrate over time into Brazil’s marine ecosystems, much as they have in the Caribbean. Given this reality, our most pragmatic and effective strategy is to reduce lionfish populations below levels that cause unacceptable ecological harm.

Regions along the coast that are still lionfish-free might benefit from early and preventive actions. Comprehensive surveillance plans should include environmental education programs about exotic species; early detection approaches, using techniques such as analyzing environmental DNA; citizen science initiatives to monitor and report lionfish sightings, participate in organized culls and help collect research data; and genetic surveys to identify patterns of connectivity among lionfish populations along Brazil’s coast and between Brazilian and Caribbean populations.

Brazil missed its initial opportunity to prevent the lionfish invasion, but I believe that with strategic, swift action and international collaboration, it can mitigate the impacts of this invasive species and safeguard its marine ecosystems.

This article has been updated to reflect that the correct number of endemic reef fish species in the southwestern Atlantic is 111.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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This article was originally published on Undark.

It could have been a scene from Jurassic Park: ten golden lumps of hardened resin, each encasing insects. But these weren’t from the age of the dinosaurs; these younger resins were formed in eastern Africa within the last few hundreds or thousands of years. Still, they offered a glimpse into a lost past: the dry evergreen forests of coastal Tanzania.

An international team of scientists recently took a close look at the lumps, which had been first collected more than a century ago by resin traders and then housed at the Senckenberg Research Institute and Natural History Museum in Frankfurt, Germany. Many of the insects encased within them were stingless bees, tropical pollinators that can get stuck in the sticky substance while gathering it to construct nests. Three of the species still live in Africa, but two had such a unique combination of features that last year, the scientists reported them to be new to science: Axestotrigona kitingae and Hypotrigona kleineri.

Species discoveries can be joyous occasions, but not in this case. Eastern African forests have nearly disappeared in the past century, and neither bee species has been spotted in surveys conducted in the area since the 1990s, noted coauthor and entomologist Michael Engel, who recently moved from a position at the University of Kansas to the American Museum of Natural History. Given that these social bees are usually abundant, it’s unlikely that the people looking for insects had simply missed them. Sometime in the last 50 to 60 years, Engel suspects, the bees vanished along with their habitat.

“It seems trivial on a planet with millions of species to sit back and go, ‘Okay, well, you documented two stingless bees that were lost,’” Engel said. “But it’s really far more troubling than that,” he added, because scientists increasingly recognize that extinction is “a very common phenomenon.”

The stingless bees are part of an overlooked but growing trend of species that are already deemed extinct by the time they’re discovered. Scientists have identified new species of bats, birds, beetles, fish, frogs, snails, orchids, lichen, marsh plants, and wildflowers by studying old museum specimens, only to find that they are at risk of vanishing or may not exist in the wild anymore. Such discoveries illustrate how little is still known about Earth’s biodiversity and the mounting scale of extinctions. They also hint at the silent extinctions among species that haven’t yet been described — what scientists call dark extinctions.

It’s critical to identify undescribed species and the threats they face, said Martin Cheek, a botanist at the Royal Botanic Gardens, Kew, in the United Kingdom, because if experts and policymakers don’t know an endangered species exists, they can’t take action to preserve it. With no way to count how many undescribed species are going extinct, researchers also risk underestimating the scale of human-caused extinctions — including the loss of ecologically vital species like pollinators. And if species go extinct unnoticed, scientists also miss the chance to capture the complete richness of life on Earth for future generations. “I think we want to have a full assessment of humans’ impact on nature,” said theoretical ecologist Ryan Chisholm of the National University of Singapore. “And to do that, we need to take account of these dark extinctions as well as the extinctions that we know about.”

Many scientists agree that humans have pushed extinctions higher than the natural rate of species turnover, but nobody knows the actual toll. In the tens of millions of years before humans came along, scientists estimate that for every 10,000 species, between 0.1 and 2 went extinct each century. (Even these rates are uncertain because many species didn’t leave behind fossils.) Some studies suggest that extinction rates picked up at least in the past 10,000 years as humans expanded across the globe, hunting large mammals along the way.

Islands were particularly hard hit, for instance in the Pacific, where Polynesian settlers introduced pigs and rats that wiped out native species. Then, starting in the 16th century, contact with European explorers caused additional extinctions in many places by intensifying habitat loss and the introduction of invasive species — issues that often continued in places that became colonies. But again, scientists have a poor record of biodiversity during this time; some species’ extinctions were only recognized much later, most famously the dodo, which had disappeared by 1700 after 200 years of Europeans hunting and then settling on the island in the Indian Ocean island it inhabited.

Key drivers of extinction, such as industrialization, have ramped up ever since. For the past century, some scientists have estimated an average of 200 extinctions per 10,000 species— levels so high that they believe they portend a mass extinction, a term reserved for geological events of the scale of the ordeal that annihalated the dinosaurs 66 million years ago. Yet some scientists, including the authors of those estimates, caution that even these numbers are conservative. The figures are based on the Red List compiled by the International Union for Conservation of Nature, or IUCN, a bookkeeper of species and their conservation statuses. As several experts have noted, the organization is slow to declare species extinct, wary that if the classification is wrong, they may cause threatened species to lose protections.

The Red List doesn’t include undescribed species, which some estimate could account for roughly 86 percent of the possibly 8.7 million species on Earth. That’s partly due to the sheer numbers of the largest species groups like invertebrates, plants, and fungi, especially in the little-explored regions around the tropics. It’s also because there are increasingly fewer experts to describe them due to a widespread lack of funding and training, noted conservation ecologist Natalia Ocampo-Peñuela of the University of California, Santa Cruz. Ocampo-Peñuela told Undark that she has no doubt that many species are going extinct without anyone noticing. “I think it is a phenomenon that will continue to happen and that it maybe has happened a lot more than we realize,” she said.

Studies of animal and plant specimens in museum and herbaria collections can uncover some of these dark extinctions. This can happen when scientists take a closer look at or conduct DNA analysis on specimens believed to represent known species and realize that these have actually been mislabeled, and instead represent new species that haven’t been seen in the wild in decades. Such a case unfolded recently for the ichthyologist Wilson Costa of the Federal University of Rio de Janeiro, who has long studied the diversity of killifish inhabiting southeastern Brazil’s Atlantic Forest. These fish live in shady, tea-colored acidic pools that form during the rainy season and lay eggs that survive through the dry period. These fragile conditions make these species extremely vulnerable to changes in water supply or deforestation, Costa wrote to Undark via email.

In 2019, Costa discovered that certain fish specimens collected in the 1980s weren’t members of Leptopanchax splendens, as previously believed, but actually represented a new species, which he called Leptopanchax sanguineus. With a few differences, both fish sport alternating red and metallic blue stripes on their flanks. While Leptopanchax splendens is critically endangered, Leptopanchax sanguineus hasn’t been spotted at all since its last collection in 1987. Pools no longer form where it was first found, probably because a nearby breeding facility for ornamental fish has diverted the water supply, said Costa, who has already witnessed the extinctions of several killifish species. “In the case discussed here, it was particularly sad because it is a species with unique characteristics and unusual beauty,” he added, “the product of millions of years of evolution stupidly interrupted.”

Similar discoveries have come from undescribed specimens, which exist in troves for diverse and poorly-studied groups of species, such as the land snails that have evolved across Pacific Islands. The mollusk specialist Alan Solem estimated in 1990 that, of roughly 200 Hawaiian species of one snail family, the Endodontidae, in Honolulu’s Bishop Museum, fewer than 40 had been described. All but a few are now likely extinct, said University of Hawaii biologist Robert Cowie, perhaps because invasive ants feasted off the snails’ eggs, which this snail family carries in a cavity underneath their shells. Meanwhile, Cheek said he’s publishing more and more new plant species from undescribed herbaria specimens that are likely already extinct in the wild.

Sometimes, though, it’s hard to identify species based on individual specimens, noted botanist Naomi Fraga, who directs conservation programs at the California Botanic Garden. And describing new species is not often a research priority. Studies that report new species aren’t often cited by other scientists, and they typically also don’t help towards pulling in new funding, both of which are key to academic success, Cheek said. One 2012 study concluded it takes an average of 21 years for a collected species to be formally described in the scientific literature. The authors added that if these difficulties — and the general dearth of taxonomists — persist, experts will continue to find extinct species in museum collections, “just as astronomers observe stars that vanished thousands of years ago.”

Museum records may only represent a fraction of undescribed species, causing some scientists to worry that many species could disappear unnoticed. For some groups, like snails, this is less likely, as extinct species may leave behind a shell that serves as a record of their existence even if collectors weren’t around to collect live specimens, noted Cowie. For instance, this allowed scientists to identify nine new and already-extinct species of helicinid land snails by combing the Gambier Islands in the Pacific for empty shells and combining these with specimens that already existed in museums. However, Cowie worries about the many invertebrates such as insects and spiders that won’t leave behind long-lasting physical remains. “What I worry about is that all this squishy biodiversity will just vanish without leaving a trace, and we’ll never know existed,” Cowie said.

Even some species that are found while they are still alive are already on the brink. In fact, research suggests that it’s precisely the newly described species that tend to have the highest risk of going extinct. Many new species are only now being discovered because they’re rare, isolated, or both — factors that also make them easier to wipe out, said Fraga. In 2018 in Guinea, for instance, botanist Denise Molmou of the National Herbarium of Guinea in Conakry discovered a new plant species which, like many of its relatives, appeared to inhabit a single waterfall, enveloping rocks amid the bubbly, air-rich water. Molmou was the last known person to see it alive.

Just before her team published their findings in the Kew Bulletin last year, Cheek looked at the waterfall’s location on Google Earth. A reservoir, created by a hydroelectric dam downriver, had flooded the waterfall, surely drowning any plants there, Cheek said. “Had we not got in there, and Denise had not gotten that specimen, we would not know that that species existed,” he added. “I felt sick, I felt, you know, it’s hopeless, like what’s the point?” Even if the team had known at the point of discovery that the dam was going to wipe it out, Cheek said, “it’d be quite difficult to do anything about it.”

While extinction is likely for many of these cases, it’s often hard to prove. The IUCN requires targeted searches to declare an extinction — something that Costa is still planning on doing for the killifish, four years after its discovery. But these surveys cost money, and aren’t always possible.

Meanwhile, some scientists have turned to computational techniques to estimate the scale of dark extinction, by extrapolating rates of species discovery and extinctions among known species. When Chisholm’s group applied this method to the estimated 195 species of birds in Singapore, they estimated that 9.6 undescribed species have vanished from the area in the past 200 years, in addition to the disappearance of 58 known species. For butterflies in Singapore, accounting for dark extinction roughly doubled the extinction toll of 132 known species.

Using similar approaches, a different research team estimated that the proportion of dark extinctions could account for up to just over a half of all extinctions, depending on the region and species group. Of course, “the main challenge in estimating dark extinction is that it is exactly that: an estimate. We can never be sure,” noted Quentin Cronk, a botanist of the University of British Columbia who has produced similar estimates.

Considering the current trends, some scientists doubt whether it’s even possible to name all species before they go extinct. To Cowie, who expressed little optimism extinctions will abate, the priority should be collecting species, especially invertebrates, from the wild so there will at least be museum specimens to mark their existence. “It’s sort of doing a disservice to our descendants if we let everything just vanish such that 200 years from now, nobody would know the biodiversity — the true biodiversity — that had evolved in the Amazon, for instance,” he said. “I want to know what lives and lived on this Earth,” he continued. “And it’s not just dinosaurs and mammoths and what have you; it’s all these little things that make the world go round.”

Other scientists, like Fraga, find hope in the fact that the presumption of extinction is just that — a presumption. As long as there’s still habitat, there’s a slim chance that species deemed extinct can be rediscovered and returned to healthy populations. In 2021, Japanese scientists stumbled across the fairy lantern Thismia kobensis, a fleshy orange flower only known from a single specimen collected in 1992. Now efforts are underway to protect its location and cultivate specimens for conservation.

Fraga is tracking down reported sightings of a monkeyflower species she identified in herbaria specimens: Erythranthe marmorata, which has bright yellow petals with red spots. Ultimately, she said, species are not just names. They are participants of ecological networks, upon which many other species, including humans, depend.

“We don’t want museum specimens,” she said. “We want to have thriving ecosystems and habitats. And in order to do that, we need to make sure that these species are thriving in, you know, populations in their ecological context, not just living in a museum.”

Katarina Zimmer is a science journalist. Her work has been published in The Scientist, National Geographic, Grist, Outside Magazine, and more.

This article was originally published on Undark. Read the original article.

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Bleaching occurs when a stressed marine creature, most commonly a coral, expels its symbiotic algae and turns a ghostly white, often in response to a warming sea. But bleaching affects more than just corals. Giant clams—massive mollusks that can grow more than 1.2 meters in diameter and weigh as much as 225 kilograms—can bleach, too. And in recent research, scientists have learned more about how bleaching disrupts these sessile giants, affecting everything from their nutrition to their reproduction.

Giant clams live on coral reefs and are the largest bivalves on Earth. Like corals, giant clams bleach when they’re stressed, often as a response to excessively warm water. As with a coral, a bleached giant clam expels the algae, called zooxanthellae, that live inside it. These algae dwell in the soft tissue of the clam’s mantle and provide energy for the animal through photosynthesis, leaving a bleached clam with less energy and nutrients. At worst, bleaching can kill giant clams through food deficiency.

Scientists have been studying bleaching in giant clams for decades. In 1997 and 1998, during a brief period that saw extensive coral bleaching worldwide with corals succumbing in at least 32 disparate countries, bleached giant clams were observed from Australia’s Great Barrier Reef to French Polynesia after water temperatures in the South Pacific rose significantly. In 2010, similar temperatures in the water off Thailand’s Ko Man Nai Island also led to scores of deaths.

Of the 12 species of giant clams, some are more resistant to heat stress than others. But as scientists are finding, even when a giant clam survives bleaching, other physiological functions can still be severely impaired.

A recent study in the Philippines of wild clams, for example, found that bleaching can hamper their reproduction. Bleaching reduces the number of eggs giant clams produce, and the more severe the bleaching, the fewer eggs they make. Reproducing “takes a lot of energy. So instead of using that energy for reproduction, they just use it for their survival,” says Sherry Lyn Sayco, the lead author of the study and a graduate student at the University of the Ryukyus in Japan.

Mei Lin Neo, a marine ecologist and giant clam expert at the National University of Singapore who was not involved in the study, says the work contributes to the story of how climate change can have “repercussions on the longevity of species.”

In general, she says, we know much more about how climate change affects corals than marine species with similar physiologies. “By understanding how other symbiotic species respond to climate change, each species becomes a unique indicator on how the overall reef ecosystem is doing.”

Bleached giant clams, it turns out, are often better than corals at coping with bleaching. Near Ko Man Nai Island, 40 percent of the bleached clams re-colored after a few months as the zooxanthellae repopulated in their tissues when temperatures cooled again. After the 1997–1998 bleaching event, over 95 percent of the 6,300 bleached clams near Australia’s Orpheus Island recovered.

Giant clams seem amenable to restocking, too. In the Philippines, where the largest species, Tridacna gigas, went locally extinct in the 1980s, restocking has brought it back.

“Clams are not just any organism,” Sayco says. “It’s not that we are just conserving them for them to be there,” she adds, “they have lots of benefits and ecosystem services, such as [boosting] fisheries [and] tourism.”

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It’s been just about 20 years since Finding Nemo was released in theaters and the lost “little clownfish from the reef” swam his way into our hearts. However, there is way more to coral reef fish than their beautiful scales and fictional tales. 

[Related: This rainbow reef fish is just as magical as it looks.]

A study published May 11 in the open access journal PLOS Biology found that some of the fish that live in anemones and reefs go through intense physiological changes when they switch from speedy swimming in the open ocean as larvae to settling down to life on the reef.  

Nemo and his young sea turtle pal named Squirt may have had a bit more in common than their age. Like sea turtles, many coral reef fish spawn away from where the animals will eventually settle and live. Adult coral reef fish spawn their larvae in the open ocean and the larvae swim against strong currents to get back to the reef where they will live as adults. Other bottom dwelling marine organisms like sea stars, corals, and urchins also follow this pattern. 

“These first weeks of life can be the most vulnerable for coral reef fishes, and if they don’t make it, that means they cannot grow up to be healthy adults and contribute to coral reef ecosystems,” co-author and James Cook University marine biologist Jodie L. Rummer told PopSci.

All of this swimming demands a lot of energy from the tiny fish, but then once they are settled on the reef floor, they must drastically switch gears and survive in a low-oxygen, or hypoxic, environment at night. 

To learn more about how this adjustment  works, the team collected daily measurements of the cinnamon anemonefish (Amphiprion melanopus) larvae’s swimming speed, oxygen update, and hypoxia tolerance. They observed them in a laboratory setting from the time that they hatched until when they settled down, usually around day nine of life.

“Coral reef fishes, including anemonefishes, as larvae are swimming among the fastest relative to their body size,” study co-author Adam Downie told PopSci. Downie is currently an animal physiologist at the University of Queensland in Australia and conducted the research as part of his PhD at James Cook University. “In our study, maximum speeds were over 12 centimeters [4.7 inches] per second, but for a fish that is the size of your pinky finger nail, that is 10-12 body lengths per second. Comparatively, relative to their size, larval coral reef fishes, including clownfish, outcompete most other marine life in a swimming test and all humans!”

Additionally, they saw that their hypoxia tolerance in the fish increased around day five while their oxygen intake decreased. To investigate how their bodies cope with these lack of oxygen, they sequenced mRNA from larvae of different ages to look for changes in gene activity that occurs during development. These physiological changes were correlated to areas of the gene where hemoglobin are produced and the activity of 2,470 genes changed during development.

[Related: Invasive rats are making some reef fish more peaceful, and that’s bad, actually.]

“These baby fish can change the expression patterns of certain genes that code for oxygen transporting and storage proteins just in time to cope with such low oxygen conditions on the reef,” said Rummer. “These proteins, like hemoglobin and myoglobin, are found in our bodies too and are important in getting oxygen from the environment and delivering it to the muscles, heart, and other organs. Indeed, timing is everything!”

The study found that relative to their body size, cinnamon anemonefish (also called cinnamon clownfish) larvae have the highest oxygen uptake rate of any bony fish currently measured. The genetic changes they can make to take in more oxygen underpin how reef fish can swim at speeds that would make even the most decorated Olympians envious. According to Downie, some studies have clocked clownfish at up to 50 body lengths per second, compared with Michael Phelps’ just under two body lengths per second. 

Since the effects of climate change threatens all marine life, the team believes that warmer ocean temperatures could impair clownfish swimming since the energy demands are so high. The warming waters put reef ecosystems at even more risk, in addition to coral bleaching, ocean acidification, disease, and more. 

“Next steps would be to see how different climate change stressors, such as temperature and pollutants may impact swimming performance of larval clownfishes and their ability to successfully transition from the open ocean to coral reefs,” said Downie. 

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Dead fish were everywhere, speckling the beach near town and extending onto the surrounding coastline. The sheer magnitude of the October 2021 die-off, when hundreds, possibly thousands, of herring washed up, is what sticks in the minds of the residents of Kotzebue, Alaska. Fish were “literally all over the beaches,” says Bob Schaeffer, a fisherman and elder from the Qikiqtaġruŋmiut tribe.

Despite the dramatic deaths, there was no apparent culprit. “We have no idea what caused it,” says Alex Whiting, the environmental program director for the Native Village of Kotzebue. He wonders if the die-off was a symptom of a problem he’s had his eye on for the past 15 years: blooms of toxic cyanobacteria, sometimes called blue-green algae, that have become increasingly noticeable in the waters around this remote Alaska town.

Kotzebue sits about 40 kilometers north of the Arctic Circle, on Alaska’s western coastline. Before the Russian explorer Otto von Kotzebue had his name attached to the place in the 1800s, the region was called Qikiqtaġruk, meaning “place that is almost an island.” One side of the two-kilometer-long settlement is bordered by Kotzebue Sound, an offshoot of the Chukchi Sea, and the other by a lagoon. Planes, boats, and four-wheelers are the main modes of transportation. The only road out of town simply loops around the lagoon before heading back in.

In the middle of town, the Alaska Commercial Company sells food that’s popular in the lower 48—from cereal to apples to two-bite brownies—but the ocean is the real grocery store for many people in town. Alaska Natives, who make up about three-quarters of Kotzebue’s population, pull hundreds of kilograms of food out of the sea every year.

“We’re ocean people,” Schaeffer tells me. The two of us are crammed into the tiny cabin of Schaeffer’s fishing boat in the just-light hours of a drizzly September 2022 morning. We’re motoring toward a water-monitoring device that’s been moored in Kotzebue Sound all summer. On the bow, Ajit Subramaniam, a microbial oceanographer from Columbia University, New York, Whiting, and Schaeffer’s son Vince have their noses tucked into upturned collars to shield against the cold rain. We’re all there to collect a summer’s worth of information about cyanobacteria that might be poisoning the fish Schaeffer and many others depend on.

Huge colonies of algae are nothing new, and they’re often beneficial. In the spring, for example, increased light and nutrient levels cause phytoplankton to bloom, creating a microbial soup that feeds fish and invertebrates. But unlike many forms of algae, cyanobacteria can be dangerous. Some species can produce cyanotoxins that cause liver or neurological damage, and perhaps even cancer, in humans and other animals.

Many communities have fallen foul of cyanobacteria. Although many cyanobacteria can survive in the marine environment, freshwater blooms tend to garner more attention, and their effects can spread to brackish environments when streams and rivers carry them into the sea. In East Africa, for example, blooms in Lake Victoria are blamed for massive fish kills. People can also suffer: in an extreme case in 1996, 26 patients died after receiving treatment at a Brazilian hemodialysis center, and an investigation found cyanotoxins in the clinic’s water supply. More often, people who are exposed experience fevers, headaches, or vomiting.

When phytoplankton blooms decompose, whole ecosystems can take a hit. Rotting cyanobacteria rob the waters of oxygen, suffocating fish and other marine life. In the brackish waters of the Baltic Sea, cyanobacterial blooms contribute to deoxygenation of the deep water and harm the cod industry.

As climate change reshapes the Arctic, nobody knows how—or if—cyanotoxins will affect Alaskan people and wildlife. “I try not to be alarmist,” says Thomas Farrugia, coordinator of the Alaska Harmful Algal Bloom Network, which researches, monitors, and raises awareness of harmful algal blooms around the state. “But it is something that we, I think, are just not quite prepared for right now.” Whiting and Subramaniam want to change that by figuring out why Kotzebue is playing host to cyanobacterial blooms and by creating a rapid response system that could eventually warn locals if their health is at risk.

Whiting’s cyanobacteria story started in 2008. One day while riding his bike home from work, he came across an arresting site: Kotzebue Sound had turned chartreuse, a color unlike anything he thought existed in nature. His first thought was, Where’s this paint coming from?

The story of cyanobacteria on this planet goes back about 1.9 billion years, however. As the first organisms to evolve photosynthesis, they’re often credited with bringing oxygen to Earth’s atmosphere, clearing the path for complex life forms such as ourselves.

Over their long history, cyanobacteria have evolved tricks that let them proliferate wildly when shifts in conditions such as nutrient levels or salinity kill off other microbes. “You can think of them as sort of the weedy species,” says Raphael Kudela, a phytoplankton ecologist at the University of California, Santa Cruz. Most microbes, for example, need a complex form of nitrogen that is sometimes only available in limited quantities to grow and reproduce, but the predominant cyanobacteria in Kotzebue Sound can use a simple form of nitrogen that’s found in virtually limitless quantities in the air.

Cyanotoxins are likely another tool that help cyanobacteria thrive, but researchers aren’t sure exactly how toxins benefit these microbes. Some scientists think they deter organisms that eat cyanobacteria, such as bigger plankton and fish. Hans Paerl, an aquatic ecologist from the University of North Carolina at Chapel Hill, favors another hypothesis: that toxins shield cyanobacteria from the potentially damaging astringent byproducts of photosynthesis.

Around the time when Kotzebue saw its first bloom, scientists were realizing that climate change would likely increase the frequency of cyanobacterial blooms, and what’s more, that blooms could spread from fresh water—long the focus of research—into adjacent brackish water. Kotzebue Sound’s blooms probably form in a nearby lake before flowing into the sea.

The latest science on cyanobacteria, however, had not reached Kotzebue in 2008. Instead, officers from the Alaska Department of Fish and Game tested the chartreuse water for petroleum and its byproducts. The tests came back negative, leaving Whiting stumped. “I had zero idea,” he says. It was biologist Lisa Clough, then from East Carolina University and now with the National Science Foundation, with whom Whiting had previously collaborated, who suggested he consider cyanobacteria. The following year, water sample analysis confirmed she was correct.

In 2017, Subramaniam visited Kotzebue as part of a research team studying sea ice dynamics. When Whiting learned that Subramaniam had a long-standing interest in cyanobacteria, “we just immediately clicked,” Subramaniam says.

The 2021 fish kill redoubled Whiting and Subramaniam’s enthusiasm for understanding how Kotzebue Sound’s microbial ecosystem could affect the town. A pathologist found damage to the dead fish’s gills, which may have been caused by the hard, spiky shells of diatoms (a type of algae), but the cause of the fish kill is still unclear. With so many of the town’s residents depending on fish as one of their food sources, that makes Subramaniam nervous. “If we don’t know what killed the fish, then it’s very difficult to address the question of, Is it safe to consume?” he says.

I watch the latest chapter of their collaboration from a crouched position on the deck of Schaeffer’s precipitously swaying fishing boat. Whiting reassures me that the one-piece flotation suit I’m wearing will save my life if I end up in the water, but I’m not keen to test that theory. Instead, I hold onto the boat with one hand and the phone I’m using to record video with the other while Whiting, Subramaniam, and Vince Schaeffer haul up a white-and-yellow contraption they moored in the ocean, rocking the boat in the process. Finally, a metal sphere about the diameter of a hula hoop emerges. From it projects a meter-long tube that contains a cyanobacteria sensor.

The sensor allows Whiting and Subramaniam to overcome a limitation that many researchers face: a cyanobacterial bloom is intense but fleeting, so “if you’re not here at the right time,” Subramaniam explains, “you’re not going to see it.” In contrast to the isolated measurements that researchers often rely on, the sensor had taken a reading every 10 minutes from the time it was deployed in June to this chilly September morning. By measuring levels of a fluorescent compound called phycocyanin, which is found only in cyanobacteria, they hope to correlate these species’ abundance with changes in water qualities such as salinity, temperature, and the presence of other forms of plankton.

Researchers are enthusiastic about the work because of its potential to protect the health of Alaskans, and because it could help them understand why blooms occur around the world. “That kind of high resolution is really valuable,” says Malin Olofsson, an aquatic biologist from the Swedish University of Agricultural Sciences, who studies cyanobacteria in the Baltic Sea. By combining phycocyanin measurements with toxin measurements, the scientists hope to provide a more complete picture of the hazards facing Kotzebue, but right now Subramaniam’s priority is to understand which species of cyanobacteria are most common and what’s causing them to bloom.

Farrugia, from the Alaska Harmful Algal Bloom Network, is excited about the possibility of using similar methods in other parts of Alaska to gain an overall view of where and when cyanobacteria are proliferating. Showing that the sensor works in one location “is definitely the first step,” he says.

Understanding the location and potential source of cyanobacterial blooms is only half the battle: the other question is what to do about them. In the Baltic Sea, where fertilizer runoff from industrial agriculture has exacerbated blooms, neighboring countries have put a lot of effort into curtailing that runoff—and with success, Olofsson says. Kotzebue is not in an agricultural area, however, and instead some scientists have hypothesized that thawing permafrost may release nutrients that promote blooms. There’s not much anyone can do to prevent this, short of reversing the climate crisis. Some chemicals, including hydrogen peroxide, show promise as ways to kill cyanobacteria and bring temporary relief from blooms without affecting ecosystems broadly, but so far chemical treatments haven’t provided permanent solutions.

Instead, Whiting is hoping to create a rapid response system so he can notify the town if a bloom is turning water and food toxic. But this will require building up Kotzebue’s research infrastructure. At the moment, Subramaniam prepares samples in the kitchen at the Selawik National Wildlife Refuge’s office, then sends them across the country to researchers, who can take days, sometimes even months, to analyze them. To make the work safer and faster, Whiting and Subramaniam are applying for funding to set up a lab in Kotzebue and possibly hire a technician who can process samples in-house. Getting a lab is “probably the best thing that could happen up here,” says Schaeffer. Subramaniam is hopeful that their efforts will pay off within the next year.

In the meantime, interest in cyanobacterial blooms is also popping up in other regions of Alaska. Emma Pate, the training coordinator and environmental planner for the Norton Sound Health Corporation, started a monitoring program after members of local tribes noticed increased numbers of algae in rivers and streams. In Utqiaġvik, on Alaska’s northern coast, locals have also started sampling for cyanobacteria, Farrugia says.

Whiting sees this work as filling a critical hole in Alaskans’ understanding of water quality. Regulatory agencies have yet to devise systems to protect Alaskans from the potential threat posed by cyanobacteria, so “somebody needs to do something,” he says. “We can’t all just be bumbling around in the dark waiting for a bunch of people to die.” Perhaps this sense of self-sufficiency, which has let Arctic people thrive on the frozen tundra for millennia, will once again get the job done.

The reporting for this article was partially funded by the Council for the Advancement of Science Writing Taylor/Blakeslee Mentored Science Journalism Project Fellowship.

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They found the victims floating in the water. Some had eyeballs full of air bubbles, others had their stomachs pushed up into their mouths. Many had severe internal bleeding.

Volcanoes can be life-threatening for fish. A major eruption in 2011 in Chile, for instance, killed 4.5 million of them. Researchers have studied how lava flows, hot gases, and deadly debris can cause mass die-offs or even cut fish off from the sea in suddenly landlocked lakes. But few have been able to document in detail the grisly fates experienced by the unlucky fish that find themselves at the mercy of an angry volcano. That’s why when one erupted underwater off the coast of El Hierro in the Canary Islands for 150 days in late 2011 and early 2012, researchers including Ayoze Castro Alonso at the University of Las Palmas de Gran Canaria saw the perfect opportunity to study the intricacies of these piscine casualties.

Ten years later, the devastating eruption of a terrestrial volcano on nearby La Palma, another of the Canary Islands, gave Alonso and his colleagues a chance to see an altogether different way that volcanoes can butcher unsuspecting fish—by overwhelming them with debris.

The scientists detail in a new paper the shocking injuries suffered by 49 fishes killed by the El Hierro eruption and 14 fishes killed by the volcanism near La Palma. “It’s a volcanic eruption in both cases, but the pathological syndromes are completely different,” says Alonso. “One is acute, the other is chronic.”

The underwater eruption near El Hierro superheated the water by as much as 19 °C, reduced the oxygen level, and rapidly acidified the ocean. Alonso and his colleagues found fishes with gas bubbles in their bodies. The team concluded the injuries occurred while the fishes were still alive because the scientists found inflammatory cells indicative of physical trauma and a severe build-up of blood in the fishes’ tissues.

The researchers’ detailed necropsies also hint that the fishes made a fateful dash for safety. Once the El Hierro eruption was underway, Alonso says, the fishes ascended rapidly. “They tried to escape,” he says.

As the fishes swam upward, sudden depressurization likely caused the gases dissolved in their bodies to bubble out, accounting for the bubbles in their eyes and under their skin. Depressurization would also explain why the animals’ stomachs were pushed up into their mouths and why some had overinflated swim bladders. These gas-filled organs expand when fish rise toward the surface.

On La Palma, though, molten lava flowed over land and into the ocean where the sudden clash with cold water quenched it into a glassy rock known as hyaloclastite. Within a week, huge clouds of volcanic ash settled into the water. Fish died after their gills became clogged with ash, or after their digestive tracts were impacted with fragments of glassy hyaloclastite.

Some of the findings are familiar to Todd Crowl, an ecosystem scientist at Florida International University who was not involved in the current study but who witnessed an eruption on Dominica in the Caribbean during the 1990s. A few centimeters of ash fell on the island, Crowl says, contaminating streams and killing thousands of filter-feeding shrimp. “All that ash just completely clogged up [the shrimp’s] filters,” he says.

Alonso and his colleagues’ research is the first to analyze the wounds fish suffer during a volcanic eruption in such detail—in part because getting access to the victims while their bodies are still fresh is incredibly difficult. After the eruptions at El Hierro and La Palma, local officials gathered up stricken fishes and shipped them on ice to the researchers within a matter of days.

Crowl says this rapid collection let the scientists conduct their analyses before the fishes rotted away. “We get fish kills all the time in Florida because of algal blooms and stuff like that,” Crowl says. “But by the time we get the specimens, there’s lots of degradation.”

Volcano ecologist Charlie Crisafulli, formerly of the US Forest Service, who was not involved in the work, agrees that the study of such fresh victims is novel: “We haven’t seen this before.” However, Crisafulli isn’t certain that the fishes killed by the El Hierro eruption actively tried to flee. Alternatively, they might have been stunned by the rapid changes in their environment and simply floated upward in a state of shock.

Though all of this seems deeply unpleasant, Crisafulli stresses there is a bigger picture here worth thinking about. Volcanoes kill, but they also create. Eruptions contribute nutrients to the environment, and lava flows build new land—sometimes entire islands.

“With this so-called destruction and loss of life, also there’s the creation of new habitats,” Crisafulli says. “What was initially a loss ends up becoming a gain through time.”

This article first appeared in Hakai Magazine and is republished here with permission.

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The unusual looking mudskipper has a startling face, and a fascinating backstory. The fish is actually amphibious and has evolved traits that ensure its survival in both water and on land. They have eyes on the top of their heads for better aerial vision and also use oxygen from their water stored in their gill chambers to breathe on land. However, the mudflat-dwelling fish’s ability to blink its eyes is shedding light on how our own ancestors evolved from living in the water to walking on land.

A study published April 24 in the Proceedings of the National Academy of Sciences (PNAS) found that the blinking behavior serves many of the same functions of our blinking, and it may be part of that suite of traits that allowed tetrapods to evolve on land. Tetrapods are the group of animals, including today’s amphibians, birds, reptiles and mammals, that evolved to exist on land in a rapid turn of events roughly 375 million years ago.

[Related: Our four-legged ancestors evolved from sea to land astonishingly quickly.]

Animals blink to keep the eyes wet and clean and protect them from injury. Sometimes, blinking can even be a form of communication. Humans and other tetrapods blink constantly through the day and despite it being a subtle action, it is quite complex. Strangely enough, mudskipper’s blink lasts roughly the same length of time as a human’s. 

“Studying how this behavior first evolved has been challenging because the anatomical changes that allow blinking are mostly in soft tissues, which don’t preserve well in the fossil record,” co-autor and Penn State University biologist Thomas Stewart said in a statement. “The mudskipper, which evolved its blinking behavior independently, gives us the opportunity to test how and why blinking might have evolved in a living fish that regularly leaves the water to spend time on land.”

To better understand how mudskippers evolved the ability to blink, the team analyzed blinking using high-speed videos. They compared the mudskippers’ anatomy with a closely related water-bound fish that doesn’t blink. Mudskippers blink with eyes that bulge out of the top of their heads, similar to a frog’s eyes. They momentarily retract their eyes down into the sockets, when they are covered by a sketchy membrane called a dermal cup. 

“Blinking in mudskippers appears to have evolved through a rearrangement of existing muscles that changed their line of action and also by the evolution of a novel tissue, the dermal cup,” co-author and Seton Hall University biologist Brett Aiello said in a statement. “This is a very interesting result because it shows that a very rudimentary, or basic, system can be used to conduct a complex behavior. You don’t need to evolve a lot of new stuff to evolve this new behavior — mudskippers just started using what they already had in a different way.”

To understand why the mudskippers blink on land, the team looked to the roles that blinking plays in other tetrapods. Tears in humans are critical to keeping the eye’s cells oxygenated and healthy, so the team looked to see if mudskippers blink to keep their eyes wet when exposed to the air.  

[Related: Tiktaalik’s ancient cousin decided life was better in the water.]

“We found that, just like humans, mudskippers blink more frequently when confronted with dry eyes,” said Aiello. “What’s incredible is that they can use their blinks to wet the eyes, even though these fish haven’t evolved any tear glands or ducts. Whereas our tears are made by glands around our eyes and on our eyelids, mudskippers seem to be mixing mucus from the skin with water from their environment to produce a tear film.”

They also found that blinking in mudskippers is triggered to protect the eye from injury as well as  clearing their eyes from possible debris. The finding suggests that mudskipper blinking appears to fulfill blinking’s three major functions—protecting, cleaning, and maintaining moisture.

“Based on the fact that mudskipper blinking, which evolved completely independently from our own fishy ancestors, serves many of the same functions as blinking in our own lineage, said Stewart. “We think that it was likely part of the suite of traits that evolved when tetrapods were adapting to live on land.”

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Industrial mining in the deep ocean is on the horizon. Despite several countries including Germany, France, Chile, and Canada calling for a pause on the field’s development, the International Seabed Authority (ISA), the organization tasked with both regulating and permitting deep-sea mining efforts, is nearing the deadline to finalize rules for how companies will operate. Companies, meanwhile, are busy testing the capabilities of their machines—equipment designed to collect polymetallic nodules, rocks rich in cobalt, nickel, copper, and manganese that litter some parts of the seafloor.

Top of mind for many scientists and politicians is what ramifications deep-sea mining might have on fragile marine ecosystems, including those far from the mining site. At the heart of the debate is concern about the clouds of sediment that can be kicked up by mining equipment.

“Imagine a car driving on a dusty road, and the plume of dust that balloons behind the car,” says Henko de Stigter, a marine geologist at the Royal Netherlands Institute for Sea Research. “This is how sediment plumes will form in the seabed.”

Scientists estimate that each full-scale deep-sea mining operation could produce up to 500 million cubic meters of discharge over a 30-year period. That’s roughly 1,000 six-meter-long shipping containers full of sediment being discharged into the deep every day, spawning from a field of mining sites spread out over an area roughly the size of Spain, Portugal, France, Belgium, and Germany.

These sediment plumes threaten to smother life on the ocean floor and choke midwater ecosystems, sending ripples throughout marine ecosystems affecting everything from deep-sea filter-feeders to commercially important species like tuna. Yet discussions of the plumes’ potential consequences are clouded by a great deal of uncertainty over how far they will spread and how they will affect marine life.

To clarify just how murky deep-sea mining will make the water, scientists have been tagging along as companies conduct tests.

Two years ago, Global Sea Mineral Resources, a Belgian company, conducted the first trials of its nodule-collecting vehicles. Scientists working with the company found that more than 90 percent of the sediment plume settled out on the seafloor, while the rest lingered within two meters of the seabed near the mined area. Other studies from experiments in the central Pacific Ocean found that the sediment plumes reached as far as 300 meters away from the disturbed site, though the thickest deposition was within 100 meters. This is a shorter spread than earlier models, which predicted deep-sea mining plumes could spread up to five kilometers from the mining site.

Beyond the sediment kicked up by submersibles moving along the seafloor, deep-sea mining can muddy the water in another way.

As polymetallic nodules are lifted to the surface, the waste water that’s sucked up along with the nodules is discharged back into the ocean. Doug McCauley, a marine scientist at the University of California, Santa Barbara, says this could potentially create “underwater dust storms” in upper layers of the water column. Over the course of a 20-year mining operation, this sediment could be carried by ocean currents up to 1,000 kilometers before sinking to the seabed.

Some particularly fine-grained particles could remain suspended in the water column, traveling long distances with the potential to affect a wide range of marine animals. According to another recent study, it’s these tiny particles that are the most harmful to filter-feeders like the Mediterranean mussel.

To avoid these consequences on midwater ecosystems, at least, scientists are advising would-be deep-sea miners to discharge waste water at the bottom of the ocean where mining has already created a disturbance. This would be a departure from the ISA’s messaging, which is to not specify at what depth waste water should be released.

For its own trials last December, the Metals Company (TMC), a Canadian company, says it worked hard to minimize the amount of sediment discharged in the waste water it released at a depth of 1,200 meters.

“We’ve optimized our system to leave as much sediment on the seabed as possible,” says Michael Clarke, environmental manager at TMC. Clarke says he’s skeptical of previously published research projecting vast sediment plumes. “When we were trying to measure the [midwater] plume a few hundred meters away from the outlet, we couldn’t even find the plume because it diluted so much.”

Clarke says the company is currently analyzing both baseline and impact data for its test mining, including looking at how far small particles spread and how long they remain suspended. The results will be submitted to the ISA as part of an environmental impact assessment.

As deep-sea mining inches closer and scientists ramp up their research efforts, it’s important to keep one thing clear: “I can tell you that we’re not going to discover that deep-sea mining is good for marine ecosystems,” McCauley says. “The question is, How bad will it be?”

This article first appeared in Hakai Magazine and is republished here with permission.

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In Dick Ogg’s 25 years of commercial fishing, he’s had a few close encounters with whales—mostly while pulling Dungeness crab pots off the ocean floor. “I’ve had whales right next to me,” within about five meters, says Ogg. “They follow me, they watch, they’re curious. And then they go on about their business.”

Ogg is fortunate his interactions have been so leisurely. For nearly a decade, California’s whales and crabbers have been locked in a persistent struggle. From 1985 to 2014, the National Oceanic and Atmospheric Administration (NOAA) reported an average of 10 whales were entangled in fishing gear each year along the west coast of the United States. But between 2015 and 2017, that number jumped to 47 entanglements per year. Since 2015, most of the identifiable gear found on entangled whales has been from crab pots. For crabbers, efforts to protect whales from entanglement often hit their bottom line.

The Dungeness crab fishery is one of California’s largest and most lucrative; until recently, it was considered one of the most sustainable fisheries in the state. In recent years, managers have sought a balance between protecting whales and ensuring crabbers’ livelihoods. But as climate change transforms the northeast Pacific and whales are increasingly at risk of being entangled in crabbers’ lines, that delicate balance is beginning to unravel.

The 2015 crabbing season was a catastrophe for both crabbers and whales. A marine heatwave nurtured a bloom of toxic algae that pushed anchovies close to shore, and the whales followed. That year, NOAA recorded 48 entangled whales along the US west coast—nearly five times the historical average. The algae also rendered the crabs inedible, and the California Department of Fish and Wildlife (CDFW) delayed the start of the fishing season by several months. The federal government declared the failed season a fishery disaster.

In 2017, the environmental nonprofit Center for Biological Diversity sued the CDFW over the spate of entanglements, prompting the department to set up a rapid risk assessment and mitigation program that closes portions of the Dungeness crab fishery when whales are nearby. The new approach has decreased entanglements, but it’s come at a high price for commercial fishers.

The CDFW has a handful of other tools they can use to protect whales, such as shortening the crabbing season and limiting the number of traps crabbers can drop. But according to a recent study, the only measure that could have effectively protected whales during the heatwave—shortening the crabbing season—is the one that would have hampered crabbers the most. And even then, these strong restrictions would have only reduced entanglements by around 50 percent.

If a similar marine heatwave hits again, entanglements could spike, too, says Jameal Samhouri, a NOAA ecologist and author of the paper. “It’s going to be really hard to resolve these trade-offs,” he says. “There may be some hard choices to make between whether we as a society want to push forward conservation matters or allow the fishery.”

Every year since the CDFW set up its mitigation program, the fishery has faced closures. Since 2015, the crabbing season has only opened on time once. Though the heatwave is gone, a boom of anchovy has kept whales close to shore.

For Ogg, the most difficult part of the season is waiting to go fish and not having any income. “It’s been really, really tough for a lot of guys,” he says. Another recent study calculates that in 2019 and 2020, whale-related delays cost California Dungeness fishers US $24-million—about the same as they lost during the heatwave in 2015.

Smaller boats, the study showed, were most severely impacted by the closures. It’s a trend Melissa Mahoney, executive director of Monterey Bay Fisheries Trust, has seen firsthand. While a large boat might set hundreds of crab pots in a day, smaller vessels can’t make up for a shortened season. “I just don’t know how long a lot of these fishermen can survive,” Mahoney says.

With climate change, marine heatwaves are now 20 times more frequent than they were in preindustrial times. As the Earth grows warmer, heatwaves that would have occurred every 100 years or so could happen once a decade or even once a year. In this hotter world, balancing the needs of both crabbers and whales will only grow more difficult.

This article first appeared in Hakai Magazine and is republished here with permission.

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The high seas — the ocean waters that begin 230 miles offshore — cover 43% of the planet’s surface and are home to as many as 10 million species, yet remain one of the least understood places on Earth. Among the region’s many mysteries are how Pacific salmon, one of the West’s most beloved and economically important fish, spend the majority of their lives — and why many populations are plummeting. Combined with how little we know about what climate change is doing out there, such questions make the area an international research and conservation priority.

These sprawling waters, though, are a mostly lawless zone, beyond the reaches of any national authority and governable only by international consensus and treaties. They face tremendous challenges that no nation can address alone: Climate change is causing marine heat waves and acidification, while overfishing and pollution are crippling ecosystems, even as pressure grows from companies and nations eager to drill and mine the ocean depths. In early March, negotiators representing nearly 200 nations came to a historic agreement aimed at protecting the ocean’s creatures and ecosystems. When the new United Nations High Seas Treaty was announced, marine scientists and conservationists around the globe rejoiced.

But what will the treaty actually mean for conservation in a region about which humanity knows less than the moon? When it comes to Pacific salmon, will the new treaty’s tools — and the international symbolism and momentum involved in agreeing to them — aid efforts to manage and protect them? Do the provisions go far enough? Here’s what the experts say.

The treaty’s protective tools may not be what salmon need

The treaty’s top provision establishes a road map for creating marine protected areas (MPAs) in international waters. Like national parks for the ocean, MPAs are zones that typically limit fishing or other activities to preserve ecosystems and species. When adequately enforced, they are widely considered to be a powerful tool for ocean and coastal conservation. They are also seen as key to reaching the U.N.’s goal to protect 30% of the planet’s oceans by 2030 — a goal the world is woefully behind on, with just 3% to 8% currently protected.

But when it comes to Pacific salmon, it is unclear whether MPAs can do anything at all. Salmon fishing in international waters has been banned since the 1990s, so future MPAs there will not reduce fishing. And while boosting enforcement of fishing bans may benefit other species, many believe illegal salmon fishing on the high seas is extremely low.

Still, some salmon experts believe that high seas marine preserves could provide indirect protection: By limiting other fishing, they could prevent salmon from being caught accidentally. They might also help preserve important marine food webs, though such ecosystems are vast, mobile and hard to monitor.

“If salmon used those (protected areas) as part of their migration and ocean habitat, then, yes, it could be beneficial,” said Brian Riddell, retired CEO and current science advisor to the Canadian nonprofit Pacific Salmon Foundation. “But to associate changes in marine survival to (an MPA), I think would be very, very difficult.”

MPAs also don’t address climate change or the marine heat waves that many researchers believe are a key factor in recent salmon declines. Matt Sloat, science director at the Oregon-based Wild Salmon Center, said that limiting global emissions would do more to protect salmon.

Although much remains unknown, recent research suggests that salmon ranges in the ocean are shifting or shrinking because of temperature changes. Salmon are also getting smaller, suggesting there may be more competition for fewer resources. “And then (hatcheries) are putting billions more hungry mouths into that smaller area,” Sloat said, referring to the sometimes-controversial state, federal and tribal hatcheries in the U.S. and other countries that raise and release quotas of juvenile salmon each year to maintain local fisheries. He believes that improving international coordination of the scale of those releases, rather than governing remote ocean habitats, might also improve salmon survival in the ocean.

It may boost collaboration and high seas research

Another section of the treaty bolsters collaborative research in international waters. Although the treaty’s language is directed more at support for developing nations — to ensure that new knowledge reflects the priorities of more than just the wealthiest coastal nations — salmon researchers hope that any overall increase in funding and interest in high seas research could help solve the mystery of what actually happens to salmon there.

While much is known about the environmental factors affecting salmon in their coastal and riverine habitats, scientists call the open ocean a “black box” into which salmon disappear for years. “We don’t even know where our salmon are,” said Laurie Weitkamp, a research biologist at the National Oceanic and Atmospheric Administration. In 2022, seeking answers, she led an expedition that was part of the largest-ever high seas salmon research effort in the North Pacific, during which five vessels and more than 60 international scientists surveyed 2.5 million square kilometers (nearly 1 million square miles) in the Gulf of Alaska.

The open ocean has always been a bottleneck for salmon survival; Weitkamp said that, even historically, “95% of the salmon that enter the ocean never come back.” Once, those numbers were predictable based on coastal and river conditions. Now, she said, scientists’ guesses are often wildly wrong. All known conditions will point to a good return, Weitkamp said, “And then it’s just like, where are they? What happened?”

Researchers have been trying to understand what they’re missing in salmon’s ocean habitats, but work on the high seas is extremely expensive: Expeditions cost tens of thousands of dollars a day, but can collect only small amounts of data because salmon are widely dispersed and hard to find. She said the scale of the information gathered during the 2019-2022 expeditions she was part of was possible only because so many ships and nations worked together. It’s the kind of collaboration the treaty may help to inspire — directly in some cases, and symbolically in others — as nations sign on.

“Collaboration is absolutely essential,” said Riddell, who was also part of the 2019-22 expeditions. “We need a dedicated, ongoing program,” to understand what’s happening to salmon and to strengthen ocean and climate models. He hopes the High Seas Treaty will lead to more support and interest in that work.

Ratification and Indigenous inclusion are not guaranteed

This year, many salmon runs are expected to hit record lows, impacting the ecosystems, economies and communities that depend on them. Chinook returns in Oregon, California and Alaska are forecast to be so low that offshore recreational and commercial fishing this spring has been cancelled in many areas. The Klamath River chinook run, upon which the Yurok Tribe relies for cultural and economic security, is expected to be the lowest in history.

“International effort to preserve and protect ocean habitat is critical to restoring these historic salmon runs,” said Amy Cordalis, an attorney, fisherwoman and Yurok tribal member who has served as the tribe’s general counsel. But “those efforts must accommodate traditional uses of those areas.”

In 2020, during negotiations on what became the High Seas Treaty, a group of scientists published a report calling on the United Nations to better incorporate Indigenous management perspectives, which they said were not adequately represented in discussions at that time. The final treaty, which includes language recognizing Indigenous rights, did better than most to include Indigenous peoples and traditional knowledge, said Marjo Vierros, a coastal policy researcher at the University of British Columbia and lead author of the report. “How that plays out in implementation is of course a different question.”

The draft treaty, which is now being proofread, still must be ratified by member nations — a political process that may yet stall out in the U.S. Due to conservative Republican opposition, the United States has yet to ratify the 40-year-old U.N. Convention on the Law of the Sea — the last treaty to govern international waters — though U.S. agencies say the country observes the law anyway.

That treaty drew the current boundary between state-controlled waters and the high seas, established rights for ships to navigate freely in international waters, and created an international body to develop deep-sea mining rules — a process that also remains, for now, unfinished. 

Researching at sea, “you gain a whole new understanding for how big (the ocean) really is,” Weitkamp said, and how much of its influence on salmon, climate and humanity remains unknown. “The ocean, especially the North Pacific, is just enormous.”

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Offshore wind is one of the fastest-growing sources of renewable energy, and with its expansion comes increasing scrutiny of its potential side effects. Alessandro Cresci, a biologist at the Institute of Marine Research in Norway, and his team have now shown that larval cod are attracted to one of the low-frequency sounds emitted by wind turbines, suggesting offshore wind installations could potentially alter the early life of microscopic fish that drift too close.

Cresci and his colleagues made their discovery through experiments conducted in the deep fjord water near the Austevoll Research Station in Norway. The team placed 89 cod larvae in floating transparent mesh chambers that allowed them to drift naturally, then filmed as they subjected half the fish in 15-minute trials to the output of an underwater sound projector set to 100 Hz to mimic the deep thrum put out by wind turbines.

When left to their own devices, all of the cod larvae oriented themselves to the northwest. Like the closely related haddock, cod have an innate sense of direction that guides their ocean swimming. When the scientists played the low-frequency sound, the baby fish still had a northwest preference, but it was weak. Instead, the larvae favored pointing their bodies in the direction of the sound. Cresci thinks the larvae may be attracted to the 100-Hz sound waves because that low frequency is among the symphony of sounds sometimes part of the background din along the coastline or near the bottom of the ocean where the fish might like to settle.

As sound waves propagate through water, they compress and decompress water molecules in their path. Fish can tell what direction a sound is coming from by detecting changes in the motion of water particles. “In water,” says Cresci, fish are “connected to the medium around them, so all the vibrations in the molecules of water are transferred to the body.”

Like other creatures on land and in the sea, fish use sound to communicate, avoid predators, find prey, and understand the world around them. Sound also helps many marine creatures find the best place to live. In previous research, scientists have shown that by playing the sounds of a thriving reef near a degraded reef they could cause more fish to settle in the area. For many species, where they settle as larvae is where they tend to be found as adults.

Even if larval fish are attracted to offshore wind farms en masse, what happens next is yet unknown.

Since fishers typically can’t safely operate near turbines, offshore wind farms could become pseudo protected areas where fish populations can grow large. But Ella Kim, a graduate student at the Scripps Institution of Oceanography at the University of California San Diego who studies fish acoustics and was not involved with the study, says it could go the other way.

Kim suggests that even if fish larvae do end up coalescing within offshore wind farms, the noise from the turbines and increased boat traffic to service the equipment could drown out fish communication. “Once these larvae get there,” Kim says, “will they have such impaired hearing that they won’t be able to even hear each other and reproduce?”

Aaron Rice, a bioacoustician at Cornell University in New York who was not involved with the study, says the research is useful because it shows that not only can fish larvae hear the sound, but that they’re responding to it by orienting toward it. Rice adds, however, that the underwater noise from real wind turbines is far more complex than the lone 100-Hz sound tested in the study. He says care should be taken in reading too much into the results.

As well as noise pollution, many marine species are also at risk from overfishing, rising ocean temperatures, and other pressures. When trying to decide whether offshore wind power is a net benefit or harm for marine life, says Rice, it’s important to keep these other elements in mind.

“The more understanding that we can have in terms of how offshore wind [power] impacts the ocean,” he says, “the better we can respond to the changing demands and minimize impacts.”

This article first appeared in Hakai Magazine and is republished here with permission.

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Microplastics wreak havoc on fish in myriad ways, disrupting everything from eating behavior to brain development. While it’s clear these pesky particles can cause animals a world of trouble, scientists have found it much harder to pin down exactly how they cause so many problems.

“We know that if you expose animals to plastics, then oftentimes we’ll see pathology,” says Andrew Wargo, a disease ecologist at the Virginia Institute of Marine Science (VIMS). “But what we don’t really know are the secondary effects.”

That, however, is starting to change.

In controlled laboratory experiments, Wargo and his VIMS colleagues have shown how microplastics leave rainbow trout more vulnerable to a common salmonid disease, infectious hematopoietic necrosis virus (IHNV). The effect can be dramatic: by exposing trout to a high concentration of either polystyrene beads or nylon microfibers for one month and then subjecting them to IHNV, the scientists found that fish were three to six times more likely to die, respectively, than IHNV-infected fish that hadn’t been exposed to plastics.

As well as increasing the lethality of IHNV, the microplastics also caused the exposed fish to have higher viral loads and shed more virus.

Taking tissue samples from the fish at different points in the experiment, the scientists found that the plastics were damaging the fish’s gills and provoking an inflammatory response. This likely makes it easier for the virus to invade the fish’s body, leading to more severe disease.

“There’s this kind of priming happening with some plastics,” says Meredith Evans Seeley, an environmental chemist at the National Institute of Standards and Technology and the study’s lead author. “That allows the pathogens to be more successful at colonizing the host.”

“Understanding the mechanism of how microplastics can increase the virulence of a virus? That’s pretty new,” says Bettie Cormier, an aquatic ecotoxicologist at the Norwegian University of Science and Technology who was not involved in the work.

The deadly synergy between microplastics and viruses could be especially troubling in aquaculture operations, Wargo says. Infections spread easily on fish farms, and farmed fish frequently encounter plastics such as nylon and polystyrene, which are used for buoys and nets.

Wild fish encounter microplastics and viruses, too, Cormier adds, so similar interactions between microplastics and pathogens could be having ecosystem-level effects.

“Plastics and pathogens are everywhere,” Wargo says. “I think if we want to understand the effects of both, we probably need to consider them together.”

This article first appeared in Hakai Magazine and is republished here with permission.

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Pushing off from the dock on a boat called the Capelin, Sandy Milner’s small team of scientists heads north, navigating through patchy fog past a behemoth cruise ship. As the Capelin slows to motor through humpback whale feeding grounds, distant plumes of their exhalations rise from the surface on this calm July morning. Dozens of sea otters dot the water. Lolling on backs, some with babes in arms, they turn their heads curiously as the boat speeds by. Seabirds and seals speckle floating icebergs in this calm stretch of Alaska’s Glacier Bay.

Some two hours later, the craft reaches a rocky beach where Wolf Point Creek meets the sea. The creek is a relatively new feature on the landscape: Land at its mouth first became ice-free in the 1940s due to the melting and retreat of a glacier. It took shape through the 1970s, fed by a mountain lake that slowly formed as an isolated chunk of glacier ice slowly melted. Wolf Point Creek is special because almost its entire life span — from the first, sparse trickles melting out under the ice edge to a mature stream ecosystem teeming with aquatic life, from tiny midge larvae to small fish, and with willows and alder weaving along its edges — is known in intimate detail, its history painstakingly documented.

Milner, a stream ecologist at the University of Birmingham in the UK, has returned almost annually to this spot since the 1970s to catalog how life — particularly aquatic invertebrates — has arrived, thrived and changed over time. He was here to observe meager midges in 1977 and to spot a hundred prospecting pink salmon in 1989. A decade later, his team cataloged 10,000 of the fish spawning in Wolf Point Creek.

The creek now supports all manner of creatures that make their living on its riches, from tiny algae to midges to salmon and their predators. Salmon will soon be arriving, and some of their ardent fans are here today. As National Park Service boat captain Justin Smith idles the motor, preparing to let the crew wade ashore, he casually mentions that a mother brown bear and cubs were recently sighted. Sweeping the crescent-shaped shoreline from left to right with binoculars, he stops and announces, “There she is,” pointing to the far side of the beach. Perhaps 500 meters away, a massive, sandy-brown head chomps on tall grass as three dark brown cubs scamper at her feet.

“Do you still want me to drop you off?” Smith asks. Milner nods and vocalizes consent. The wader-clad crew disembarks into shallow water and heads to the beach, backpacks loaded with collecting gear.

This spot — where Wolf Point Creek meets Muir Inlet — is a dynamic place. Once entirely icebound, Muir Inlet is now a watery expanse over 20 miles long. The inlet is part of the even more massive Glacier Bay that boasts more than a thousand glaciers — at least for now. Over the past 200 years, the glaciers here have receded rapidly as the planet has warmed. Alaskan glaciers are among the fastest-shrinking on Earth, making this place a natural laboratory for ecologists.

How will the ecosystems change? Glacial melting is shining a spotlight on the science of ecological succession, the name given to the patterns of arrival of one species after another as they show up in habitats previously lacking in life. There are longstanding ecological debates around succession that the work by Milner and others may help to settle.

And how will salmon adapt? Though wild salmon are known for their homing instincts, not all return to their natal streams. That’s important in a warming climate, because the fish that stray can colonize new streams that form where glaciers are melting — places long covered in ice. As streams in traditional salmon spawning grounds to the south become increasingly inhospitable with warming waters, some fish are, indeed, dispersing to new regions, filling new niches that open up.

New streams are creating conundrums, too, including for Indigenous people whose livelihoods depend heavily upon salmon. Some now find salmon shifting to spawn in places unprotected from development. Tribes and nations may be excluded from fishing access to these new habitats, even when their rights, on paper, are legally enshrined.

Succession: An ecological obsession

Milner first arrived in Glacier Bay in 1977 as a University of London graduate student in his mid-twenties, lured by a Time-Life book about the region and captivated by the opportunity to witness a fundamental ecological process in real time. He wanted to better understand how natural systems gradually change: how species arrive, survive and persist to form communities in brand new habitats like these young streams, how one community gives way to another.

Known as primary succession, this process of change is one of the oldest concepts in ecology, engrossing scientists since the discipline’s dawn. After the dramatic 1980 eruption of Mount Saint Helens, for example, life in the volcanic blast zone started fresh. At first, the catastrophically altered landscape appeared lifeless. But over time, lightweight seeds and insects swept in on the breeze. Seeds grew into plants, attracting more insects, plus birds, deer and elk. Heavier seeds got carried in on droppings or feathers. Today, some of that formerly barren landscape is regaining its forest.

When the young Milner first arrived, there had been no studies of stream succession, he says. Glacier Bay seemed the perfect spot to start such a project. Today, his is the longest-running research program in Glacier Bay National Park, a protected area of mountain peaks, lush temperate rainforest and shifting glaciers melting into cavernous fjords. This dynamic birthplace for new waterways is the site of one of the longest continuous studies anywhere of stream community formation.

Milner has returned most summers since then, missing one to get married, one when he was in Japan and two when travel was pandemically paused. Documenting the aquatic invertebrates lurking on Wolf Point Creek’s riverbed each year and sampling less frequently in other streams of various ages, he has cataloged the minutiae of incremental change for more than four decades. His silver-stubbled face and slow gait underscore this passage of time as he wades the stream again on this summer’s day.

A century ago, the beach where we stand bore the weight of the ice of Muir Glacier, thousands of feet thick. But even then, Muir was in rapid retreat. An 1888 note in the journal Science reported that this ice river was melting out at a rate of 65 to 72 feet per day. As late as the 1980s, tourists on boats could see icebergs from Muir Glacier calving into the bay, but today Muir no longer meets the tidewater. It terminates on land, about a mile from the sea.

As our team plods upstream from the creek’s mouth, the stream is flanked by alder and cottonwood trees. When Milner first walked here, “there was no vegetation,” he says. Now its banks support a forest. To get upstream, we forcefully maneuver through dense brush. Shouting is futile, inaudible above the rushing river, so Milner periodically sounds an air horn, warning wildlife of human interlopers.

So much has changed here, a point underlined as we push and shove our way through eye- and leg-poking alder thickets. First detected in the stream after the stream mouth emerged from glacial ice were larvae of chironomids, cold-loving midges. Later, other invertebrates came. Arriving in the 1980s were mayflies, stoneflies and caddis flies; stream ecologists call this trio EPT, from the orders Ephemeroptera, Plecoptera and Tricoptera.

The first plant life to establish near the stream was a few mats of mountain avens, a hairy, nitrogen-fixing Dryas plant with delicate white-petaled flowers, related to the rose. On top of the Dryas mats, Milner later found clumps of tiny alder and willow trees establishing themselves. Young cottonwood and Sitka spruce began taking hold on the wider floodplain. What happens in the stream and beside it is tightly linked, Milner found: Willow catkins are food for caddis flies, and alder roots provide chironomids with safe homes.

The year of 1987 brought a critical event, the first appearance of fish — insect larva-loving Dolly Varden char. Two years later, coho and pink salmon showed up.

The salmon sighting came in 1989, during a regionally massive pink run. That year, a hundred pink salmon found their way to the stream. “Then it really took off,” says Milner. By 1997, he counted more than 10,000 spawning pinks. Now they consistently return to Wolf Point Creek in the thousands. Pink salmon don’t need food in the stream in order to establish, explains Milner, just a place to lay their eggs, since their fry make their way straight to the ocean after emergence. But other salmon, like sockeye, need streams that lead up to lakes, and food in the water that feeds their babies, like plankton or insects. Wolf Point Creek’s waterfalls more than 30 meters high mean sockeye will never live here. They need more gradual, navigable paths to lakes in order to feel at home.

After more than an hour of wading and bushwhacking, we arrive at the sampling site. Our quarry are macroinvertebrates — backboneless animals like midge, mayfly and stonefly that are visible to the naked eye.

Ecologist Fred Windsor of Wales’ Cardiff University, Milner’s former graduate student, is brimming with excitement to see this legendary stream for the first time. He teaches National Park intern Sofia Elizarraras to brace a square-rimmed sampling trap against streambed rocks. Reaching down, long gloves protecting arms from frigid waters, Windsor gently shakes and rubs trapped rocks to dislodge clinging creatures. The flow of water sweeps the harvest to the back of the net. Windsor takes the catch to Milner, seated on gravel nearby. Milner extracts the critters and their twiggy sludge, then preserves and bags them.

EPT are today’s main haul. These are useful indicator species of stream health and community complexity, explains Windsor, because of their sensitivity to things like water flow, temperature and oxygen. Back at the lab, Milner will microscopically examine them and identify the species.

In the Rockies, more change

Living things farther down the ecological food chain also change as streams mature. Almost a thousand kilometers to the south, ecologist Karson Sudlow clambers the Rocky Mountains examining algal diversity in glacial streams.

Sudlow lights up about algae. “Algae are amazing!” he says. At multiple stream sites, his team has an unusual technique for systematically scrubbing rocks to collect them: an electric toothbrush run through one 30-second brushing cycle. Scrubbings are rinsed into a tray, then poured into a storage vial for microscopy and analysis.

Streams coming straight from glaciers are cold, nutrient-poor, turbid and fast-flowing. “All of this creates an ecosystem that is extremely hard to live in,” says Sudlow. So these newborn streams have very limited algal diversity, supporting mostly diatoms — species of small, single-celled algae with glass-like silica shells. Clinging tightly to rocks, “they can handle the worst conditions,” says Sudlow. Streams less influenced by glaciers have more diverse communities with more green algae and cyanobacteria, but with fewer cold-tolerant diatoms. Glacial streams become more akin to them as the ice recedes. Sudlow’s research underlines what others have found, too: Over time, as glaciers melt and streams warm, we gain stream diversity.

These Rocky Mountain streams melting out from glacial ice, with algae their main life form, may be what Wolf Point Creek was like in its very early days, before Milner arrived.

There are gaping holes in our understanding of ecological change after glaciers recede, says zoologist Gentile Francesco Ficetola of the Università degli Studi di Milano in Milan, Italy, who co-wrote an article about the ecology of glacial retreat in the 2021 Annual Review of Ecology, Evolution, and Systematics. His own work in the Alps, where the shrinking and disappearance of glaciers has been hard to ignore, is that “every glacier is different,” he says. Compounding the challenges of understanding ecological patterns as glaciers disappear is that the ecosystems that form afterwards are complex, like puzzles that build over time by assembly of thousands of pieces.

And though plants, microbes, insects and larger organisms all interact, field studies — for practical reasons — tend to focus on just one puzzle piece, generating an incomplete understanding of the ecosystem as a whole.

Succession as a theory has changed, and continues to change. As Ficetola explains, early work on succession was largely focused on plants. And it was proposed that succession led eventually to a “climax” community — a single stable endpoint based on an area’s climate and geography. Ecologists today recognize that succession is less predictable. Three different successional models dating back to the 1970s were put forward to explain how communities change. Early on, ecologists ardently defended one model over another, but today it seems that these models, and newer ones, are not mutually exclusive or universally supported: Some arrivals fit one model and others, another.

One model, facilitation, argues that early arriving “pioneer” species modify the environment to make it more suitable for later colonizers. Pioneer species do this by increasing habitat suitability and likelihood of survival. For example, when a glacier first recedes there is no soil, explains Ficetola. So if an arriving plant or microorganism can convert nitrogen from the abundant but inaccessible nitrogen gas in the air to its biologically useful ammonia form, this pioneer can facilitate establishment of more plant species later on because of improved soil nutrition. Those later species often, in turn, make life tougher for the pioneers.

A second model, inhibition, suggests that early colonizers make the environment less suitable for later arrivals. In this model, species that reproduce quickly and disperse easily are likely to get there first, but which of those organisms win real estate over time is a matter of chance. An example of inhibition in action is early-arriving plants that release growth inhibitors into the soil.

In a third model, tolerance, interactions among arriving organisms are more neutral. Any species, and not specifically pioneers, can start the succession. Under tolerance, later arriving species are more likely to successfully establish and persist if they can live with limited resources, enabling them to outcompete or exist alongside species already there. So succession under the tolerance model sees the steady arrival of species over time, with a progressive tolerance of incoming species to the changing environment.

Milner has found that what matters most to stream life gradually shifts. Physical factors are the most important at first — especially water temperature and channel stability. Once the water warms, other factors may come into play. And once vegetation takes hold near the stream, it helps to buffer changes in water flow and to facilitate the development of stream ecosystems.

His catalog of the shifts in macroinvertebrates in Wolf Point Creek, made through season after season of trapping and painstaking lab microscopy for identification, provides what he and colleague Anne Robertson argue is a rare example of tolerance.

If facilitation had been occurring in Wolf Point Creek, there would have been more extinctions — species disappearing. If inhibition had been a major driver, the number of species would have remained stable or increased only slowly with stream development. That’s not what they found. Instead, they found marked increases in diversity, with few extinctions. With the exception of the stream’s cold-tolerant first colonizers that disappeared due to competition as waters warmed, Milner’s team found that once organisms arrived, they tended to stay, unless disturbed by a dramatic event such as periodic flooding.

On the second day of fieldwork in Glacier Bay, we head to another stream Milner has studied over decades. Rush Point Creek is more than two centuries old, much older than Wolf Point Creek. This stream lost its glacial source long ago. Unlike Wolf Point, it has no high-elevation lake moderating its drainage. That makes it prone to severe flooding, and as we wade up its course, the carnage is obvious. This stream is strewn with mammoth conifers felled into the water as the banks were violently undercut.

Lakes above streams, including those fed by glaciers, help to regulate whether stream communities can remain stable and maintain the species gains made little by little. Flooding, Milner and colleagues found, acts like a stream time machine. A major flood in 2005 at Wolf Point Creek washed out species and reset stream life to a simpler community like the one in existence 15 years earlier. For salmon, though they’re adapted to breed in fast-flowing streams, the extreme flows of floods can scour and wash away eggs and tiny fish.

Milner’s team has found that the timing of arrival for species in a new stream is partly due to chance, and partly due to distance from a source. It took nearly half a century after stream formation for salmon to colonize Wolf Point Creek, for example, but they colonized another stream in Milner’s study more quickly. At Stonefly Creek, which emerged from a glacier in the 1970s, pink salmon were counted just 10 years after stream formation.

Milner also discovered that the arrival of fish represents a pivotal moment for new streams. To spawn, salmon dig small depressions called redds to lay their eggs. This disturbance can evict some invertebrates, like chironomids, from streambed homes, but favor persistence of others, like blackfly larvae, which spin silken tethers to affirm their rocky grip in fast-flowing waters. And because salmon die after spawning, their carcasses contribute nutrients like nitrogen to the stream, especially when trapped by woody debris that falls in as bankside trees mature.

Ghosts of last year’s salmon bounty are still visible along Wolf Point Creek as skeletons and bones in the gravel bars. Nutrients that salmon bring after formative years in the ocean stimulate algae production, supporting an entire community of algae, invertebrates, small fish and bigger fish — all the way up the food chain.

Climate change, salmon and the new north

As climate change marches on, how widespread are new salmon habitats in deglaciating areas? Kara Pitman and Jon Moore at Simon Fraser University, along with 10 colleagues including Milner, examined exactly that. With a computer model, they digitally peeled back the ice from 46,000 glaciers in southern British Columbia, Canada and south-central Alaska. Taking into account ice thickness, they could examine the land terrain underneath and apply mechanical movements and physics to see what future streams might have a path with a gradient not too steep for salmon to swim up.

They estimated from this exercise that glacier retreat will create over 6,000 kilometers of new Pacific salmon streams by 2100. That could mean, within the area that they studied, 27 percent more salmon habitat compared with today. “We hear so much about loss of salmon populations in the Pacific Northwest,” says Milner. But melting glaciers are “creating unique opportunities for new salmon populations to form.”

Will salmon habitat gains outweigh habitat losses? “This is a key piece in understanding salmon futures,” says Pitman. Of course, salmon success depends on more than just the freshwater habitats where they spawn — conditions in the oceans where they pass their adult lives matter keenly, and those waters are warming too, bringing with them the ecological turbulence and uncertainty of climate change. But broadly speaking, it appears as though salmon that spawn in some northern regions like Glacier Bay are poised to be climate change winners, gaining more streams to breed in following their youthful years at sea.

Northern gains will be paralleled by southern losses, though. Indeed, farther south in British Columbia, Washington, Oregon and California, salmon streams are already rapidly warming, leaving cold-loving salmon like sockeye physiologically challenged. And on a local scale, that may make a food source people once relied on reliable no longer.

Some 300 miles to the south of Wolf Point Creek, that’s a reality already being experienced by the Gitanyow First Nation in northern British Columbia. The Gitanyow have long depended on the sockeye salmon spawning habitat of the Hanna and Tintina rivers, and a land use plan signed in 2012 by the Gitanyow and the British Columbia government protects these streams.

But in the decade since protection, salmon preferences have changed. In three out of eight recent summers, returning salmon have found the Hanna and Tintina rivers dry. Now streams to the west, like Strohn Creek, fed by the rapidly melting Bear glacier near British Columbia’s Alaskan border, provide new, more favorable spawning habitat. So salmon have begun going there instead.

“We’ve just completed a glacier study in our entire territory,” to examine changes expected by 2050 or 2100 due to glaciers melting, said Chief Malii/Glen Williams, Gitanyow president, in a press conference. The study predicts that Hanna and Tintina creeks will continue to warm and to dry out more frequently. Strohn creek, more shaded and fed by north-facing slopes, is likely to remain cooler into the future.

Recognizing this salmon shift, and to safeguard this increasingly important habitat for salmon and food security, in August 2021 the Gitanyow declared the Meziadin Indigenous Protected Area to protect the region including Strohn Creek. But the British Columbia government has yet to recognize this new protected area or fulfill the Gitanyow request to prohibit mining near the stream. Retreating ice also exposes tantalizing mineral riches that mining companies have their sights on.

Succession: The human story

Back at the beach, our days of sampling complete, we board the Capelin to head back to base. En route, Smith points to a recently fractured mountainside; evidence of a gigantic landslide. As glaciers recede here, it’s not just new streams that form. Sometimes the underlying land, no longer covered in ice, gives way to instabilities as water and gravity take their toll. Melting glaciers are changing our world in myriad ways.

Glaciers are, by nature, on the move, I’m told by glaciologist Taryn Black, a recent doctoral graduate at the University of Washington who studied glaciers in Greenland and Alaska. People often think of them as moving slowly, she says, at “a glacial pace,” but they are actually really dynamic. And the dynamics of glacial advancement and recession have profoundly affected human ecology.

For thousands of years, from time immemorial, Huna Tlingit people lived year-round on the rich lands that today lie in Glacier Bay National Park. Khudeiyatoon/Darlene See, cultural program manager for the Huna Indian Association, explains that the land near National Park headquarters and the dock at Bartlett Cove, where we set off on our boat trip, was once wide open marshland by a key salmon river. “We had a year-round village there,” she says, called S’é Shuyee (Edge of the Glacial Silt).

“In the mid-1700s, the glacier came down and destroyed the village site,” says See. The Huna Tlingit fled. By 1750, the peak of the Little Ice Age, Glacier Bay was entirely filled with ice. From their new home 30 nautical miles southeast in Xunniyaa (Hoonah) meaning “sheltered from the north wind,” scouts would periodically check the glacial ice, says See. In the early to mid-1800s, Huna Tlingit did return to Sít’ Eeti Gheeyí, the “Bay in Place of the Glacier,” finding a land transformed.

But the declaration of a national monument, then national park, kept the Huna Tlingit out. National parks were a conception for protecting wildlife and plants, not Indigenous people.

The icy relationship between the National Park Service and the Huna Tlingit has begun to warm with collaboration on building projects like commemorative totems and the park’s Huna Tribal House. Though the tribe still requires the park’s permission to harvest traditional foods like the salmon that are recolonizing streams on their ancestral homeland, there have been small advances — such as reestablishment of the annual Huna Tlingit harvest of glaucous-winged gull eggs.

As our boat approaches the dock at Bartlett Cove one last time, Milner is reticent when asked whether he will return next year. He is equipping Windsor, his young protégé, to succeed him and take this project into the future. I ask Milner why his research matters. “It helps us better understand one of the most fundamental concepts in ecology,” he says. Yet it is much more than that. Succession following glacial retreat is not only a scientific curiosity. It affects countless living beings, including ourselves.

Glaciers are transient. Climate is changing. Some streams are drying up. Others are forming. In our warming world, there is much still to learn about the enigmatic ways succession ushers in new life, upturning our ancient ways.

This article originally appeared in Knowable Magazine, an independent journalistic endeavor from Annual Reviews. Sign up for the newsletter.

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A team of scientists from Australia and Japan didn’t need a super-long fishing pole to catch the deepest fish ever recorded. All it took was a camera, some bait, and a deep-sea submersible support vessel. The team managed to snap a photo of an unknown snailfish species from the genus Pseudoliparis  at a record-breaking 27,349 feet below the ocean’s surface. 

In August 2022, the team boarded the research ship DSSV Pressure Drop for a two-month long expedition to explore three deep trenches of the northern Pacific Ocean: the 23,950 feet deep Ryukyu trench, the 26,246 feet deep Japan trench, and the 30,511 feet deep Izu-Ogasawara trench. The research was part of a 10 year-long study into the deep sea dwelling fish populations. 

[Related: Researchers found signs of human pollution in animals living six miles beneath the sea.]

The small fish was caught on camera in the In the Izu-Ogasawara Trench, south of Japan. This deep sea dweller beats the previous record of 26,830 feet  set in 2017 by a Mariana snailfish found in the Mariana trench near Guam. 

The team also collected two fish in traps a few days later, this time in the Japan trench at a depth of 26,318 meters. These snailfish named Pseudoliparis belyaevi are believed to be the first fish collected from depths greater than 26,000 feet and have only ever been seen at a depth of 25,272 feet back in 2008.

“The Japanese trenches were incredible places to explore; they are so rich in life, even all the way at the bottom,” University of Western Australia marine biologist Alan Jamieson said in a statement. “We have spent over 15 years researching these deep snailfish; there is so much more to them than simply the depth, but the maximum depth they can survive is truly astonishing. In other trenches such as the Mariana Trench, we were finding them at increasingly deeper depths just creeping over that 8,000m [26,246 feet] mark in fewer and fewer numbers, but around Japan they are really quite abundant.”

Jamieson also discovered the previous record winner in 2017 discovery and worked with a team from the Tokyo University of Marine Science and Technology to deploy the baited cameras in the deepest parts of the trenches.

According to the team, despite a large and “somewhat lively” population of fish that dwell at these intense depths, the solitary Pseudoliparis individual that they found was a very small juvenile. Most young snailfish are typically found living at greater depths than the adults, unlike other deep-sea fish. 

“Because there’s nothing else beyond them, the shallow end of the range overlaps with a bunch of other deep-sea fish, so putting juveniles at that end probably means they’ll get eaten,” Jamieson told The Guardian. “When you get down to the mega deep depths, 8,000 plus [meters or [26,246 feet], a lot of them are very, very small.”

[Related: Millions of dead crabs ended up in the deep sea. Scientists still aren’t sure why.]

Almost 10 years ago, Jamieson and his colleagues had hypothesized that it may be biologically impossible for fish to survive at depths greater than this, but after 250 deployments at sea, it seems to be getting closer to becoming a more solid hypothesis.

“The real take-home message for me, is not necessarily that they are living at 8,336m [26,246 feet], but rather we have enough information on this environment to have predicted that these trenches would be where the deepest fish would be,” Jamieson said. “In fact until this expedition, no one had ever seen nor collected a single fish from this entire trench.”

The post Say hello to the deepest-dwelling fish ever caught on camera appeared first on Popular Science.

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As humans age, our bodies are often graced with fine lines, gray hairs, and flecks of hyperpigmentation on our skin known as age spots. Indo-Pacific bottlenose dolphins get spots with age, too. And as scientists have revealed in a recent study, the onset of dolphins’ speckling is so predictable it can be a noninvasive way to gauge the dolphins’ age.

Age is a crucial metric for understanding dolphin populations. Many ways of calculating a dolphin’s age exist, such as counting the layers of dental material in their teeth or analyzing DNA from a skin sample. But they’re all somewhat invasive. That’s why developing a model for estimating age by simply looking at dolphins’ dots is so interesting.

Ewa Krzyszczyk, a dolphin researcher at Bangor University in Wales who was not involved in the study, says the new technique “is a really useful tool.” By estimating a dolphin’s age, Krzyszczyk says, scientists can answer important questions, such as when a dolphin stops weaning, when it reaches sexuality maturity, or when a dolphin shows signs of deterioration from old age. “It gives a more well-rounded idea of what’s going on in your population that can then help with conservation,” she says.

The discovery that dolphins’ dots reflect aging stems from research led by Genfu Yagi, a marine mammal researcher at Mie University in Japan. Previously, Yagi had analyzed a compendium of underwater footage taken of Indo-Pacific bottlenose dolphins off the coast of Mikura Island, near central Japan. Since many of the individual dolphins were known from birth, Yagi could trace how their speckles emerged as they grew.

“The speckles first appear around the genital slit at 6.5 years of age,” says Yagi. Over time, he says, this treasure trail expands toward the head and up toward the back. By the time dolphins are around eight years old, speckles start on their chest, and by around 17, the spots reach their jaw. Wild bottlenose dolphins typically live between 30 and 50 years.

To use these speckles to estimate age, Yagi created a new system that quantifies the density of speckles on various parts of the body. This weighted speckle density score is then correlated with age. Yagi says his speckle-counting method works for dolphins between the ages of seven and 25 and has a margin of error of 2.58 years—more accurate than estimating age from DNA samples.

“The strength of this study is that it does not require special techniques, facilities, high costs, or any invasive surveying,” says Yagi. “Anyone can estimate a dolphin’s age.”

At the moment, Yagi’s formula can only be used for the Mikura Island Indo-Pacific bottlenose dolphin population because speckling onset could differ between geographic locations. He says, however, that the same modeling technique could work for other dolphin populations.

So far, dolphins are the only cetacean known to develop spots, with pantropical and Atlantic spotted dolphins getting dark spots on their bellies and light spots on their backs. Yagi says scientists don’t know exactly how or why these speckles form.

“This is a very rare trait, as few mammals other than dolphins continue to change body coloration throughout their lives,” he says.

This article first appeared in Hakai Magazine and is republished here with permission.

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On land, rivers and mountain ranges can divide species into genetically distinct populations. In the vast expanse of the ocean, where there is seemingly little to stop fish and other sea creatures from going where they please, scientists have long expected marine species to find it easier to mix. But ongoing research shows there’s more than just geographic barriers keeping populations separate, and marine species often have a higher genetic diversity than anticipated.

Hannes Baumann, a marine scientist at the University of Connecticut, says that for years the prevailing notion was that species in the ocean didn’t form separate populations. “But the last 20 years has demolished that concept,” he says. “Now everywhere we look we see differentiation.”

Protecting that genetic diversity is a focus of conservationists. At a recent meeting of the United Nations Convention on Biological Diversity (CBD), the agency’s members adopted a new framework setting overarching goals for conservation efforts, including preserving genetic diversity within species to safeguard their ability to adapt to changing conditions.

“Genetic diversity is especially important for resilience,” says Sebastian Nicholls, from the Pew Charitable Trusts’ ocean conservation program, which works closely with CBD member states to help them meet their commitments on marine conservation issues. “If there is too little diversity, a species may be susceptible to a single pathogen or environmental stressor.”

A strong example of the value of that diversity comes from the recent discovery by Baumann and his colleagues that the northern sand lance, an important forage fish, is actually two populations.

By sequencing the genomes of hundreds of northern sand lance living from Greenland to New Jersey, the scientists found that the fish population is split in two—one group dwells north of the Scotian Shelf, off the east coast of Canada, and one lives farther south.

There is something curious about the Scotian Shelf, says Baumann. No obvious barrier prevents fish from crossing the divide and mixing with their neighbors, but it seems that their offspring do not survive when they do. Baumann suspects a change in water temperature centered around the shelf is to blame—the southern waters are too warm for the cold-adapted northern fish, and vice versa. The shelf also separates populations of other species, including lobsters, scallops, and cod. “This confirms with yet another species that the Scotian Shelf is almost a universal genetic barrier,” says Baumann.

More than a curiosity, the genetic minutiae of this little fish is surprisingly important. Sand lance are a cornerstone of ocean ecosystems. Just about everything eats the slender forage fish, including 72 species of fishes, birds, and mammals.

Theoretically, the existence of a population adapted to warmer water should help the species weather the stresses of climate change because it is more likely to thrive and spread northward as the ocean warms. But that doesn’t mean we should give up on their northern neighbors, since other unique adaptations could become important in the future, Baumann says. “Even if we don’t know which variant is the important one, we need to preserve all of them.”

The problem is, scientists know very little about the genetic diversity of most marine species, especially in the deep sea, says Nicholls. Many marine ecosystems are remote and difficult to get to, making it challenging to understand what diversity actually exists. “We don’t really know what’s out there; we’re discovering new species all the time,” he says, “so it’s even harder to get information about genetic diversity.”

Nicholls says the best tools to preserve both the genetic diversity we know about, and that which we don’t, are strong networks of marine protected areas. At the CBD meeting, members also agreed on a target of protecting 30 percent of coastal and marine areas by 2030. “If we protect enough of the ocean, populations can replenish themselves and spill over into adjacent areas, maintaining diversity both within and outside their boundaries,” Nicholls says.

This article first appeared in Hakai Magazine and is republished here with permission.

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Animal feed plays a major role in the environmental impact of your diet. In dairy and beef production, it accounts for about 36 and 55 percent of greenhouse gas (GHG) emissions, respectively. The raw materials for animal feed typically consist of crops like soybean and wheat and animal-based products like fish meal and fish oil. But the production of these ingredients could be detrimental to the environment. 

About 33 percent of croplands are dedicated to livestock feed production, which may result in nutrient and pesticide runoff. Crops for animal feed also make up about six percent of the GHG emissions from global food production. Meanwhile, increasing demand for feed made from marine byproducts may be unsustainable for ocean ecosystems.

“When we feed these ingredients to animals that have their own environmental impact from production, the overall impact is much higher than if we just ate the ingredients themselves, “ says Caitlin D. Kuempel, conservation scientist and lecturer at the Griffith University School of Environment and Science in Australia. “The more feed required to grow an animal, the higher this overall pressure can become.” 

Global food production, including plant and animal agriculture, is estimated to make up 26 percent of the total GHG emissions around the world. Therefore, to reduce the environmental impact of animal products, it may be beneficial to look at their diets and work on making them more sustainable as well.

Animal feed production has a significant environmental impact

For many types of farmed animals, feed typically accounts for 50 to 70 percent of production costs, says Kurt A. Rosentrater, food engineer and associate professor at Iowa State University whose research focuses on improving the sustainability of agricultural-based systems. 

“Ironically, the production of feed and the ingredients that go into these feeds can often result in up to about 70 percent of the environmental impacts from eating products from these animals,” says Rosentrater. That’s not the case for all species, especially since ruminants produce significant GHG emissions during digestion. But for most animal-based products, the most significant portion of environmental impacts happen on the farm before they are even processed into food products, he adds.

[Related: Smarter fertilizer use could shrink our agricultural carbon footprint.]

For instance, animal feed given to farmed broiler chickens and farmed salmonids (including salmon, marine trout, and Arctic char) account for more than half of their respective industries’ environmental impact, according to a recent Current Biology study. Feed production accounts for at least 78 percent of the environmental pressures of farmed chicken, and over 67 percent for that of salmon.

Chicken and salmon are the largest animal-sourced food sectors on land and the sea, which makes them a fitting focus for research. “We combined data on four pressures—greenhouse gas emissions, freshwater use, nutrient pollution, and land and sea disturbance—into a single metric to get a more holistic view of the environmental footprint of these two production systems,” says Kuempel, who was involved in the study.

The findings revealed that 95 percent of the environmental footprints of chicken and salmon are concentrated in just five percent of the world, which includes some of the largest producers like the US and Chile. Knowing the spatial distribution helps give more local context. This could help identify areas that may have resource competition, and focus on location-specific policies to reduce environmental impact, says Kuempel.

Moreover, the study found that more than 85 percent of farmed chicken and salmon’s environmental footprints overlap primarily due to their shared feed ingredients. Commercial poultry feed often consists of crops like corn and wheat, but they also contain fish meal and fish oils. At the same time, salmon aquaculture requires 2.5 million tons of crops like soybean and wheat for feed, but they still eat fish meal.

“Since feed contributes such a high percentage of their environmental footprint, this is an obvious area where changes could potentially be made to lower their environmental pressures overall,” says Kuempel.

Improve the sustainability of feed production

Some actions can improve the sustainability of feed production, including changing the dietary composition of feed ingredients to include more environmentally friendly options, says Kuempel. This can be effective since the environmental impacts of feeds are primarily influenced by their ingredients.

In a 2021 study, the authors found that reducing the proportion of high-impact ingredients, like cereals and oils, while increasing the proportion of low-impact ones, like peas or fava beans, may result in eco-friendlier pig production without harming animal performance.

[Related: What the ‘B’ label on your favorite drinks and snacks means.]

The fast-growing aquaculture industry has also influenced a shift to crop-based feed ingredients to maintain sustainability in ocean ecosystems. However, for carnivorous farmed fish, plant-based diets would affect their nutritional profile, and subsequently, human nutrition. More studies are needed to understand the impact of different feed formulations on various farmed fish.

A 2020 Scientific Reports study found that reducing the fish meal component from 35 to 15 percent in the feed for the Atlantic salmon parr reduced their growth. However, partially replacing it with fish protein hydrolysate (FPH) supplementation in a high plant protein diet might result in a similar growth performance with the fish fed with a 35 percent fish meal.

Kuempel also suggests introducing novel feeds like microalgae and insects to potentially reduce environmental pressure. Microalgae could successfully replace fish meal and fish oil in aquaculture diets while also improving growth and meat quality in poultry and pigs. Feeding trials conducted on chickens, several fish species, and pigs concluded that insect meal could replace over 25 percent of soy meal or fish meal in animal feed with no adverse effects.

Overall, animal feed production has the capacity to become more sustainable. “Many researchers are hard at work trying to improve the efficiency of ingredient growth and processing, as well as improved digestibility and reduced GHG emissions during digestion,” says Rosentrater. “Many promising developments are underway that will soon reduce the impacts of feed and ingredient production, processing, and digestion.”

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There’s a case to be made that the world’s greatest forests are not terrestrial. That’s in large part due to kelp. Like their less watery counterparts, kelp forests play an important role in carbon cycling across the planet, converting carbon dioxide into oxygen through photosynthesis and sequestering the carbon beneath the ocean’s surface. 

Kelp forests are located in shallow coastal waters across the globe, including in the northeast and all along the Pacific coast in the United States. Despite taking up only a tiny fraction of the ocean, they’re incredibly diverse. Charles Darwin marveled at just how many species are present in kelp forests in his diary while aboard the HMS Beagle. However, they are incredibly fragile ecosystems. Once disrupted, it’s very difficult for the forests to recover.  

[Related: Sea urchin sperm is surprisingly useful to robotics experts.]

With the presence of purple sea urchins off the coasts of the western United States, the destruction of kelp forests has become much faster. But new research from Oregon State University published today in the journal Proceedings of the Royal Society B shows that the sunflower sea star, a 24-armed behemoth of a sea star living in kelp forests on the west coast may be a major asset to preserving those important ecosystems, namely by fighting off pesky sea urchins.

Sea urchins are a natural part of the ecosystem, and act as scavengers, feeding on dead kelp and other detritus that falls to the ocean floor. However, when there’s not enough food for them to go around, past research has found that they’ll begin feasting on living kelp. This disrupts the ecosystem, and if not left in check, leads to the formation of an urchin barren, with no kelp to be seen and urchins packed tightly along the ocean floor. Once a barren forms, the rebirth of a kelp forest is all but impossible. Any new kelp growth will promptly be devoured by the urchins, which are able to survive with little food and will live for at least 20 years. 

Marine biologists long ago realized that the predators of sea urchins are part of the problem. Sea otters, considered one of the keystone species of the ecosystem, have been hunted to endangered status. Other predators, like the sunflower sea star, would have to pick up some of the slack. Unfortunately, a sea star wasting disease has decimated the population in the last decade, leaving the population critically endangered. 

This study examined just how effective the sunflower sea star is as a predator of sea urchins by raising well-fed and starving sea urchins in a lab setting. After about six weeks of collecting and raising urchins, the researchers let 24 sea stars free to feed. The sea stars consumed an average of 0.68 urchins a day, and when the urchins were starving, like they are in nutrient-poor urchin barrens, sea stars ate even more. That is a major difference between the sea stars and other predators, like otters, who are picky when it comes to choosing what urchins to eat, preferring healthy urchins that are less common in a barren. 

[Related: A virgin birth in Shedd Aquarium’s shark tank is baffling biologists.]

“Eating less than one urchin per day may not sound like a lot, but we think there used to be over 5 billion sunflower sea stars,” Sarah Gravem, a research associate at Oregon State said in a release. Although there’s no consensus on just how devastating sea star wasting disease has been, most estimates place the loss at around 90 percent of the population. “We used a model to show that the pre-disease densities of sea stars on the U.S. West Coast were usually more than enough to keep sea urchin numbers down and prevent barrens,” Gravem adds.

With this knowledge in mind, future research can focus on how exactly to use sunflower sea stars to keep sea urchin populations in check—and hopefully restore kelp forests in the process.

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The waters of the 360-million-year-old subcontinent Gondwana were a dangerous place for a swim. A killer, bony fish the length of an adult California sea lion stalked freshwater rivers as a top predator. It was massive—as a new discovery reveals, this was the largest prehistoric bony fish ever discovered in southern Africa. 

Its ferocity is reflected in its name, Hyneria udlezinye (H. udlezinye), which means the “one who consumes others,” in IsiXhosa, an Indigenous language spoken widely in southeastern South Africa where its bones were found.

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians.]

“Picture a fish looking a bit like a gigantic alligator. About 8 feet long, but with a more rounded head like the front end of a torpedo,” Per Ahlberg, a paleontologist and zoologist at Uppsala University in Sweden, tells PopSci. Ahlberg is the co-author of a study published February 22 in the journal PLOS One describing the carnivore. “The small eyes are located near the front of the head. In the mouth there were rows of small pointed teeth together with pairs of large fangs, up to a couple of inches tall.”

The specimen was found on the edge of Makhanda, South Africa, at the Waterloo Farm lagerstatte, a fossil site rich in specimens from the Late Devonian world, about 419.2 million and 358.9 million years ago. Co-author Rob Gess, a paleontologist from the Albany Museum and Rhodes University, South Africa has been collecting specimens from the site since 1985, where he has uncovered bones, teeth, and small invertebrates, as well as weeds and plants. 

“This fossil site is globally significant for understanding biogeography of the Late Devonian world as it provides us with the only known window into a polar ecosystem during this pivotal time interval,” Gess tells PopSci.

But the remains of bigger things lurk there, too. H. udlezinye belongs to an extinct group of lobe-finned fish called the Tristichopterids. Late in the Devonian period, one branch of the Tristichopterid family developed into a cluster of giants. These huge Tristichopterids possibly arose in Gondwana, the ancient supercontinent, before migrating to Euramerica. The study authors determined that H. udlezinye is closely related to its North American cousins by comparing it with specimens of Hyneria lindae found in Pennsylvania’s Catskill Formation. The authors say that this supports the idea that all of these giants originated in Gondwana and adds a piece to their evolutionary puzzle.

[Related: Tiktaalik’s ancient cousin decided life was better in the water.]

All other fish in the Tristichopterid group were largely believed to live in the more tropical, or central, regions of the subcontinent, but these specimens were found south of where the paleoantarctic circle (our southern polar circle) was at this time. This suggests a more global distribution of the fish, from the equator down closer to the poles. 

H. udlezinye was a ferocious predator that would have eaten most of the larger kinds of fish—including the relatives of modern coelacanths—and four-legged animals found near the site. Their body shape also suggests that they were likely “lie-in-wait predators,” who quietly hid and then quickly lunged to grab passing prey with fanged jaws. 

As fearsome as it must have been, this apex predator was not completely invulnerable. The Tristichopterids, along with many other species of lobe-finned and armor-plated fish, “went extinct in the End Devonian Mass Extinction event 358.9 million years ago—the second of the big five global extinction events that radically altered the make-up of life on Earth,” explains Gess.

Learning more about the Denovian world can help scientists better understand not only the flora and fauna that went extinct during this mass extinction event, but also more about evolution and even ourselves as humans.

“This was a particularly interesting time in the history of the planet, when life had recently become established on land and was diversifying rapidly,” Ahlberg says. “Our own distant ancestors”—the earliest animals with four limbs, or tetrapods—“emerged out of the water during the Devonian.” 

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This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Existing in a seemingly infinite array of shapes, sizes, and colors, marine fishes are easy enough to tell apart. Unfortunately, the same cannot be said about their eggs.

The eggs of marine fish are so difficult to discern from one another that even aquarium curators like Kylie Lev, who works at the California Academy of Sciences’ Steinhart Aquarium, often have no clue which fishes spawned the eggs floating around in their aquarium’s multispecies exhibits. The inability to identify these embryos is a major hurdle to building a more sustainable aquarium trade, Lev says.

Although many aquariums have breeding pairs on display, the majority of tropical marine fish in public aquaria come from the wild, says Lev. “We can offset some of that by raising fish,” she says.

Though the number of fish species bred in captivity is growing larger all the time, aquarists and private breeders have only figured out how to culture a small fraction of the marine fish species often seen at aquariums, such as clownfish and blue tang. Tens of millions of fish are removed from coral reefs and other sensitive marine habitats each year to keep private and public aquaria stocked. Although scientists have yet to determine the full ecological impact of the aquarium trade, what they do know doesn’t look good.

That’s why, for the past year, Lev and her colleagues have been working with other aquariums creating an open-source catalog of marine fish eggs.

By using this catalog, which launched late last year, aquarists can easily identify the stray eggs in their saltwater exhibits, allowing them to focus their limited rearing resources on species they have the best chance of raising successfully. The catalog already contains nearly 50 different species, including—thanks to Lev—the highly coveted peppermint angelfish, a spade-shaped fish with candy cane–esque coloration that costs thousands of dollars. Peppermint angelfish are considered the holy grail of ornamental fish.

While no one has figured out how to breed peppermint angelfish in captivity, knowing what their eggs look like may help aquariums breed them in the future—a feat that would save time, money, and a tremendous amount of effort. The breeding pair the Steinhart Aquarium currently has on display was collected during an expedition to Moorea in French Polynesia, where divers had to use specialized equipment to reach the fish 90 meters below the ocean’s surface.

Aquarists at the New England Aquarium and scientists from Roger Williams University in Rhode Island hatched the idea for a catalog more than a decade ago. The idea sat on ice until 2021, when a grant from the Association of Zoos and Aquariums allowed them to develop the catalog into what it is today.

To create the catalog, aquarists like Lev have been collecting fish eggs from their aquarium’s marine exhibits, photographing them under a microscope, then sending them to a lab for DNA barcoding. Although most eggs look identical to the naked eye, their differences become clearer under a microscope. The size of the oil globule, a fatty deposit found in the yolk of fish eggs, varies from species to species, as does the hue of the tissue surrounding it. While most eggs are clear, some eggs are tinted yellow or pink. Some even have spots.

The catalog provides new insights into the early life stages of many marine fish species and creates opportunities for aquarists to raise fish that have never been reared in captivity.

“I think it’s a great initiative,” says Joanna Murray, a marine ecologist at the United Kingdom’s governmental Centre for Environment, Fisheries and Aquaculture Science.

Murray, who was not involved in the creation of the catalog, hopes that new husbandry protocols developed in the wake of the catalog’s publication are shared with the countries where the fish originate. “I think sharing that [information] with source countries could have a really positive impact on the long-term sustainability of the trade,” she says.

Right now, six public aquariums across the United States contribute to the catalog, and new fishes are added to it every few months.

“I think it’s something to be celebrated,” says Lev. “It takes a huge amount of people to make this work.”

This article first appeared in Hakai Magazine and is republished here with permission.

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A team of researchers has captured some epic footage of a sailfish hunt—from the perspective of the sailfish. The researchers from Nova Southeastern University Guy Harvey Research Institute designed a tag with high-tech sensors and a Go Pro-like video camera. After catching sailfish while fishing from Tropic Star Lodge in Panama, they tagged and released their catches. The research was initially meant to show how sailfish recovered from being caught by fishermen but instead, the researchers shifted their focus to sailfish predation.

According to the study’s authors, relatively little is known about the hunting patterns of sailfish, which are considered the fastest fish on the planet. The most commonly-known type of sailfish hunting occurs when the apex predators group up and attack baitfish, using their sharp bills to slash and stun their prey. These predation events are easily seen by people because they occur entirely at the surface level of the ocean. But the recent research looked at what happens when sailfish hunt alone.

“Most of the day they dive back and forth between the surface and the thermocline layer, where the water gets cold. The thermocline can concentrate prey that don’t want to enter the cold water, so it looks like the sailfish might be using this to its advantage,” lead author Ryan Logan told Phys.org. “Most of what you see in the videos is just a lot of blue water, but when I saw the sailfish start to swim really fast toward the surface, I knew something was up.”

The researchers captured footage of a 100-pound sailfish blitzing the surface of the ocean from a depth of 200 feet in pursuit of a small tuna. The sailfish charges the tuna several times, each time splashing at the surface of the water, before successfully killing the tuna. Researchers say that the footage, along with measurements of metabolic rates of sailfish, is a step towards understanding previously unknown aspects of sailfish biology such as how often they need to eat.

“While the energetic gains from this predation event were substantial compared to what was expended during the pursuit, the amount of energy burned in search of prey over the course of the day and night was considerable,” wrote the researchers. “The approach we have taken could be used as a starting point to inform future energetic and trophic models and improve our understanding of the role of these pelagic predators in our oceans.”

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In 2015, scientists surveying a protected area of seafloor in the Pacific Ocean’s Clarion-Clipperton Zone (CCZ), a region known for its high concentration of the polymetallic nodules sought after by would-be deep-sea miners, came across an eerie sight: a mass grave of millions of red crabs. This many dead crabs in one place is shocking enough, but at a depth of 4,000 meters, it was a baffling find.

“It took us three or four days to actually realize that these are pelagic crabs”—animals that are supposed to be much nearer the surface—says Erik Simon-Lledó, the lead author of a paper documenting the find and a marine biologist at the United Kingdom’s National Oceanography Centre. “It is a bit embarrassing, but it [was] so unexpected. Nobody had heard of such a massive deposition in the abyss.”

While red crabs are abundant in the eastern Pacific and are noteworthy for washing up en masse on beaches in California and Baja California, Mexico, finding them at such depth in such numbers is unheard of. Even more bizarre, the grave was 1,500 kilometers offshore. This is so far from the crabs’ spawning areas off the northwestern United States that it would have taken the current at least a year to push them to the point where they eventually sank.

So many crabs drifting far offshore and sinking to the seafloor would have attracted droves of hungry predators and scavengers, so the scientists aren’t sure how the crabs remained relatively intact. Most creatures on the abyssal seafloor feed on the tiny bits of waste that fall from the surface, making these crabs, in comparison, a fantastic dinner. “Get your forks, mates, we have quality dinner now,” says Simon-Lledó with a laugh.

The researchers suspect the sheer number of crabs involved has something to do with it. Millions of crabs descending to the seafloor are simply too many to be eaten. “Swarms can have millions and millions of crabs, especially when there are perfect conditions for their development, like algal blooms or different climatic events,” explains Simon-Lledó.

The scientists can’t say whether this mass “crab fall” is just a one-off coincidence or a periodic event. Masses of millions of dead crabs do wash up on beaches every couple of years, so in principle the same could be happening in the abyss but has gone unnoticed until now. That’s Simon-Lledó’s preferred interpretation, which is supported by the fact that there were two to three times more scavengers in the crab graveyard than in the rest of the scientists’ survey area in the CCZ.

The researchers calculate that this single event represents one and a half times the carbon flux that the area would normally get in a whole year. The excess carbon will eventually make its way into the food web, supporting a richer ecosystem than we would typically imagine existing here—an ecosystem where deep-sea mining could do a great deal of damage.

The area where Simon-Lledó and his colleagues found the crabs is not being eyed for mining. But Amanda Ziegler, a researcher at UiT the Arctic University of Norway who was not involved in the study, says it is the same kind of habitat as other areas in the CCZ that do have claims for deep-sea mining. “So it is possible that this kind of crab fall [has] occurred somewhere that might also be a claim area, but that’s hard to say since it’s so difficult to assess such a big area,” she says.

Trips to the deep sea are expensive, and funding bodies often prioritize mapping a new area over returning to one that is already mapped. So the research team has not been able to return to see the aftermath of the crab fall or to see whether there have been more depositions.

“Our paper shows that there is more environmental variability than we would think in abyssal areas,” says Simon-Lledó. “It also shows how little we know about this environment that we will potentially be mining in a few years.”

This article first appeared in Hakai Magazine and is republished here with permission.

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Way back in 1994, engineers at MIT unveiled Robotuna. Inspired by the 160 million-year-old species, the aptly named, four-foot-long submersible robot required over 2,800 components, including 40 ribs, tendons, a vertebrae-like backbone, and even a Lycra covering to mimic the fish’s skin. Now, nearly two decades later, yet another MIT research team (including one Robotuna veteran) have unveiled their new underwater successor to the breakthrough fishbot—a modular creation composed of simplified, repeating structures instead of individualized pieces that can resemble everything from an eel to a hydrofoil wing.

Their findings, published recently in the journal Soft Robotics, showcase MIT’s new advances in developing deformable, dynamically changing underwater robotic structures. This ability is key for submersible robots, since it allows them to move through water much more efficiently, as countless varieties of fish do in rivers, lakes, and the open ocean.

[Related: This amphibious robot can fly like a bird and swim like a fish.]

The team’s new design relies on lattice-like pieces called voxels, which are stiff in structure yet still low-density, and allow for large scalability potentials. The voxels are made to be load-bearing in one direction, yet soft in others through a combination of various materials and proportions, including cast plastic pieces. The entire design was then encased in a rib-like support material, and all of that was covered in waterproof neoprene.

To demonstrate these advances, the team created a meter-long, eel-like robot composed of four structures, each made of five voxels. An actuator wire attached to each end’s voxel allows the robot to undulate accordingly, causing the snakebot to move through water. Unlike the two-year construction time for its Robotuna ancestor, however, the new robot only took two days to build.

[Related: Bat-like echolocation could help these robots find lost people.]

“There have been many snake-like robots before, but they’re generally made of bespoke components, as opposed to these simple building blocks that are scalable,” Neil Gershenfeld, an MIT professor and research team member, said in a news release.

Aside from scalability, the voxels allow for numerous other design potentials, including a winglike hydrofoil also built by the team. Resembling a sail, the second construction shows promise for integration onto shipping vessel hulls, whether they could generate drag-inducing eddies to improve energy efficiency. There’s also talk of a “whale-like submersible craft” capable of creating its own propulsion. Given the voxels’ drastically shorter build times, however, that prototype could be here before we know it.

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Fossils have been recovered in a number of strange and surprising places including museum drawers and deep in present day deserts. More than a century ago, a 319-million-year-old fossilized fish was found at the Mountain Fourfoot coal mine in Lancashire, England. It was safely stored at the Manchester Museum and scientists are still learning from it 125 years later.

A CT scan of the fossil has revealed it contains the oldest example of a well-preserved vertebrate brain. The findings are documented in a study published February 1 in the journal Nature. The brain and cranial nerves are about an inch long and belong to the extinct Coccocephalus wildi (C. wildi). This was an early ray-finned fish that likely ate small crustaceans, cephalopods, and aquatic insects while swimming around estuaries. Backbones and fins supported by bony rods called rays are a feature of all ray-finned fishes. 

[Related: One wormy Triassic fossil could fill a hole in the evolutionary story of amphibians.]

Surprisingly, Friedman wasn’t looking for a brain when examining the C. wildi skull fossil.

“I scanned it, then I loaded the data into the software we use to visualize these scans and noticed that there was an unusual, distinct object inside the skull,” said co-author and University of Michigan (U-M) paleontologist Matt Friedman, in a statement.  

The unusual unidentified blob was brighter on the CT image, which means it was likely denser than skull bones or rock surrounding the fossil. It also displayed multiple features common in vertebrate brains, including bilateral symmetry, hollow spaces that look similar to ventricles, and multiple filaments.

These softer parts of vertebrate fossils are preserved, via a unique fossilization process where the soft tissues that made up the fish’s brain and cranial nerves were replaced with a dense mineral that preserved three-dimensional structure in remarkable detail.

The skull fossil is the only known C. wildi specimen of its species, so the team could only use nondestructive techniques to study it. The team used CT scanning to look inside these early ray-finned fish skulls to learn more about their anatomy and make inferences on evolutionary relationships.

 “With the widespread availability of modern imaging techniques, I would not be surprised if we find that fossil brains and other soft parts are much more common than we previously thought. From now on, our research group and others will look at fossil fish heads with a new and different perspective,” said co-author and U-M doctoral student Rodrigo Figueroa, in a statement.

[Related: Spinosaurus bones hint that the spiny dinosaurs enjoyed water sports.]

Specimens from early ray-finned fishes like Coccocephalus can fill in the gaps about initial evolutionary phases of the roughly 30,000 ray-finned fish species living today. According to the authors, the brain structure of Coccocephalus shows that there is a more complicated pattern of fish-brain evolution than is suggested by what’s found in living species alone. 

“Not only does this superficially unimpressive and small fossil show us the oldest example of a fossilized vertebrate brain, but it also shows that much of what we thought about brain evolution from living species alone will need reworking,” said Figueroa.

The findings also highlight why it’s important to preserve specimens and maybe clean out junk drawers every now and then. 

“Here we’ve found remarkable preservation in a fossil examined several times before by multiple people over the past century,” Friedman said. “That’s why holding onto the physical specimens is so important. Because who knows, in 100 years, what people might be able to do with the fossils in our collections now.”

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A team of scientists in China have found a unique (and admittedly a little weird) fish inside a pitch black pool in a cave in a mountainous region called the Guizhou province.

In a study published in January in the journal ZooKeys, the team described the newly discovered Sinocyclocheilus longicornus (S. longicornus). The fish have fairly colorless scales due to lack of pigmentation, little eyes that most likely can’t really see anything, and a signature horn jutting out of their foreheads like the mythical unicorn. 

[Related: What rockfish genes can teach humans about living past 100.]

S. longicornus belongs to a genus of fish similar to minnows and carps called Sinocyclocheilus that are only found in China. Most of the 76 known Sinocyclocheilus species live within tiny pools cloaked in darkness like S. longicornus, but there are a handful of Sinocyclocheilus species that dwell in brighter waters and don’t have the unusual features that their gloomy cousins have. 

Only some of them have these signature horns, that also vary in length and appearance, as some species like S. bicornutus and S. furcodorsalis even have forked horns. Some Sinocyclocheilus species have actually evolved to lose their eyes completely. This process is called regressive evolution, where a species will lose useless features over generations. 

This horn is part of what the new species is named after. Longicornus is derived from two Latin words– longus or “long,” and cornu, which means “horn of the forehead.”

S. longicornus is between 4.1 and 5.7 inches long and uses barbels that look like tiny whiskers to feel their way around in the dark. The team is still not sure what the horn-like appendage is used for, but the researchers believe that it might have something to do with navigating their dark and dreary environment, since the species that live in more sunny spots do not have these structures on the top of their heads. 

[Related: A primitive part of the zebrafish brain helps them find their way home.]

Most species of Sinocyclocheilus species (including S. longicornus) also have an organ called a lateral line that is made up of sensitive cells that run  along their body. This organ can detect changes in water salinity, temperature, and pressure, so a horn wouldn’t be necessary for detecting those environmental factors. 

The team believes that  the unusually large horn on the S. longicornus, as well as the  fact that DNA analysis revealed that it’s not closely related to other long-horned species means that longer horns may have emerged on two separate occasions within the genus. One way to decode that these mysterious horns are actually used for would be to compare S. longicornus’ environmental conditions with other long-horned relatives. 

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This article was originally featured on Field and Stream.

Are you familiar with the fur-bearing trout? This mythical creature has been part of Scottish and Icelandic folklore since the 17^th century. In 1929, there was even a fur-bearing trout catch reported in the Arkansas River, where it was theorized that a large amount of hair tonic accidentally dumped into the water caused the trout to grow a thick coat of polar bear-like fur. These fish are, of course, pure fiction, though I’d love to own one of the ancient taxidermied fur trout that pop up in bars and museums from time to time. It would look great next to my jackalope. But while a fur-bearing fish isn’t like to smack your spinner or gulp your live shiner, catching something with fur can happen.

According to this (vague) story on Whiskyriff.com, a couple of friends ice fishing in an undisclosed location were rolling video on what they assumed was a nice fish on a tip-up line, only to be shocked when a muskrat pops through the hole. The fuzzy little fellow quickly spits out the shiner and dives back in. This kind of mammalian ice catch isn’t that uncommon, though. In February 2022, Massachusetts angler Keith Poisant made headlines when he hooked a huge otter through the ice. This kind of thing happens more than people think and not just on the hardwater.

The Usual Suspects

I know someone who was fly fishing for brown trout at night when he snagged an ornery beaver that started tail slapping all around his drift boat. I’m betting his reel’s drag hasn’t spun at higher RPMs since. But there are certain locations and scenarios where having a critter actually take shot at your bait or lure is a real possibility. The craziest first-hand account I ever heard was from a friend trolling Barnegat Bay in New Jersey for striped bass. When his rod doubled over, he was convinced he had a record-class fish on the line only to have that glory dashed when a harbor seal surfaced with his shad swimbait dangling from its lip. The seal looked at my buddy, and then dove back under and took 100 yards of line off the reel in 3 seconds before it broke off.

That’s a very rare occurrence, but if you talk to southern anglers that fish were gators swim, you’ll hear plenty of stories about these reptiles—usually the smaller ones—grabbing cut baits and even attacking topwater lures. Though I’ve never experienced that in the States, I have witnessed the aggression of juvenile caimans in South America, which seemed particularly attracted to Spook-style walking topwaters that produced a loud clack.

Birds are probably the most common non-aquatic animal that anglers hook, and this can happen in many ways. Coastal birds like sea gulls and terns routinely grab lures and live baits fished near the surface, especially during the frenzy of a striped bass, bluefish, or Spanish mackerel blitz. Cormorants will dive down 5 feet or more to feed, and more than a few times I’ve had these pesky and often problematic birds wind up on my hook. Of course, if you want to pin down the most common critter bycatch, one that thousands of anglers deal with every year, it’s turtles. Whether you’re fishing worms for bluegills or shad chunks for catfish, turtles will find it. It’s almost unavoidable, but what you can avoid is making an annoying situation worse whether you hook a little painted turtle or a mad otter.

What to Do When Unexpected Animals Bite

Regardless of the scenario, the safety of the animal should take top priority when deciding how to handle an inadvertent hooking. Naturally, it’s a case-by-case thing. Small turtles, as an example, are relatively harmless. If the hook is visible and the turtle will cooperate, try to remove it. Turtles, however, often retract their heads into their shells when scared, in which case, prodding and prying to remove a hook can cause more damage than simply clipping it off as close as possible and letting the animal work the hook out or have it rust out.

Snapping turtles, which plague me in several spots where I like to target catfish and bowfins, are another matter. Given their ability to reach around with their long necks and bite you, I never attempt to free the hook from a snapping turtle. I have a pocketknife ready to cut the leader as close as possible. Beyond their ability to harm you, keep in mind that snappers—even smaller ones—are incredibly strong. Most of the time, once they get close enough to see you, they’ll go on the defensive by burying in the mud or backing away quickly. Trying to use your rod to force a turtle—or any larger animal, for that matter—onto land is a fast way to destroy your gear while putting unnecessary stress on the animal. During that trip to South America, I watched a guide hell bent on getting his lure back grab a baby caiman that had hit a topwater. The caiman shook and sent a hook into his hand. As the reptile rolled in the boat, it violently tore the hook out of the guide’s finger and snapped a rod in the process.

Birds can often be dealt with more easily, but again, the risk to your safety varies by bird. Whenever birds of prey like hawks or eagles are involved, it’s best to notify wildlife authorities for instruction whenever possible, as many of them are protected. I’ve released many hooked and tangled sea gulls, though, by grabbing them gently behind the head and placing a rag over their eyes, which calms them down. If you are ever unlucky enough to hook something furry and it’s experiencing no further trauma beyond a sore lip, however, your best bet is to cut the line as close as possible, but don’t try to fight a seal or otter or beaver right up to the boat. Most of the time when these creatures are hooked, they break the line for you. On the other hand, if you ever hook a fur-bearing trout, play it gently and reach out to me with the photos first before contacting the local news.

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This article was originally featured on Undark.

The world’s aquatic habitats are a heady brew of pollutants. An estimated 14 million tons of plastic enter the ocean as trash each year. Further inland, more than 40 percent of the world’s rivers contain a pharmacopeia from humans, including antidepressants and painkillers. Heavy metals like mercury from industrial waste can also make an appearance. And agricultural fertilizer can leach from the soil into rivers, eventually reaching the ocean.

There are an estimated 20,000 species of fish in the world — and possibly many more. They and many other organisms that live in “contaminated systems are contaminated with a cocktail of chemicals,” said Michael Bertram, a behavioral ecologist at the Swedish University of Agricultural Studies.

Bertram and other researchers are increasingly finding that these compounds may alter fish behavior. In some experiments, the pollutants appear to alter how fish socialize, either by exposing them to psychoactive drugs or by altering their natural development, which may change how they swim together and mate. Others appear to make fish take more risks which, in the wild, could increase their odds of getting unceremoniously taken out by predators.

The effects of the pollution, according to researchers working in the field, still have many unknowns. This is due in part to the vast number of variables in real ecosystems, which can limit scientists’ abilities to infer how pollutants impact fish in the wild, said Quentin Petitjean, a postdoctoral researcher in environmental sciences at Institut Sophia Agrobiotech in France, and co-author of a 2020 paper that looked at existing literature on pollution and fish behavior. “In the wild, fish and other organisms are exposed to a plethora of stressors,” he said.

Still, these altered behaviors could have big impacts, according to Bertram. Like many living things, fish are important parts of their ecosystems, and changing their behavior could hinder or alter their roles in unexpected ways. For instance one study suggests that various chemical pollutants and microplastics can impact the boldness of prey fish species. Although the authors note that this isn’t likely to lead to population collapse, these “subtle behavior modifications” could reduce fish biomass, alter their size, and ultimately harm predators as well. Just this one effect, they add, “may be a hidden mechanism behind ecosystem structure changes in both freshwater and marine ecosystems.”

But humans have a funny way of showing their appreciation. One example: People regularly flush psychoactive substances, which then find their way into aquatic ecosystems. In 2021, Bertram and a team of researchers published a paper digging into how a common antidepressant, fluoxetine, better known under the brand name Prozac, affected guppies’ propensity for shoaling, or swimming in groups. Over two years, the team exposed groups of guppies to different concentrations of fluoxetine: a low concentration (commonly seen in the wild), a high concentration (representative of an extremely contaminated ecosystem), and no fluoxetine at all.

At the high exposure concentration, the guppies appeared to be more social, spending more time shoaling. However, this was only the case in of male-female pairs, not when the fish swam solo. Previous research by Bertram and colleagues shows that the medication increases the amount of time guppy males spend pursuing females. “Being intensely courted” by males, Bertram said, the females will preferentially choose the larger school to distract them and “to avoid this incessant mating behavior.”

While drugs like Prozac are designed to change brain function, there are other, perhaps less obvious ways pollution can change behavior. For instance, pollutants may alter the microbiome, the collection of microscopic organisms like fungi and bacteria that exist on or in an organism. In humans, disruptions of microbial life have been linked to disorders such as autism spectrum disorder, dementia, or even simply cognitive impairment. Research published in 2022 suggests that fish brains may also rely on the collection of minuscule organisms.

In the study, researchers worked with two groups of zebrafish embryos that they had rendered germ-free, functionally stripping them of microbes. Into the containers holding one group of embryos, the team immediately introduced water from a tank with full-grown zebrafish to give the disinfected population a microbiome. After a week, they did the same for the other group.

After yet another week, the researchers ran a series of experiments, putting two fish from the same group in neighboring tanks to see if they would swim alongside each other, a shoaling behavior previously identified.

The fish deprived of an early life microbiome spent much less time doing this behavior than those in the control group. Of the 54 control fish, nearly 80 percent spent their time near the divider between the tanks, compared to around 65 percent of the 67 in the other group. Exposure to microbes early in life is important for the development of social behavior, said Judith Eisen, a neuroscientist and one of the paper’s authors.

The researchers also looked at the brains of the fish using powerful microscopes. Normally, cells called microglia move from the gut to the brain early in the fishes’ lives, Eisen said, around the time their microbiome starts to develop. The fish that lived without microbiomes for a week, she and the team found, had fewer microglia in a particular brain region which has been previously linked to the shoaling behavior. In normal brains (including human ones), these cells perform synaptic pruning, which clears away weaker or less used connections.

Of course, the germ-free state of those zebrafish, Eisen said, would not exist in nature. However, some human pollutants like pesticides, microplastics, and metals like cadmium appear to alter fish microbiomes. Considering shoaling is often a protective behavior, a diminished shoaling response may cause problems in the wild. “If it doesn’t want to hang out with other fish — that might open it up to predation,” Eisen said.

Pollutants can impact behavior beyond shoaling, and saltwater ecosystems as well. In a 2020 study, researchers took Ambon damselfish larvae back to the lab and exposed some of them to microplastic beads. Then, they returned the young fish to different stretches of the Great Barrier reef — some of which were degraded and others that were still healthy — and observed how they acted. The team had also tagged the fish with tiny fluorescent tags, and returned to the reef several times over three days to check on their survival rate.

The fish that had been exposed to microplastics showed more risk-taking behavior and survived for less time before being preyed upon, according to the study. Nearly all the tagged fish that were exposed to microplastics and set free near dead reefs died after around 50 hours. Meanwhile, around 70 percent of unexposed fish released near living reefs survived past the 72-hour mark. According to the paper, while the health of the reef was a factor in risk behavior, fish exposed to the plastics had a survival rate six times lower than those not exposed to the compounds.

According to Alexandra Gulizia, one of the paper’s authors and a Ph.D. student at James Cook University, there needs to be more work looking into the components of plastics and how they affect fish. For instance, bisphenol-A, more commonly known as BPA, is a common additive to make plastics more flexible. It also appears in natural habitats and research suggests it can decrease aggression in fish. Gulizia added: “I think that we’re only just touching the surface of the chemical impacts that microplastics are having on fish and fish behavior.”

How this all plays out in the wild is hard to assess. Eisen noted that other factors that could impact the microbiome include nutrients in the water, water temperature, diet, and salt concentration. Another, perhaps more direct complication: Contaminants can appear simultaneously, and in different amounts, Petitjean said. For instance, one 2016 paper shows that 13 percent of 426 pollutants in European rivers have been shown to be neuroactiv

Another complication is simply that not all organisms will act the same — even within the same species. According to Eisen, model organisms, such as zebrafish, are chosen to represent a wide range of species, just as mice are often used to study human health in medical research. But changes to pollutants and other factors could differ from species to species. Bertram noted that using model organisms saves researchers the trouble of studying every single species, but also that there should be more studies into different fish.

At face value, some behavior changes might not even look that bad. Increased mating behavior — like in the case of guppies exposed to fluoxetine — could seem like a boon for the species. However, one species thriving over another tends to throw natural habitats out of whack, Bertram said. His previous work suggests that Prozac similarly increases invasive eastern mosquitofish mating behavior. This could help it thrive and outcompete native species. Additionally, at some concentrations, cadmium can increase fish activity, potentially helping them find food. However, the more they eat, Petitjean said, the more exposed they could be to microplastics.

Given these circumstances, he added, experiments in the lab need to inject as much complexity as possible into their methods to better replicate real, wild systems. Some research does try this. Bertram’s work showed the test guppies either a predatory or a similarly sized, non-predatory fish prior to their experiments, while Gulizia and her team performed parts of their experiment in the wild. Some studies also expose fish species to water taken from the environment — and the pollutants that come with it.

Despite the unknowns, Bertram said that changes to how fish go about socializing, mating, or finding food are unlikely to be good. “At the end of the day,” he continued, “any change to the expression of natural behaviors will have negative, unintended consequences.”

This article was originally published on Undark. Read the original article.

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Earthlings, get ready for your closeups.

Close-up Photographer of the Year has revealed its fourth annual contest winners, and the results are a doozy. With 11 different categories, the Top 100 features everything from octopuses and Atlas moths, to trails of pheromones and the delicate cross sections of leaves.

The story behind the overall winner (seen above):

“Northern pitcher plants (Sarracenia purpurea) are carnivorous, allowing them to survive in nutrient-poor bog environments. Here there is no rich soil, but rather a floating mat of Sphagnum moss. Instead of drawing nutrients up through their roots, this plant relies on trapping prey in its specialised bell-shaped leaves, called pitchers. Typically, these plants feast on invertebrates—such as moths and flies—but recently, researchers at the Algonquin Wildlife Research Station discovered a surprising new item on the plant’s menu: juvenile spotted salamanders (Ambystoma maculatum).

This population of Northern Pitcher Plants in Algonquin Provincial Park is the first to be found regularly consuming a vertebrate prey. For a plant that’s used to capturing tiny invertebrate, a juvenile spotted salamander is a hefty feast!

On the day I made this image, I was following researchers on their daily surveys of the plants. Pitchers typically contain just one salamander prey at a time, although occasionally they catch multiple salamanders simultaneously. When I saw a pitcher that had two salamanders, both at the same stage of decay floating at the surface of the pitcher’s fluid, I knew it was a special and fleeting moment. The next day, both salamanders had sunk to the bottom of the pitcher.”

– Photographer Samantha Stephens

The next entry period for the Close-up Photographer of the Year awards will open in March. But before you start prepping your cameras, get a little inspiration by scrolling through more of the recent winners below.

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While eating locally grown produce is great for the environment, eating locally caught freshwater fish might be more dangerous for human health than we realized. A study from the Environmental Working Group (EWG) finds that freshwater fish in the United States contain dangerous levels of “forever chemicals” including one called PFOS (Perfluorooctane sulfonic acid). PFOS is part of a group of manufactured additives known as perfluoroalkyl and polyfluoroalkyl substances, or PFAS.

“PFAS are called forever chemicals because they do not break down in the environment and often bioaccumulate in people and species, like fish,” said David Andrews, a senior scientist at EWG senior scientist and one of the study’s lead authors, in an email to PopSci. “PFOS was the primary ingredient in 3M’s ScotchGard. It was also used in other products, like aqueous film forming foam used for fighting fires. PFOS is one of thousands of per- and polyfluorinated alkyl substances.”

PFOS is just one of the PFAS that have since seeped into drinking water and accumulated in the bodies of fish, livestock, dairy, and game animals. The team in this study found that eating one fish in a year is equal to drinking water with PFOS at 48 parts per trillion (ppt) for one month.

[Related: 3M announces it will cease making ‘forever chemical’ PFAS by 2026.]

“People who consume freshwater fish, especially those who catch and eat fish regularly, are at risk of alarming levels of PFAS in their bodies,” Andrews said in a statement. “Growing up, I went fishing every week and ate those fish. But now when I see fish, all I think about is PFAS contamination.”

According to the team, the research bolsters calls for stronger regulations of these chemicals, more testing on fish, and raises environmental justice concerns for the communities who depend on eating freshwater fish, including local Native American tribes.

The study found that the median amounts of PFAS in freshwater fish were 280 times greater than the forever chemicals detected in some commercially caught and sold fish. Eating a single meal of freshwater fish could lead to similar PFAS exposure as eating store-bought fish every day for a year, according to testing data.

“These test results are breathtaking,” said Scott Faber, EWG’s senior vice president for government affairs, in a statement. “Eating one bass is equivalent to drinking PFOS-tainted water for a month.”

The team analyzed data from more than 500 samples of fish fillets collected from 2013 to 2015 under monitoring programs by the Environmental Protection Agency (EPA), the National Rivers and Streams Assessment, and the Great Lakes Human Health Fish Fillet Tissue Study.

“PFAS contaminated fish across the U.S., with higher levels in the Great Lakes and fish caught in urban areas,” said Tasha Stoiber, an EWG senior scientist and study co-author, in a statement. “PFAS do not disappear when products are thrown or flushed away. Our research shows that the most common disposal methods may end up leading to further environmental pollution.”

PFOS-contaminated fish can raise blood serum levels of PFOS in people and even infrequent consumption of freshwater fish can raise PFOS levels in the body. A report from the National Academies of Sciences, Engineering, and Medicine found that the chemicals in the PFAS family are linked to cancer, high cholesterol, various chronic diseases, and a limited antibody response to vaccines in children and adults.

[Related: Certain PFAS were destroyed with a common soap ingredient in lab tests.]

“The extent that PFAS has contaminated fish is staggering”, said Nadia Barbo, a graduate student at Duke University and lead researcher on this project, in a statement. “There should be a single health protective fish consumption advisory for freshwater fish across the country.”

In the early 2000s, manufacturers agreed to voluntarily stop using long-chain PFAS in the US, but they can still be found in some imported items. The FDA phased out the use of PFOS in food packaging in 2016. Still, there could be more than 40,000 industrial polluters of PFAS in the US, according to EWG estimates.

“For decades, polluters have dumped as much PFAS as they wanted into our rivers, streams, lakes and bays with impunity. We must turn off the tap of PFAS pollution from industrial discharges, which affect more and more Americans every day,” added Faber.

Along with perfluorooctanoic acid (PFOA), PFOS is a “long-chain” PFAS, made from an 8-carbon chain. According to the CDC, over 9,000 different PFAS exist and the chemicals have been reworked to be 4- and 6-carbon chains. Some experts say that these newer versions could have many of the same dangerous health effects as the 8-chain PFAS, continuing the risk to consumers and the environment.

Avoiding PFAS is nearly impossible, with the chemicals in everything from cookware to clothing to carpeting. They were found in 52 percent of tested cosmetics in a 2021 study. The coating used on nonstick pans (polytetrafluoroethylene) has been found to be the most common additive.

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The lifespan of humans has grown in the past two centuries from an average of 30 to 72 years old. Despite this impressive change in health, our longevity pales in comparison to the rockfish. Rockfish can live over 100 years on the seafloor of shallow waters, spending most of their days hiding under rocks. (Some have been reported to live over 200 years). The secret to rockfish longevity is more complex than stumbling on an underwater fountain of youth. Geneticists at Harvard propose that the answer could lie with how they control their genes.

A new study published today in Science Advances found that rockfishes have a complex genetic network that likely influences the species’ length of life. These same genes also seem to be found in humans. “The way fish are regulating traits like longevity is actually very similar to how mammals are regulating longevity,” says lead study author Stephen Treaster, a postdoctoral research scientist at Boston Children’s Hospital and Harvard Medical School. Understanding these genetic variations involved in longevity in animals like a rockfish could one day help with treating age-related diseases in humans. 

“It’s exciting to see rockfish genomics in the spotlight,” says Joseph Heras, an assistant professor of biology at California State University, San Bernardino, who was not involved in the study. “For many years, there have been many speculations around rockfish longevity, but now with modern genomic techniques, studies like this one provide more insight into the topic.”

[Related: Could reptiles and amphibians hold the key to the fountain of youth?]

While the rockfish is considered one of the longest-lived fishes, they have a wide range in lifespan. But the exact genetic mechanism that determines how long or short a rockfish will live remained a mystery. The study authors unraveled the genetic code of 23 different rockfish species that live from 22 to 108 years. Across all tissue samples, the team found a common network of genes involved with insulin signaling—a well-known regulator of aging that may have evolved as a survival tactic to better conserve energy. A 2021 study found that the longest-lived rockfish were more likely to express three types of genes, including those influencing the insulin signaling pathway. The new findings bring more evidence that insulin-regulating genes are a main contributor to rockfish longevity.

“The authors were able to confirm and extend on many of the observations we recently made in our sequencing of rockfish genomes, including the increased constraint on pathways associated with insulin signaling,” says Peter Sudmant, an assistant professor of integrative biology at the University of California, Berkeley, and senior investigator of the 2021 study.

But there was an additional result that was unexpected, says Treaster. The team identified another set of genes found across all rockfish that were involved in flavonoid metabolism. Flavonoids are chemicals produced in plants with anti-inflammatory, antimutagenic, and anticancer properties. Since they are known to be associated with modulating several cellular signaling and enzymatic pathways, the authors suggest flavonoid metabolism could induce anti-aging effects. According to Sudmant, the authors’ emphasis that flavonoid metabolism could play an important role in extending lifespan is a “very interesting and novel pathway to follow up on.” 

After identifying two potential genetic contributors to rockfish longevity, the team searched for any similar connections in human genes. They found the flavonoid metabolism genes are not only found in humans but are significantly linked to survival. “We have these two completely different vertebrate models, humans and rockfish, and both of them have the same pathway associated with longevity,” Treaster says.

[On PopSci+: Has the fountain of youth been in our blood all along?]

Rockfishes are not the oldest living vertebrates (a 392-year-old Greenland shark nabbed the title in 2016) and are not a typical animal model to study aging. While short-lived invertebrates such as fruit flies and roundworms are more likely to be selected to study changes in lifespan, they may not apply to vertebrates like humans who live an average of 70 to 75 years. 

Unlike other long-lived species, the shift in rockfish longevity was not a one-off event. Treaster says different lineages of rockfish evolved independently to have a lengthy lifespan. “This magnitude of change is unheard of, especially in vertebrates,” he says. This gave scientists an opportunity to “wash out unrelated changes” and hone in on relevant longevity contributors that are shared by the whole species.

While Treaster is excited about identifying an association between longevity and genes in the flavonoid metabolism pathway, he knows there’s a long way to go to understand how those genes/the link help with survival. Next, his team plans to genetically modify the genes involved in insulin and flavonoid metabolism in zebrafish to see if they could reverse signs of aging. Understanding exactly what these genes are doing—and if they can be manipulated—to extend lifespan can be valuable information for slowing down the aging process in humans. “The end goal of all this research is to intervene or prevent all these age-related diseases—cancer, Alzheimer’s, heart disease—that we have a difficult time solving with modern medicine,” says Treaster. 

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This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

The constant thrum of ship engines and other human noises can be a real nuisance for many sea creatures, disrupting their feeding, navigation, and communication. Now a new study shows that ship noise can also kill the mood for amorous crabs.

To date, most studies on marine noise pollution have focused on how it affects large marine mammals such as whales. Kara Rising, a graduate student in marine ecology at the University of Derby in England, however, was curious how it affects often-overlooked crustaceans. No previous studies have looked at how noise affects mating behavior in invertebrates, she says, despite its obvious influence on the success of a species.

“All animals are there for the three f’s,” says Rising: “Fighting, feeding, and … mating. If any one of those is interrupted, you expect it to have some population effects.”

To find out how noise pollution affects crab mating, Rising collected male green shore crabs from beaches in Cornwall, England, and placed them one by one in a small aquarium. Next to the crab, she put a decoy female—really, a yellow sponge with toothpick legs doused in synthetic sex pheromones. “Sight is not the most important sense for the crabs when mating, but they do like a nice pair of gams,” Rising says.

Crab sex is more complicated than you might think. Shore crabs mate after the female has molted when her shell is still soft. The male rises up onto his legs and, with claws held outstretched, climbs onto the female’s back, wrapping his legs around her in a “love embrace,” says Rising. They stay that way for a couple of days, with the male protecting the vulnerable soft-shelled female until she is ready to release her eggs.

In general, the crabs seemed happy trying to impregnate the pheromone-soaked sponge. But then Rising started the real experiment. By playing recordings of ship sounds, she found that too much noise can disrupt this delicate affair. The crabs were far less likely to attempt to mate with the sponge decoy when it was loud than when it was quiet.

Carlos Duarte, a marine biologist at King Abdullah University of Science and Technology in Saudi Arabia, says the work adds to scientists’ growing understanding of how animals are affected by noise pollution. He says this study is particularly significant because it’s focused on an understudied species and because it looks at how noise affects a behavior with a direct effect on population dynamics.

Duarte hopes that as it becomes clearer how many ways human-caused noise can affect marine species, regulators will take stronger steps to protect against it. “This adds to the pool of evidence that should eventually lead to more regulation of how humans introduce noise into the environment,” he says.

Rising says that because her study was fairly small and preliminary, there are things she’d like to investigate further under more robust, controlled laboratory conditions, such as whether males will abandon the females if the noise starts after they have established their embrace. But she says it is an important first step in expanding our understanding of the consequences of underwater noise.

“We should be looking more at how noise affects the species we don’t think about as much,” she says. “Everyone thinks about the whales, but the poor little crabs need to have sex, too.”

This article first appeared in Hakai Magazine, and is republished here with permission.

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Rats and rodents are typically are more associated with trash heaps and urban space—not the abundance of colorful life that surrounds the ocean’s coral reefs. True to their invasive nature, rats can even actually be found on tropical islands where they certainly are not native. Black rats (Rattus rattus) can be found on the remote Chagos Archipelago in the Indian Ocean, roughly 1,000 miles off the coast of the southern tip of India. Many of the rats arrived in the 1700s as stowaways on ships from Europe, and they have noticeably affected the ecosystem on about 34 of the 55 islands in the archipelago.

A study published January 5 in the journal Nature Ecology and Evolution looked at five black rat-infested and five rat-free islands in the archipelago. The rats appear to have changed the territorial behavior in some of the fish on the surrounding coral reefs.

[Related: Rats can’t barf—here’s why.]

One of these is the jewel damselfish (Plectroglyphidodon lacrymatus), an herbivorous species of tropical reef fish that tends to and “farms” algae in the branches of corals. They appear to have altered their behavior because the rats have disrupted an important nutrient cycle.

The region’s seabirds travel into the open ocean to feed and then return to nest on the islands. When they return, they deposit nutrients through their poop and that are then washed into the ocean, which fertilizes the coral reef ecosystems.

The rats attack and eat some of the small seabirds and their eggs, which has severely hurt their populations. According to the study, the density of seabirds is up to 720 times smaller on the rat-infested islands.

Fewer seabirds means fewer nutrients reaching the water surrounding rat-infested islands, to the tune of 251 times less nitrogen flowing onto the coral reefs around these islands. This lowers the nutrient content in the seaweed that herbivorous fish eat.

On the islands without any rats, the farming damselfish aggressively defend their small patches reef to protect their food source called turf algae. The team observed that the farming damselfish on the reefs next to rat-infested islands were more likely to have larger territories and five times more likely behave less aggressively than the fish who lived on reefs adjacent to islands without rats.

[Related: This rainbow reef fish is just as magical as it looks.]

“Jewel damselfish around rat-free islands aggressively defend their turf because the higher enriched nutrient content means they get ‘more for their money’, and this makes it worth the energy cost needed to defend,” said Rachel Gunn, who conducted the research as part of her PhD at Lancaster University and who is now at Germany’s Tuebingen University, in a statement. “Conversely, the fish around rat-infested islands behave less aggressively. We believe that the presence of rats is lowering the nutritional benefit of the turf to the extent that it is almost not worth fighting for, which is what we are observing with these behavior changes.”

Observing both the reduction of nutrients due to the presence of rats on the island and the changes in behavior in the damselfish possibly has wider implications for the spread of different coral species, how other reef fish are distributed, and the resilience of damselfish due to changes in genetic traits over multiple generations.

“The algal farming of damselfish affects the balance of corals and algae on the reef. Their aggression towards other fish can influence the way those fish move around and use the reef,” said Gunn. “We do not yet know what the consequence of this behavioural change will be but ecosystems evolve a delicate balance over long time-scales, so any disruption could have knock-on consequences for the wider ecosystem.”  

The study also provides more evidence that invasive rat populations should be eradicated from tropical islands, since they can effect ecosystems on land and in the water.

“Rat eradication has the potential to have multiple, cross-ecosystem benefits. The removal of invasive rats could restore the territorial behavior of farming damselfish, which could scale up to benefit coral reef community composition and resilience,” said Gunn.

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In 2003, a lost fictional clownfish named Nemo swim his way to box office success. If Nemo hadn’t ended up in a dentist’s fish tank, it’s possible an older region in the back of his brain could have kicked in to help him find his way back to his home to a reef, according to a new study.

A team of scientists at Howard Hughes Medical Institute’s (HHMI) Janelia Research Campus are now better understanding how animals know where they are in relation to their environment—and how to find their way back on the path they were taking. A study published December 22 in the journal Cell details how a region called the hindbrain helps animals determine location and use that information to plan where to go next.

[Related: Fish brains provide insight on how humans store memories.]

The hindbrain is an older region located in the back of the brain that has been evolutionarily conserved, or virtually unchanged throughout the process of evolution. The authors looked at tiny translucent zebrafish. They have historically been used in research, especially in genetics, for many reasons, including their quick growth rates, translucent bodies that can help scientists peer inside, and similar genetic structure to humans. The zebrafish genome was fully sequenced in 2013.

The fish were placed in an environment that simulates currents, and were then pushed off course when the currents shifted unexpectedly. However, they were able to course-correct and get back where they started. While the zebrafish were swimming, the researchers used a whole-brain imaging technique to measure what was going on inside the fish’s brain. The scientists could search the entire brain to note which circuits were activated when the zebrafish course corrected and separate the individual activities.

The team expected to see the forebrain, where the hippocampus that houses an internal map of an animal’s environment is stored. Instead, they saw several regions of the medulla activate. This is where information about the animal’s location was being transmitted through a newly identified circuit. A part of the hindbrain called the inferior olive used motor circuits to move the information to the cerebellum that made the fish move. The fish were unable to move back to its original spot when these pathways were blocked.

[Related: These jellyfish don’t have brains, but still somehow seem to sleep.]

“We found that the fish is trying to calculate the difference between its current location and its preferred location and uses this difference to generate an error signal,” says En Yang, the first author of the new study, and a post doctoral researcher at Janelia’s Ahrens Lab, in a statement. “The brain sends that error signal to its motor control centers so the fish can correct after being moved by flow unintentionally, even many seconds later.”  

Previous studies have shown that the inferior olive and the cerebellum performed actions related to reaching and locomotion, but not this type of navigation. According to the team, this hindbrain network could also lay the basis for other navigational skills, including when a fish swims to a specific spot to take shelter.

“This is a very unknown circuit for this form of navigation that we think might underlie higher order hippocampal circuits for exploration and landmark-based navigation,” said Misha Ahrens, Janelia Senior Group Leader, in a statement.

Further study is needed to determine whether these same networks are involved in similar behavior in other animals.

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This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Fishers around the world are desperate for a reliable way to stop dolphins from plundering their catch. Dolphins’ net burgling—known as depredation—costs fishers income, but it also puts dolphins at risk of injury and entanglement. Proposed solutions to finally win the battle of wits, such as using noisemakers or reflective camouflage, have come up short. So researchers in Greece went back to the drawing board in search of the perfect deterrent: something so unpleasant it would ward away dolphins and keep them away. They came up with fishing nets coated with a resin laced with capsaicin, the chemical compound that gives chili peppers their signature heat.

Giving predators a spicy surprise might seem like a far-out solution, but capsaicin-based deterrents have proved successful on land with other mammals such as deer, squirrels, rabbits, and rodents. Even some insects and birds seem to dislike the substance.

Yet after five months of test fishing with capsaicin-coated nets, the research team co-led by Maria Garagouni, a marine biologist at Aristotle University of Thessaloniki in Greece, faced a tough realization: their idea didn’t work. The bottlenose dolphins that interacted with their nets were entirely unfazed.

Despite the disappointing result, Garagouni says she was wowed by how adept the dolphins were at pilfering their nets. Garagouni began collaborating with fishers to study depredation in the Aegean Sea a decade ago, and even still, the animals’ prowess surprised her. When dolphins come in for a netted meal, she explains, it’s more than a smash-and-grab job. The animals often run methodical missions into the nets until they’ve eaten their fill.

“The initial shock for me was seeing it happen in real time,” she says. The first time dolphins interacted with their hot sauce­–spiked nets, two individuals spent no more than 15 minutes tearing 217 holes in the gear.

“And then the victory laps!” Garagouni says. “The play afterwards, when there were young calves in the group—after they’d get their fill of fish—the young ones would go off and do leaps in the air, almost as if to burn off all this new fuel. If this was our livelihood, I think it would be the most infuriating element to watch. But for me, obviously, it was amazing.”

So does this mean dolphins could slurp down Da’Bomb Beyond Insanity on their way to Hot Ones glory? Aurélie Célérier, a neuroscientist at the University of Montpellier in France who specializes in marine mammal communication and was not involved in the study, says it’s too early to make that call. While it’s known that many cetaceans, including bottlenose dolphins, lack four of the five primary tastes—they can only pick up salty—spiciness is registered by a different set of sensory cells through chemesthesis. This process, which signals sensations such as pain and heat, is little studied in the species. Other toothed whales do appear to have the hardware required for capsaicin detection, notes Célérier, but there’s a lot left to learn.

There could be something else at play in the dolphins’ triumph over spice: cetacean super smarts. From corralling fish with plumes of mud to tenderizing tough prey by tossing it sky high, dolphins are known for a wide variety of intelligent feeding strategies. Their propensity to innovate, combined with the fact that they’re notoriously unfussy eaters, helps them survive, but it’s also partly what puts them into increasing conflict with fishers. The dolphins may simply have figured out a way to break into the spicy nets without making much contact.

The capsaicin coating didn’t deter dolphins, but intriguingly, it did appear to affect another animal. An unidentified predator, possibly a sea turtle, seal, or shark, tore large holes in the scientists’ plain control nets but not the spicy nets.

The research team is putting a pin in their red-hot research for now, but Garagouni hopes it will serve as a springboard for others on the quest to outwit dolphins. Even a study that fails, she says, offers helpful clues and leads to new questions.

This article first appeared in Hakai Magazine, and is republished here with permission.

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This article originally appeared in Nexus Media News and was made possible by a grant from the Open Society Foundations.

For most of the Shinnecock Nation’s history, the waters off the eastern end of Long Island were a place of abundance. Expert fishermen, whalers and farmers, the Shinnecock people lived for centuries off the clams, striped bass, flounder, bluefish and fruit native to the area.  

Today, the area is best known as a playground for the rich, where mansions sell for tens of millions of dollars. The Shinnecock community no longer lives off the water as it once did — rapid development, pollution and warming waters have led to losses in fish, shellfish and plants that were once central to the Shinnecock diet and culture. 

That’s why Tela Troge, an attorney and member of the federally recognized tribe, started planting kelp.  

Kelp is a large, fast-growing brown seaweed that sequesters carbon and harmful pollutants. It’s also full of nutrients and is used in foods, pharmaceuticals and fertilizers—making it a big business. 

The global commercial seaweed market is valued at around $15 billion and is projected to reach $25 billion by 2028. In the United States, the kelp market is expected to quadruple by 2035, according to the Island Institute.

For the estimated 800 residents of the Shinnecock Reservation, where Troge said some families live on just $6,000 a year, kelp farming could be an economic lifeline. On one side of Shinnecock Hills, “you have billionaire’s row where some of the wealthiest people in America have homes,” Troge said. “Then, on the other side, you have Shinnecock territory, where 60 percent of us are living in complete poverty.” 

In 2019, Troge, an attorney who has represented the Shinnecock Nation in federal land rights cases, was looking for a way to create jobs and clean up Shinnecock Bay. That’s when GreenWave, a nonprofit that promotes regenerative ocean farming, approached the community about starting a kelp hatchery.

Troge and five other women from her community formed the Shinnecock Kelp Farm, the first Indigenous-run farm of its kind on the East Coast.

Greenwave’s model “so closely matched our skills, our expertise, our traditional ecological knowledge,” Troge said. The Shinnecock practiced regenerative ocean farming long before the term existed; they farmed scallops, mollusks, oysters and clams—all natural water purifiers—together with seaweed. 

This system of kelp removing nitrogen near the surface while shellfish do the same down below creates powerful water filtration, said Charles Yarish, an emeritus marine evolutionary biologist at the University of Connecticut. It’s an ancient model. “If you go into Chinese literature, even to ancient Egypt, you will see examples of those cultures having integrated aquaculture,” he said.

Kelp feeds off excess carbon dioxide, nitrogen and phosphorus. The last two are pollutants responsible for harmful algal blooms that have killed off plants and animals in Shinnecock Bay, said Christopher Gobler, a marine scientist at Stony Brook University on Long Island. Kelp blades are lined with cells containing sulfated polysaccharides, essentially chains of sugar molecules that give kelp its slimy texture. These polysaccharides bind with nitrogen and phosphorus, pulling both out of the water and dissolving the nitrogen into a compound called nitrate. The dissolved nitrogen is what makes kelp a potent natural fertilizer.

These kelp forests promote biodiversity, lessen ocean acidification and remove dissolved carbon dioxide from the water. One meta-analysis by researchers at the National Oceanic and Atmospheric Administration found that, on average, these farms remove 575 pounds of nitrogen per acre. (Projections based on another study, from Stony Brook University, put that figure at 200 pounds of nitrogen per acre.) Seaweed aquaculture could absorb nearly 240 million tons by 2050, equal to the annual emissions from more than 50 million fossil fuel–powered cars, according to a 2021 study published in Nature.

Compared to land-based crops, kelp requires very few resources—just spores, sea, and sunlight—and far less labor and harvesting equipment, said Halley Froehlich, a marine biologist at the University of California, Santa Barbara. But, Froehlich added, kelp’s real superpower is that it grows quickly—faster than almost any other plant on the planet.

In December of 2021, Troge and her business partners started planting 20 spools of kelp off the shore of St. Joseph Villa, a retreat space just across the bay from the reservation. The villa, which offers easy access to the water, had once belonged to the Shinnecock nation. Today, it is run by a Catholic ministry known for its environmental and social justice work.

Troge and her fellow farmers ran the business out of a cabin donated by the ministry and encountered their share of challenges. It took longer than they had expected to find the right species of kelp—one that they deemed hearty enough for the hatchery. 

“We got out later than we had hoped, as December is quite late,” said Danielle Hopson-Begun, who co-founded the Shinnecock Kelp Farm. Sugar kelp is normally planted in the mid-fall, in time for a January growth spurt. 

Then they suffered outbreaks of slip gut—a type of algae that grows on sugar kelp and suffocates it. 

But by the spring of 2022, the Shinnecock women harvested 100 pounds of kelp, most of which they dried and sold as organic fertilizer. They donated their excess spores back to GreenWave, which distributed the excess to other growers. This was a small harvest compared to established kelp farms. Gobler, the marine scientist, estimated that a one-acre ocean farm could generate 70,000 pounds of kelp.

This year, the farmers plan to expand from 20 spools of kelp to 200. They are expecting a significantly larger yield and are exploring different uses for the crop, like food and cosmetics. They’re also talking with other hatcheries about exchanging spools of kelp in order to experiment with different species of seaweed. The farm is already cleaning up the area, Hopson-Begun said; since operations began she said the water appears clearer and more birds fly overhead.

As Troge and her colleagues plan ahead, they’re also looking to bring on additional staff to help manage the harvests. They plan to hire from within the Shinnecock community. “I’m just really excited about building up to the point to offer people living-wage jobs,” Troge says.

—

This article was made possible by a grant from the Open Society Foundations. Nexus Media News is an editorially independent, nonprofit news service covering climate change. Follow us @NexusMediaNews.

Iris M. Crawford is a climate journalist and the Climate Justice Sr. Editor at Nonprofit Quarterly. 

The post How kelp farming is helping revive the economy and ecology of a Long Island bay appeared first on Popular Science.

Articles may contain affiliate links which enable us to share in the revenue of any purchases made.

This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Jonny Williams squeezes into a soaped-up wetsuit near the base of British Columbia’s Tantalus Range, a series of 2,000-plus-meter peaks that give rise to the region’s moniker, Sea to Sky. The water he slips into is like glass, an unexpected gift in a glacier-etched fjord known to funnel high winds. As he kicks his fins along the shoreline, jets of seawater sparkle as they meet the sun. A while later he bobs back up and yells, “I almost smoked my head!” With plankton in bloom, visibility in the shallow water is an arm’s-length ahead, and rocks seem to come out of nowhere.

It’s Tem Lhawt’ [tem thlout], the time of the herring, in the heart of Sḵwx̱wú7mesh [skw-ho-mish] homelands. In early spring, the small team of young citizen scientists Williams belongs to fires up the outboard engine and zips an aluminum boat to locations along the steep western wall of these shores. At each stop, someone suits up, dives in, and scans every nook, searching for signs of a population of herring that Fisheries and Oceans Canada deems too peripheral for regular monitoring.

From above, Howe Sound, known as Átl’ḵa7tsem [at-kat-sum] among other names, looks like an open crab claw with a meandering, river-fed arm. Tucked into the base of its arm is the District of Squamish, an old mill town turned luxe outdoor haven midway between Vancouver and Whistler, that colonizes the name Sk̲wx̲wú7mesh. Where the crab claw meets the Salish Sea, the pinchers hook around a cluster of islands.

The spectacle of herring spawn—adult fish returning to these shores to blanket tens of thousands of eggs with a milky, turquoise cloud of seminal fluid known as milt—is over in a matter of days. Some of the eggs, glommed onto vegetation such as rockweed, will be fertilized, and if the waves that wash across them are gentle and predators stay away, larval fish will emerge. To me, the clear bubble-like eggs the size of millet that Williams searches for seem too minuscule to be of much consequence in Átl’ḵa7tsem. But to Williams and the four other citizen scientists who make up the core herring search team, knowing where these eggs land and flourish enables them to put a finger to the pulse of a waterway that environmentalists once declared dead.

The ghosts of resource extraction surround us: two pulp mills that choked the sound with logs and bleaching agents like chlorine dioxide, chemical plants that leached mercury, underwater dump sites from dredged sediment, and a beachfront copper mine that was once the biggest source of toxic metals in North America’s waterways.

Biologists studying herring can’t say specifically how these industries correlate with the fish’s health, but locals are confident that the impact from past industrial practices was only negative. Looking around at rusty chemical tanks and other remains along the shores, it’s hard to imagine herring choose to surrender their eggs to these shallows at all.

Pacific herring in this northern part of the Salish Sea, where the Átl’ḵa7tsem claw sits, appear to be faring better in general than those farther south, though many former spawning sites beyond Átl’ḵa7tsem are abandoned, in the stretch of water between the city of Vancouver and Vancouver Island. Herring all but disappeared from the shorelines around Squamish in the mid-1970s, likely due to overfishing and the mess industrialists made of spawning sites.

Environmental regulations, such as limits on how pulp mills could dump bleaching agents into the ocean starting in the late 1980s—followed by the shutdown of some major operations—have coaxed herring back to some of their former shoreline nurseries in Átl’ḵa7tsem and boosted their chances of survival. Locals started keeping an eye on the fledgling herring in this area in the early 2010s. Over the years, environmental groups and Sḵwx̱wú7mesh Úxwumixw [Squamish Nation], have worked on additional conservation efforts in cooperation with local industry, such as ensuring that toxic pilings are wrapped with protective materials to prevent herring eggs from dying. Just as the combined effects of development and extraction once smothered these shoreline habitats, hopefully now the cumulative effect of many efforts to restore them will preserve a precarious rebound for herring. In recent years, locals have witnessed additional signs that the ecosystem is rebounding—the return of dolphins, porpoises, humpbacks, and killer whales, after a nearly 100-year-long absence.

Herring are still up against far-reaching forces here—the fjord is acidifying, deoxygenating, and warming quickly. Marine biologists aren’t sure if the herring’s return will be short-lived or represents a sustained comeback. The most straightforward way to know is to track where the fish leave eggs and how they fare each spring. That work falls to Williams and his fellow citizen scientists. A contingent of volunteers also monitors the spring spawn by bushwhacking the Squamish estuary in waders. The overall initiative bears a sense of urgency: while the largest beachfront mills and mines have shuttered, a new era of oceanfront development is unfolding, with blueprints having been drawn for luxury apartments and a liquefied natural gas facility.

As the team finds spawning locations and gathers supporting data, they funnel the information to biologists at the conservation organization Átl’ḵa7tsem/Howe Sound Marine Stewardship Initiative (MSI). By knowing where herring spawn, roughly how many eggs are produced, and how they develop, scientists will have a baseline to compare future changes against. Observations about how any new industrial activity impacts herring at their favored spawning sites can also help advocates fight for more habitat protection.

The herring search team does most of its work scanning the sound for slhawt’ [th-lao-t] on evenings and weekends. Three young Sḵwx̱wú7mesh members, including Williams, and a herring survey coordinator are paid with funds raised through MSI, but their work is supported by community generosity. Their wetsuits are donated by a local dive company. Conservation groups, as well as people like Neil Baker, a Sḵwx̱wú7mesh fisherman, offer supplies and knowledge about local herring and the ecosystem. And the boats the team uses are provided by the Sḵwx̱wú7mesh Úxwumixw.

But the Search for Slhawt’, as the herring project is known, is about more than the forage fish. One of the wider goals is to restore people’s relationship with the sound. For millennia, the spring journey of slhawt’ back to their spawning areas marked the first feast after a long winter for humans and marine beings alike, from seabirds to eagles to porpoises. Communities held ceremonies in late winter that helped welcome slhawt’ home. Roe was gathered and eaten fresh, dried, or smoked—sometimes with salmonberry shoots.

In recent history, colonial policies aimed at severing Sḵwx̱wú7mesh people’s relationship with their territory to extract wealth limited how these first stewards could carry out their traditions of monitoring and harvesting along the shores. As slhawt’ disappeared, so did salmon and more. The return of slhawt’ restores relationships between the fish and other species, including the humans who may encourage or impede their survival.

In between shoreline snorkels, 24-year-old Williams and two other young Sḵwx̱wú7mesh members on the survey team learn to operate the vessel, identify flora and fauna, and set crab and prawn traps to harvest food for family and friends—experiences they might not otherwise have access to. Some team members speak Sḵwx̱wú7mesh as they work, reuniting words with the practices that gave rise to them. The search for slhawt’ feeds a new generation of Sḵwx̱wú7mesh stewardship.

The young surveyors are supported by Matthew Van Oostdam, a commercial fisherman turned schoolteacher of Dutch and French ancestry who has spent six years working under the direction of Sḵwx̱wú7mesh community members and elders. His current role is land-based education coordinator for kindergarten to grade 10 students at St’a7mes School, where he bridges Sḵwx̱wú7mesh and settler ways of knowing. One of his initiatives is to adapt the community’s teachings into learning activities for younger students, guided by Williams’s mother, Charlene Williams.

On a typical school day, Van Oostdam is out with the kids skinning river otters, teaching knife skills, smoking salmon, or collecting oyster shells to make “shell phones.” To Van Oostdam’s younger students, slhawt’ is known as Harriet the Herring, a googly-eyed character inspired by a film made by BC naturalist Briony Penn. Harriet writes letters about her travels and the ecosystem she supports, which Van Oostdam reads aloud. The Search for Slhawt’ team’s surveys inform Harriet’s itinerary; in February, she wrote a letter to the kids telling them not to worry—that she was on her way.

Although I’m out with the survey team on a Sḵwx̱wú7mesh thunderbird-emblazoned vessel in early April, relatively late in a typical spawning season, Williams and the others have seen little sign of spawn. The cycle of slhawt’ is unpredictable, influenced by a symphony of events led by an unknown conductor. Van Oostdam has playfully distributed missing posters throughout the school.

The Search for Slhawt’ began as a request from elders. Kiyo-wil Robert Baker, and others, wanted to see a traditional harvest of herring roe on hemlock branches led by youth and the wider community once more. As a staple food source for First Nations along the Pacific coast, herring eggs are typically collected in clumps from racks of kelp fronds or boughs of coniferous trees placed in shallow water.

At the time of Baker’s request, Van Oostdam and his guide, Charlene, didn’t know much about slhawt’, or where they could be found. As Charlene reached out to other Sḵwx̱wú7mesh elders with firsthand knowledge, Van Oostdam phoned a couple of local conservation organizations and asked if anyone knew anything about the foundational fish. Through Squamish Streamkeepers, he met John Buchanan, a long-serving citizen scientist and self-described “environmental cop” who has voluntarily monitored where local herring spawn for over a decade from his boat.

Over coffee, “he basically knowledge-bombed me with, like, 12 years of herring data,” recalls Van Oostdam. Armed with Buchanan’s maps of shoreline spawning sites—blue lines for sites surveyed and red lines for sites with spawn, overlaid on a Google Earth map of the sound—Van Oostdam scoped spots along the glacially steepened west wall of Átl’ḵa7tsem in his small boat to familiarize himself with the fish. Soon, Buchanan encouraged him to take over the herring surveys, and Van Oostdam invited Jonny Williams to join him.

At the time, Williams was working with MSI as an Indigenous youth engagement coordinator. Through family and friends, he helped arrange their use of Sḵwx̱wú7mesh Úxwumixw–owned vessels and recruited the other members of the core survey team.

That first spring of Search for Slhawt’, in 2019, students led a ceremony, just as elders had requested. They chose Nexen Beach, where a chemical plant once produced bleaching agents for the pulp and paper industry. After learning about the importance of slhawt’ in the ecosystem and Sḵwx̱wú7mesh ways of harvesting roe, kids sang songs welcoming slhawt’. They made racks from hemlock branches and draped them in the intertidal zone with rope. At the time, even Buchanan was skeptical—he thought the odds of collecting roe from Nexen Beach were slim. The group returned a week later to find the boughs heavily cloaked in eggs. For the first time in living memory, community members tasted herring roe from the sound, a delicacy the kids described as “salty popcorn.”

A developer has since filled this site with sand and dirt to make way for a 4.5-hectare oceanfront park, part of a multimillion-dollar development set to house 6,500 residents.

Out on the water, Williams climbs back onto the boat and changes into sweatpants bannered with Tribal Journeys, the name of a festival he participated in, paddling hundreds of kilometers in a dugout canoe. Vivian Joseph, sporting a camo hoodie and round glasses that frame soft brown eyes, cuts the engine as she expertly steers into an alcove razed by thousands of years of rushing water. The surge of creek water from deeper within this cathedral drowns the sound of planes above. With the tide still low, a band of curled, pasta-like rockweed marks the high-tide line, centimeters above the water. “See the spawn?” Van Oostdam asks, gesturing to the rockweed. I squint and lean closer.

Joseph, who is 30 years old, calmly noses the boat right up to the cliff so Van Oostdam can reach out and pull a piece of rockweed. Kieran Brownie—a local photographer who joins the trips to lend a hand—points out that it’s possible to make out eyes on a few of the tiny eggs. But only a small percentage of these eggs are developing into larvae—the rest have died. Van Oostdam speculates that the rushing creek water may have impeded fertilization.

As we exit the alcove, Williams spots a good cliff to jump from when the weather warms—though on second thought he decides it’s maybe a little too high. Last year, to celebrate the end of the survey season, Van Oostdam and Williams jumped from a nearby, lower, cliff. A big part of this project is having fun, says Van Oostdam. His allegiance is to young people and the ecosystems they’re related to—laughter facilitates these connections.

The survey team—which is Joseph and Williams today—records the GPS coordinates of each spawning location they find, and Van Oostdam measures the water temperature—4.7 °C—and takes note of the weather and how the larvae are developing. He’ll summarize the findings in a daily report and share it with the MSI biologists, as well as an email list and a lively Facebook group, where Sḵwx̱wú7mesh elders and herring fans can pepper posts with comments.

The team’s three years of data, along with Buchanan’s from years previous, are now among several hundred open-source data sets hosted in a new interactive and interdisciplinary map of Átl’ḵa7tsem, put together by MSI, that reveals everything from Sḵwx̱wú7mesh place names to at-risk eelgrass beds to rare pockets of glass sponge reefs, which formed over thousands of years. These efforts contributed to the region’s designation as Canada’s 19th UNESCO biosphere region last year.

For Van Oostdam’s turn to get in the water and conduct a survey, we’re near Swiy̓át, a spiritual place now occupied by relics of a pulp mill. As Joseph trails the boat behind Van Oostdam and an entourage of sea lions, Williams sits on the stern rubbing his hands together—though he says the cold doesn’t bother him. Átl’ḵa7tsem was the original water-based highway between winter and summer villages in the Salish Sea, he reminds me. Elders talk about 50-year-old women canoeing the roughly 70-kilometer stretch to Vancouver and back in one day. “My people had to be tough.”

During regular work hours, Williams works for Ta na wa Yúus ta Stitúyntsam, Sḵwx̱wú7mesh Úxwumixw’s rights and title department, whose name translates to “the ones who take care of what was handed down or what will be handed down.” He just finished an environmental technician course and plans to get his scuba ticket. He wants to work on the water protecting his homelands, and get paid for it. “If we don’t, who will?”

Joseph shares Williams’s sentiment. At the time of our outing, she was a fish enumerator for Sḵwx̱wú7mesh Úxwumixw, walking the rivers to monitor fish mortality. Before the herring surveys, she’d never been out on the ocean aside from an occasional ferry trip. Now she’s learning about how much marine life is connected to the little eggs they track, like killer whales and dolphins.

As the wind kicks up, the clouds eject hail, so we throttle back to the harbor. A discussion ensues about who should be given the ice cream pail of prawns and five large crabs the team has gathered throughout the day while their surveys were underway. Fisherman Neil Baker gets a few for sure, since he provided the bait and traps.

A week later, Van Oostdam will set out in a canoe to pull a bough from this year’s harvest location, Sta7mes, the oldest Sḵwx̱wú7mesh village and one of several reserves in this part of the territory. In the video he posts to Facebook, a row of students leans over the railing at a dock to watch. “You guys want to taste a little bit?” Van Oostdam asks, holding up a hemlock branch glutted in milky roe. “Yeah!” the kids cry in unison. He gathers a bucket of hemlock sprigs, one for each student, but leaves the dozens of remaining branches drifting in the water. If conditions permit, some of the eggs clinging to them might hatch, mature, and spawn, and a new generation of stewards will welcome them home.

This article first appeared in Hakai Magazine, and is republished here with permission.

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This article was originally featured on Undark.

Wild Alaskan salmon are a gold standard for American seafood. The long journey from the river to the ocean and back builds the muscle mass that gives the fish their distinct texture and flavor, and the clean rivers of the north produce seafood with very low levels of mercury and other contaminants. Indigenous communities have been harvesting salmon in Northwestern North America for more than 10,000 years and some still depend on subsistence fishing for survival. In southeastern Alaska, salmon fishing and processing adds an annual total of about $70 million to the local economy.

But 21st-century salmon face many stressors, including habit loss, climate change, and overfishing. As a result, salmon populations are declining across the United States. The fish still thrive in some parts of Alaska, but local residents and scientists are increasingly concerned about an additional stressor: the mining industry. Active mines, proposed mines, and dozens of exploratory projects span the transboundary region of southeastern Alaska and British Columbia, which includes three major salmon-bearing rivers. One of these proposed mines, the Kerr-Sulphurets-Mitchell project in Canada, will extract ore from what is reportedly the largest undeveloped gold-copper deposit in the world.

For decades, scientists have been trying to understand the impact of mining on salmonids, a family that includes salmon, trout, and other closely related fish. In July, the journal Science Advances published a review study evaluating more than 100 research papers and documents, concluding that the earlier research has underestimated the impacts of mining operations on Pacific salmonids. Mining activities are of special concern today, the authors wrote, because demand for metals is rising as manufacturers seek raw materials for low-carbon technologies like electric car batteries.

Even under normal circumstances, mining can release contaminants like heavy metals into nearby watersheds, threatening the health of salmon. And mine tailings — the slurry of silt, fine sand, clay, and water that’s left behind after ore is extracted — need to be carefully stored beyond the life of the mine. Without proper environmental mitigation, scientists say, current and proposed mining activities could have devastating effects on Alaskan salmon and their watersheds.

In interviews with Undark, several mining representatives underscored the industry’s efforts to keep watersheds free of contaminants. But many scientists and locals remain skeptical, and they worry about losing the region’s salmon. The nonprofit Salmon Beyond Borders was created to protect transboundary rivers and ways of life. “Wild salmon are at the center of my life,” said Heather Hardcastle, a campaign adviser for the organization, “as they are at the center of most people’s lives in this region.”

Northwestern North America represents a convergence of natural resources, wrote the July paper’s 20-plus authors, most of whom are affiliated with the region’s universities, First Nations, or environmental nonprofits. Northwestern North America holds substantial reserves of coal and metals. It is also home to “some of the most productive and least disturbed salmonid habitat remaining on Earth,” the authors wrote. These fish are unique for their large home ranges and for their tendency to use all of the accessible parts of the watershed. For these and other reasons, it can be difficult to assess and mitigate the risks of mining.

The review was comprehensive, analyzing not only peer-reviewed studies, but also government databases and reports, and industry disclosure documents and technical materials. The results were sobering: Mining operations often fail to meet their own water quality goals, the review found. Further, few studies have compared the predicted impacts of mining with the industry’s actual impacts. Cumulative effects of multiple mines and other stressors are often underestimated. Mitigation strategies aren’t always based on proven technology, and they rarely consider the effects of climate change in years to come.

Lead researcher Chris Sergeant said the July paper is the first of its kind to comprehensively review and summarize the impact of mining on salmon and provide guidance on how to improve the science that supports mining policy. The scale of the review allowed researchers to see a big picture, which can be difficult to visualize based on individual datasets, especially when the data comes from the mining companies themselves.

“It’s nearly impossible with the data we’re given by mining operations these days to do a kind of pre-project assessment of risk,” Sergeant said. “The data quality is so non-transparent and not done systematically.” Sergeant also said he wasn’t surprised by his paper’s findings, given that there are so many individual examples of how mining operations can affect watersheds. Having those examples all together in one place, though, makes the extent of the problem clearer.

Jonathan Moore, a professor at Simon Fraser University in British Columbia who worked on the July review, noted that salmon also help support the overall health of local watersheds. More than 100 species are believed to have some kind of relationship with salmon, whether direct or indirect. Trout eat salmon eggs and young salmon, for example, and bears eat the spawning adults. When salmon die, their bodies contribute nutrients like nitrogen and phosphorus to the watershed and the forests that grow nearby.

The ecological impact of these nutrients is sometimes visible to the human eye. A 2021 study found that the “greenness” of vegetation along the lower Adams River in British Columbia increased in the summers following a productive sockeye salmon run. Another study found that the presence of dead salmon in spawning grounds influenced the growth rate of Sitka spruce trees not just close to the riverbank but also farther into the forest, where researchers said “bear trails and assumed urine deposition were prevalent.”

Environmental activists and scientists are wary of new mining projects, in part, because mining disasters are still happening, even though modern infrastructure is supposed to be robust enough to prevent them. During a 2014 dam failure at the Mount Polley Mine in British Columbia, for example, 32 million cubic yards of wastewater and mine tailings spilled into a nearby lake. From there, the mine waste traveled down a creek and into a second lake, which supports one of the region’s most important salmon habitats.

The mining company, Imperial Metals, maintains that the tailings from the Mount Polley spill did not cause largescale environmental damage. The tailings contained very little pyrite, a mineral that can generate sulfuric acid when exposed to air and water, wrote C.D. Anglin, who worked as the company’s chief scientific officer in the aftermath of the Mount Polley accident, in an email to Undark. Sulfuric acid is one of the most environmentally concerning consequences of mining. When the compound enters a watershed, it doesn’t just threaten the health and survival of fish and other animals, it can also dissolve other heavy metals like lead and mercury from rock it contacts. But, Anglin wrote, “the Mount Polley tailings are considered chemically benign.”

Still, a 2022 study found that the dam failure did have environmental consequences. The study, which was not included in the July review, was led by Gregory Pyle, a researcher at the University of Lethbridge in Alberta, Canada. Pyle and his colleagues took water, sediment, and invertebrate samples from sites impacted by the spill and from a nearby waterbody, Bootjack Lake, that was not impacted by the spill. In the areas most affected by the spill, Pyle’s team found elevated copper levels in the sediment, as well as high concentrations of copper in the bodies of invertebrates living in those areas. Notably, the researchers also found elevated copper levels in Bootjack Lake, which suggests that the environmental impact of the Mount Polley mine predates the spill itself.

Anglin said the study’s results are misleading. “While the copper levels are slightly higher than in some of the organisms in unimpacted areas,” she wrote, “they are not at a level of environmental concern.”

Pyle disagrees. In an interview with Undark, he pointed to a follow-up study in which his team exposed freshwater scuds (a shrimplike mollusk) to contaminated and uncontaminated water and sediment collected four years after the Mount Polley spill. “When they were in contact with the sediments for as little as 14 days,” he said, “it impaired their growth and survival.” The results of Pyle’s study have implications for salmon since scuds and other invertebrates are an important food source for these fish.

Copper can also build up in the bodies of salmon, as well as their prey, impacting their growth and survival. Studies have found that even sub-lethal copper levels can harm salmon’s olfactory system, which may make it harder for them to avoid predators and orient themselves in their habitat. “Copper has these really insidious effects in terms of salmon’s ability to navigate,” said Moore. “Salmon might not be able to find their way home, for example, in a system that has excess copper.”

Even when contaminants are taken out of the equation, scientists say, the sheer volume of material entering the watershed during a spill like the one at Mount Polley can have physical consequences. “These big disasters like Mount Polley, they transform these systems,” said Moore. For example, the slurry of fine sediment and waste material can cover the gravel where salmon would otherwise lay their eggs, making it useless as spawning habitat.

The lingering effects of past mining have activists and scientists concerned about new projects like the proposed Kerr-Sulphurets-Mitchell mine, which is expected to begin construction in the summer of 2026. Hardcastle said Salmon Beyond Borders wants the region to take a precautionary approach to new mining projects.

“What’s the point otherwise of trying to decarbonize and get to a clean energy future,” she asks, “if all we’re doing is swapping the big oil and the fossil fuel industry for big mining?”

Christopher Mebane, assistant director for hydrologic studies at the U.S. Geological Survey, studies metals, toxicity, and mining and jokingly describes himself as “a dirty water biologist.” He called the July study, in which he was not involved, “a fair assessment” of the problems that mining activities can create for salmonids. “I can’t find a single misstatement or error,” he said. “But you know, if this were written by a group of mining engineers, it would have a very different tone and probably conclusions.”

Indeed, mining industry representatives say the mistakes of the past won’t be repeated. “Mines with tailing storage facilities are required by law to implement new design and operational criteria using best available technology,” said Michael Goehring, president and CEO of the Mining Association of British Columbia, a trade group. And Brent Murphy, senior vice president of environmental affairs at Seabridge Gold, the company that will operate the proposed KSM mine, said the KSM tailings management facility won’t drain into Alaskan waters. Although the mine itself will be located in a watershed that drains into a transboundary river, Murphy said the tailings facility will drain only into Canadian waters and does not require water treatment.Salmon are believed to have a relationship, direct or indirect, with more than 100 different species. In Alaska, brown bears famously fish for adult salmon as they swim upstream to spawn. Visual: RooM via Getty Images

Murphy added that the tailings facility will be in a confining valley, closed off by two large dams. “We’re containing all of the potential acid-generating material, which is only 10 percent of the total volume of the tailings produced, within a lined facility,” he said. That part of the facility will be surrounded by more than 1.8 miles of compacted sandy material. The design, Murphy said, was implemented to address the concerns of local First Nations.

To satisfy agency and community concerns over the long term, mining operations may also propose water treatment plans that span centuries. Seabridge Gold said water treatment will continue for 200 years after the KSM mine closes, though Murphy told Undark that the water at the site is already naturally contaminated with copper, iron, and selenium and won’t be further contaminated by mine operations.

Christopher Sergeant, who led the July review, said he’s skeptical. “I don’t know of any successful examples of anyone treating water for 200 years,” he said. “And my understanding of corporate structure is that there’s not really a motivation once the project is not creating profit anymore. That’s a big concern of mine: Who is going to be on the hook for making sure that that water is treated in what’s basically perpetuity?”

Goehring said the cost of ongoing water treatment is paid for upfront. British Colombia already holds 2.3 billion Canadian dollars ($1.7 billion ) from the mining industry for the express purpose of containing mine waste, he said. This ensures that after the KSM mine closes, he added, “water treatment, if required, will continue to take place.”

Even so, the future effects of climate change could threaten infrastructure at KSM and other mines. “A lot of the calculations that are made for engineering are based on what the current environment looks like,” said Sergeant, adding that there’s really no way to predict how different the environment will be 10 or 20 years into the life of a mine. Destructive weather events are becoming more common, he noted, and they “aren’t necessarily considered in engineering designs.”

For now, environmental groups like Salmon Beyond Borders aim to convince agencies and policymakers to put a pause on new and expanding mines in shared watersheds until Canadian law can be revised to include provisions for downstream stakeholders. More significantly, Salmon Beyond Borders said it also wants a permanent ban on tailings dams near transboundary rivers. But because mining is so lucrative, permanent bans may not be practical or possible.

Moore said the July paper showcases the key challenges to protecting salmon populations in a region touched by the mining industry. He hopes the research points toward “a productive path forward,” he added, in which the mining industry can coexist with thriving salmon systems and the communities that depend on them.

UPDATE: A previous version of this piece incorrectly stated that the KSM tailings management facility will be located in a watershed that drains into a transboundary river and that wastewater will be piped to a treatment facility miles away. While the mine itself is located in such a watershed, the tailings management facility drains only into Canadian waters and does not require water treatment. The piece also originally referred to Heather Hardcastle as the campaign director for Salmon Without Borders. She is a campaign adviser.

The post What new mining projects could mean for Alaskan salmon appeared first on Popular Science.

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Every year, more than 14 million tons of plastic pollute the ocean and threaten the life of various marine species. About 80 percent of all marine debris is plastic, which demonstrates the extent of global plastic pollution.

Boat builders, sailors, and engineers have developed technological innovations like the Seabin to minimize all sorts of litter floating in the ocean. These mechanical cleanup inventions are fixed-point devices designed to separate and remove marine debris from various bodies of water. They work by sucking water from the surface and intercepting floating debris or lifting trash from the water onto a conveyor belt that gathers everything in a dumpster.

However, they might have a limited benefit in reducing plastic pollution. Research shows the devices may even capture unknowing marine organisms, which is a problem because they threaten marine life.

The rate of waste generation exceeds the rate of litter cleanup

A recent Marine Pollution Bulletin study examined a Seabin in the Southwest United Kingdom and found that it captured an average of 58 litter items per day, mainly consisting of polystyrene balls, plastic pellets, and plastic fragments. The authors also found that the device caught one marine organism—like sand eels, brown shrimps, and crabs—for every 3.6 items of litter captured (or roughly 13 marine organisms per day), half of which were dead upon retrieval.

The marine organisms may be attracted to the device to forage or seek refuge. Their mortality rate also appeared to increase with retention time in the machine. Some died due to being captured, possibly under the weight of the surrounding material, says Florence Parker-Jurd, study author and research assistant in the International Marine Litter Research Unit at the University of Plymouth in the United Kingdom.

“At its current stage of development, the study found that in the environment examined, the quantity or mass of litter being removed by the device was minimal when considered alongside the risk of by-catch,” says Parker-Jurd. She adds that manual cleaning efforts with nets from pontoons tend to be more efficient and less resource intensive than the Seabin in environments like marinas, harbors, and ports, even though it was designed to operate in these locations.

“Technological innovations have a part to play in reducing marine litter, particularly in coastal environments where they can complement existing cleanup efforts,” says Parker-Jurd. “This study has highlighted the need for robust, formal evaluations of such devices, especially given the increasing use and geographic spread of the Seabin and similar devices.”

[Related: A close look at the Great Pacific Garbage Patch reveals a common culprit.]

Although the study only formally evaluated one device, similar issues may apply to other marine cleaning devices. Things like the lack of an escape route, long periods of operation, and the time out of the water to separate marine life from organic matter and litter before it returns to the water can all contribute to the entrapment of marine organisms, says Parker-Jurd.

Moreover, the current capacity of technological efforts to reduce plastic collection is limited in comparison to the extent of the plastic pollution problem. “Though there are no estimates of the overall removal of plastic and other debris from these devices, there is near consensus among experts that the magnitude of trash collected pales in comparison to the amount of waste that enters our environment,” says Meagan Dunphy-Daly, director of the Duke University Marine Laboratory Scholars Program. She was not involved in the study.

There haven’t been many scientific studies on the effectiveness of various technologies in removing plastic pollution from the environment—or their rate of marine by-catch—but self-reported effectiveness is often higher than peer-reviewed reports on the efficacy, says Dunphy-Daly. Weather, current, and the location of the device deployment have to be considered when it comes to the effectiveness of cleanup technologies outside their pilot phases.

Dutch non-profit The Ocean Cleanup went under fire recently for the heap of plastic debris they cleaned from the Great Pacific Garbage Patch, which some experts say was too clean for plastics that were supposedly in the water for years. The organization argued that there was no visible build-up of algae and barnacles because the water in the garbage patch lacked nutrients. Most of the plastic floated above the water, but conservation experts also refuted that.

“Further studies need to evaluate the types of marine life being captured in these devices to determine population-level effects and weigh the risks and benefits of using these cleanup technologies,” says Dunphy-Daly.

Technology must go hand-in-hand with reducing plastic production and use

Developing and implementing technologies to reduce litter is only part of the solution. When there’s an oil spill, you don’t just focus on removing the oil from the surface of the water—you stop the leak and clean it up, says Dunphy-Daly.

The leak has undoubtedly continued in the case of global plastic pollution. She adds that combating it requires a comprehensive approach that targets all stages of the plastic life cycle, from reducing overall production to cleaning up what has entered the environment.

That said, the invention of cleanup devices effectively draws attention to the problem of marine litter. Last year, Coldplay partnered with The Ocean Cleanup and sponsored an Interceptor, a watercraft or vessel intended to remove plastic from rivers before they reach the ocean.

[Related: Horrific blobs of ‘plastitar’ are gunking up Atlantic beaches.]

“Hopefully, by generating public interest with these technologies, we can also gain support for targeting other life stages of plastic and reduce overall plastic pollution,” says Dunphy-Daly.

A 2021 report from the National Academies of Sciences, Engineering, and Medicine argued that recycling processes and infrastructures are insufficient to manage the gross amount of plastic waste produced. The authors recommended several interventions to reduce waste generation, like establishing a national cap on virgin plastic production and a ban on specific disposable plastic products.

Mechanical marine cleaning devices can shape perceptions around the issue of marine litter and potentially create a reliance on technological solutions to environmental problems. Therefore, these sorts of interventions should continue to be evaluated, says Parker-Jurd. According to a 2022 Societies paper, there is excessive optimism around technology and scientific advancement. Still, the man-made problems of the planet cannot be solved by modern and efficient technology alone.

Even though the invention of cleanup devices is unlikely to alleviate one’s responsibility for waste and litter completely, evidence of their psychological impacts is currently lacking and should still form a crucial part of future research, says Parker-Jurd. She adds, “our primary focus should remain on implementing a systematic change in the way we produce, use, and dispose of plastics.”

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This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

Every three years, Reinhold Hanel boards a research ship and voyages to the only sea in the world that’s located in the middle of an ocean. The Sargasso, bounded by currents instead of land, is an egg-shaped expanse that takes up about two-thirds of the North Atlantic, looping around Bermuda and stretching east more than 1,000 kilometers. Dubbed the “golden floating rainforest” thanks to the thick tangles of ocher-colored seaweed that blanket the water’s surface, the Sargasso is a slowly swirling sanctuary for over 270 marine species. And each year, the eels arrive.

The European eel and the American eel—both considered endangered by the International Union for Conservation of Nature—make this extraordinary migration. The Sargasso is the only place on Earth where they breed. The slithery creatures, some as long as 1.5 meters, arrive from Europe, North America, including parts of the Caribbean, and North Africa, including the Mediterranean Sea. Hanel, a fish biologist and director of the Thünen Institute of Fisheries Ecology in Bremerhaven, Germany, makes his own month-long migration here alongside a rotating cast of researchers, some of whom hope to solve mysteries that have long flummoxed marine biologists, anatomists, philosophers, and conservationists: What happens when these eels spawn in the wild? And what can be done to help the species recover from the impacts of habitat loss, pollution, overfishing, and hydropower? Scientists say that the answers could improve conservation. But, thus far, eels have kept most of their secrets to themselves.

The idea that eels have sex at all is a fairly modern notion. Ancient Egyptians associated eels with the sun god Atum and believed they sprang to life when the sun warmed the Nile. In the fourth century BCE, Aristotle proclaimed that eels spontaneously generated within “the entrails of the earth” and that they didn’t have genitals.

The no-genital theory held for generations. Roman naturalist Pliny the Elder asserted that eels rubbed against rocks and their dead skin “scrapings come to life.” Others credited eel provenance to everything from horses’ tails to dew drops on riverbanks. In medieval Europe, this presumed asexuality had real economic consequences and helped make the European eel a culturally important species, according to John Wyatt Greenlee, a medieval cartographic historian who wrote part of his dissertation on the subject. Frequent Christian holidays at the time required followers to adhere to church-sanctioned diets for much of the year. These prohibited adherents from eating “unclean” animals or meat that came from carnal acts, which could incite, as Thomas Aquinas put it, “an incentive to lust.” Fish were the exception, Greenlee says, and eels, given their abundance and “the fact that they just sort of appear and that nobody can find their reproductive organs at all,” appealed to anyone trying to avoid a sexy meal.

Eels could be practically anything to anyone: dinner or dessert; a cure for hangovers, drunkenness, or ear infections; material for wedding bands or magical jackets. They were even used as informal currency. Since yearly rent and taxes in medieval Europe were often due during Lent—the roughly 40-day period preceding Easter—and monasteries owned land people lived on, tenants sometimes paid with dried eels. Entire villages could pay 60,000 eels or more at once.

Eventually, spontaneous generation theories died. But eel genitals landed in the spotlight again after an Italian surgeon found ovaries in an eel from Comacchio, Italy, and the findings were published in the 18th century. The legitimacy of the so-called Comacchio eel remained in question for decades until an anatomist published a description of ovaries from a different Comacchio eel, launching a race to find testicles. Even the granddaddy of psychosexual development theory got involved: near the beginning of his career, in 1876, Sigmund Freud dissected at least 400 eels in search of gonads. It would be about another two decades before someone discovered a mature male eel near Sicily.

It’s no surprise that it took so long to find eel sex organs. There are more than 800 species, about 15 of which are freshwater varieties, and their bodies change so dramatically with age that scientists long thought the larvae were a different species than adult eels. Eels transform from eggs to transparent willow-leaflike larvae, to wormy see-through babies called glass eels, and onward until full size. Like most eel species, American and European eels don’t fully develop gonads until their last life stage, usually between 7 and 25 years in. Around that time, they leave inland fresh and brackish waters, where people can easily observe them, and migrate up to about 6,000 kilometers—roughly the distance from Canada’s easternmost tip to its westernmost—to the Sargasso.

By now, researchers have seen eels mate in lab settings, but they don’t know how this act plays out in the wild. The mechanisms that guide migration also remain somewhat enigmatic, as do the exact social, physical, and chemical conditions under which eels reproduce. Mature eels die after spawning, and larvae move to freshwater habitat, but when that happens and how each species finds its home continent are also unknown.

“We think that the European eel reproduces in the Sargasso Sea because this is the place where we have found the smaller larvae, but we have never found a European eel egg or the eels spawning,” says Estibaliz Díaz, a biologist at AZTI marine research center in Spain, who studies European eel population dynamics and management. “It’s still a theory that has not been proven.” The same applies to the American eel, and yet more questions remain about how many eels survive migration, what makes the Sargasso so singular, and how factors like climate change might affect it.

Both species have dropped in number, but researchers debate which threat is the biggest. Habitat loss is huge—humans have drained wetlands, polluted waters with urban and agricultural runoff, and built hydropower turbines that kill eels and dams that block the animals from migrating in or out of inland waters. Fishing further reduces eel numbers. Commercial fisheries for adult eels exist, but most eels consumed globally come from the aquaculture industry, which pulls young glass eels from the wild and raises them in farms. American and European eels are among the top three most commercially valuable species alongside the Japanese eel, which is also endangered. While it’s legal to fish for all three, regulations on when, where, and how many eels can be sold vary between countries. The European Union requires member nations to close their marine fisheries for three consecutive months around the winter migration season each year—countries themselves determine exact dates—and prohibits trade outside of member countries, but these management efforts are undermined by black-market traders who illegally export more than 90 tonnes of European eels to Asia every year.

The International Union for Conservation of Nature (IUCN) lists European eels as critically endangered—populations have plummeted more than 90 percent compared with historical levels, and it’s “rather unclear,” as one report notes, whether the decline continues today. By counting glass eels in estuaries and inland waters, researchers found that eel numbers dropped precipitously between the 1980s and 2011, but plateaued afterward without clear cause. American eels are thought to be faring better—they’re considered endangered only by IUCN standards, not by other conservation and research groups—though their numbers have also decreased since the 1970s.

Captive breeding might one day reduce the aquaculture industry’s dependence on wild catches, but isn’t yet viable. Scientists must induce eel gonad development with synthetic hormones. It’s also hard to keep larvae alive. Many researchers believe that, in their natural habitat, larvae eat marine snow—a mélange of decaying organic matter suspended in the water that is impractical to reproduce at commercial scales. Illuminating what happens in the Sargasso could help guide better conservation measures. That’s why Reinhold Hanel heads to sea.

After three years of COVID-19-related delay, in 2023, Hanel will send a research vessel on a 14-day trip from Germany to Bermuda. He’ll fly there and meet up with 11 other eel researchers, then he’ll spend about a month slowly traversing the southern Sargasso, recording ocean conditions, trawling for eel larvae with mesh plankton nets, and sampling for environmental DNA—genetic material shed from skin, mucus, and poop—to track eels by what they leave behind.

Hanel has led voyages like these since 2011. His main goal is to document the abundance of larvae and young eels and, secondarily, to identify possible locations for spawning. By sampling estuaries and inland waters, researchers can identify trends over time to figure out if glass eels in continental waters are increasing or not, but without comparing those trends with similar ones in the Sargasso, it’s impossible to judge whether either American or European eels are bouncing back. Meanwhile, protective regulations aren’t enough, Hanel contends. In 2007, the European Union mandated that member countries develop European eel recovery plans, but several prominent fishery and marine science organizations have criticized the particulars.

In tandem with other measures aimed at reducing eel mortality, provisions like closing fisheries make sense, Hanel says—last year, an international consortium of researchers, of which Hanel is a member, recommended closing fisheries until glass eel stocks recover. But other requirements aren’t rooted in research, including one to ensure 40 percent of adult eels survive to migrate from inland waters to the sea each year. “Scientists cannot say if 40 percent is sufficient to recover the stock,” Hanel says.

That’s why Hanel’s work is so important, says Martin Castonguay, a marine biologist and scientist emeritus at Fisheries and Oceans Canada, who has collaborated with Hanel. Financial obstacles often prevent eel scientists from conducting research outside of inland waters. Research vessels can cost anywhere from CAN $30,000 to $50,000 per day, or just under $1-million for a month-long trip, Castonguay says, requiring scientists to have hefty grants or government support to venture all the way to the Sargasso.

Despite the barriers, scientists keep trying to find answers to how to help eels recover. They have planted hydroacoustic devices in hopes of tracking migrating eels by sound, pored over satellite photos, and injected eels with hormones to induce gonad development before releasing them into the Sargasso to try to study how deep beneath the surface they spawn. Back at home in the lab, they’ve developed algorithms to scan for and spot eels in sonar images of inland waters and built hyperbaric swimming tubes to observe how eels respond to changes in pressure and current strength. They’ve even tried to follow them with satellite transmitters.

In the mid-2010s, Castonguay and four other researchers sewed buoyant trackers to 38 American eels and released them off the coast of Nova Scotia. Every 15 minutes, the trackers recorded the depth at which the eels were swimming, the water temperature, and light levels. The sensors were designed to detach several months later and transmit the data along with the eels’ final location. Unfortunately, they detached before the eels reached any specific spawning locations, though one eel got as close as 100 to 150 kilometers from the spawning region. Still, “it was the first time that an [adult American] eel was documented in the Sargasso,” says Castonguay. Previously, only larvae had been found there. “We were extremely excited.”

If more governments and research institutions were willing to spend the resources, Castonguay adds, these eels wouldn’t be so mysterious. Research on a similar species in Japan offers a case study for how that could work.

On the other side of the globe from the Sargasso, the Japanese eel makes a 3,000-kilometer annual migration from Japan and surrounding countries to the West Mariana Ridge in the western Pacific Ocean. With support from the Japanese government and other scientific institutions, researchers there have identified a spawning location, collected fertilized eggs, and tracked tagged eels swimming to their spawning area—all feats never attained in the Sargasso. They’ve found that Japanese eels spawn over a period of a few days before the new moon, at depths of 150 to 200 meters, and that spawning is triggered in part by temperature shifts that happen as eels move from deep to shallower water. Some eels, they learned, might spawn more than once during a spawning season.

Public outreach efforts have also been important, says University of Tokyo eel biologist Michael Miller. The researcher who led most of the eel work, Katsumi Tsukamoto—a University of Tokyo scientist emeritus known as Unagi Sensei, or Dr. Eel—has worked hard to raise the eels’ public profile. His findings have helped build the case that eels are “something other than just a meal,” Miller says. “It’s something [that’s] part of the Japanese culture and it’s worth conserving,” which has helped boost efforts to protect them.

Hanel is trying to do the same for the eels of the Sargasso and for other species. He speaks to the press and the public as often as he can. He believes, as many others do, that successfully conserving these creatures hinges on whether there’s a unified international effort to do so. But so long as data snapshots come only every few years, answers to questions about spawning and species well-being will stay hidden somewhere in the watery depths, just like the eels themselves.

This article first appeared in Hakai Magazine, and is republished here with permission.

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On a snowy January morning in 2022, I walk into Duo, an exclusive little restaurant in the heart of the southern Italian town of Lecce, carrying a polystyrene box filled with two frozen plate-sized jellyfish. Antonella Leone, a senior researcher at the Italian National Research Council’s Institute of Sciences of Food Production, is with me holding an authorization letter for chef Fabiano Viva to legally handle the sea creatures. Viva awaits us at the restaurant’s entrance, greets us with a hearty handshake, and takes the cooler. Within minutes, his assistant is defrosting the jellyfish under the tap. Viva laces up his white apron, fills a pot with water, and ignites the stove.

Leone is part of a small group of scientists who have been studying Mediterranean jellyfish for the past 12 years. For the last seven, they have involved chefs, testing ways to get the general public interested in eating the marine invertebrate.

“The idea of eating a jellyfish never crossed our minds, because we would only see one every once in a while,” Leone explains. But as several species of local and alien jellyfish became increasingly abundant—such as in 2014 when a jellyfish bloom saw 400 tonnes of the barrel jellyfish per square kilometer carpeting the massive Gulf of Taranto—Leone wondered what they could do with them.

But convincing Italians to eat jellyfish is like enticing them to try pineapple on pizza––not a simple task. Southern Italians eat octopus, sea urchin, and other sea creatures, but jellyfish are largely ignored. Selling jellyfish for human consumption is prohibited in the European Union, as regulators still do not consider the sea creature a safe, marketable food due to historical lack of interest in them as a food source, which is why Leone arrived at Duo with a permission letter in hand.

Safety concerns around jellyfish don’t seem to be a problem in China, where jellyfish have been on the menu for almost two millennia. (A favorite is an appetizer of chilled jellyfish seasoned with dark vinegar, sugar, soy sauce, chicken stock powder, and sesame oil.) Today, 19 countries harvest up to one million tonnes of the gelatinous sea dweller, contributing to a global industry worth around US $160-million.

Paired with forward-looking chefs like Viva, Leone and her team began researching ways to make jellyfish tasty and safe for Mediterranean menus in 2015. As ocean fish stocks continue to deplete at alarming rates, and jellyfish seem to be thriving, more and more people are asking if eating jellyfish will effectively mitigate the jellyfish problem, and if they will become a sustainable and safe source of food. But can jellyfish become a food of the future, not just for adventurous diners eating at upscale restaurants, but for all?

Jellyfish are in a broad group of aquatic animals that marine biologists refer to as “gelatinous macrozooplankton.” There are some 4,000 known species worldwide, probably others unknown. They can be as small as a cereal flake, like the highly venomous Irukandji box jellyfish mainly found off the coast of Australia, or have tentacles up to 36 meters long, like the enormous lion’s mane jellyfish. Jellyfish are an important part of marine ecosystems and serve as meals to 124 fish species and 34 other animals, such as the leatherback sea turtle.

But all is not well in the jellyfish world. Since the turn of this century, scientists have witnessed a worrying increase in jellyfish populations in various parts of the world. According to Lucas Brotz, a researcher who has long studied jellyfish at the Institute for the Oceans and Fisheries at the University of British Columbia, it’s not easy to understand the reasons behind the phenomenon.

“Not all jellyfish are increasing in all places, but we do see a sort of sustained major increase in many areas around the world,” says Brotz. And there are myriad reasons that could be driving this change, among them alien jellyfish species being introduced into new areas and range expansion as climate change and warming waters favor some species over others.

Like other marine invertebrates, jellyfish will reproduce in great numbers when conditions are right. Nutrient pollution and warming waters in some parts of the world have resulted in higher-than-normal jellyfish blooms and situations that can have negative repercussions on infrastructure, tourism, and more. Video by the Hakai Institute

The jellyfish increase is being felt particularly hard in places like the Mediterranean Sea and along the coast of Japan. Hordes of jellyfish have destroyed fish farms, clogged power plants, capsized fishing boats as they weighed down nets, and upended tourism by making waters unsafe for swimming. And their presence can impact creatures they share the sea with, too.

“Imagine [something the size of] the biggest oil tanker in the world, traveling along the Mediterranean coasts to Israel, consuming all the plankton,” says Stefano Piraino, Leone’s husband and a marine biologist and jellyfish expert at the University of Salento in Lecce, as he explains how massive blooms of jellyfish can hog all the plankton that other planktivores need.

Seeing the new availability of jellyfish in the Mediterranean, Piraino joined Leone in her quest to find possible culinary uses of jellyfish.

Back at Duo, Viva slips on latex gloves and carefully lifts the Rhizostoma pulmo jellyfish from below the running tap. They’re still a bit frozen, quite unlike the dried jellyfish used in Eastern cuisine, which must be rehydrated before use. Viva slips the jellies into a pot of boiling water and starts to stir.

When Leone started studying how jellyfish could be used for food or food ingredients—and how they could be preserved for later use—she stumbled upon one main problem. The primary method to preserve jellyfish, as perfected in Asia, was to dehydrate them using the chemical compound alum. But alum is considered toxic for human consumption and its use doesn’t meet the European Food Safety Authority’s standards. So Leone and her colleagues set out to devise a new and nontoxic way to desiccate edible jellyfish.

Her team overcame the drying challenge by using calcium salts instead of alum and went on to experiment with dried, fresh, and frozen jellies, turning them into mousse, meringue, seasonings, and thickeners.

The magic of turning gelatinous macrozooplankton into food and food products happens in Leone’s lab at the Institute of Sciences of Food Production, where she and her team of seven run their experiments. A long steel testing table with two shelves of transparent jars and scales at its center separates the expansive room. Inside an industrial fridge rest racks of test tubes containing jellyfish extracts to study.

But it is one thing to do research in a lab, and another to convince Italians to consider replacing fish with jellyfish in a soup. According to a 2020 study led by Luisa Torri, a professor of food science and technology at the University of Gastronomic Sciences of Pollenzo, there might be some hope for acceptance. The study surveyed 1,445 people on their attitude toward the idea of consuming jellyfish, taking into consideration traits such as age, behavioral habits, and mouthfeel, and showed that young, well-traveled people with higher education levels and sensitivity to the environment are the ones more likely to eat jellyfish.

I fit that category, so when Viva invites me to take a whiff of the white foam now bubbling rapidly on the stove, I try to keep an open mind.

I close my eyes and breathe deeply. “It smells like oysters,” I tell him.

“You need to disconnect your brain from what you know,” says Viva. “You need to detach yourself from the food in your memory.”

Is the key to accepting an unusual food making new food memories? If that’s the case, we’ll need to find a way to get jellyfish from the sea to dinner tables.

As well as helping to deal with future seas full of jellyfish, fishing for these creatures has been touted as a way to help small-scale European fishers, who are struggling with low fish stocks.

“A source of income? That would be great!” says Rocco Cazzato, a sixth-generation small-scale fisher from Tricase Porto, at the idea of fishing jellyfish. “But I would never eat them, not even if it’s the last thing left in the world to eat.”

Cazzato recounts the pain of pulling on his fishing nets crowded with jellyfish that he could not sell, and he says that if jellyfish were in demand locally like the commonly consumed scorpionfish, those jellyfish in the net would help small fishers like him make ends meet.

Although Leone is working to fill the information void, knowing which jellyfish are edible and safe for consumption is still a question few researchers are tasked with answering. According to Brotz, while many different jellyfish types are increasing worldwide, only a handful of them are preferred for human consumption. And just because they seem to be more abundant, it doesn’t mean that fishing them will be a panacea. The title of a 2016 paper Brotz coauthored says it all: “We should not assume that fishing jellyfish will solve our jellyfish problem.”

The paper advises caution: jellyfish are understudied, and the effects of removing them from the ecosystem, even when they are in excess, are unknown and potentially negative. Some jellyfish, for instance, act as nurseries for juvenile fish, and jellyfish can be both predator and prey in food chains.

Silvestro Greco, research director at the Anton Dohrn Zoological Station, echoes the concern that fishing isn’t necessarily the way to combat jellyfish blooms. He fears that once industrial jellyfish extraction begins, quick depletion might have unexpected consequences on local marine environments. In the early 2000s, for instance, a portion of the fishing fleet in the Gulf of California, Mexico, diverted its efforts to harvesting jellyfish. Fishers and processing plant workers quickly profited from the new market, but overfished the resource, leading to the rapid depletion of jellyfish.

Still, some fishers are poised to launch if a fishery opens—there is already Asian interest in fishing jellyfish in the Mediterranean. But even with interest from fishers, if there’s no market, then there’s no point.

According to Leone, the enterprise of getting jellyfish to the masses needs an entrepreneur willing to invest the several thousand euros needed to request that the European Food Safety Authority (EFSA) accepts jellyfish as edible food for sale, allowing them to be legally sold in fish markets and restaurants.

Leone believes that, with her team, she’s gathered the scientific research to support such an application to EFSA and that some entrepreneurs have shown interest. It’s only a matter of time before some species of jellyfish make the list of approved European foods, she says, and she’s keen to broker the divide between fishers, markets, and chefs.

Creating this market could help artisanal fishers, the ones most affected by jellyfish blooms, Leone says. “They come back with nets full of jellyfish and three fish inside. If jellyfish would become accepted edible food, they could sell it as sea products like others.”

Leone first targeted curious chefs—ones without preconceptions, eager to accept a challenge—in 2015, and they became important team members. Leone and her team are part of the EU-funded GoJelly project that looked into innovative uses for jellyfish—including in fertilizers, cosmetics, and nutraceuticals, and for snaring microplastics. Membership means that Leone can regularly bring Viva and other chefs jellyfish to experiment with in their kitchens and find ways to make the sea creature appetizing. Over the years, Viva has tried the jellyfish pickled and dehydrated like chips, and as an ingredient in soups and pasta sauces.

The most significant difficulty that Pasquale Palamaro, chef of the Michelin-star restaurant Indaco on the island of Ischia, encountered was the drop in weight as the jellyfish was cooked.

Jellyfish are 95 percent water and a small percentage of proteins, so when the animal dies, it loses much of the water. To avoid this loss, Palamaro believes they have to be consumed fresh within a few hours of harvest or stored safely frozen or preserved with the calcium salt technique that Leone developed.

Palamaro boils the Pelagia jellyfish from the Mediterranean for one minute, marinates it in citruses for an hour, and then seasons it with pumpkin seed oil before serving it with quinoa. Gennaro Esposito, chef of the Michelin-star restaurant Torre del Saracino in Vico Equense, prefers to pair the jellyfish with marinated cucumbers, chili kefir, and lettuce paste. Leone has collected the more successful recipes of these chefs and others in the freely available European Jellyfish Cookbook.

But not all chefs are convinced of the jellyfish’s culinary potential. In 2017, Greco, a marine biologist but also a food scientist and an avid cook, fried 50 kilograms of Pelagia jellyfish at the Slow Fish conference in Genova, Italy, to create awareness about the rapid rise in jellyfish numbers in the Mediterranean.

“It was a success,” Greco says, “but because they were fried. Everything fried is good.”

He believes jellyfish don’t have an interesting texture and don’t make a compelling case for culinary indulgence. All in all, he doesn’t believe that jellyfish will be quickly adopted by cuisines that traditionally never used them.

But according to Leone, jellyfish today are in the same situation as tomatoes in the 16th century. Tomatoes, now a key ingredient in traditional Mediterranean cuisine, were unknown before being brought over from the Americas around the 1550s. At first, they were thought to be toxic and unhealthy. Still, possibly thanks to forward-looking cooks, or simply because of necessity, tomatoes began appearing on pizzas and in parmigiana and pasta sauce, ultimately becoming part of the Mediterranean diet.

Whether or not jellyfish take a similar trajectory and become accepted in Western markets is hard to say, but many of our favored seafoods are declining or have already collapsed explains Brotz. “We may get to a point where there is no other seafood available.”

Back in the kitchen at Duo, Viva has turned one of the two jellyfish into a soup, adding tomato sauce, olive oil, a garlic clove, and a pinch of parsley. He offers me a serving.

I spot the turgid tentacles and part of the cap floating in the orange liquid, and my stomach turns. The first spoonful of broth goes down quickly. It tastes like a delicious––and fishy––tomato soup. Then I search for a piece of the jellyfish. I hesitate. I slurp it up.

It feels like a gulp of the sea itself as the flavor of the jellyfish unfurls in my mouth with the strength of a tsunami. The texture reminds me of calamari or a piece of fat from a cooked steak. As I chew, trying to repress the impulsive disgust, I think of cooked tripe. I swallow.

I look at Viva and say, honestly: “It tastes like the sea!” He smiles, agreeing.

As I take a few more polite spoonfuls, the words of Esposito, the chef of Torre del Saracino, come to mind. He’d pointed out that jellyfish carry a stigma of fear, but that the instinct to avoid them can be unlearned. Through cuisine, “we transform a fear and a dread into a taste, which is better,” he said.

I reflect that my hesitancy might be a result of cultural heritage—this food is as unfamiliar to me as a tomato was to my ancestors over 500 years ago—as Viva prepares the other jellyfish. He coats it with flour and deep-fries it in vegetable oil.

This time, it is crunchy and crispy—like a French fry. And, of course, it tastes great.

This article first appeared in Hakai Magazine, and is republished here with permission.

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Fifty years ago today, Congress passed the Marine Mammal Protection Act (MMPA), a law that set the global benchmark for conserving marine mammals. It was the first piece of legislation to call specifically for, “an ecosystem-level approach to wildlife protection.” According to the National Oceanic and Atmospheric Administration (NOAA), not a single marine mammal species has gone extinct in US waters since the law was passed in 1972, and the protections enacted have helped stop declines among many marine mammal species. The policy has even led to the recovery of many species including gray seals, California sea lions, and humpback whales.

In the Pacific Ocean, fish and humans alike are seeing some of the same benefits from strong regulations. At 582,578 square miles, the Papahānaumokuākea Marine National Monument in Hawaii is the world’s largest no-fishing zone and marine protected area (MPA). It was established in 2006 and expanded 10 years later with the goal of, “seamless integrated management to ensure ecological integrity and achieve strong, long-term protection and perpetuation of NWHI ecosystems, Native Hawaiian culture, and heritage resources for current and future generations.” And it appears to be working.

[Related: Eating sustainably may mean skipping the lobster for now.]

A study published this week in the journal Science finds that carefully placed no-fishing zones like Papahānaumokuākea can help restore tuna and other large fish species. “We show for the first time that a no-fishing zone can lead to the recovery and spillover of a migratory species like bigeye tuna,” says co-author John Lynham, a professor in the Department of Economics at the University of Hawaiʻi at Mānoa’s College of Social Sciences, in a press release.

The team used data collected from fishing boats and found that the catch rate of yellowfin tuna increased by 54 percent in the fishable waters close to the Papahānaumokuākea protected area since 2010. Additionally, the catch rates for bigeye tuna increased by 12 percent and it was 8 percent for all fish species combined in the years since the MPA was expanded.

Both the size of the no-fishing zone (about four times the size of California) and apparent homing behaviors of some tuna species possibly played a role in these positive effects. The Hawaiian islands appear to be a nursery for baby yellowfin tuna and many of the fish stay in the region, according to study co-author Jennifer Raynor, a professor in the Department of Forest and Wildlife Ecology at the University of Wisconsin-Madison.

[Related: A tuna robot reveals the art of gliding gracefully through water.]

Additionally, the positive results seen in this study aren’t necessarily an isolated global incident. “This study echoes similar work done in the Galapagos Marine Reserve, showing large and persistent fishery benefits for highly migratory species,” Boris Worm from the Department of Biology at Dalhousie University in Nova Scotia says in an email to Popular Science. “It builds a strong case for large-scale marine protected areas not just as biodiversity conservation, but as fishery rebuilding tools. Responsible fishing and conservation do not oppose each other – they are two sides of the same sustainability strategy.” Worm was not involved in the study.

These big fish are also big business. Fortune Business Insights estimates that the global tuna fish market will be worth $48.19 billion by 2028. Yellowfin tuna and bigeye tuna (which you may have seen listed on a sushi menu as ʻahi) cost an average of $28 to $35 per pound and the most expensive on record sold for more than $3 million at a 2019 auction in Tokyo, Japan.

However, they are are historically important to Hawaii’s diet and culture. One of the study’s co-authors, Sarah Medoff, was born and raised in Hawaii and pointed to how ‘ahi is a focal point at family gatherings and celebrations, and conservation will ensure that that tradition can continue.

“Conservation and economic progress are often viewed as opposing forces, meaning, you cannot achieve one without sacrificing the other. This study is a perfect example of how conservation objectives can be met without sacrificing the livelihood of people who depend on this resource. If we construct a well thought out conservation plan, we can reverse environmental damages,” Medoff, a researcher at the School of Ocean and Earth Science and Technology at the University of Hawaiʻi at Mānoa, says in an email to Popular Science.

Papahānaumokuākea is considered sacred by Native Hawaiians and the monument is co-managed by Native Hawaiians and the state and federal government. “This research by Medoff et al. reaffirms the value of large scale marine protected areas in the Pacific,” Kekuewa Kikiloi, associate professor in the Kamakakūokalani Center for Hawaiian Studies at the University of Hawaii at Mānoa, says in a press release. “The protections that were fought for by Native Hawaiians and other stakeholders for Papahānaumokuākea serve to benefit everyone, including fishing interests.”

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Wearing a navy-blue polo neck emblazoned with the Florida Aquarium logo, Keri O’Neil hugs a white cooler at Miami International Airport. “Coral babieeeeees,” she says, before letting out a short laugh. Relief. The container holds 10 plastic bottles teeming with thousands of tiny peach-colored specks. Shaped like cornflakes and no more than a millimeter in length, they are the larvae of elkhorn coral, an endangered species that is as characteristic to the reefs of the Florida Keys and the Caribbean as polar bears are to the Arctic or giant sequoias to Sierra Nevada.

With the larvae kept at 27 °C inside their insulated cooler nestled in the trunk of her car, O’Neil drives back to the Florida Aquarium in Tampa, where she works as senior coral scientist at the aquarium’s Center for Conservation. Once there, the larvae begin their metamorphosis from free-swimming specks into settled polyps, the beginnings of those branching, antler-like shapes that define this species. O’Neil and her colleagues provide everything the coral needs for a strong start in life: warm water with a gentle flow, symbiotic algae that find a home inside the coral’s cells, a soft glow of sunlight, and some ceramic squares “seasoned with algae” that act as landing pads for the larvae.

The transformation of larvae into polyps was the final step in a coral breeding project that began on the shores of Curaçao, an island off the coast of Venezuela, in the summer of 2018 and involved a cadre of conservationists and scientists who each specialize in one specific stage of coral development. From collection of eggs during mass spawning events to the cryopreservation of sperm, and from fertilization to larval growth, every step had to go swimmingly for the project to have any chance of success. “It’s like the most stressful relay on Earth,” says Kristen Marhaver, a coral scientist at the Caribbean Research and Management of Biodiversity Foundation in Curaçao, who helped start this relay race by collecting eggs during a nighttime dive at a reef that’s a 45-minute drive from her laboratory. As O’Neil was picking up her coral “babies” in Miami, a second team of scientists at Mote Marine Laboratory and Aquarium in Sarasota, Florida, received its own. The pressure on both labs was immense. To fail now would be to drop the baton just before the final straight.

But, if anything, their efforts were too successful; hundreds of larvae settled as translucent and fragile blobs of tissue (each a single polyp) and then started to divide, branching into the clear waters of their shallow, open-top tanks. Elkhorn coral grows an average of five to 10 centimeters per year, a bamboo-like pace for corals in general. To stop them becoming entangled, O’Neil had to cut, separate, and move her colonies to different paddle pool–sized tanks over the course of the next year. “We almost ended up with a six-foot-by-four-foot [1.8-meter-by-1.2-meter] solid piece of elkhorn coral made up of 400 different individuals,” she says. “They were just outgrowing the tanks.”

The rows of coral in O’Neil’s tanks are a window into a former world. The reefs of the Florida Keys were once dominated by elkhorn coral. Visiting these islands that curl southward from Florida like the tip of a bird of prey’s beak, biologist, conservationist, and writer—most notably of Silent Spring, but also of several books on the ocean—Rachel Carson peered into the shallows using a “water glass,” an instrument akin to a glass-bottom bucket. Through this simple portal, she saw great stands of “trees of stone,” a forest of coral. Today, after decades of disease, coastal development, and bleaching, over 95 percent of the state’s elkhorn coral have been lost. And this population isn’t just depleted in number, like a forest that’s been felled, but is also impoverished from within. Some reefs in the Keys descend from a single individual that has reproduced via fragmentation—bits break off the parent coral and start a new colony. This mode of reproduction allows corals to spread, but without the genetic mixing that comes with sex, these clones are more susceptible to disturbances such as disease. The coral larvae raised by O’Neil at the Florida Aquarium are different; they are the product of sperm and egg, a shuffling of genes, and the growth of genetically unique clumps of coral. Reintroducing them could provide a boost to the coral’s genetic diversity—a quick stir to the gene pool—and could save a denuded ecosystem. Their reintroduction could also spell its doom.

Hidden inside the genetic code of the Florida Aquarium’s coral is a map of an atypical origin: the eggs collected from Curaçao were fertilized using sperm from the Caribbean, including Florida. Although the same species (Acropora palmata), these coral populations would never breed in the wild. The distance between the two is hundreds of kilometers and contains the island blockade of the Greater Antilles—an impossible journey for any sperm. The coral housed in the Florida Aquarium are the products of human hands, the latest addition to a recent—and often controversial—trend in conservation known as “assisted gene flow,” shuttling existing genetic diversity to new places.

No hands have offered more assistance to these coral than those of Mary Hagedorn, senior research scientist at the Smithsonian Conservation Biology Institute, who is based at the University of Hawai‘i at Mānoa. Hagedorn flew to the Caribbean to guide this project from start to finish. It is her research that made this work possible. Since 2004, she has developed cryopreservation techniques that can freeze coral sperm and—just as importantly—keep them fertile upon thawing. Although cryopreservation has been used for IVF in humans and other mammals for decades, it’s only in the last few years that other coral conservationists have adopted Hagedorn’s techniques for coral sperm. At a time when these methodologies are most needed, Hagedorn’s work has matured into a solid science, says Tom Moore, a coral restoration manager at the National Oceanic and Atmospheric Administration at the time of this project and now in the private sector. “I think we’re going to start seeing a lot more of this done in the course of the next few years.”

Without the option to freeze sperm, coral conservationists have been forced to work within the few hours these sex cells remain viable. In Florida, Moore says, scientists from the Lower Keys would drive north to meet colleagues from the Upper Keys and swap sperm samples on the side of the road, fertilizing eggs there and then before the sperm stopped swimming. With the option to freeze sperm using liquid nitrogen, however, samples can be transported long distances—from Florida to Curaçao, for example. Then, when eggs are collected from the reef, the sperm can be thawed and used in concentrations that make fertilization most likely. Hagedorn’s work opens up new possibilities that, just a few years ago, were largely ignored.

Self-funded for many years, Hagedorn’s research was nearly stopped altogether in December 2011. Her savings had run out and funders didn’t seem to see the potential of her work. “I was a month away from closing my lab,” she says. Then she received an unexpected call from the Roddenberry Foundation, a philanthropic organization set up in memory of Gene Roddenberry, the writer of Star Trek. Since Hagedorn’s work fit the criteria for bold and unique science, the foundation wanted to fund her research for five years. Since then, her work has grown to include frozen larvae, frozen coral symbiotic algae, and frozen coral fragments, and it has been adopted by labs around the world. To help her cryopreservation methods spread, Hagedorn runs workshops and shares her techniques freely; the instructions to build her equipment can be downloaded and then manufactured with a 3D printer.

As with IVF in humans, coral fertilization is not a perfect science. In a study published in 2017, Hagedorn and her colleagues showed that fertilization rates from frozen coral sperm are significantly lower than from fresh sperm, roughly 50 percent versus over 90 percent. And these figures were based on coral that lived as neighbors on the same reef. The researchers wanted to increase genetic diversity in the future (through assisted gene flow), but it was still unknown whether populations that had been isolated for thousands of years could produce viable offspring, especially after their sperm had been frozen. The idea to breed elkhorn coral from the Florida Keys with those from Curaçao was the most extreme test yet of Hagedorn’s methods. It was a moonshot for coral conservation, says O’Neil. “We wanted to do something that had never been done before.”

Marhaver thought that they had a five to 10 percent chance of success. To have hundreds of healthy coral now sitting in tanks barely crossed her mind. Conservationists are more attuned to the vibrations of endangerment, extinction, and loss. To have a moonshot succeed is unfamiliar territory. With the impossible now possible, the next hurdle is moving from the lab to the ocean, a leap that not everyone is comfortable with.

As in medical practice, the first rule of restoring ailing ecosystems is primum non nocere, “first, do no harm.” And what concerns Lisa Gregg, program and policy coordinator at the Florida Fish and Wildlife Conservation Commission (FWC), the organization that decides the fate of the Florida-Curaçao coral, is that they aren’t suited to the local conditions of the Florida Keys, a place that Carson referred to as having an atmosphere that is “strongly and peculiarly [its] own.” These islands are formed from sedimentation, while those of Curaçao and the eastern Caribbean are founded on volcanic activity. Plus, the Florida Keys also have their own unique combination of problems, from infectious disease to coastal development, and from hurricanes to coral bleaching. “We have a lot of problems here,” says O’Neil. “And it is quite likely that the corals that are still alive in Florida after everything that’s happened to them are probably the ones that are best suited to living in Florida and providing offspring that may be capable of surviving in Florida.” If Curaçao genes were introduced, they might lead to lower rates of reproduction, shorter life spans, or lowered resistance to local diseases. Imperceptible at first, such “outbreeding depression” can slowly weaken a population, generation by generation. To introduce genes that haven’t experienced the same history could be a ratchet toward extinction.

The risk of such outbreeding depression is very low, however—a doomsday forecast for Florida’s reefs, many conservationists think. “I’m not so concerned that there’s a huge risk of the Curaçao [genes] causing a major detriment to the native Florida population,” says Iliana Baums, head of marine conservation and restoration at the University of Oldenburg, Germany, who has studied elkhorn coral since 1998. “But that’s based on my knowledge of the literature for other species and modeling and so on. I don’t have any direct evidence for that.” Direct evidence would require reintroduction, a catch-22 of conservation; the very thing that is controversial and potentially dangerous is also the route to understanding.

Gregg was clear with O’Neil, Marhaver, Hagedorn, and their colleagues from the beginning of this project. “They knew right off the bat … that they were not going to be able to out-plant [the coral]. It was never in question.” The FWC has a “nearest neighbor” policy when it comes to conserving Florida’s coral reefs, she says. “With Acropora palmata, I believe the nearest neighbor would be Cuba or Belize. But other acceptable areas to bring corals in from would be Mexico or the Bahamas. If you’ve got corals coming from Curaçao, that’s leaps and bounds away from Florida.”

After nearly 20 years of research and the near closure of her lab, Hagedorn is tired of waiting. She is sympathetic to the FWC’s approach, but also believes that this large population of captive coral should be introduced—in “a restricted and monitored fashion”—given the critical status of A. palmata. “There’s so little coral in Florida now, it’s just a joke,” she says. In addition to tracking their precipitous decline, scientists have tried to find evidence that new, sexually produced elkhorn coral are settling in the area, but they regularly come back empty-handed. Since this species releases sperm and eggs en masse once a year, the lack of natural recruitment is a worrying sign that such mass spawning events are failing. Warmer waters, pollution, a thick covering of algae, and the rarity of mature coral all add up to prevent new baby coral from settling. Whatever the case, successful sexual reproduction—the fertilization of egg and sperm to create a swimming larva—is so low that it no longer supports this population. “Every year, we seem to lose more [coral] without making more, because sexual reproduction isn’t working,” says Baums. “None of us could’ve imagined that these coral populations would die out this fast. I don’t think any one of us could have really wrapped our heads around that, even 10 years ago … I think we’re at the stage that we need to try something new.”

Even with this precipitous decline, there is still time to try a less extreme version of assisted gene flow, O’Neil says. Now that the Florida-Curaçao experiment has been a success, her team can consider crossing coral from Mexico, the Bahamas, or Cuba—just a relative stone’s throw away—with Florida stock. These populations are able to mix naturally: although sperm can’t survive the journey, the planktonic larvae can travel the current from the Bahamas to Florida so are considered part of the same subpopulation. Gregg says that she would support any elkhorn restoration project that conforms to the FWC “nearest neighbor” policy. Until then, such assisted gene flow will remain limited to laboratories and aquariums.

In December 2021, O’Neil said goodbye to the coral she had raised from peach-colored larvae to hand-sized elkhorn recruits. With the project’s end, they were being transported from the Florida Aquarium to the Mote Marine Laboratory and Aquarium, where they joined the rest of the coral grown as part of this study. Some are being exposed to warmer temperatures to see if they are better able to survive in the warmer waters predicted for the future. Others will be transported to museums and aquariums around the United States. The rest sit patiently and continue to divide, to grow, polyp by polyp. They may never be introduced into the wild, but their mere existence opens a wide-angle vista for coral conservation. If such disparate populations can be crossed and grown by the hundred, almost anything is possible. The next coral babies that O’Neil collects from the airport will have simply traveled a shorter distance in their cooler.

This article first appeared in Hakai Magazine, and is republished here with permission.

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Batteries to store renewable energy and power electric vehicles are essential if countries, communities, and businesses hope to meet climate change and clean energy goals. But, these technologies require complicated-to-mine materials like lithium, cobalt, and nickel. And the demand for these minerals is only expected to increase—the market for battery cells is predicted to grow by more than 20 percent annually until 2030.

This increasing demand for batteries rustles up interest in seabed mineral extraction because the deep seafloor may contain enough minerals to support the transition to a low-carbon energy system.

However, deep-sea mining—the process of extracting minerals from the ocean below 200 meters—may destroy habitats and cause the loss of marine species. Is mineral extraction initiatives in shallow sea areas the key to meeting mineral demand sustainably? It’s unlikely, according to researchers.

Shallow-water mining isn’t necessarily a sustainable option

Shallow-water mining, defined as extracting materials at depths less than 200 meters deep under the water, is a contentious subject. Two factors are often considered it comes to the sustainability of deep-sea mining versus shallow-water mining: We have better knowledge of shallow-water ecosystems, and their biological communities have shorter recovery times, says Laura Kaikkonen, visiting scholar at the University of Helsinki Ecosystems and Environment Research Programme.

Deep-sea ecosystems are incredibly understudied, and the lack of data makes predicting the long-term impacts of mining very difficult. In addition, deep-sea species are long-lived and reproduce less often than their shallow-water counterparts. Therefore their populations will take much longer to recover, she adds. However, a recent study published in Trends in Ecology & Evolution argues that there are no thorough and impartial comparisons between the two. Consequently, the paper argues there are no justifications in favor of shallow-water mining.

“Despite ​claims about how shallow-water mining can be the environmentally and socially sustainable alternative to traditional mining, thus far there have not been any thorough evaluations of the impacts of different mining practices to back these claims,” says Kaikkonen, who was involved in the new study.

Shallow-water mining may save operational costs because it takes place closer to the shore, and dredging shallow seafloor minerals is often efficient. But, any mineral extraction from the seabed will result in several environmental changes, including disrupting shallow-water minerals and their massive role in the habitat of seafloor organisms. And when seafloor organisms hurt, those impacts can be felt all the way up the chain of marine life, Kaikkonen adds.

However, shallow-water ecosystems may be more tolerant of mining-related stressors like elevated turbidity, sediment burial, and noise levels, says Craig Smith, professor emeritus in the Department of Oceanography at the University of Hawai’i at Mānoa who was not involved in the study. That’s because shallow-water ecosystems usually experience noise and disruption from the surface more often than their deep-sea counterparts due to human activity.

That said, no matter how minimal, the noise, vibrations, and other impacts of mining operations may be detrimental—especially since the effects added would be on top of the stressors that already exist from human activities, pollution, and the impacts of climate change, says Kaikkonen. She adds that we must evaluate whether the short-term benefit from seafloor minerals is worth the permanent damage to ecosystems.

Shallow-water mining is likely to cause heavy metal contamination of the marine environment, damaging different habitat types that may take decades to recover, says Andrew K. Sweetman, professor of deep-sea ecology at the Heriot-Watt University who was not involved in the study. 

A 2021 Environmental Science and Pollution Research study assessed water and fish samples from fourteen monitoring stations to determine heavy metal contamination in the Persian Gulf. The authors found high concentrations of heavy metals like copper, nickel, and lead in water samples from stations near petrochemical plants. They also discovered that fish populations dwelling near the seafloor were more contaminated than those living within the top five meters of the water column, making them hazardous to human health.

More research about the environmental impacts of shallow-water mining is needed

Before rushing to exploit new mineral resources, research and development should be targeted to improve the use of what we already have, says Kaikkonen.

According to a 2022 commentary in One Earth, seabed mining is often justified by the incorrect assumption that land-based metal reserves are rapidly depleting. But, this isn’t true—the identified resources of nickel and cobalt on land can meet global demand for decades. Therefore, it’s essential to embrace circular economy practices that reuse, repurpose, and recycle minerals as much as possible to avoid the expansion of mining into the ocean.

For instance, nickel has a high recycling efficiency, and about 68 percent of all nickel from consumer products is recycled. However, plenty of factors stand in the way of increased recycling of cobalt and lithium. This includes inefficient collection infrastructure, product design without thinking of second-life uses, and price fluctuations of raw materials.

Although some extractive activity might be necessary to move to a carbon-negative economy, it must be done properly—which means doing baseline and impact assessments, says Sweetman. Smith suggests proceeding very slowly with deep-sea and shallow-water mining, allowing only one operation to happen until the resulting intensity and extent of the disturbance to ecosystems is well-understood. It’s essential to close the significant knowledge gaps on the potential impacts of mining before seafloor mining is allowed to proceed at a large scale, he adds. 

Protecting large areas from mining may also preserve regional biodiversity and ecosystem services, says Smith. The International Seabed Authority (ISA), an intergovernmental body of 167 member states and the European Union, was formed to protect the marine environment by regulating mining operations in international seabed areas. But, the group has faced controversy given that they have granted at least 30 exploration contacts covering more than 1.3 million square kilometers of the deep seafloor, leading some environmental activists to argue that they prioritize the development of deep-sea mining over environmental protection.

Shallow-water mining activities should not be considered the silver bullet to resolving the growing global need for metals. Fully powering the world’s growing demand for electric vehicles and storage—even with all currently known mineral resources—is unrealistic, says Kaikkonen. For a future that is sustainable for human life and the ecosystems that will be affected by growing demand, shrinking energy use is just as important as finding new ways to power the world.

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Without its scary rows and rows of razor sharp teeth, your average great white shark (Carcharodon carcharias) wouldn’t be quite as terrifying. Their ancient ancestors (known as acanthodians) were even more prickly, with bristly spines along their fins. Now, a new fossilized fish skeleton found in China is older than the next-oldest specimen by a whopping 15 million years and is the, “oldest undisputed jawed fish.”

In a paper published in the journal Nature, the team of researchers from the Chinese Academy of Sciences, Qujing Normal University, and the University of Birmingham in the United Kingdom write that the new species Fanjingshania renovatais (F. renovata for short) has a body is similar to a spiny acanthodian. They lie somewhere between the class chondrichthyans (modern sharks and rays) and the group osteichthyans (bony fish). They lived in the the Paleozoic period, and F. renovata may be the close relative of a yet-to-be discovered common ancestor of both modern class and group of fish.

The team thousands of tiny skeletal fragments to reconstruct F. renovata, which show that it is a is a funky fish with an external bony “armor” and multiple pairs of fin spines. These spines set it apart from current jawed fish as well as cartilage containing sharks and rays and bony ray- and lobe-finned fish. The new species was uncovered in the bone bed samples of the Rongxi Formation in South China and named after the UNESCO World Heritage Site Fanjingshan.

[Related: 3D models show the megalodon was faster, fiercer than we ever thought.]

“This is the oldest jawed fish with known anatomy,” ZHU Min from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences said in a press release. “The new data allowed us to place Fanjingshania in the phylogenetic tree of early vertebrates and gain much needed information about the evolutionary steps leading to the origin of important vertebrate adaptations such as jaws, sensory systems, and paired appendages.”

This discovery shows evidence that major vertebrate groups began to diversify tens of millions of years before the beginning of the Devonian period, or the Age of Fishes, about 419.2 million and 358.9 million years ago when many different kinds of fishes began to swim Earth’s oceans.

According to the study, there are several features that set apart F. renovata from any known modern or ancient vertebrate. Its has armor along its shoulders that fuse together as a unit that covers more area than other known acanthodians.

Its spiny fins were covered in unusual teeth-like scales, that possibly would fall out in clumps and regrow. Sharks living today also shed and regrow teeth, but aren’t replaced in this way. F. renovata‘s fossilized bones show evidence of resorption, or when parts of bones or teeth break down and are later replaced. This process usually occurs during the organism’s development.

[Related: This whale fossil could reveal evidence of a 15-million-year-old megalodon attack.]

“This level of hard tissue modification is unprecedented in chondrichthyans, a group that includes modern cartilaginous fish and their extinct ancestors,” lead author Plamen Andreev, a researcher at Qujing Normal University, said in a statement. “It speaks about greater than currently understood developmental plasticity of the mineralized skeleton at the onset of jawed fish diversification.”

F. renovata is one of several fossils that this same team uncovered at the Rongxi Formation site. The team describes another species of extinct jawed fish (Qianodus duplicis or Q. duplicis) published in a separate study in Nature. This species is also about 439 million years old, but it was described only from fossilized scales and teeth, so the researchers are more uncertain about exactly which fish group it may have been a member of.

Three other extinct fish species unearthed at the site include Xiushanosteus mirabilis, Shenacanthus vermiforis, and Tujiaaspis vividus. While none of them were quite as old as F. renovata or Q. duplicis, X. mirabilis and S. vermiforis are still older than any other known species of early jawed fish.

The newly discovered species are changing what scientists already knew about the evolution of jawed fishes. While researchers first estimated this evolution took place about 420 million years ago, now we can place its jump 20 million years earlier than that.

“The new discovery puts into question existing models of vertebrate evolution by significantly condensing the timeframe for the emergence of jawed fish from their closest jawless ancestors,” said Ivan J. Sansom from the University of Birmingham, in a statement. “This will have profound impact on how we assess evolutionary rates in early vertebrates and the relationship between morphological and molecular change in these groups.”

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Weeks before we even think about getting sandbags or boarding up windows to prevent hurricane damage, an underwater evacuation begins. Sharks, sea snakes, and other wildlife will make preparations to escape becoming trapped or hurt as massive storms approach a coast. 

Much of Florida’s aquatic life—including species as diverse as manatees and alligators—know what to do in a storm like Hurricane Ian. After all, these native animals have had millions more years of practice than us. But those age-old skills will only become more useful as hurricanes become more intense from climate change. 

“Aquatic animals respond to storms for the same reason we do—to avoid injury, death, and the destruction from hurricanes,” says Bradley Strickland, a postdoctoral researcher who studies aquatic animal response to hurricanes and climate change at William and Mary’s Virginia Institute of Marine Science. Still, some animals are better equipped to weather or evade the storms than others. And sharks are among the best. 

[Related: Sharks are learning to love coastal cities]

Even when a hurricane is far on the horizon, the atmosphere changes: the barometric pressure drops. “From two weeks out of a hurricane, sharks can actually detect the change and start heading for deeper water,” says Neil Hammerschlag, director of the shark research and conservation program at the University of Miami. The air around Hurricane Ian has gradually been decreasing in pressure as the storm strengthens, and sharks can sense that, allowing them to flee long before Florida’s human residents were given mandatory evacuation orders. 

“Similar to the way we use meteorological technologies and observations about the changing wind and temperature before a storm, aquatic animals have ways to sense the approach of a storm,” Strickland says. Sharks use their sensitive inner ears to detect a gathering storm’s pressure changes, he adds. And, because of their incredible swimming abilities (some can swim up to 45 miles per hour), they can quickly escape oncoming storms—that is, if they choose to. 

Smaller shark species and juveniles opt to escape to deeper water to avoid the turbulence near the shore. For them, “staying in shallow water would be like a shark tornado,” Hammerschlag says, because hurricanes can push currents up to 300 feet below the ocean’s surface. For smaller sharks that remain in the shallows, they risk being swept inland.

Yet other larger predators, like tiger sharks that grow up to 14 feet and 1,400 pounds, view hurricanes as an opportunity for the ultimate sea smorgasbord. By tracking tiger sharks during and after Hurricane Irma, Hammerschlag noticed that “not only did they not run away, but they may have been taking advantage of the things that were dying, either birds that got washed into the water or fish and invertebrates that collided with debris.” After the storm, he adds, there were “higher numbers of tiger sharks in the area for about two weeks.”

For aquatic and semi-aquatic animals that can’t ride out the storm or swim beyond its reach, finding shelter may be the superior option for survival. “Sea snakes will seek refuge in volcanic rocks to avoid typhoons,” Strickland says. “Alligators likely hunker down to weather a storm by finding easy to get in and out of places,” he adds. Some smaller gators may get swept away by hurricanes; others might change their foraging patterns altogether to stay safe. 

Other species may be less lucky. The graceful manatee, for example, has been found in particularly sticky situations post-hurricane. Although weight-wise they are comparable to a tiger shark, speed-wise they are definitely not, cruising up to 15 mph only if they really push it. And try as they might to hunker down before a storm, this doesn’t always work out for them. Instead, they may get swept out of coastal waters by floods. Others, curious to explore new streams, have been found stuck in smaller ponds, forests, or even by roads after post-storm swims through flooded areas. Yet hurricanes rank low on the dangers to manatees, a threatened keystone species in Florida often imperiled by watercraft.

Even if Hurricane Ian is the first big tempest that a Floridian animal will experience, the odds are good it will take some kind of action. “We see animals evacuating the places they call home in advance of a major storm despite, in some cases, having never experienced a hurricane within their lifetime,” Strickland says. “This shows just how innate it is to protect yourself from a storm by preparing or fleeing compared to just waiting it out.”

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Humans have consumed meat all throughout history, but more recently, meat consumption has exploded. Global meat production reached about 375 million tons in 2018, more than triple the amount that the world produced fifty years ago. 

The production of animal-based foods carry heavy environmental impacts, using approximately 2422 cubic gigameters of water yearly. They also account for about 57 percent of all greenhouse gas (GHG) emissions from food production—almost twice the emissions from plant-based foods—not to mention that livestock grazing takes up about 26 percent of the Earth’s ice-free land.

Given its impact on climate change, many argue that it’s time to reduce red meat consumption and explore viable alternatives. For some meat lovers, seafood may be the ideal swap.

Seafood is a relatively low climate impact source of highly nutritious food. The authors of a new Nature study analyzed the GHG emissions associated with the production of various seafood like whitefish and crustaceans as well as their respective nutrient densities. They found that reducing the consumption of red meat and replacing it with certain seafood species may improve nutrition and reduce GHG emissions at the same time.

[Related: Eating sustainably may mean skipping the lobster for now.]

Seafood contains nutrients that other foods don’t have, or only in very low levels, such as iodine, vitamin D, and omega-3 fatty acids, says Friederike Ziegler, study author and senior scientist at the RISE Research Institutes of Sweden. In terms of nutrition and greenhouse gas emissions, those that performed best or had the lowest emissions per nutrient density were small pelagic species (like anchovies, mackerels, and herrings), bivalves like mussels and oysters, and salmonids, she adds.

Based on the study, large pelagics like yellowfin tuna also had high nutrient density scores, but they produced more emissions than small pelagics, bivalves, and salmonids. Meanwhile, most whitefish species—like the Atlantic cod—had fewer GHG emissions per edible product than large pelagics, but they weren’t as nutritious.

“Diet shift is a key strategy to reduce greenhouse gas emissions,” says Greg Keoleian, director of the Center for Sustainable Systems at the University of Michigan’s School for Environment and Sustainability who was not involved in the study. Shifting from beef to different seafood may lead to a large reduction in emissions, but sustainability is hardly ever that simple. 

A primary concern for switching from turf to surf is the sustainable production of each seafood species. This depends on various factors such as the source and production method as well as the feed for aquaculture, he adds.

In 1974, about 10 percent of fish stocks were being fished at biologically unsustainable levels, meaning they were being caught at a rate faster than the fish can recover its population. Since then, this percentage has tripled—rising to 31 percent in 2013 and 34 percent in 2020. Overfishing, the main driver of ocean wildlife population decline, can cause the loss of breeders, disruption of natural communities, and a massive depletion of many species, thereby harming ocean biodiversity.

“Many small pelagic fish stocks are currently overfished and they play a vital role in aquatic ecosystems,” says Keoleian. “These fish are also heavily fished for fishmeal used in aquaculture.  Many salmon stocks are also overfished and bivalves populations are declining due to climate change, so sustainability of production from increased demand could be a concern.”

There is potential to increase production and total consumption of small pelagic species by making use of underexploited species. Additionally, utilizing other species that typically end up in fishmeal and fish oil in aquafeeds could be beneficial, says Ray Hilborn, professor at the University of Washington School of Aquatic and Fishery Sciences.

Salmon, on the other hand, is pretty much fully exploited. “Any hopes for increased hatchery production are dubious because there appears to be competition for food in the North Pacific ocean, so more hatcheries would not likely increase total production,” says Hilborn.

Policymakers play a major role in shaping sustainable seafood production. They affect the food system from different angles, ranging from dietary advice that influences people’s eating habits to fishing regulations or aquaculture licensing procedures that shape the sustainability and volume of production in fisheries and aquaculture, says Ziegler.

For example, the Keep Finfish Free Act of 2019 aimed to prohibit the issuance of permits to conduct finfish aquaculture in the US Exclusive Economic Zone, unless specifically authorized by Congress. The health and integrity of Alaska’s wild fish stock must be protected and properly managed, otherwise, industrial aquaculture operations may threaten the ecosystem with non-native and genetically modified fish species, according to Alaska Rep. Don Young who filed the legislation.

[Related: How to eat sustainably without sacrificing your favorite foods.]

To increase seafood production without causing further environmental harm, all wild stocks must be managed sustainably, which means fishing within their biological limits and protecting the ecosystem they depend on, says Ziegler. This maximizes the harvest from capture fisheries.

Ensuring that the harvested fish biomass is used for food and not wasted along the supply chain would also make a difference. A lot of fish processing trimmings are used in feeds, even though it is fully possible to utilize more of these side streams to produce nutritious food or food ingredients, she adds.

Meanwhile, designating marine protection areas (MPA) can be effective in restoring ecosystems, says Keoleian. Labels informing consumers of sustainable seafood production may also influence consumers’ consumption, he adds. For instance, the Marine Stewardship Council certification is a way to show that a particular fishery meets established standards and best practices for sustainable fishing.

Overall, if you want to reduce your carbon footprint and eat red meat less frequently, try incorporating more sustainably-sourced seafood into your diet. Not only will you be helping the planet, but you’ll also benefit from having a more varied diet.

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This article was originally featured on High Country News.

Lake Merritt, in the center of Oakland, California, is a tidal estuary connected to the Pacific Ocean. It usually teems with life, both human and marine. In early September, its 3-mile shoreline was bustling with joggers. But in the sunset-blackened waters, the gleaming white corpses of thousands of decaying fish bobbed along in the gentle tide and piled up in mounds along the lagoon’s edges.

In late July, an algae bloom began spreading in San Francisco Bay, which stretches 60 miles north to south. The bloom has since exploded, expanding north into San Pablo Bay, including the shores of Napa County, and conditions in mid-September were still dire, with the fish kill reaching into the tens of thousands. It is the largest and longest-lasting algae bloom in the bay’s recorded history.

Though the conditions—a combination of warm summer waters, sunlight and heavy nutrients—have been ripe for an algae bloom for decades, the scale of the resulting fish die-off exceeded scientists’ most dire models. Tens of thousands of anchovies, bat rays, striped bass, leopard sharks, bottom-dwelling worms and mollusks — even humongous, decades-old white sturgeon—are washing ashore dead while countless more are sinking to the bottom.

The devastating casualties are linked to an algae bloom of Heterosigma akashiwo. In the first stage of the bloom, H. akashiwo kills fish through some kind of toxic effect, the specifics of which are still unknown. Once the algae start to die, bacteria in the seawater get busy decomposing them, a process which sucks up oxygen, as confirmed by the dissolved oxygen readings taken by scientists throughout Lake Merritt and the bay in early September. And fish can’t survive in oxygen-depleted water. “It’s like a wildfire in the water,” said Jon Rosenfield, a senior scientist at the San Francisco Baykeeper, an environmental advocacy group. “Once this got to a certain stage, there was really nowhere for (the fish) to swim to.”

Lake Merritt was once a healthy estuary that provided water, food and a way of life to the Ohlone people who lived near its shores. But in the 19th century, after pushing Indigenous people out of the area, European colonists used Lake Merritt’s waters as a dumping ground for sewage and wastewater. For decades the city still routed sewage pipes into its waters. As one historian noted, by the turn of the 20th century, Lake Merritt had become “a cesspool and a menace to public health.” It wasn’t until the 1980s that the city began infrastructure projects to clean up the lake, including rerouting the sewage pipes to wastewater treatment plants. Since then, Lake Merritt has seen a steady increase in water quality.

On a recent Sunday in late August, Damon Tighe, a local naturalist who documents Lake Merritt’s incredible biodiversity, went out to Lake Merritt and told me that he was horrified by what he saw. “Every corner had dead gobies”—a type of small bony fish—he said. It was a heart-wrenching reversal of the lagoon’s centuries-long recovery story. Worried about the mounting death toll and frustrated by the lack of public information available, Tighe set up a community science iNaturalist project page, where people could upload their observations of dead fish and compile data points in real time. Because fish decay within days of death, timely data collection is essential for understanding the magnitude of the disaster.

Keith Bouma-Gregson, a biologist with the U.S. Geological Survey’s California Water Science Center, was taking water samples around the bay when he saw dead sturgeon floating in the water. “That’s like going out to the forest and seeing your old-growth long-lived species (like redwoods) getting hit pretty hard,” he said. “That was a real sobering moment of recognizing that this this bloom truly was harmful.”

Though the current bloom is unprecedented, it’s not unexpected; this particular species of algae is commonly found throughout the bay. In order to grow, algae need sunlight, warm water and nutrients. In the summertime, San Francisco Bay gets plenty of sunlight. The average temperature of the bay’s waters has also increased over the years, following the general patterns of climate change. And nutrients regularly flow into the water from urban stormwater and agricultural runoff, though the largest contributor by far is recycled sewage from the region’s 37 wastewater treatment plants.

During a recent phone interview, Rosenfield compared the bloom to a catastrophic wildfire where the conditions — created by human mismanagement — are prime for ignition. “The spark is analogous to the cigarette that starts the big wildfire,” he said. “The conditions were always here to start this algal bloom.”  Scientists are still working to figure out what exactly set off this year’s destructive bloom, but the key to preventing disasters of this scale is better management.  “We know what we can do to mitigate algal blooms or prevent them from happening in the future,” he said. 

One solution would be to recycle more water. Restoring the marshes around the bay could also help by sucking excess nutrients out of the water, and it would also provide other benefits to people and wildlife. “But,” Rosenfield said, “policy is slow, and people are slow to spend money until we have disasters.”

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Weighing in up to 330,000 pounds and 110 feet long, the blue whale (Balaenoptera musculus) is bigger than even the largest dinosaurs, despite subsisting on a tiny organism called krill (in huge quantities). They’re the largest animal on Earth currently, and one of the largest animals to have ever lived on our planet in all of history. Still, the magnificent creatures have been on the endangered species list since 1970. They remain at risk due to vessel strikes, risk of entanglement, and a steep decline in their main food source, krill, which can be linked back to ocean acidification and climate change.

In an effort to protect a unique population of these endangered gentle giants from the threat of vessel strikes, the largest shipping and logistics conglomerate in the world, Mediterranean Shipping Company (MSC), has rerouted their shipping lanes near the coast of Sri Lanka in the Indian Ocean. The blue whales here aren’t migratory and have distinct vocalizations. The vessels will now travel about 15 nautical miles (roughly 17 miles) to the south of the previous shipping route.

“MSC Mediterranean Shipping Company has taken a major step to help protect blue whales and other cetaceans living and feeding in the waters off the coast of Sri Lanka by modifying navigation guidance in line with the advice of scientists and other key actors in the maritime sector,” MSC said in a statement provided to Insider.

[Related: Whale ‘roadkill’ is on the rise off California. A new detection system could help.]

The move comes in response to a request from the International Fund for Animal Welfare (IFAW) and OceanCare. According to the IFAW, Sri Lankan blue whales are in these waters year round. Current international shipping lanes off Dondra Head bring vessels right through the area with the most whales and whale watching activity.

“By ensuring these small changes, MSC is making a significant difference for these endangered whales. Whales often die as a result of collisions and this population is at risk. Ship strikes are both a conservation and a welfare problem, and even one whale death is one too many,” said Sharon Livermore, Director of Marine Conservation at IFAW, in a press release.

This voluntary rerouting from MSC does not impact other shipping carriers in the area (like Hapag-Lloyd or Maersk), but environmental advocates hope that this could lead to a chain reaction of permanent changes to the official shipping lane that would impact all container ships. According to the IFWA, research shows that adjusting the shipping lane would reduce the risk of a ship striking a whale by 95 percent.

“Re-routeing is the key hope to turn the tide for blue whales off Sri Lanka. It also demonstrates to the Sri Lankan government that now is the time to take appropriate action and move the shipping lane out of blue whale habitat for all merchant vessels,” said Nicolas Entrup, Director International Relations at OceanCare, in a press release.

[Related: Whale-monitoring robots are oceanic eavesdroppers with a mission.]

While commercial whaling is banned worldwide, blue whales were on the brink of extinction as recently as the 1960s. The ban on whaling helped the population rebound, but populations are still lower than pre-whaling numbers. It’s estimated that there may have been about 200,000 to 300,000 whales in the Southern Hemisphere before commercial whaling, compared to 2,300 in 1998. Populations are rising at about 7 percent per year.

Vessel strikes are a major issue for a number of whale species, not just blue whales. The critically endangered North Atlantic right whale (Eubalaena glacialis) is especially suffering—NOAA Fisheries has documented four lethal (death and serious injury) right whale vessel strike events in US waters over the past two and a half years.

There are fewer than 350 right whales in the wild and they are not reproducing fast enough to maintain their numbers. In July, NOAA Fisheries announced proposed changes to vessel speed rules to, “further reduce the likelihood of mortalities and serious injuries to endangered right whales from vessel collisions.” The proposed changes would broaden the spatial boundaries and timing of seasonal speed restriction areas along the eastern coast of the United states and expand the mandatory speed restrictions of 10 knots or less to include most vessels 35–65 feet in length.

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It’s lobster season right now in New England, but this year it might be more of an event for endangered whales than for foodies.

The North Atlantic right whale (NARW) has been migrating over 1,000 miles from Florida to calve and Canada to feed for thousands of years. Razor toothed predators like great white sharks or orca attacks haven’t been their biggest threat over all that time. Instead, it’s been human activity from commercial whaling (now banned), vessel strikes, and certain types of fishing. There are currently fewer than 340 NARWs remaining and the population has dwindled by 28 percent over the past 10 years.

In an effort to try and save these whales, Monterey Bay Aquarium’s sustainability guide Seafood Watch has placed American lobster caught by pot and gillnet on a “red list” of seafood to avoid due to the threat lobstering poses to this critically endangered cetacean. Some other red listed seafood include European anchovies, wild-caught cod from both the US and abroad, and Atlantic rock crab.

In a press release, Seafood Watch stated that it reviewed all available data on the issue and gathered input from scientific, government, industry, and conservation experts and through a public comment period. “After reviewing all available scientific data, as well as existing legal requirements and regulations, Seafood Watch determined that current Canadian and US management measures do not go far enough to mitigate entanglement risks and promote recovery of the North Atlantic right whale. As a result, Seafood Watch assigned a red rating to those fisheries using pots, traps, and gillnets.

[Related: Post-pandemic seafood could be more sustainable. Here’s how tech is driving the change.]

Seafood Watch also cited a US court decision from June which determined that the National Oceanic and Atmospheric Administration (NOAA) violated the Endangered Species Act and the Marine Mammal Protection Act by “failing to quickly reduce impacts to the North Atlantic right whale.”

In addition to being struck by ships, entanglement in fishing gear used to catch crab, lobster, and other species is hurting NARW populations. According to NOAA, their migration route is littered with more than 1 million vertical lines from pots and traps, 622,000 of which in US waters. The ropes from fishing gear can become embedded in a whale’s skin, weighing it down and preventing it from swimming or feeding properly. In 2020, there were 53 large whale entanglements confirmed in the US and more than 80 percent of NARWs have been entangled in fishing gear at least once.

The Maine lobster industry is worth an estimated $752 million and this new designation has raised concern from the state and fishing industry. “Seafood Watch is misleading consumers and businesses with this designation,” said Governor Janet Mills in a press release. “Generations of Maine lobstermen have worked hard to protect the sustainability of the lobster fishery, and they have taken unprecedented steps to protect right whales—efforts that the Federal government and now Seafood Watch have failed to recognize. No right whale death has been attributed to Maine gear, and there has not been a right whale entanglement attributed to Maine lobster gear in eighteen years.”

[Related: Whale-monitoring robots are oceanic eavesdroppers with a mission.]

In an interview with the Portland Press Herald, executive director of the Maine Lobsterman’s Association said, “Lobster is one of the most sustainable fisheries in the world due to the effective stewardship practices handed down through generations of lobstermen. These include strict protections for both the lobster resource and right whales.” The association has been involved in protections since the late-1990’s.

Some conservationists and scientists praised the decision. “For every North Atlantic right whale calf that is born, three right whales are estimated to die,” senior scientist and Veterinarian in the Biology Department at Woods Hole Oceanographic Institution Michael Moore tells PopSci. “Thus, recovery of the species will require not only minimal mortality but also increased reproductive health.”

“The Seafood Watch listing has significant potential benefit,” Moore adds, “even in areas where whale densities are relatively low.”

But this doesn’t mean customers have to give up their lobster-filled favorite foods. “Consumers should seek low risk of entanglement for their trap caught seafood,” he says, “such as areas only open to on-demand fishing (aka Ropeless), where entanglement risk is minimized, while still enabling trap fishing.”

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One of the last places you want to be hungry out on the open ocean is the North Pacific Subtropical Gyre. Being home to the Great Pacific Garbage Patch is just one factor. A gyre is a large system of rotating currents ocean currents. There are five of major ocean gyres, where the ocean churns up eddies (smaller and more temporary loops of swirling water), whirlpools, and deep ocean currents. Even without trash islands, gyres are typically nutrient poor (ie not a lot of snacks), yet help sustain some of the ocean’s top predator fish.

The reason may lie in some of the gyre’s eddies. A study published yesterday in the journal Nature finds that marine predators (tunas, billfishes, and sharks, for example) get together in rotating ocean eddies that spin clockwise and are anticyclonic, or rotating around the center of a high pressure in the reverse direction of a cyclone. The study suggests that the predators are moving with these temporary loops of water as they travel throughout the open ocean and foraging on the biomass (or life) that is within the eddies.

“We discovered that anticyclonic eddies—rotating clockwise in the Northern Hemisphere—were associated with increased pelagic predator catch compared with eddies rotating counter-clockwise and regions outside eddies,” said Martin Arostegui, a Woods Hole Oceanographic Institution (WHOI) postdoctoral scholar and paper lead-author, in a press release. “Increased predator abundance in these eddies is probably driven by predator selection for habitats hosting better feeding opportunities.”

[Related: Climate change is making the ocean lose its memory. Here’s what that means.]

The team from WHOI and the University of Washington Applied Physics Laboratory (UW APL) focused on more than two decades of commercial fishery and satellite data from the North Pacific Subtropical Gyre, as well as an mix of predators from varying ocean depths, regions, and physiologies (both cold and warm-blooded animals). They investigated predator catch patterns within and around the eddies, concluding that the swirling loops of ocean water influence the ecosystems of the open ocean at all levels of the food chain.

The data suggests a fundamental relationship between opportunities for predators for forage and the underlying physics of the ocean.

“The idea that these eddies contain more food means they’re serving as mobile hotspots in the ocean desert that predators encounter, target and stay in to feed,” added Arostegui.

[Related: “With new tags, researchers can track sharks into the inky depths of the ocean’s Twilight Zone.”]

Understanding how eddies influence the dining behavior of open ocean predators in these food-scarce areas of the deep ocean can better inform species, fisheries, and ecosystem management. It can also help policymakers regulate harvesting and fishing for deep ocean plants and animals without negatively affecting dependent predators or the ocean’s ability to store carbon and regulate the climate.

“The ocean benefits predators, which then benefit humans as a food source,” said Arostegui. “Harvesting the food that our food eats, is something we need to understand in order to ensure the methods are sustainable for both the prey and the predators that rely on them. That is critical to ensuring both ocean health and human wellbeing as we continue to rely on these animals for food.”

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Since they were first recorded by Irish scientist John Tyndall in 1859, scientists have observed how greenhouse gases (GHG) like carbon dioxide, methane, and nitrous oxide and act like a giant blanket around the Earth. Like a greenhouse does for plants, these gasses trap heat and warm the planet. In May, the National Oceanic and Atmospheric Administration’s (NOAA) Mauna Loa Baseline Observatory measured the amount of carbon dioxide in the atmosphere at an astounding 421 parts per million, a range not seen on Earth in millions of years.

This drastic change to the chemistry in the atmosphere has lead to major consequences to our land and seas and it will only worsen as the climate continues to change. A study published on August 22 in the journal Nature Climate Change found that if greenhouse gases continue to be emitted at their current rate, nearly 90 percent of all marine species could face extinction by the end of this century. The most impacted groups would be the ocean’s top predators (particularly tuna and shark, since they are hunted by humans for food), areas with large amounts of biodiversity, and coastal fisheries of low-income nations, according to the study.

The international team of researchers created a new scorecard called the Climate Risk Index for Biodiversity (CRIB). They used it to examine about 25,000 species of marine life, including animals, plants, protozoa, and bacteria.

[Related: Climate change is making the ocean lose its memory. Here’s what that means.]

“We created a ‘climate scorecard’ for each species and ecosystem that tells us which will be winners or losers under climate change,” says Daniel Boyce, the study’s lead author and a research associate at Dalhousie University, in a press release. “It allows us to understand when, where and how they will be affected, as well as how reducing emissions can mitigate climate risk.”

In a blog post for CarbonBrief, Boyce explains that the framework uses data from analyzing how a species’ innate characteristics like body size and temperature tolerance interact with past, present, and future climate conditions. They evaluated climate risk under two different scenarios: one where emissions continue to be high and another where emissions are sharply reduced in accord with the Paris Agreement’s goal to keep warming below 3.6 degrees Fahrenheit (2 Celsius).

According to the study, under the worst-case emissions scenario, 87 percent of marine species would be under high or critical climate risk, species were at risk across 85 percent of their distribution on average, and climate risk was heightened in coastal ecosystems and closer to the equator, disproportionally threatening tropical biodiversity hotspots and fisheries

However, if GHG emissions are curbed, there is an opportunity to course correct and prevent this mass extinction from happening. Reducing GHG emissions would limit the risk for virtually all species on Earth and help minimize disruption to 98.2 percent of the fisheries and ecosystems in the study.

[Related: These Hawaiian corals could hold the secret to surviving warming waters.]

“The benefits of emission mitigation for reducing climate risk are very clear,” said co-author Boris Worm in a press release. “Mitigation provides the most straightforward path to avoiding the worst climate impacts on oceans and people, setting the stage for global recovery under improved management and conservation.”

On August 16th, President Biden signed the Inflation Reduction Act, which provides $369 billion to fund energy and climate projects with the goal of reducing carbon emissions by 40 percent in 2030. While climate experts have called a major step in curbing GHG emissions, the legislation also comes soon after the Supreme Court of the United States ruled to limit the Environmental Protection Agency’s (EPA) ability to regulate emissions at power plants. in West Virginia v. EPA.

“The reality is that climate change is already impacting the oceans, and even with effective climate mitigation, they will continue to change,” Boyce and co-author Derek Tittensor wrote in CarbonBrief. “Therefore, adapting to a warming climate is crucial to building resilience for both ocean species and people.”

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The next time you go for a swim, try this: Close your eyes, paddle in place, and imagine using the feeling of the water on your skin to map the shape of everything nearby—from the contours of the pool to the location of a hapless bug struggling on the surface. That’s kind of what it’s like to be a fish with a marvelous sensory apparatus known as the lateral line system.

Composed of exquisitely sensitive skin-based cells and snaking nerves, lateral lines are as integral to a fish’s perception as their sight or hearing. For a human, trying to wonder what it’s like to have one is an exercise in transcending the boundaries of our own ümwelt, or notion of our place in the world.

Doing so might also help us better understand what our gilled counterparts’ lives are like, and how to better care for them, particularly in captive environments. Waves reflecting off aquarium walls could be a source of distress for animals with such a keen sensory system, while common diseases that degrade lateral lines might deprive them of an important part of their everyday experiences.

“The lateral line basically means their entire outer body is sensitive to vibrations in the water,” says Culum Brown, a behavioral ecologist who studies fish at Australia’s Macquarie University. “[People] just don’t have anything like that. It’s very difficult to describe.”

The first scientific observations of lateral lines in fish were made in the 17th century by Dutch naturalist Nicolas Steno, who believed they helped produce the mucus that typically coats the creatures’ scales. Steno’s mistaken belief stuck around until the 1800s, when a few scientists started to suspect that lateral lines formed a so-called “sixth sense.”

At the time, German zoologist Franz Eilhard Schulze described the system’s anatomy. A fish’s body is covered in tiny structures called neuromasts, each containing a cluster of hairlike sensory cells inside a jelly-looking dome. The neuromasts are embedded on the surface of a fish’s body and in distinct, mucus-filled canals that run along the animal’s sides—giving the lateral line its name. The cells respond to changes in pressure and movement, and when stimulated, send signals through specialized nerves directly to a fish’s brain.

While researchers of the era understood the basic physiology of the system, most of them assumed it was involved in hearing, sort of like a whole-body accessory to the inner ear. Finally, after a set of experiments in 1910 showed that pike could avoid walls when blinded, but not when their lateral lines were severed, biologists started to draw the connection to water flows.

Subsequent research has illuminated how fish use lateral lines. Blind cave fish, for example, produce waves with their mouths as they swim; as the turbulence hits obstacles, it creates patterns of flow and pressure that helps them navigate. In another case, surface-feeders locate prey in complete darkness by homing in on the surface waves generated by fallen insects. Meanwhile, far below the surface, mottled sculpin pinpoint the paddling motion of aquatic fleas suspended in the water column.

Rheotaxis—the movements that allow a fish to intercept odors and food in a current without expending too much energy or being swept downstream—is now known to be mediated by the lateral line system. So is the extraordinary behavior of schools turning in perfect unison as though controlled by a single mind. Using their lateral lines, fish can also perceive the wakes of individuals who passed by minutes ago, helping them hunt (and perhaps do much more).

Depending on their environment, some species might even adapt their lateral lines to send and receive communications. Male betta fish make waves to alert offspring of approaching predators; rainbow trout perform a courtship dance akin to an elaborately synchronized caress.

Those are just some of the functions of lateral lines. But what does the “sixth sense” feel like? “It is nearly impossible to know what fish actually perceive through their lateral line,” wrote Sheryl Coombs and Horst Bleckman, modern pioneering scientists on the topic. Meaning that while we’ve described the facts of lateral line perception, we can only try to do the same with the subjective experience.

In his attempt, Dutch physiologist Sven Dijkgraaf called it “touch at some distance,” a term that resonates with Christopher Braun, who studies fish perception at Hunter College. It’s as if “your skin is three-dimensional” so you can feel nearby objects without making direct contact, he explains. Brown from Macquarie University uses the analogy of placing your hand atop a woofer speaker while wearing noise-muffling headphones. “I think that’s just about as close as you could imagine,” he says. The main difference, of course, is that humans are “not designed to respond to that kind of information, whereas fish are highly attuned.”

There’s even less information on how lateral lines intertwine with the animals’ psychological well-being—a gap that can be chalked up to the delayed realization that fish are no less cognitively sophisticated than mammals or birds, along with a disregard for their welfare in general. With their seemingly inexpressive faces and underestimated minds, the gilled creatures don’t get much attention on their inner lives. In fact, it wasn’t long ago that most scientists thought they were incapable of pain.

Today we know better. That leads to some troubling possibilities, specifically for those animals swimming behind glass walls. For one, waves bouncing off aquariums could produce an echo-chamber effect, leaving fish pummeled by endless reverberations. “It would be like having constant loud noise,” says Mary Power, a river ecologist at the University of California, Berkeley. She even questions whether some of the abnormal behaviors she has observed in captivity—such as extreme aggression in typically easygoing fish and abnormally repetitive cleaning habits—are symptoms of discomfort from overstimulated lateral lines.

“There’s bound to be some kinds of problems,” Brown weighs in. He suggests aquarium owners add habitat-enriching structures like logs and plants to help disrupt those flows. He does speculate, however, that captive fish would eventually adapt to the stimulation, not unlike how an annoying, persistent noise can fade into the background.

John Montgomery, a fish biologist at the University of Auckland, says that if aquarium-wall reflections really are a problem, a fish’s lateral line system might simply degrade, much as how constant loudness leads to deafness in people. “Continuous overstimulation would be more likely to result in sensory loss,” Montgomery explains, “rather than continuing acute physical discomfort.”

A less-speculative problem is lateral line erosion, a collection of conditions better known, with gruesome evocativeness, as hole-in-the-head disease. Caused by parasites, poor water quality, and nutrient deficiencies—and perhaps exacerbated by the stress of captivity itself—the scourge is common in aquarium and aquaculture fish. Afflicted fish might have their lateral lines literally rot away.

The fallout doesn’t seem to cause immediate physical pain, but it raises the question of whether there is longer-term psychological distress when such an integral sense is taken away. It also raises the idea of providing captive fish with a happier, not just healthier, life.

Becca Franks, a cognitive psychologist who specializes in animal behavior and fish welfare at New York University, points to a 2019 study on how zebrafish in tanks prefer habitats with areas of flowing water. Perhaps that’s because in dynamic conditions, they can use their lateral lines, just as we respond to having our own senses engaged. “There is so much more to be done,” says Franks, but she considers it “equivalent to the difference for us between living in a room with a view, so to speak, and living in the dark.”

Of course, zebrafish preferences may not be shared by everyone. After all, there are at least 30,000 fish species swimming the world’s water bodies, each with lateral line systems suited to the environments in which they evolved. A great deal remains to be studied and learned about how fish sense their surroundings and where they feel at home.

We hope you enjoyed “Pet Psychic,” Brandon Keim’s new column. Check back on PopSci+ in October for the next article.

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Some of the most significant scientific inventions—penicillin, gunpowder, the microwave—were discovered by accident. Now a group of researchers investigating how some animals live in the freezing Arctic have another to tack on the list: natural antifreeze. A new study published today in the journal Evolutionary Bioinformatics found that a tiny snailfish species living in Greenland contained sky-high levels of antifreeze proteins that made it possible to survive subzero temperatures.

In 2019, study coauthor David Gruber, a research associate at the American Museum of Natural History in New York and a distinguished biology professor at CUNY’s Baruch College, was out with his team on an expedition to eastern Greenland to look for animals that glowed in the dark under the ice. Located in the Arctic Circle, this region of Greenland gets near-full days of summer sun, but is plunged in darkness during the winter months. The team’s goal was to understand the role light plays in marine species living in these environments with such drastic seasonal periods of never-ending and very limited sunlight. Their search led them to a juvenile biofluorescent snailfish, a small fish with a tadpole-like body typically found in frigid waters dipping well below freezing , at 28.4 degrees Fahrenheit. Biofluorescence is when an animal absorbs blue light and emits either green, red, or yellow light—a rarity among Arctic fishes that live in darkness for most of their lives.

To better understand how snailfish create light, the biology team examined its entire transcriptome—every gene it is making—where they were surprised to find that one of the most actively made proteins in the body was antifreeze proteins. “Similar to how antifreeze in your car keeps the water in your radiator from freezing in cold temperatures, some animals have evolved amazing machinery that prevent them from freezing, such as antifreeze proteins, which prevent ice crystals from forming,” Gruber said in a press release.

Marine biologists had already uncovered the existence of antifreeze proteins 50 years ago. Several species from fish, reptiles, insects, to bacteria are known to have evolved antifreeze proteins to survive in icy habitats. For snailfish, antifreeze protein is developed in the liver where it prevents large ice grains from forming inside cells and body fluids. Without antifreeze protein, the blood of snailfish would turn frozen solid. 

[Related: Fish blood could hold the answer to safer de-icing solutions during snowstorms]

Since the initial discovery, biologists have since found that antifreeze proteins are created through five different gene families. But marine biologists did not know how much energy snailfish spent in creating antifreeze proteins. “In retrospect it makes sense—of course a juvenile fish living on an iceberg is making lots of proteins that prevent it from freezing,” explained Gruber. In their genetic analysis, the team found two gene families in charge of encoding two types of antifreeze proteins, called Type I and LS-12-like proteins. These genes were highly expressed, making up the top 1 percent of expressed genes in snailfish.

The study authors suggest that the high expression levels for these antifreeze proteins are essential for living in extremely cold waters. Some marine biologists, however, have casted some doubts on how big of a conclusion to draw from these results. C.-H. Christina Cheng, an evolutionary biologist at the University of Illinois Urbana-Champaign who was not affiliated with the study, said that LS-12-like proteins also present in the Northwest Atlantic longhorn sculpin did not provide much help in preventing fish from freezing to death. Instead, she says it’s possible the snailfish could be expressing this protein for another developmental reason. What’s more, the expression Type I antifreeze protein found in the snailfish is different from other Type I proteins from the same species. 

Cheng said these discrepancies could be resolved by further looking at antifreeze protein activity directly in the blood plasma. “If all these detected transcripts are actually made into functional antifreeze proteins, the plasma antifreeze activity would be high,” she explains. “But if the plasma antifreeze activity is low, then it’s questionable that these transcripts are made into active antifreeze proteins.”

[Related: How polar animals cope with frigid darkness for months at a time]

Still, the new study does highlight the importance of antifreeze proteins in the survival of snailfish living in the Arctic—an environment that is particularly vulnerable to rising global temperatures. Since the past century, the Arctic has been warming four times as fast as the rest of the planet, with predictions projecting an ice-free Arctic ocean in 30 years.

As the region undergoes dramatic changes, ice-dwelling fish will be forced to adapt to warmer climates or face extinction. “For these juvenile snailfish, their superpower of making lots of antifreeze proteins will no longer be a superpower in an Arctic without icebergs,” Gruber said. To make matters worse, warmer waters may introduce more fish species that tend to reside in temperate climates, increasing competition for food and shelter.

In the future, Gruber and his team plan on further investigating the nuances of antifreeze in snailfish and other species living in these frozen environments. “Snailfishes are an interesting family as they have representatives that live at surface to beyond 8,000 meters deep [in the ocean],” he said. “We are curious to investigate if there are any connections between snailfishes ability to survive extreme cold and extreme pressure environments.”

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How do you keep a fish alive without water? 

This contradictory question is the reality that Thomas Archdeacon, a fish biologist with the New Mexico Fish and Wildlife Conservation Office, is having to ask himself more often each summer. The Rio Grande river typically runs low between monsoon rains, and for decades, dams have left stretches of the river in southeastern New Mexico dry during the summer irrigation season. But this year, the river dried up completely where it runs through Albuquerque, New Mexico, for the first time since the 1980s. The development doesn’t bode well for the subject of his research, the Rio Grande silvery minnow.

“This is the new normal, the new floor,” says Archdeacon.

The endangered fish, an unmarked strip of silver small enough to fit in the palm of your hand, used to have a range that tracked the river through Colorado, New Mexico, and Texas. Now, the species is only found on short stretches north and south of where it flows through Albuquerque, thanks to habitat loss, warmer water temperatures, and disruptions to historic flow patterns as dams were constructed and channels narrowed for irrigation. Before this summer, carefully managed releases from upstream reservoirs meant that that the northern length of river could usually be counted on to have running water at most times.

But that wasn’t the case this year, due to what that Archdeacon calls a “perfect storm” of disruptions to the river’s flow. Besides the pulse from the reservoirs arriving too early, repairs to the El Vado Dam upstream meant that the water usually held throughout the summer to tide the system over during dry spells wasn’t available. A disputed water agreement between the governments of New Mexico and Texas is putting even more strain on the limited supply. 

At the end of July, technicians from the New Mexico Fish and Wildlife Conservation Office were running nets through the small, shallow pools left in the river bed. They were trying to scoop up the silvery minnows stranded in the standing water to relocate them upstream, where there was still enough moisture to tide them over until the next rain. “It’s not a long-term solution,” says Archdeacon, whose research has found that the rescued fish have a very low survival rate even once they’ve been moved to somewhere with more water. “You can’t get the fish to live because they are really stressed out before the pools begin to form. They’re crowded and too warm.”

The total loss of their habitat for days between summer monsoon rains isn’t the only threat to the minnow’s persistence. To reproduce, they depend on a surge of water in the spring when the snowpack melts, which triggers the females to release their eggs. The males release sperm into the high water at the same time, fertilizing the eggs.

But for decades, rising average temperatures from climate change have been melting the snowpack progressively earlier in the year, so the springtime surge rushes down the Rio Grande before the minnows are ready to release their eggs. State officials responsible for stewarding the species can create an artificial one with the dams used to regulate the river’s flow to prompt the fish to spawn. This year, though, their efforts yielded only a single egg, nowhere near the 10,000-egg minimum needed to make the effort worthwhile. 

As a backup, hatcheries run by state and federal conservation agencies collect eggs from the river in the spring, raise them, and then release the minnows into the river in the fall or winter when it’s flowing consistently. “If this happens again, if this happens next year, it’d be a big problem,” says Archdeacon. The hatchery has enough eggs and fish to weather a bad year or two, but if they aren’t able to collect any next year, they’ll be hard-pressed to boost the silvery minnow population with genetically diverse, captive adults.

The main thing the fish need to survive is more water, a seemingly simple proposition that becomes incredibly complicated with Western water politics. The Southwest is undeniably growing more arid, but the periods of intermittent drying imperiling the silvery minnow are due to decisions to release reservoirs on a schedule that prioritizes the needs of farmers and other human users. 

Tricia Snyder, the interim Wild Rivers Program Director for the conservation nonprofit WildEarth Guardians, says that it’s time for a “reckoning in the West” over water use. “We have an over-allocated system here on the Rio Grande, with every drop and then some promised to somebody.” 

[Related: America thrived by choking its rivers with dams. Now it’s time to undo the damage.]

Last year, WildEarth Guardians published an intent to sue local and federal officials with a role in managing the Rio Grande, saying water governance planning didn’t adequately take endangered species into account. They haven’t had to file an actual lawsuit yet, as the announcement brought the necessary leaders to the table for conversation. 

“We’re really hopeful that we can find some workable solutions,” says Snyder. “The intent here is that we create a water management system that accounts for all water uses, including plant and wildlife communities. When we make the ecosystem better for endangered species, we make it better for everyone.”

In the meantime, scientists like Archdeacon will have to keep scooping minnows out of the parched river, trying to keep a Rio Grande fish alive without the Rio Grande.

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This article was originally featured on High Country News.

Every June, Serena Fitka goes home to her Yup’ik community of St. Mary’s, Alaska, near the confluence of the Yukon and Andreafsky rivers in the southwest part of the state. Usually, she helps her family fish for salmon and preserve it in the smokehouse for the leaner winter months. But this year, that didn’t happen: This year, there were no salmon to catch.

“I could feel the loss,” she said. “I didn’t know what to fill my days with, and I could sense it was like that for everyone along the Yukon River.”

There are five kinds of salmon in Alaska: Chinook, sockeye, chum, coho and pink. Chum is the most harvested fish on the Yukon, but both chum and chinook are crucial to the lives and culture of the roughly 50 communities around Alaska who rely on the river and its tributaries for subsistence.

Around the state, chinook counts have been declining for a decade, but this year’s run is the lowest ever recorded. Chum counts took a nosedive in 2021, and this year’s count is the second-lowest on record; as a result, state and federal fishery managers have closed chum fishing on the Yukon. This will affect more than 2,500 households in the region that rely on chum to feed their families. “That annual harvest is gone,” said Holly Carroll, a Yukon River subsistence fishery manager for the U.S. Fish and Wildlife Service. Scientists haven’t figured out why chum and chinook runs have been so poor in parts of western Alaska, but many theorize that warming ocean conditions are impacting the salmon early on in their life cycles—and some local subsistence fishers believe that commercial fishing operations in other parts of the state could be contributing as well.

Warmer waters have caused a downturn in chinook and chum numbers across the Pacific, and those changes are hurting salmon in the Yukon as well. In one study of chum, researchers found that the fish were eating things outside their usual diet, like jellyfish, and, because of that, likely didn’t have enough energy stored in their bodies to survive the winter. “That’s associated with these marine heat waves that we’ve seen in the Bering Sea as well as the Gulf of Alaska,” said Katie Howard, a fisheries scientist with the Alaska Department of Fish and Game Salmon Ocean Ecology Program. During marine heat waves, chum eat prey that is easier to catch, but often less calorically dense. Drought in the spawning grounds of Interior Alaska and Canada could also contribute to lower numbers of chinook, since it leads to lower water levels and makes the water warmer.

Meanwhile, nearly 400 miles south in Bristol Bay, a warming climate might actually be helping salmon runs instead, said Jordan Head, a state biologist working in the region. Bristol Bay fishers have harvested over 57 million sockeye this year, breaking the all-time record of 44 million fish set in 1995. The region has seen over 74 million sockeye return so far this season, the largest number in the fishery’s history. With the warmer temperatures, the lakes are frozen for less time, and the juvenile sockeye may have been able to grow larger and be more competitive as they enter the ocean, thereby increasing their odds of survival. But as the Bering Sea continues to warm, it too could see the same salmon declines as the Yukon.

Many people in the Yukon region believe that fisheries management also plays a role in which areas see increases or declines, said Fitka, the executive director of the Yukon River Drainage Fisheries Association. In particular, subsistence fishers are frustrated because commercial fishers are allowed to catch salmon in Area M, a state-managed section of waters south of the Alaska Peninsula and west of Bristol Bay.

Some of the fish caught there are passing through on their way to spawning grounds in the Yukon. Area M fishery operations have been controversial for decades, but clashes have intensified since the 2021 salmon season. Typically, about 1.7 million chum migrate up the Yukon River, but last year, only 150,000 appeared, while commercial fishermen in Area M caught nearly 1.2 million chum at sea. While Area M fishers harvest some chum salmon destined for the Yukon River and its tributaries, this does not alone explain the poor returns, according to the Alaska Department of Fish and Game, which says that a majority of the chum harvested in this fishery are not destined for the Yukon drainages.

“It’s a huge loss of food, but most importantly—and we’re hearing this every week from tribes, from people who live on the river—the most traumatic thing is a loss of culture, traditional identity,” said Carroll, the Yukon fisheries manager. “It’s traumatic.” Linda Behnken, the executive director of the Alaska Longline Fishermen’s Association, said the dwindling salmon numbers in the Yukon-Kuskokwim area are a climate justice issue, but also an opportunity to build community. “Everybody in Alaska cares about salmon and recognizes the importance of maintaining healthy salmon runs and how important that is to culture and food security and to the economy of this state,” says Behnken—and that presents an opportunity for connection.

In an effort to share the salmon wealth, programs like Fish for Families have popped up to distribute Bristol Bay’s surplus fish to communities across Alaska that are experiencing dismal salmon returns.  

Volunteer coordinators work with local fishers to acquire the salmon, process it and package it into 50 pound boxes, which will be flown to remote communities in the Yukon-Kuskokwim Delta and Chignik, an area in Southwest Alaska. About 5,000 pounds of salmon have been donated to the four communities in Chignik, and the program has four communities in the middle and upper portions of the Yukon River lined up for future deliveries.

George Anderson is a fisherman and president of Chignik Intertribal Coalition, a group of tribal members and Chignik fishery stakeholders that formed in 2018 when sockeye runs failed in the area. Donations to Chignik started in 2020, when COVID-19-related supply chain disruptions combined with record-low salmon runs prompted a food shortage in the community. That year, the community received more than 30,000 pounds of sockeye from Bristol Bay. Families receive the fish whole so they have the option to process the salmon to their liking and share their cultural traditions with younger generations. 

“We’d really, really prefer to be harvesting our own fish that are coming here,” Anderson said, but he and other Chignik families are grateful for the donations. “We’re learning all the time that there is always a surprise around the corner, whether you don’t have enough or if you have too much.”

After two years of no chum fishing, Fitka said people in the Yukon region have turned to harvesting other species. In addition to small amounts of pink and sockeye salmon, fishers in the Yukon River and its tributaries are also catching sheefish, grayling, burbot, pike and whitefish. “We have to rely on what we have,” Fitka said.

Carroll, the Yukon River fishery manager, is hopeful that the salmon will recover in the long run. Western Alaska’s chinook and chum crashed simultaneously around 2000, she said, but both species saw large returns within a few years. Today, a warming ocean and poor food quality for chum could make it harder for them to bounce back, but overall, salmon are resilient. “I think we’ll be fishing for those species again,” Carroll said. “I just hope that folks can kind of hold on to that, and toe the line and try to find other food sources, other ways of practicing their cultural traditions until we can get back to fishing.”

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Did it rain fish in Texarkana, Texas/Arkansas, last December? Or did a massive gulp of cormorants spontaneously hurl their payloads? Sharon Hill, an independent researcher from Pennsylvania, and Paul Cropper, an author from Australia, investigated the odd phenomenon and have come to a conclusion: It was the regurgitating gulp.

“We’re both interested in finding out what, if anything, happened in a strange situation,” Hill told the Dallas Morning News at the onset of their investigation. “We’re not going to be dismissive, we’re not going to default to a paranormal explanation, but we’re looking to document what happened and what can be the possible natural causes.”

The strange situation occurred when Gizzard shad seemed to rain from the Texarkana skies during a thunderstorm at the end of last year. Multiple residents reported their encounters with the fish and shared photos and videos through social media. 

Experts hypothesized that the storm whipped up a tornadic waterspout from the resident lake, lifting a school of small fish into the air and dropping them in a less friendly environment. It has been known to happen. But, National Weather Service meteorologist Brandon Thorne said there was no evidence backing that theory. “As we looked at the storm and went back and looked at the data, we really didn’t find anything that would indicate that there was any kind of waterspout,” Thorne told the Dallas Morning News. “We’re kind of confused as to how it happened as well, to be honest.”

So Hill and Cropper took up the case. First, they considered whether the whole thing was just a hoax. But too many eyewitnesses reported consistent accounts—in four different sections of town—of 12 to 30 fish on the ground. City officials had received numerous calls. At the airport, crews had shoveled up ten pounds of fish, delaying one flight. Video evidence had even surfaced. 

So, Hill and Cropper looked into other possible explanations. They, too, found no evidence of a tornado, a waterspout, or flooding (some fish were found on rooftops). They checked flight records to rule out the possibility that the shad had been accidentally dropped from an airplane. There were no flights at the time. 

Finally, the pair received a tip, implicating avian suspects. Residents told Hill and Cropper that large flocks of cormorants (known as gulps) typically flew over the airport at the time that storm had occurred. Some of the fish, Hill and Cropper found, seemed partially digested. And cormorants are known to regurgitate the contents of their stomachs.

The University of Texas Biodiversity Center in Austin will verify the findings. However, Hill told the Dallas Morning News, she is confident that she and Cropper have solved the mystery.

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From the murky depths of Southeast Asia’s Mekong River, a new world record has emerged. The biggest freshwater fish caught anywhere, ever, was captured and released last week near Koh Preah Island on the Mekong River in the Stung Treng area of northern Cambodia. Fisherman Moul Thun, seeking smaller quarry to sell in the local fish market, accidentally hooked the giant stingray on the night of June 13, using a simple hook and line. 

Instead of bringing his catch to the market, however, Thun called a team of scientists working with Wonders of the Mekong, a USAID-supported research project studying the biodiversity, climate, and hydrology of the Mekong River Basin. The group had been installing underwater receivers in the area over the past several months for a project tracking fish migrations. Over that time, they had asked local fishermen to contact them if they landed any fish of interest. In recent months, they helped tag and release two other giant stingrays.

But those weren’t world records.  FISHBIO, a partner on the Wonders of the Mekong project, officially weighed Thun’s nearly 13-foot snout-to-tail catch at 661 pounds, crushing the previous record, a 646-pound Mekong giant catfish, caught on the Mekong in 2005, in Thailand. 

Zeb Hogan, a fish biologist at the University of Nevada who leads Wonders of the Mekong and hosts National Geographic’s Monster Fish television series, told National Geographic, “It proves these underwater leviathans, which are in critical danger, still exist.”

FISHBIO tagged the giant freshwater stingray and released it back into the river, expressing optimism that it remained healthy and would survive the 18-hour process from catch to release. The tag, which emits an acoustic signal, will help them track the fish’s movements and learn more about the species’ behavior.

Hogan said that giant stingrays feed on shrimps, mollusks, and small fish on the bottom of the river, which it sucks up with its banana-shaped mouth. It is believed that the Stung Treng stretch of the river is an important pupping ground for the river’s largest fish. Hogan told NBC News, “It’s a particularly healthy stretch of the river with a lot of deep pools—pools up to 90 meters deep. We started focusing on this area as a stretch of river that’s particularly important for biodiversity and fisheries, and as a last refuge for these big species.”

Still, Hogan pointed out how mysteries world’s biggest freshwater fish remain. He told NBC News that the catch “highlights how little we know about a lot of these giant freshwater fish. You have a fish that’s now the record holder for the world’s largest freshwater fish, and we know little about it.” 

For his efforts, Thun was paid market value for his amazing catch.

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After four years of digging for fossils in a churchyard in York, Pennsylvania, amateur paleontologist Chris Haefner made an intriguing find. “I knew it was worth keeping,” he said. He posted his discovery on Facebook.

I spotted his post, and realized it was a major discovery: I study fossil invertebrates at the Spanish Research Council. When I contacted Haefner, he agreed to donate the fossil to London’s Natural History Museum.

Working with colleagues in the U.S. and U.K., we determined that this was a 510 million-year-old relative of today’s starfish and sea urchins. It is highly unique, new to science, and has only a partial skeleton. We named it Yorkicystis haefneri, after its finder.

Yorkicystis has revealed new information about how early life was evolving on Earth at a time when most of today’s animal groups first appeared.

The Cambrian explosion

Yorkicystis lived during the “Cambrian explosion,” 539 million to 485 million years ago. Before this time, bacteria and other simple microscopic organisms lived alongside Ediacaran fauna, mysterious, soft-bodied creatures that scientists know little about.

The Cambrian brought a huge proliferation of species that emerged from the seas. They included groups of organisms that would eventually dominate the planet and representatives of most of today’s animal groups.

Within a few million years, complex animals with skeletons and hard shells appeared. Why this happened remains unclear, but a major change in ocean chemistry, with a higher concentration of calcium carbonate, likely played a key role.

Echinoderms weren’t the first of these found in the geological record. Brachiopods–marine animals that lived protected within seashells–predated them. So did arthropods, a group that had well-formed calcite exoskeletons, including trilobites.

For context, dinosaurs appeared 294 million years after the dawn of the Cambrian.

The first echinoderms

There are more that 30,000 extinct echinoderm species, but they are very rare in places with exceptional Cambrian preservation, like the Burgess Shale in Canada and Chengjiang in China.

Some of the first primitive echinoderms were quite different from their present-day relatives, which have five arms extending from the center of their bodies, a structure called “pentamerous symmetry.”

Cambrian echinoderms had a wide range of body structures. Eocrinoids had vase-shaped bodies protected by geometrically patterned plates and a number of armlike structures. Helicoplacoids, shaped like fat cigars, were plated in calcite armor with a “mouth” that spiraled around its body. Blastoid species took various shapes, often resembling exotic flowers.

The Edrioasteroidea looked similar to today’s sea star, and with five arms that radiated from its mouth, it is the organism that Yorkicystis haefneri most resembles. So we classified it within this group on the evolutionary tree.

Yorkicystis, the echinoderm without a skeleton

While many Cambrian organisms formed sophisticated skeletons and defense structures to protect them from predators, Yorkicystis did the opposite. It “demineralized” its skeleton. It was a partially soft animal, with no protection over much of its body.

To understand this organism’s anatomy, we partnered with a paleoillustrator to visualize this creature from the fossil evidence we had. Hugo Salais first modeled each part of the skeleton in 3D and then used that to create a reconstruction, a high-resolution replica.

From this replica, we observed that only its arms, or ambulacra, were calcified, protecting its “food grooves”—its feeding parts, which are yellow in the fossil. A series of plates covered its tentacles and opened and closed during feeding. The rest of its body was soft, represented in the fossil by a dark, carbon-enriched film.

Most present-day echinoderms, which are found from the world’s coastlines to the ocean’s dark abyssal depths, have an internal skeleton. The exceptions are sea cucumbers and some species that live buried beneath the seabed. Their skeletons, like Yorkicystis, are formed by porous calcite plates.

Bringing Yorkicystis to life

As paleontologists, we seek to understand extinct organisms. Yorkicystis presented a major challenge, since no similar animal is known, neither living nor extinct.

Very little is known about why and how some echinoderms lost parts of their skeleton. But advances in molecular biology have revealed that there is a specific set of genes responsible for the formation of a skeleton in echinoderms. All living echinoderms carry these genes; we assume that extinct groups did, too.

But in Yorkicystis, there is a marked difference between the calcification of its rays, or arms, and the lack of it on the rest of its body. It raises the hypothesis that the genes involved in skeleton formation may have acted independently in different parts of Yorkicystis‘ body. It’s a mystery that only molecular biologists will be able to unravel.

Our studies have allowed us to form some hypotheses about this animal, though many questions remain. We believe that without a skeleton in an important part of its body, Yorkicystis was able to conserve energy for other metabolic processes such as feeding or breathing. It also enhanced flexibility, allowing for more active respiration by means of pumping.

There’s another intriguing possibility: The lack of skeleton might be related to some kind of stinging protection system, like that used by present-day anemones that paralyze prey with stinging cells on the tentacles that surround their mouths. That question, though, and many others, can’t be answered with just a fossil.

But the amazing discovery of Yorkicystis has provided more insight into a period in divergent evolutionary history at the dawn of the Cambrian explosion, a time when some organisms adopted skeletons to avoid predators–and others adapted in very different ways.

Samuel Zamora is a Lead Scientist of Paleontology at the Instituto Geológico y Minero de España (IGME – CSIC). Disclosure: Samuel Zamora receives funding from the Spanish Ministry of Science, Innovation and Universities (grant no CGL2017-87631), co-financed by the European Regional Development Fund and the project ‘Aragosaurus: Recursos Geológicos y Paleoambientales’ (E18_17R) funded by the Government of Aragon.

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Remora fish, known commonly as suckerfish, are technically not parasites. They’re just along for the ride. You’ll often see them stuck onto a large marine animal like a shark or a whale and sometimes even small boats, getting free transportation across miles of the ocean while spending very little energy.  

These odd creatures have flat foreheads that look like the bottom of a shoe. But it’s this strange suction-cup forehead that allows remora fish to cling onto dolphins even as they twirl into the air and slam back down into the water. In fact, scientists have long wondered whether the remora’s ribbed head held the secrets to better adhesives. Recently, this feature has become the intrigue of a group of international engineers from Beihang University, Imperial College London, and Swiss Federal Laboratories for Materials Science and Technology, who have sought to fabricate a version of this sucker structure to help drones get a better grip. 

The result is a remora-inspired aerial-aquatic hitchhiking robot. A paper out in Science Robotics this week details how they made and tested this drone, which can fly, swim, and stick onto surfaces in air and water. It can also easily move between the two mediums, like a flying fish. 

To make a drone like a remora, first the researchers had to observe the real fish. They used a camera to track a remora as it attached to the sides of an aquarium, and they saw that the suction disc could still hold on to the aquarium wall even if some parts of it were not in contact with the surface. They also used micro-computed tomography (micro-CT) to scan the head of a remora and look at the different bony and soft tissue structures inside the disc. 

[Related: Engineers created a robotic hand with a gecko-like grip]

The technique showed them that the remora disc had a gill-like membrane of soft tissue, under which was a layer of bony structures. The membrane can rotate or tilt at an angle, which could help it stick. Both these membranes are joined by connective tissue situated between them and the disc lip, or the edge of the suction cup. The muscles that moved the two membranes sat beneath them and are interspersed with blood vessels. 

Then, the team used 3D printing to construct an oval prototype disc with a gill-like grid structure that was 87 mm long and 46 mm wide. The prototype had four functional layers, a soft layer mimicking the connective tissue, a main disc mimicking the gilly membranes, and fluid-controlled channels that act as a motor for rotating the membrane as well as erecting and depressing each row in the membrane. There’s also another fluid-controlled motor that’s used for bending the disc. The disc lip forms the seal, and as the disc moves and rotates, it creates pressure differences between the various compartments and the external environment, resulting in adhesion. 

The team then made a hybrid aerial-aquatic robot to which they added the remora-like disc. On the modified quadcopter robot, the disc was accompanied by two motor components, including the hydraulic systems that pump fluid to manipulate the membrane and bend the disc, and a cable system that curls the disc lip to detach. The control system on the robot itself includes a flight control module, a speed regulator, a communications system, a remote control, and a battery. “Passive morphing propellers” were also custom-made for the robot. These propellers will fold underwater (the blades go inward when in contact with water) and unfold in the air (centrifugal force from increasing rotation speed unfolds blades). 

The resulting remora-like robot can attach to flat and curved surfaces, wet or dry. In swimming pool tests, the robot was able to steer to, attach to, and detach from a larger underwater robot. During attachment, the robot can cut power to its propellers and switch to “standby mode,” traveling with its host. In field tests, out in the ocean, the robot can take underwater videos and retrieve submerged objects. 

“The robot’s air-water transition (per cycle) consumed 1.9 times the power of hovering in the air. Notably, the robot’s hitchhiking state can reduce power consumption up to 51.7 times (in air) and 19.2 times (under water) compared with a hovering state,” the paper’s authors wrote. “Such robotic forms may be promising for several open-environment applications, including long-term air and water observations, cross-medium operations, submerged structure inspections, marine life surveys, and iceberg detections.”

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We recently came across a 2019 story about team of researchers in Canada who found wild hybrid salmon in the Cowichan River near Victoria, British Columbia. These fish were crosses between coho and chinook—and two were even found to be second-generation crosses, meaning that at least one of their parents was also a hybrid. The surprising discovery was considered the first documentation of second-generation coho-chinook hybrids in the wild, and there has been additional research since.

“For a hybrid to exist, we need overlapping spawning grounds and timing,” Andres Araujo, Department of Fisheries and Oceans biologist, told the CBC. That overlap likely resulted because of drought, which led to historically low flows. The chinook’s traditional early-fall spawn in the area was being pushed into late fall due to summer drought conditions extending into September. That delay put the chinook spawn in sync with coho’s typically late-fall spawn cycle. Hybrid chinook-cohos are identified by their different spots, fin shape, and mouth color, with some also having abnormal scale patterns near the tail.

Though the discovery was initially announced in the fall of 2019, a November 2021 study published in Ecology and Evolution provides greater detail about the rare phenomenon. The researchers confirmed that the hybrid salmon naturally occur in the Cowichan River each year and that the event is “likely exacerbated by prolonged low water levels which limit habitat and delay Chinook salmon spawning.” The study highlights climate change as a likely driver of the phenomenon. The frequency of a hybrid salmon originating in the Cowichan River was 4.92 percent compared to non-hybrid salmon, according to the study.

 Wild hybridization of salmon is exceptionally rare. The natural phenomenon has been better documented in trout. For instance, the “cuttbow” is a hybridization between non-native rainbows and native cutthroat trout. Cutbows have become common in many watersheds in the West, where rainbows have diluted the gene pools of many populations of native cutties through hybridization. 

In the recent study, researchers raised concerns about the ecological impact of hybridization on coho and chinook salmon in the Cowichan. They’re especially concerned about “introgression,” which is when genetic information is crossed into hybrids and then transferred back into one of the original species through “backcrossing.” The researchers who focused on salmon in the Cowichan worried that this could lead to reduced survival fitness due to the dilution of important genes specific to each species of salmon. 

“Given the potential negative impacts of hybridization, identification of hybrid fish extends beyond scientific curiosity,” emphasize the authors of the study. “Hybrid occurrence can be used as a monitoring tool of ecosystem changes and determining its origin with certainty warrants the value of a large-scale genetic monitoring program.”

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I never enjoyed fishing as a kid. It was boring, early, long, and we didn’t catch much. Now that I’m a parent, however—and a regular fisherman—I’ve been teaching my kids to fish. Though I never would have imagined it as a child, I’ve come to treasure those hours out on the lake, and know they will as well.

If you’re not an avid angler yourself, but want to get the family involved in the sport, you’ll need to make sure it’s fun for them. That means catching fish—lots of fish. Kids just starting out would much rather catch 40 little sunfish than the biggest bass in the lake like you or I would. Fishing with children is all about quantity over quality, and there are several ways to increase your chances of having a big day.

Fishing is also hyper-local, so focus on gaining knowledge about your area, not three states away. One way to do so is to find a fishing guide, says Kearning. This could be a friend or family member (I was lucky enough to have my father-in-law), or someone you hire. Fishing guides can tailor your experience to the type of fishing you want to do, familiarize you with your equipment, and give you specific tips for how to catch fish in your area. A guide can eliminate much of the trial and error in learning to fish, and get you and your kids catching faster. 

YouTube is another wonderful platform for getting local fishing information, Kearning adds. There are thousands upon thousands of fishing videos there, and there are certainly dozens that feature fishers in your area—maybe even on your local lake, river, or shoreline. These videos can give you a sense of what types of fish are available; where in the water they spend their time; some of the best tackle, lures, and baits to catch them; and the best time of day to try. 

Tyler Brady, a former charter fisherman and founder of afellowfisherman.com, recommends looking through TakeMeFishing.org, a federally funded site that offers a variety of resources about fishing. One of the most valuable is the map of the United States that shows the location of just about every lake in the country and provides information about what has been caught on that lake, and when. The map syncs with the Fishbrain app, which allows users to share pictures and information about their catch. This app is available through your browser and free to download for Android and iOS. Monthly upgrades start at $10.

Also pick up some practice weights, particularly if your kids are younger. It’s far safer to practice casting for the first time in the backyard without a hook than on shore or out on a boat.

[Related: It’s surprisingly hard to tell if someone is drowning, so we made you a guide]

Finally, make sure you have scissors or clippers to cut the line, a fishhook extractor and pliers, a fish identification guide for your area, a ruler, and a trash bucket or bag to collect your garbage. 

One of the easiest ways to keep children happy and entertained is snacks. I never take the kids out without a pocket full of snack bars, fruit snacks, or trail mix. When fishing slows down, the food comes out until we can find the fish again. 

Nature is also all around you, waiting to be explored. Brady keeps binoculars and a bird identification book on board. When the fish disappear, his kids start bird-watching. My kids love to look at the lily pad flowers and try to spot the turtles and frogs hiding on the shoreline. Kearning keeps a facemask and a snorkel on his boat. Weather permitting, when the kids need a break, they mask up and jump overboard to explore the lake from a different vantage point. Similarly, my kids and I sometimes fish from shore near a beach. When the fishing slows down, the kids go swimming. 

Finally, don’t be afraid to cut a trip short. Sometimes you just need to call it a day and get some ice cream. 

Respect for the environment also means having a plan for what to do when you catch a fish, says Brady. It’s very easy to accidentally kill fish. Know how to take a hook out of different kinds of fish mouths. Catch a bass, for example, and you can usually just remove the hook with your hands. Other fish, like pickerel, have large, sharp teeth, and you’ll need to use a pair of pliers or a hook extractor. And it’s a different story when the fish swallows the hook.

Also decide if you want to keep or catch and release. For the most part, we catch and release. As part of that, we try to get the fish back in the water as quickly and with as little damage as possible. We bring them into the boat, take the hooks out, take a picture, and throw them back. If you choose to take home any of the fish you catch, Kearning says you should first ensure it’s legal to do so, then dispatch the fish humanely and quickly. 

Learning to respect and conserve aquatic ecosystems is the best way to ensure that they are healthy and enjoyable for everyone for years to come. Maybe your kids will want to cast a line with their kids someday.

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Smoking fish is as old as fishing itself. Some techniques, and of course equipment, have evolved since our ancestors first tied a line to a stick, but some universal truths remain as relevant as ever. It isn’t complicated to smoke your own fish, but there are some mistakes you want to avoid. Whether you’re smoking saltwater or freshwater fish, if you want the best texture and flavor, keep the following in mind.

Know the difference between cold smoking and hot smoking

Cold smoking requires a consistent low temperature (65-85 degrees F) to cure fish over several days, and without a lot of experience or the right equipment, there’s a bit of a learning curve. Hot smoking on the other hand is easy to do with pellet grills, electric smokers, and log burners. The tips below are for hot smoking fish. With smokers set around 160 degrees F, hot smoking doesn’t take as long as cold smoking and produces a fantastic finished product. 

How to choose the best kinds of fish to smoke

Bottom line: The fattier the fish, the better. Fat helps fish stay moist, and it absorbs more smoke, which results in more flavor. Some great fish to try smoking are trout, steelhead, salmon, tuna, swordfish, mackerel, and sturgeon.

You can smoke leaner fish like walleye and sunfish, but they’re usually better when cooked in other ways. If you are determined to smoke leaner fish regardless, follow the methods here but include an extra step for applying a thin coat of grapeseed oil to the fish before smoking. Doing so adds a very small amount of fat to the exterior, but more importantly, since grapeseed oil is a semi-drying oil, it will partially harden when exposed to air, forming another layer to help lean fish absorb flavor from the smoke.

The best wood for smoking fish

Choosing wood for smoking is largely based on personal preference, but most people who smoke fish agree that some woods are too “harsh” for the flavor of fish. Top fish smoking woods include alder, maple, pecan, apple, and even cherry—while you may want to stay away from hickory and mesquite unless it’s mixed with another wood. For me, a mesquite and cherry mix is likely the strongest wood mix I would ever use for smoking fish.

The best kinds of smokers for smoking fish

Electric smokers, pellet grills, and log burners all work for smoking fish. In my experience, log burners offer a far more thorough smoke but come with a lower degree of control, and require more work to operate. For example, you’ll need to cut logs to a specific size (larger logs burn at lower temps for longer) instead of using chips, and you’ll want to cut off any bark because it adds harsh tones to the smoke.

Generally speaking, pellet grills and electric smokers are the easiest to use. But the smoke is far less concentrated and, in turn, the smoky flavor is less concentrated. After all, there is a reason world-famous smokehouses and barbecue pits have trailers of wooden logs delivered each day. Ultimately, though, the choice is yours.

Smoking fillets vs. smoking the whole fish

It’s up to you whether you want to fillet a fish out or try smoking it whole. I prefer to smoke fish in the size I might serve. For example, if I have a limit of small to medium-sized trout, I’ll cut out their backbones, butterfly them, brine and smoke them whole, then serve. For a single, larger salmon, I might cut a fillet into 8-ounce pieces before brining and smoking.

Nevertheless, the sight of a whole fishing smoking is something special, and smoked skin from trout is also tasty. Do note that removing the backbone helps keep the fish opened up so smoke can penetrate the cavity. I like to use a grill mesh, in which I can situate the fish and then clamp the mesh shut to keep the fish spread open. You could also use a wooden skewer to pin open a fish and expose the fillets to more smoke. 

Preparing the fish before smoking: Dry brine vs. wet brine

There are those who argue there’s no such thing as a dry brine because a brine requires water, but I’d also argue salting meat pulls out moisture that then gets reabsorbed, creating what one might call an autonomous brine (as the moisture, thanks to salt, pools on top of meat). But this concept is also more true for red meat, so it is indeed possible a dry brine for fish is merely “salting the fish.”

A wet brine, by definition, is water with a high concentration of salt and includes other ingredients. To be clear, whether dry or wet, salt is the main component here, as it will penetrate meat while any other ingredients add more surface-level flavor. Salt binds to muscle fibers, which boosts flavor and helps retain moisture while cooking.

I’ve moved away from wet brines for most forms of cooking. Minerals in water (especially tap water) can denature protein (not in a good way, typically speaking) and affect flavor. And your tap water will vary from my tap water in terms of mineral content. If you’re determined to use a wet brine, I suggest buying spring water from the store and making sure to boil in a healthy amount of salt before adding a saltwater fish. Dry-salting a fish, is quicker and produces something called a pellicle on the exterior of the meat—which is a thin, sticky membrane to which smoke can adhere.

Whether wet brining or salting, you’ll need to rinse the salt off of the meat, pat off any moisture with a towel, then let the meat fully dry before smoking. (Wet fish creates a mushy texture and won’t absorb a lot of smoke.) To fully dry the fish, you can either leave it on a grate overnight in the fridge or place it under a fast-running fan in a cool (no more than 60 degrees), shaded place for an hour. The goal is a dry fish that’s a little bit sticky.

Basic smoked fish recipes

As mentioned at the beginning, this article is meant to establish some guardrails but still allow you some room to improvise. Below are some basic brines and methods for smoking your favorite fish.

Wet brine ingredients:

• 1 gallon spring water
• 1/2 cup kosher salt
• 3/4 cup brown sugar
• 1/2 bulb fresh garlic, smashed
• 1/2 cup black peppercorns

Bring to a simmer and stir until the salt and sugar has dissolved. Cool in fridge and add your fish only once the brine has completely cooled. Brine 8- to 16-ounce cuts of fish or whole fish for 6-8 hours (a little longer for bigger cuts or whole fish), thoroughly rinse under cold water upon removal, pat dry, and allow the fish to fully dry before smoking at 160 degrees for 2-1/2 hours.

Dry brine / salt mix ingredients:

• 1 cup kosher salt
• 1/2 cup brown sugar
• 2 teaspoons paprika
• 2 teaspoon granulated garlic
• 2 teaspoons onion powder
• 1 tablespoon white pepper

Mix all ingredients in a non-active bin (glass or plastic) and add the fish flesh-side-down in 8-ounce pieces. Let it sit in the fridge for 1 hour. Flip the fish and let sit in the fridge for 1 more hour. Rinse off all salt under cold running water (this is a quick rinse but you want no granules or flakes left on the fish), pat dry, and allow the fish to dry either in the fridge overnight or under a fan (in a cool place) for 1 hour, until completely dry. Smoke at 160 degrees for 2 to 2-1/2 hours.

While smoking any fish, after allowing the fish to smoke for the first half hour, you can add a glaze of maple or agave syrup every half hour until the fish is done. I also like to mix in a tablespoon of pureed chipotle in adobo sauce for every 1 cup of maple or agave syrup and brush that on the fish.

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On the hunt in swamps, river mouths, and brackish coastal water, archerfish pick off insects with pinpoint precision. They don’t need arrows—instead, they shoot jets of water over a meter at their prey. The streams of water knock bugs out of the sky and are incredibly accurate. Despite their popularity—the fish are common in zoos and kept as pets—relatively little has been studied about the evolution of these aquatic sharpshooters.

In a new study published in Integrative Organismal Biology on Monday, ichthyologists and other team members at the University of Kansas investigated the archerfish, from the origin of the various species to the divergence of the family of fish. For years, the ichthyology community had debated what counts as part of the archerfish family. By taking a closer look at the tiny bones involved in the unique shooting behavior, the study authors were able to identify an unexpected evolutionary tree, branching from Asia to Australia.

“We looked at how these fishes are related and asked, ‘How did this amazing mechanism of allowing them to actually be able to spit come to evolve?”’ said lead author Matthew Girard in a press release. “We had some ideas of what other kinds of fishes they were related to, but for the first time we’ve generated a hypothesis of how all these species of archerfish are related to each other.”

The researchers created something similar to a family tree, using software to track molecular genetic data and fish tissue structure through time. By doing so, researchers were able to trace the evolution of the fish’s ability to jettison water. The results showed that all species of archerfish have grooves on the roof of their mouths as well as enlarged dental plates. These tube-like features, similar to a water gun’s barrel, enable the fish to squirt water at flying targets.

[RELATED: Fish can tell the difference between human faces]

In addition, the researchers found proof that the archerfish are closely related to beachsalmon, both genetically and in their shape. Structural similarities in the beachsalmon’s mouths possibly suggest existing physical features were co-opted by the archerfish to shoot water.

Beachsalmon don’t hunt with hyper-accurate water jets, though. “Just because other fish can move water, it’s not anything like [the archerfish],” co-author Leo Smith said in a statement. “I equate it to, ‘I could put a trumpet in my mouth, and I suppose I could make noise come out of it, but not like Miles Davis.’ It’s like a fundamentally different thing, too, a really remarkable specialization for catching insects.”

With this study, researchers may soon be able to find out even more about these uniquely gifted fish. Between the genetic data and the tissue structure, mapping the spread of these fish and the branches of the family tree contains large amounts of scientific data. Clarification of the origins of the animals may answer such questions as how many species of these maritime snipers exist.

[Related: This anglerfish has mastered a trick to light up the depths of the Pacific Ocean]

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This post was originally featured on Saveur.

Thanks to the marvels of modern refrigeration and shipping, buying seafood has never been easier. Fillets, half sides, and steaks are readily available from most grocery store fishmongers these days. But the pleasure of nose-to-tail dining, and with it, a better understanding of what’s on our plates is unbeatable—not to mention more sustainable. Maybe you like to catch your own. Or maybe you like to pick up an extra-fresh catch from the docks. Either way, knowing how to clean a whole fish is a useful skill for any home cook. 

Last month, while the SAVEUR team was in South Carolina for the Charleston Wine & Food Festival, I met up with James London, chef-owner of Chubby Fish, a dinner-only neighborhood restaurant spotlighting exclusively local seafood. London is an avid fisherman who is committed to serving responsibly caught fish. He’s also a generous teacher, and he invited me into his kitchen to demonstrate how he likes to fabricate the gorgeous whole fish he brings in from his purveyors. The species he was working with that morning was a grunt—a small, round, by-catch species identified by its bright orange mouth. The method he demonstrated will work well for round fresh- or saltwater fish of any size, including cod and salmon. Ready to take matters into your own hands? Here’s London’s step-by-step tutorial on how to clean a fish.

Set up over the sink and trim the fins

Cut down on clean-up by positioning a large wire rack directly over the sink; this will be your work surface for the first half of the process. (You can also work right in the sink if you don’t have a wire rack.), Place your fish on the rack, then use sharp kitchen shears to clip away all of the fins. Most round fish (think red snapper and branzino) have five fins (flatfish, like flounder and sole, have different anatomy.) The dorsal fins are located on the top of the fish, sometimes in two parts, or otherwise in one long fin. The anal fin is at the bottom, closer to the tail. Two pectoral fins can be found on either side, just behind the head; the pelvic fins are beneath the fish’s chin. 

Scale the fish

An inexpensive scaler makes quick work of removing the fish’s tough outer layer. To begin, turn on a slow stream of cold running water; scaling under the stream directly into the sink prevents scales from flying everywhere as you work. They’ll get caught in the drain and you can discard them when you’re done. Then, hold the scaler in your dominant hand while you hold the fish with your non-dominant hand. Using gentle but firm pressure, run the textured side of the scaler against the side of the fish in long strokes, from tail to head. “The places where the scales are most difficult to remove are by the chin and at the base of the tail on the bottom,” London explains, so make sure to concentrate on those spots. Run your hands in both directions over the fish to feel for any remaining scales, then give it a good rinse.

Remove the guts

Starting at the bottom of the fish, near the tail, slide your shears into the belly and snip open from the tail to the chin. Tuck your fingers into the opening and pull out and discard the contents. Give the fish a good rinse inside and out to wash away any blood. Next, pry open the gills behind the eyes, and using your finger, pull out the u-shaped cartilage; this will remove any guts that remain in the fish. Rinse once more, and with the water running into the cavity, run your finger along the inside spine, washing away the bloodline.

Set up your fillet station

Pat the fish dry with paper towels, then transfer to a cutting board. A clean, dry work surface is mportant, not only for sanitation purposes, but also for safety—excess moisture can lead to slipping and sliding as you cut.

Kitchen shears and a sharp fillet knife are essential for the following steps. London loves the inexpensive Dexter knife, which can be used for breaking down a chicken or even deboning a leg of lamb. This model is easy to find, holds a sharp edge, and has a flexible blade. “All the professionals use it,” he tells me, “and you can just sharpen it on a steel,” making the Dexter a perfect choice for the home cook. London also loves a traditional Japanese-style blade called a deba, which is specifically designed for filleting; its one-sided bevel shaves close to the bones, resulting in an exceptionally clean cut.

Score the skin

Use the fingertips of your non-dominant hand to find the soft spot on top of the fish’s head, then, insert the tip of the knife gently. Hold the fish firmly in place, then run the tip of the knife down the spine, scoring the skin from the base of the head all the way down to the tail.

Slice away the fillet

Following the initial cut and using no more than an inch of the blade, make long strokes with your knife to gradually slice away the fillet, while your other hand lifts the fillet as you go. (By lifting the fillet, you expose the bones, so you can see and follow the natural shape of the fish.) Try to keep your knife as close to the bones as possible as you work your way down towards the belly to keep as much of the flesh intact as possible. If you can hear the knife click against the bones as you slice, it means you’re on the right track; if not, angle the knife downwards to bring the edge closer to the ribs.

Once you make it down the belly, the fillet should only still be attached at the tail and the head ends. Place the palm of your hand over the fish, holding the fillet in place, then slide the knife between the fillet and the ribs. Carefully glide the middle of the blade through to detach the meat at both the front and back of the fish, then set the fillet aside.

Remove the second fillet

Flip the fish over so the head is now pointed towards your non-dominant hand. Use the tip of the knife to cut behind the fins, then, starting at the belly, cut along the collar bone in a u-shape, towards both the spine and the soft spot of the head. Next, starting from the tail this time, use the tip of your knife to score the skin along the spine once again until you reach the head. Repeat the same long shallow strokes as before to slice the second fillet away from the ribs. “The fish will tell me where to go,” London explains, “it tells me if I’m getting in too far and where I need to steer my knife along the bones.” At this stage, the fillet will only be attached at the tail; while holding the fillet down with your palm, use the middle of the blade to cut away that piece. Now you will have two fillets and the carcass of the fish. Reserve the fillets to cook however you like; the bones can be reserved for fish fumet or stock which can be used in soups or paella, or as a poaching liquid.

Skin the fish

At this stage, you can cook your fillets as-is. However, if you want to remove the skin, keep going. Position one of the fillets skin-side-down, with the tail end pointing toward your non-dominant hand. Grip the knife in your dominant hand and make a shallow cut into the flesh just where it meets the skin. Grab the piece of released skin and, with your knife under the meat and parallel to the cutting board, wiggle the skin and knife as you work your way down the fillet, gently separating it from the skin. You can save the skin along with the bones for stock, or discard. 

At this point, you can prepare the fllets right away, or otherwise wrap them in damp paper towels and transfer to the fridge for up to a day.

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With a color palette brighter than a bag of Skittles, you’d think the rose-veiled fairy wrasse would have no trouble standing out. But in the teeming waters of the Indian Ocean, it’s easy for a fish to swim under the radar, even when it looks like it’s ultraviolet.

For decades, the rose-veiled fairy wrasse was mistaken for its relative, the rosy-scales fairy wrasse. The two reef fish both grow up to three inches long, sport the same shocking ombre patterning, and float around the water column like dazed little sprites. But there are some subtle differences. The rose-veiled fairy wrasse has a more rounded tail fin and red-purple crosshatches on parts of its body. The adults of both species also vary in coloration, though it’s hard to tell with the dimness underwater.

[Related: An unknown Galapagos tortoise species may be lurking in museum bones]

These are the little details that helped biologists in the Maldives identify a new type of marine life—one that they were already quite familiar with. The rose-veiled fairy wrasse is a beloved aquarium fish that’s specifically found in twilight reefs, a coral habitat that thrives 100 to 300 feet under the ocean’s surface. The reefs are adapted to low-light conditions, and are generally more preserved than corals in the shallows, which are exposed to human disturbances like climate change.

“Though the species is quite abundant and therefore not currently at a high risk of overexploitation, it’s still unsettling when a fish is already being commercialized before it even has a scientific name,” Luiz Roza, curator of ichthyology at the California Academy of Sciences, said in a press release. He worked with researchers from the Maldives, Australia, and the Field Museum in Chicago to publish a species description of the rose-veiled fairy wrasse in the journal ZooKeys.

The paper compares the rose-veiled fairy wrasse specimens with several other species from the same genus, including the rosy-scaled fairy wrasse, which it was once lumped together with. The first species ranges in waters between the Maldives and Sri Lanka; the second lives farther south around the small island chain of Chagos. Both frequent “rubble bottoms scattered with loose coral cover,” according to the research.

The authors also cited photos, videos, and measurements taken from remotely operated submersibles in the twilight zone. Ultimately, they clocked enough visual differences to propose the rose-veiled fairy wrasse as its own species. They gave it the Latin name, Cirrhilabrus finifenmaa, after the national flower of the Maldives. (It translates to “rose” in the local Dhivehi language.)

The research was part of a longer expedition called Hope for Reefs, where divers and biologists band together to analyze the biodiversity of the twilight zone in the Maldives. In the process they’re coming up with strategies to conserve the deep-water corals—and all the eye candy living in them.

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When horses or cheetahs feel the need for speed, they break into a gait known as galloping. Rabbits bound. Some aquatic animals haul themselves about using forms of locomotion that rely on their fins, known as crutching or punting. All of these motions are special–the timings of left and right footfalls or fins aren’t evenly spaced apart.

Not all animals rely on these sorts of movements to get around quickly. However, so-called asymmetrical gaits aren’t a new innovation among vertebrates, scientists reported on March 8 in the Journal of Experimental Biology. The researchers analyzed observations of movements from hundreds of species and concluded that irregular gaits may have first emerged in ancient fish-like animals even before vertebrates made the journey onto land. The findings suggest that different groups of animals gained and lost the ability to use asymmetric gaits throughout vertebrate history. 

Though it was “more or less” known that land animals independently evolved these motions, “the idea that this ability is ancient for jawed fishes is relatively novel and intriguing,” John Hutchinson, a professor of evolutionary biomechanics at the Royal Veterinary College Hawkshead Campus in Hatfield, England, who wasn’t involved with the research said in an email.

When an animal walks or trots, it moves its limbs in a regular, evenly-timed pattern known as a symmetrical gait. To travel more quickly, many animals can switch to asymmetrical gaits, says Eric McElroy, a biology professor at the ​College of Charleston in South Carolina and coauthor of the findings. One classic example is a horse’s gallop.

In a gallop, all four feet hit the ground at different, unevenly spaced times, McElroy and his collaborator Michael Granatosky, of the New York Institute of Technology in Old Westbury, wrote in the paper. Mammals aren’t the only gallopers; some crocodilians have also been observed using this gait.

Gazelles can achieve another kind of asymmetrical gait called pronking, which involves springing into the air and landing on all four feet simultaneously. Toads and rabbits use bounding or half-bounding gaits, in which the two hindfeet hit the ground at the same time. Mudskippers, sea turtles, and some seals move their front flippers simultaneously in a “crutching” gait to get around on land. Some rays and other fishes punt, moving their pelvic fins simultaneously to scoot along the seafloor.

There are also some vertebrates that don’t seem to use asymmetrical gaits, including lizards, salamanders, platypuses, hedgehogs, lorises, and elephants. 

[Related: We’ve seen how tardigrades walk, and it’s mesmerizing]

To understand when these gaits first appeared, McElroy and Granatosky pored over reports of both symmetrical and asymmetrical movements in 308 different species of gnathostomes, or vertebrates with jaws. The vast majority of present-day vertebrates belong to this group, except for hagfish and lampreys. 

The researchers used computer models to investigate four different evolutionary scenarios. In one, the shared ancestor of gnathostomes had the ability to move asymmetrically, and its descendants could lose this ability but not regain it. Another model assumed that the trait could only be gained, which implied that the gnathostome ancestor didn’t have an asymmetric gait. 

In the third model, asymmetric gaits showed up and disappeared at roughly equal rates across the family tree. The fourth model removed the rate constraint. This allowed organisms to “have really fast evolution of asymmetrical gaits and really slow losses of asymmetrical gaits,” McElroy says. “They can be super different in terms of the speed of evolution.” 

He and Granatosky found that this fourth scenario was the most likely, based on how asymmetrical gaits are distributed across modern vertebrates. They calculated that the gnathostome ancestor had a roughly 75 percent probability of using some sort of asymmetrical gait.

This fish-like creature likely inhabited shallow coastal seas 400 million to 450 million years ago, around 25 million to 100 million years before some of its descendants invaded the land. The gnathostome ancestor may have used its fins to crutch or punt itself over the seabed, McElroy says, noting that many fossils of early jawed vertebrates resemble present-day fish that use these motions such as skates and rays. 

The team also determined that the ancestor that gave rise to modern mammals likely had the ability to move asymmetrically, while the ancestors of amphibians and lizards probably did not.

It’s unclear why asymmetrical gaits were lost in some groups of vertebrates. Elephants may be too large to gallop without putting dangerous amounts of stress on their bones. Certain animals, such as lorises and many turtles, may never move fast enough to need asymmetric gaits. 

Lizards can scurry along very quickly without moving their limbs in an asymmetrical pattern. “I’ve never seen a lizard gallop, and it’s weird that they don’t do it and suggests some sort of neuromuscular constraint,” McElroy says. “I’d like to take a closer look at that to really figure out are lizards just not capable of doing this, or is it something that they do very, very rarely, or there are some groups of them that can do it and we just haven’t studied those groups?” 

The 308 present-day animals that the researchers examined represent only a fraction of the estimated 69,000 vertebrate species. This, Hutchinson said, might have skewed the results of the analysis. 

Observations of modern fish species were relatively sparse, McElroy acknowledges. “Fish are going to tend to have a larger effect on the [evolutionary] reconstructions because they’re the oldest species,” he says, and represent “both a limitation and an area for future discovery.” Accounting for the locomotion of extinct vertebrates would improve these estimates, too, but little is known about how they moved.

Despite these limitations, Hutchinson said, “the study is valuable in that it synthesizes a lot of data with good evolutionary tools and will provoke further investigations into the questions it raises.”

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Michael J. Benton is a professor of Paleobiology, University of Bristol. This story originally featured on The Conversation.

The dinosaurs were killed by a meteorite impact on the Earth some 66 million years ago in what has become known as the Cretaceous-Paleogene extinction event. At what time of the year this occurred has long generated debate among palaeontology enthusiasts.

A recent study published in Nature builds on earlier evidence to suggest the dinosaurs probably met their demise in June. The fact that researchers have been able to pinpoint the timing of an event that happened millions of years ago is a remarkable feat of science—but more on that later.

The latest evidence comes from a site called Tanis, located in the Hell Creek Formation in North Dakota. Tanis is one of several geological locations around the world where scientists have observed the Cretaceous-Paleogene boundary in the succession of sediments.

Tanis has yielded wonderful fossils of dinosaurs, early mammals, fish, plants and other things. Many of these fossils are exceptionally well preserved, with some showing remains of soft tissues, such as skin, as well as bones, which can offer valuable scientific insights.

The Tanis site was first identified in 2008 and has been the focus of fieldwork by palaeontologist Robert DePalma since then. In a 2019 paper, DePalma and his colleagues argued that Tanis captured the moment of the asteroid’s impact, due to three factors.

The first was the presence of dinosaur fossils occurring in the Cretaceous sediments right up to the Cretaceous-Paleogene boundary, and exactly at the boundary at the time of impact.

The second was a layer of melt spherules: tiny glass balls that cooled in flight from molten rock. When the asteroid struck Earth in the region of what is now the Yucatán Peninsula in Mexico, it spread debris and melt spherules for thousands of kilometers.

The third was evidence of seiche waves (see-saw-like standing waves) in deep channels. The Tanis site is well inland today, but at the end of the Cretaceous period it was located on the coast of the western interior seaway that divided North America at that time, with sea levels some 200 metres higher than they are today. The site was estuarine, which means fresh and salt waters were mingling.

The seiche waves were generated by the distant impact in Mexico, which set off seismic waves that shook the Earth and caused water to flow in and out of the river channels at a fast rate, estimated as beginning one hour after the impact.

As well as melt spherules within the fossil-bearing rocks, the researchers found abundant spherules in the gill skeletons of some of the fish they examined. We can imagine that as they floundered in the violently oscillating waters of the river channel, they could have swallowed melt spherules coming from above.

Looking more closely at the fish

In December 2021, DePalma and his colleagues published an important paper about the timing of the Cretaceous-Paleogene extinction event. In this study, they analysed some of the exceptionally well-preserved fish bones, looking at how the cycle of seasons, from summer to winter, were documented in the structure and chemistry of the bones.

By comparing living sturgeon to sturgeon fossils from Tanis, they found that in a fin spine, regular layering at a scale of millimeters shows the fish died when it was seven years old. The growth rings confirm the fish alternated between fresh waters in summer months and saline waters in winter. In this and other specimens analyzed in the same study, the last growth increment matches the transition from spring to summer.

Taken together, this suggests the meteorite struck in May or June, being the cusp of spring and summer in the northern hemisphere.

Importantly, these findings confirm earlier evidence based on fossil plants, which suggested the extinction event took place in early June.

Palaeobotanist Jack Wolfe identified a location in Wyoming that showed the effect of the meteorite on a freshwater lake. At the point of impact, the lake froze, preserving fossil plants in exquisite detail.

By comparing the fossil plants to similar modern water lilies Nuphar and Nelumbo, he showed that the latest Cretaceous water lilies in the lake had been halted in their growth at a point in their trajectory of producing summer leaves, flowers, and fruit which indicated freezing in early June.

Palaeontologists often say they would need a time machine to understand the details of past life, such as the month the dinosaurs died out. But here we see extraordinary conclusions can emerge from careful analysis and rational comparison with the modern day.

The post June was probably a terrible month to be a dinosaur. Here’s how we know. appeared first on Popular Science.

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Deep below the ocean—3,000 feet beneath the surface, where sunlight cannot seep—the sea is smothered in a cold, inky darkness. But a bobbing bright light sometimes breaks through the abyss. The glimmering shades of blue and green mesmerize curious fish and squid, tempting them closer. They likely think that they’ve stumbled upon a prized floating morsel in a relatively resource-deprived habitat. Little do they know that they’re the ones about to become a meal. The last thing they’ll see is a spiny, globe-shaped shadow emerging from behind the glowing orb—then they’ll be ensnared in the toothy maw of an anglerfish. 

Researchers have known for some time that this dazzling, deadly display is a typical feeding tactic of all anglerfish species, but a study on the rare Pacific footballfish sheds new light on how they get their sparkle. 

According to results published in the Journal of Fish Biology, this particular species doesn’t just emit a glow: it also converts its shining colors into “an amazing disco ball of light,” says study author Todd Clardy, the ichthyology collections manager at the Natural History Museum of Los Angeles County (NHM).

“There’s a lot of different anglerfishes, and they all look pretty different and come in different sizes,” says Bill Ludt, a coauthor on the paper and the museum’s ichthyology curator. That level of variety extends to the glowing lure they use to attract mates and prey.

[Related: These ultra-black fish camouflage with the darkness of the deep sea]

Some anglerfish species have very simple lures—which are also known as escas—with just one little dot of light at the tip. Others have longer, more complex lures, or even multiple glowing, dangling appendages. But each shares the same source of illumination: bioluminescent bacteria. These microbes, which can be found in many sea creatures, such as the Hawaiian bobtail squid, can be used to draw in prey, create camouflage, distract predators, and communicate with members of the same species. In an anglerfish, these photobacteria live within the fleshy esca and act like little light generators, producing a soft, electric blue hue. It is the only source of light found below 650 feet in the ocean.

But as the new study demonstrates, the Pacific footballfish (Himantolophus sagamius) uses an additional trick to create its light shows: Biofluorescence. While the two qualities can be often confused, bioluminescent organisms produce light, while organisms with biofluorescence are able to change light. “You could think of it as a manipulation—the light comes in one color [or wavelength] and then gets emitted in a different color,” says Ludt. 

“Biofluorescence is pretty widespread actually in shallow water marine environments, but the fact that we’re seeing this in the deep sea where there is no ambient light makes this really fascinating,” he adds. 

In the absence of sunlight, the study authors suggest, the anglerfish has instead evolved the ability to harness and transform the light of its shining microbes. Fluorescence adds extra flair to their flashy trap.

The new insights stem from Ludt and Clardy’s examination of a female Pacific footballfish that washed up to shore in Newport Beach, California and went viral on social media in May 2021. Nicknamed “Spiny Babycakes” on Twitter, the specimen was about a foot long and probably lived between 1,000 and 4,000 feet deep. Only females grow to this size, as most males of anglerfish species are small, and often even latch on to females parasitically. It’s a rare find, with only around 30 other anglerfish specimens in collections worldwide, says Ludt. The team received the footballfish frozen and thawed her, with plans to inject the precious sample with formalin for preservation. But Clardy pumped the brakes—why not examine her in fluorescent light first? 

To their surprise, blue wavelengths of light revealed a green glow on the fish’s lure. Upon closer examination, they found small, biofluorescent crystalline structures on the illicium, or the stalk that holds the lure—where there isn’t any bioluminescent bacteria. Ludt and Clardy reason that the bioluminescent lure provides the necessary light source for the crystal structures to fluoresce. 

“Already this species has a very complicated, elaborate display that it can create with its lure, and this fluorescence adds on top of it,” says Ludt. The hanging esca bulb is noticeably larger than some other species, and is flanked by numerous tentacle-like appendages that each have a silvery, light-emitting tip. While the researchers can’t determine exactly what its function is until footballfish are observed in the wild, they suspect that this multi-color array could act as a way to attract mates or confuse prey. 

“I mean, imagine being in a pitch black cave or something and all you see in the distance is little dapples of light, like bright blues here and some tiny shades of green there,” Ludt says. “It just complicates the optical display overall for anything that’s viewing underwater.”

There are a handful of other deep sea creatures known to use this combo of biofluorescence and bioluminescence, including a crystal jellyfish and some siphonophores. One bottom-dweller called the stoplight loosejaw dragonfish uses biofluorescence to alter bioluminescent blue light into red, which acts like a flashlight that most of its prey are physically unable to see. 

The new findings suggest that biofluorescence might be more common among species of anglerfish and other deep sea organisms than previously thought. 

“This was surprising to me, particularly because biofluorescence requires a light source, and light is not something we typically attribute to the deep sea,” says Christopher Martinez, a fish biologist and an assistant professor in the department of ecology and evolution at UC Irvine. “In a region of the ocean with so many ‘strange looking’ organisms, anglerfishes stand out in their wildly divergent and extreme morphologies. Discoveries like this one are great because they bring to light new dimensions of diversity along with new ways to think about how organisms in the deep sea survive and evolve.”

“We are just starting to learn about biofluorescence in fishes and its possible functions,” says Martinez. “However, the truth is that we really don’t know how biofluorescence is used in fishes, and that is exactly why it’s so exciting.”

Ludt and Clardy are working with colleagues at NHM to survey the diversity of fishes in the museum’s collection. This latest finding highlights the elaborate—and extreme—adaptations that creatures have evolved in order to dwell in the murky depths. 

“The deep sea is not a very hospitable place—it’s cold, dark, there’s a lot of pressure,” Ludt says. “I think this [study] just really showcases how complicated these adaptations are, and how remarkable they are as well.”

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This story originally featured on Outdoor Life.

In the past two years, four hurricanes in Louisiana have caused an estimated $579 million in damages to the state’s coastal fisheries, according to findings published this month. The study, which was conducted by the Louisiana Department of Fisheries and Wildlife and the Louisiana State University Agricultural Center, found that Hurricanes Laura, Delta, and Zeta were costly by causing 30 percent of that damage in 2020, but that Hurricane Ida in 2021 caused the remaining 70 percent of damage.

The total $580 million figure includes lost revenue, infrastructure costs, and the natural resource itself. The revenue lost for the 22 coastal parishes totaled $155 million overall, with $48 million lost in 2020, $66 million in 2021, and a hangover of $40 million lost into 2022.

Mike Frenette, a long-time Louisiana fishing guide who owns and operates the Redfish Lodge of Louisiana in Venice, has felt these losses first-hand. His lodge sustained significant damage, and says the storms put a halt to much of the local fishing. But he says other fishing regions west of Venice—Grand Isle, Port Fourchon, Cocodrie—were more devastated, where fishing is even slower to recover.

“It was bad in Venice, but … they suffered a direct hit from Ida, a category-four hurricane,” he says. “Ida leveled a lot of businesses, homes, marinas, and it killed people. It was awful.”

While homes and businesses destroyed by recent hurricanes were deadly and costly, Frenette is now most concerned about what the high winds and massive tidal surges did to Louisiana’s coastline lands and marshes.

“All of these coastal areas are vitally important to the region’s fishing and the state economy,” he says. “The marshes and inshore waters are the incubators for finfish and shellfish. The long-term residual damage to these unique nursery areas is impossible to calculate.”

Frenette believes that the coastal area fisheries habitat loss will adversely impact Louisiana’s fishing future for three to five (or more) seasons. Vanishing coastal marshes have been a huge issue in recent years, and some areas where shoreline marsh bordered open inshore waters has receded miles from its original location. That means vast, important marsh, inshore pools, and bayous have disappeared as flooding, high winds, and towering tidal surges have left their marks.

Infrastructure is being rebuilt in Venice and other regions along the coast, but securing the materials and contractors to rebuild remote coastal fishing areas can be difficult, particularly in a nation that’s already grappling with supply chain issues due to the ongoing pandemic.

“Venice Marine and Cypress Cove in Venice are up and running, and have fuel and accommodations,” Frenette explains. “My lodge is still missing a roof, but we’ll be operational by the end of February.”

After Hurricane Ida, NOAA reported that all of Grand Isle’s homes were damaged, and 40 percent of the homes were “nearly-to-completely destroyed.” Farther west, in the popular Lake Calcasieu south of Lake Charles, hurricane damage to infrastructure was bad, but not as catastrophic as to the east.

“Hurricane Laura was a Category 5 storm with 150-mph winds that put us out of business for about seven weeks,” says Buddy Oakes, of well-known Hackberry Rod & Gun Club on the shores of Lake Calcasieu. “We lost about 60 percent of our business, and after duck season, we’ll be closed until March 13 to get all our lodge repairs done in time for fishing season.”

Oakes says that while Hurricane Laura and other storms hit local properties and businesses hard, the region is recovering. The turbulence does have some upsides for recreational anglers.

“We live and work on the Louisiana Coast and we know what that means in dealing with hurricanes, so we push through it,” Oakes says. “But the storm in our area cleaned out the marshes, and the fishing has been outstanding for seatrout and redfish. We’re catching limit numbers of fish, and we look to have a great 2022 fishing season.”

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Oftentimes, the most astounding scientific discoveries are made entirely by accident. It was 3 am one sunshine-filled night in February of 2021, and marine biologist Lilian Boehringer of the Alfred Wegener Institute in Germany was keeping vigil in the camera room aboard the research vessel Polarstern, watching live images of the Antarctic seafloor roll fire off every 20 seconds. More than thousands of feet beneath the floes, Boehringer saw something in the barren landscape: teeming icefish nests ringed with stones. The structures continued non stop for four hours as the camera drifted along. 

“They were everywhere,” Boehringer told The New York Times in an interview. 

[Related: Watch these rare ocean creatures caught on candid robot camera]

Boehringer’s team was in the Weddell Sea to study ocean currents and carbon cycles. Instead, the researchers stumbled upon the largest fish nursery on record. Previously, the biggest colony in the books was only 60 nests strong, The Guardian reports. But this new nesting site blows the last record out of the water, with 60 million active nests sprawling  across an area about twice the size of San Francisco. “I’d never seen anything like it in 15 years of being an ocean scientist,” deep-sea biologist Autun Purser of the Alfred Wegener Institute told CNN. Purser also witnessed the spectacular camera feed when he joined Boehringer later on that February night. “After that dive, we emailed the experts on shore who know about fish like this. They said, yep, this is pretty unique.”

Something fishy about icefish

Before the discovery of nests galore, the icefish itself had long piqued scientific interests when an individual was first caught by a Norwegian zoologist a century ago. Researchers were quick to notice the Channichthyidae family’s  physiological marvels. As The New York Times explains, its story starts 30 million years back in time when the once balmy Antarctic seas froze and became inhospitable to many of its original inhabitants. But one bottom dweller survived and adapted to thrive in these frigid waters. Its descendants dropped their scales, swapped in a clear version of blood, and thinned down their bones to the point that some organs can be seen through the translucent skeletal cages. 

This modern and revamped icefish shed many of the features that we know of from fish, simply because they were unnecessary—dangerous even—for its lifestyle. Cold water contains more dissolved gases than warm water, so the lack of scales allows the icefish to absorb oxygen from the ocean  directly through its skin. What icefish blood lacks in hemoglobin—the molecule that ferries oxygen through the body and gives blood cells their signature crimson hue—is made up for in antifreeze proteins, which halt the growth of ice crystals in the creature’s veins. Over the eons, the species gradually built up and developed floppier bones for buoyancy. It started riding on ocean upwellings to feed on krill and zooplankton, casting off part of its bottom-dweller status. 

Beneath the Weddell Sea where the Polarstern floated, the water is a toasty two degrees Celsius warmer than the surrounding seabed. That might explain why icefish flock to these churning waters—the currents probably favor their foraging habits—to establish the world’s largest known nesting site. 

A bonanza of nests

“Some animals like to be social, but there’s a limit,” John Postlethwait, a biologist at the University of Oregon who wasn’t involved in this fateful expedition, told CNN. This new throng of icefish nests defies that expected limit, and scientists don’t know why. “Congregating may give them advantages for finding mates, but provides a rich point source for predation,” he added.

The nests discovered by the researchers aboard the Polarstern, recently detailed in Current Biology, provide a glimpse into the breeding habits of the creatures. Each had an average of 1,735 eggs, the New York Times reports. In about the three-fourths of the nests, a single icefish stood guard to protect the eggs from potential predators like starfish, polychaete worms, and sea spiders. Above the breeding grounds, hungry Weddell seals also frolicked. Present and historical satellite tracking data from the seals revealed that these hunters would dive down to the nesting site to snack on icefish. Bony carcasses littering the crime scene offered further evidence of the breeding colony’s importance in the local food web, Live Science explains.

Colony on thin ice

While people don’t typically eat icefish, the survival of these enigmatic creatures is threatened by humankind just the same. As the planet heats up, the ice cover shielding the nests may disappear, exposing the vulnerable younglings to predators, according to Gizmodo. Algal patterns might shift, which could further affect the distribution of food sources that support the vast community of icefish. 

That would make this unusually large community of icefish particularly vulnerable. Their highly localized nests mean the colony has put all their eggs in one basket, Science News explains: Any shocks in the surrounding environment has the potential to wipe out the entire population. Per the New York Times, the authors say that their study provides more than enough reason to establish a marine protected area in the Weddell Sea, similar to the environmental protections placed on the Ross Sea which bans commercial fishing in its waters. In the meantime, the team has stationed a camera sentinel to photograph the colony twice a day for two years, and laid plans for returning to the region for follow-up studies.  

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Don Arnold is professor of Biological Sciences and Biomedical Sciences, USC Dornsife College of Letters, Arts and Sciences. This story originally featured on The Conversation.

All memory storage devices, from your brain to the RAM in your computer, store information by changing their physical qualities. Over 130 years ago, pioneering neuroscientist Santiago Ramón y Cajal first suggested that the brain stores information by rearranging the connections, or synapses, between neurons.

Since then, neuroscientists have attempted to understand the physical changes associated with memory formation. But visualizing and mapping synapses is challenging to do. For one, synapses are very small and tightly packed together. They’re roughly 10 billion times smaller than the smallest object a standard clinical MRI can visualize. Furthermore, there are approximately 1 billion synapses in the mouse brains researchers often use to study brain function, and they’re all the same opaque to translucent color as the tissue surrounding them.

A new imaging technique my colleagues and I developed, however, has allowed us to map synapses during memory formation. We found that the process of forming new memories changes how brain cells are connected to one another. While some areas of the brain create more connections, others lose them.

Mapping new memories in fish

Previously, researchers focused on recording the electrical signals produced by neurons. While these studies have confirmed that neurons change their response to particular stimuli after a memory is formed, they couldn’t pinpoint what drives those changes.

To study how the brain physically changes when it forms a new memory, we created 3D maps of the synapses of zebrafish before and after memory formation. We chose zebrafish as our test subjects because they are large enough to have brains that function like those of people, but small and transparent enough to offer a window into the living brain.

To induce a new memory in the fish, we used a type of learning process called classical conditioning. This involves exposing an animal to two different types of stimuli simultaneously: a neutral one that doesn’t provoke a reaction and an unpleasant one that the animal tries to avoid. When these two stimuli are paired together enough times, the animal responds to the neutral stimulus as if it were the unpleasant stimulus, indicating that it has made an associative memory tying these stimuli together.

As an unpleasant stimulus, we gently heated the fish’s head with an infrared laser. When the fish flicked its tail, we took that as an indication that it wanted to escape. When the fish is then exposed to a neutral stimulus, a light turning on, tail flicking meant that it’s recalling what happened when it previously encountered the unpleasant stimulus.

To create the maps, we genetically engineered zebrafish with neurons that produce fluorescent proteins that bind to synapses and make them visible. We then imaged the synapses with a custom-built microscope that uses a much lower dose of laser light than standard devices that also use fluorescence to generate images. Because our microscope caused less damage to the neurons, we were able to image the synapses without losing their structure and function.

When we compared the 3D synapse maps before and after memory formation, we found that neurons in one brain region, the anterolateral dorsal pallium, developed new synapses while neurons predominantly in a second region, the anteromedial dorsal pallium, lost synapses. This meant that new neurons were pairing together, while others destroyed their connections. Previous experiments have suggested that the dorsal pallium of fish may be analogous to the amygdala of mammals, where fear memories are stored.

Surprisingly, changes in the strength of existing connections between neurons that occurred with memory formation were small and indistinguishable from changes in control fish that did not form new memories. This meant that forming an associative memory involves synapse formation and loss, but not necessarily changes in the strength of existing synapses, as previously thought.

Could removing synapses remove memories?

Our new method of observing brain cell function could open the door not just to a deeper understanding of how memory actually works, but also to potential avenues for treatment of neuropsychiatric conditions like PTSD and addiction.

Associative memories tend to be much stronger than other types of memories, such as conscious memories about what you had for lunch yesterday. Associative memories induced by classical conditioning, moreover, are thought to be analogous to traumatic memories that cause PTSD. Otherwise harmless stimuli similar to what someone experienced at the time of the trauma can trigger recall of painful memories. For instance, a bright light or a loud noise could bring back memories of combat. Our study reveals the role that synaptic connections may play in memory, and could explain why associative memories can last longer and be remembered more vividly than other types of memories.

Currently the most common treatment for PTSD, exposure therapy, involves repeatedly exposing the patient to a harmless but triggering stimulus in order to suppress recall of the traumatic event. In theory, this indirectly remodels the synapses of the brain to make the memory less painful. Although there has been some success with exposure therapy, patients are prone to relapse. This suggests that the underlying memory causing the traumatic response has not been eliminated. https://www.youtube.com/embed/rHg_SlEqJGc?wmode=transparent&start=0 Conceptually tied to classical conditioning, prolonged exposure therapy is one way to treat PTSD.

It’s still unknown whether synapse generation and loss actually drive memory formation. My laboratory has developed technology that can quickly and precisely remove synapses without damaging neurons. We plan to use similar methods to remove synapses in zebrafish or mice to see whether this alters associative memories.

It might be possible to physically erase the associative memories that underlie devastating conditions like PTSD and addiction with these methods. Before such a treatment can even be contemplated, however, the synaptic changes encoding associative memories need to be more precisely defined. And there are obviously serious ethical and technical hurdles that would need to be addressed. Nevertheless, it’s tempting to imagine a distant future in which synaptic surgery could remove bad memories.

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One of the most easily visible impacts of climate change is coral bleaching. As temperatures rise worldwide, water temperatures are climbing as well, causing colorful coral to become stressed and kick out their symbiotic algae partners. These events leave the reefs without their primary food source and susceptible to disease. 

We’ve already seen this happen multiple times throughout recent history. In 2020, the Great Barrier Reef off Queensland, Australia, experienced its third major bleaching event over the span of only five years—and it might see another one by the end of this month. In some instances, the bleaching is so intense that it leads to high mortality. Reef decline impacts the communities of fish that live there, as well as the populations of people who depend on reefs for food or income. 

In 1998, the African archipelago of Seychelles experienced a massive heatwave that caused almost all the coral in the area to die out. Researchers scoping out the impacts of the disaster for the past 20 years have learned that about half of the reefs have recovered, while the other half have been replaced with seaweed. But more recently, an international team of scientists found that the fish populations, even the ones swimming around the most damaged coral, were substantially healthier than predicted—at least when it comes to nutritional value for humans. They published their findings yesterday in OneEarth. 

[Related: Fish sounds tell us about underwater reefs—but we need better tech to really listen]

“The Seychelles is a great place to study how fish contribute to people’s health because loads of people eat fish,” says James Robinson, a coral reef ecologist at Lancaster University in the UK and lead author on the paper. 

Robinson set off to find fish with a handful of local anglers and captured samples of 43 tropical reef species from both the recovered and seaweed-infested regions. He and his fellow researchers then sent off snips of frozen muscle from the subjects to analyze things like the concentration of minerals and fatty acids. 

“We wanted to first understand how nutritious are reef fish, so we took all these values and compared them to other meats like chicken, pork, and beef,” Robinson says. “What we found is that reef fish are similar or more nutritious than those meats … that was super cool, uncovering the roles that reefs are playing in people’s health.”

But they also discovered something strange: Beyond being generally healthy, the reed fish were more nutritious after the bleaching event than before. After comparing the data, the study authors found an increase in fish biomass and a corresponding increase in nutrients in fish from today versus pre-1998 fish. 

What’s more, the fish on the seaweed-heavy reefs had more iron and zinc than the same species on recovering coral sites. The significant change in the food web, moving toward nutrient-heavy macroalgae, “propagated up” the food chain to everything that eats the seaweed, Robinson says.

“This sort of says that reefs in Seychelles are continuing to provide food despite these really severe climate impacts,” Robinson says.

However, not all bleached reefs give away to productive seaweed—sometimes, they’re replaced by grassy turf algae, which hasn’t been studied in this method yet. So there’s always the possibility that other bleaching events, like the ones in recent years, won’t see the same nutritional silver lining. Still, this research emphasizes the importance of protecting coral reefs as a part of protecting the food system—even after climate impacts. 

Currently, Seychelles is heavily dependent on imports, with about 90 percent of their total food coming from outside the country. Globally, climate change poses a growing threat to food systems, whether due to smaller farming yields or troublesome impacts on fisheries.

“We should focus attention on if we can manage coral reefs to protect that food supply and understand how bleaching will affect it at the same time,” Robinson says. “Most reefs are not managed for fishing, so there’s a risk that if you fish too hard, you lose that nutritional benefit. Hopefully this is another great reason to manage and protect reef fishes.”

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This story originally featured on Nexus Media News, a nonprofit climate change news service.

On a sweltering morning in July of 2021, thousands of dead fish washed onto the northeastern shores of Pokegama Lake, 60 miles north of Minneapolis. 

Deb Vermeersch, an official with the Minnesota Department of Natural Resources, was called in to investigate. 

When she arrived, she saw a quarter-mile stretch of sand covered with the rotting carcass of walleye and Northern pike, which thrive in deep, cool waters, as well as crappies, sunfish and suckers—all warm water dwellers. “They were already pretty decomposed because of the warm water,” Vermeersch recalls. 

Because so many different types of fish had died, Vermeersch and her colleagues knew it wasn’t a species-specific parasite, a common cause of fish kills. They zeroed in on the culprit: dangerously low oxygen levels.

Oxygen is disappearing in freshwater lakes at a rate nine times that of oceans due to a combination of pollution and warming waters, according to a study published in Nature earlier this year. Lakes like Pokegama are warming earlier in the spring and staying warm into autumn, fueling algae blooms, which thrive in warm waters, and threaten native fish.

Minnesota, with its 14,380 lakes and temperatures that have risen faster than the national average, is a unique laboratory for studying how climate change is affecting temperate-zone lakes around the world. The state sits at the intersection of four biomes––two distinct prairie ecosystems and two ecologically different forest systems. This means scientists here are able to study how lakes in different ecosystems fare on a warming planet, and look for ways to stave off the worst effects of climate change. 

“If you start losing oxygen, you start losing species.“

“What’s going on at the surface is that warmer water holds less oxygen than cool water,” says Lesley Knoll, a University of Minnesota limnologist and one of the authors of the Nature report. She says that longer, hotter summers are interfering with two key processes that have historically kept lakes’ oxygen levels in check: mixing and stratification. In temperate climates, water at the surface of lakes mixes with deep waters in the spring and the fall, when both layers are similar in temperature. As the surface water warms during the summer, the water forms distinct layers based on temperature––cool water at the bottom, warm at the top. This is known as stratification. In the fall, when the surface waters cool again, the water mixes for a second time, replenishing oxygen in deeper waters. But as climate change makes surface water warmer, and keeps it warmer for longer, that mixing doesn’t happen when it should.

“As you have that stronger stratification, the water in the deep part of the lake is cut off from the oxygen at the top part of the lake. If you start losing oxygen, you start losing species,” says Kevin Rose, a biologist at Rensselaer Polytechnic Institute in New York and a coauthor of the Nature study.

Knoll, Rose and a team of 43 other researchers studied 400 temperate lakes from around the world. They found that, on average, surface waters warmed by 7 degrees Fahrenheit and have lost roughly 5 percent of oxygen since 1980; deep waters, which haven’t warmed much, have still lost an average of almost 20 percent of their oxygen. (Thanks to the state’s long-held lake monitoring programs, almost a quarter the lakes in the study were in Minnesota.)

Warming lakes emit methane

Fish kills aren’t the only reason scientists are concerned about lakes losing oxygen. In extreme cases, when deep waters go completely void of oxygen, something else happens: Methane-emitting bacteria begin to thrive.

“As lakes warm, they will produce more methane and most of that has to do with stratification,” says James Cotner, a limnologist at the University of Minnesota.

Lakes normally emit carbon dioxide as a natural part of breaking down the trees, plants and animals that decay in them, but plants in and around fresh water also absorb it, making healthy lakes carbon sinks. 

Lakes have historically emitted methane, too––about 10 to 20 percent of the world’s emissions––but the prospect of them releasing more of the greenhouse gas has Cotner and his colleagues alarmed. Methane is about 25 times more potent than CO2 when it comes to trapping heat in Earth’s atmosphere.

Cotner is leading a team of researchers who are studying what conditions allow methane-emitting bacteria to prosper in lakes and how conservationists can respond. 

“The key questions are understanding how much and when carbon dioxide and methane are emitted from lakes, and what are the key variables that can tell how much will be emitted. Certainly, oxygen is a big part of that, but stratification and warming also plays a role,” says Cotner. 

Pollution plays a big role

It’s not just longer, hotter summers that are causing lakes to lose their oxygen. Polluted agricultural runoff (pesticides and fertilizers) and logging have long plagued Minnesota’s lakes. It’s a problem that’s getting worse worldwide as climate change pushes agriculture further away from the equator and into new territory, says Heather Baird, an official with Minnesota’s Department of Natural Resources.

In northern Minnesota, potatoes now grow where pine forests have thrived for years. Phosphorus, a common fertilizer, now runs off from the soil into the region’s lakes, Baird says. Though small amounts of phosphorus occur naturally in lake ecosystems, too much of it feeds harmful algae blooms. 

Those blooms, which thrive in warm, nutrient-rich water, set off a chain of events that remove oxygen from deep lake waters.

“When phosphorus builds in lakes and creates algae blooms, those blooms eventually die. As they do, they sink. Deeper down, bacteria break down the algae, using up the remaining oxygen at those lower depths,” said Baird.

A quarter of Minnesota lakes now have phosphorus levels that are so high that the state advises against swimming, fishing or boating in them. Fueled by these nutrients, algae blooms take over, covering the lake in sometimes toxic residue that thrives in warm, nutrient-rich water, as was the case in Pokegama Lake earlier this year. The protists choke out aquatic life, especially fish that thrive in cold, deep waters. This is all exacerbated by warming air temperatures. 

The 75 percent rule

Researchers and conservationists in Minnesota are now studying the best ways to protect temperate-climate lakes from the worst effects of climate change. They have found that preserving 75 percent of deep-water lakes’ watersheds appear to keep fish stocks healthy. 

“Having a forested watershed helps keep better water quality by filtering out nutrients, which in turn can buffer against the impacts of climate change, to a point,” Knoll said. However, she added, as temperatures continue to rise, “that 75 percent may not be high enough anymore.” 

Knoll and state conservationists are focusing their research and efforts on deep, cool lakes that have a better chance of staying oxygenated than warmer, shallower lakes, like Pokegama.

July 2021, when the Pokegama Lake fish kill occurred, was the hottest month ever recorded on Earth. Parts of Minnesota were also experiencing the worst drought in 40 years, a trend some climatologists expect to persist in future summers. 

Vermeersch, the Minnesota fisheries supervisor, said it’s unclear what this will mean for the future of lakes like Pokegama. “Hopefully it’s not going to be a linear thing,” she said, adding that fish kills are “probably going to happen more often,” depending on a combination of factors. “When you get lakes like Pokegama that are shallow and already impaired, I think we are going to see more and more conditions like this.”

Correction (December 23, 2021): The story previously identified the wrong Pokegama Lake in Minnesota. The one that experienced the fish kill in July is 60 miles away from Minneapolis, not 140 miles away.

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Invasive mosquitofish are a menace to tadpoles and other amphibian communities worldwide. Eastern mosquitofish in particular are known to gorge on amphibian eggs and clash with tadpoles. They also aggressively compete for food and space against native fish. 

In the early 1900s, these mosquitofish were seen as an effective and inexpensive way to control mosquito populations and stem the spread of illnesses like malaria, since they feasted on mosquito eggs and larvae floating in the water. But it all went downhill, fast, when these fish started displacing native species, spreading beyond where they were introduced, and eating what they were not supposed to eat. 

Dealing with them today is challenging. Besides advising people to kill them on sight, there’s not really an effective, widespread way to control their population. But researchers from the University of Western Australia and NYU Tandon are trying out a new tactic to corral these invasive fish and keep them in check: by introducing a robot disguised as a mosquitofish predator. A new study the group published in iScience Thursday showed that the simple presence of a predator was enough to change mosquitofish behavior, and benefit tadpoles in the process. 

To test if this would work, they made a robotic predator that looks and moves like a largemouth bass, which is the mosquitofish’s main natural predator. With this prop set up, it was time to test some ecosystem dynamics. 

[Related: Fish sounds tell us about underwater reefs—but we need better tech to really listen]

In past tests, the team had studied the relationship between just the imposter predator and the mosquitofish. In short, those tests found that even short-term exposure to the predator kept the mosquitofish on their toes, metaphorically speaking. The presence of the robot reduced the mosquitofish’s energy reserves and nutritional health. This new study adds another creature, the Litoria moorei tadpole, into the mix. 

The team housed an even ratio of wild-caught mosquitofish and tadpoles in 12 water tanks and observed how they behaved around each other. Then, they transferred each of the groups into the experimental aquatic arena. 

For one week, researchers observed the behavior of only the mosquitofish and tadpoles in this arena. Then, for the next five weeks, random groups were selected to either stay where they are or be exposed to the robotic predator. 

Enter the robot fish. This imitation bass has a computer vision system that allows it to differentiate between the mosquitofish and tadpoles. It hovered in the tank and was moved with magnets and rods. The robot was programmed to lunge at mosquitofish when they approached tadpoles.

The team documented the group dynamics with and without the robot predator before removing all predators for the final week of behavioral assessments.

They measured the body size, weight, and shape of each mosquitofish they tested at the beginning of the experiment and then again at the very end. They also examined the sperm and eggs of the fish as a proxy for fertility. They found that the mere presence of a predator can have an impact on the dynamics of the ecosystem. Eastern mosquitofish, which cannot perceive that the robot bass was not real and couldn’t hurt them, became skittish, stressed, and anxious whenever it was around. The mosquitofish in tanks with the predator also ate more but appeared to have less energy overall. They lost weight, their body shape changed, and their fertility decreased. 

“This suggests that mosquitofish exposed to the robotic predator allocated relatively more energy to antipredator functions, at the costs of energy reserves and reproduction,” the authors wrote in the paper. Importantly, it seems like perceived risk from predators triggered the mosquitofish to adjust their bully behaviors, and leave the tadpoles alone. 

“This study won’t be a solution to the problem,” Giovanni Polverino, an author on the study, told The New York Times. Rather, what the robot did was help them uncover the pest’s weaknesses, and reveal what they fear. From this, they can deduce other methods that could work, perhaps more practically, in the wild. 

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An encouraging new experiment hints that cutting off mercury pollution to bodies of water can quickly translate into lower levels of the toxic substance in seafood.

Scientists tracked how mercury levels in fish and invertebrates in a Canadian lake changed over 15 years. During the first seven years, the researchers seeded the lake with mercury. Once the influx of new mercury ceased, the team found, contaminant levels quickly fell in both small and large fish within a few years. 

“As a demonstration, it tells us that policies that reduce mercury pollution will be effective and that mercury concentrations would be a lot higher in the absence of these policies,” says Paul Blanchfield, a research scientist at Fisheries and Oceans Canada. He and his colleagues reported the findings on December 15 in Nature.

Although the element is naturally occurring, a great deal of the mercury in the environment comes from human activities such as mining or emissions from coal-fired power plants, Blanchfield says. It can be transported long distances in the atmosphere before being rained down onto lakes and rivers or the watersheds that feed them. Once mercury gets into aquatic ecosystems, some of it will be transformed by microbes into an extremely poisonous chemical called methylmercury. 

“It tends to increase with every step in the food chain,” Blanchfield says. “The fish at the top of the food chain are the ones we humans eat, and they have the highest concentrations of methylmercury—often up to a million times higher than in [the surrounding] water.”

Most people have small amounts of methylmercury in their bodies that are too miniscule to cause health issues. At higher levels, however, this powerful neurotoxin can impair speech, hearing, walking, and vision.

[Related: Researchers found signs of human pollution in animals living six miles beneath the sea]

Demonstrating a clear link between reducing mercury pollution and lower methylmercury levels in fish has proven difficult, Blanchfield says. That’s because many variables influence how methylmercury is produced and accumulates in food chains, including human-related disruptions such as commercial fishing and the arrival of invasive species.

To understand the impacts of controlling mercury, the researchers visited the International Institute for Sustainable Development’s Experimental Lakes Area, which comprises dozens of small lakes in remote northwestern Ontario that have been set aside for scientific research. They zeroed in on a small lake populated by northern pike; their prey, yellow perch; and lake whitefish, which forage along the bottom of the lake.

For seven years, the researchers added different forms, or isotopes, of mercury to the lake surface as well as to nearby upland and wetland areas. This allowed them to disentangle the effects of newly-added mercury from different sources around the lake, and from older mercury that had been accumulating in the lake for many years. The team found that methylmercury concentrations rose by 45 to 57 percent in lake-dwelling invertebrates and small fish, and more than 40 percent in larger fish. 

Most of the mercury the researchers measured in these animals had been added directly to the lake. The researchers didn’t detect any mercury from the wetland, and only very small amounts from the upland area, Blanchfield says.

After the researchers stopped adding mercury to the lake, the team found that the isotopes they’d introduced decreased by 81 percent in lakewater, 35 percent in lakebed sediments, and 66 percent in tiny zooplankton within three years. By the end of the experiment, methylmercury made from these isotopes had dropped more than 85 percent in small fish, 76 percent in pike, and 38 percent in whitefish populations.

When the researchers analyzed tissue samples taken from the same fish over time, they found that mercury levels didn’t decline much in individual animals. “Fish do hang onto their mercury for a while,” Blanchfield says. “However, when we looked at the entire population we saw that it was declining quite rapidly.” This indicates that young fish, which weren’t exposed to the more polluted environment of the study’s early years, are driving the population’s recovery, he says. 

The researchers also noticed that methylmercury declined more slowly in the bottom-feeding whitefish than in the lake’s top predator, the pike. This is likely because the whitefish are larger, longer-lived fish that reproduce more slowly than the pike, Blanchfield says. 

Still, the speed at which the fish populations responded to the decreased amount of mercury coming into lakes came as a pleasant surprise to the researchers. “We thought it could potentially keep contributing for quite some time,” Blanchfield says.

That said, he cautions, it may yet take awhile for mercury from the wetland and upland areas to find its way into the lake. “What we did see is when that mercury got into the lake, it responded just like the mercury we added to the lake surface: It went up quickly and came down quickly,” Blanchfield says. “That tells us that [for] any amount we can reduce mercury coming into lakes, whether it’s through direct deposition through rain onto the lake surface or by runoff, you should see a fast response in the fish populations.”

This information is crucial for efforts to manage mercury contamination, says John Rudd, another coauthor of the findings and former chief scientist at the Experimental Lakes Area.

“Essentially we found that ‘mercury is mercury,’” Rudd said in an email, adding that “Policy makers need to write regulations that control the total mercury loading to lakes, not just the mercury that enters directly from the atmosphere.”

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Climate change is causing glaciers around the world to melt, which in turn worsens sea level rise and disrupts ocean currents and coastal ecosystems. But for some fish, there may be a small silver lining. 

Scientists used computer models to simulate how meltwater will feed new streams and lakes across western North America, and found that retreating glaciers could create thousands of miles of new habitat for Pacific salmon by the end of the century. Understanding where and when these piscine frontiers will emerge will be key for future conservation plans, the researchers reported on December 7 in Nature Communications.

“This showcases how climate change is fundamentally transforming ecosystems; what is now under ice is becoming a brand new river,” says Jonathan Moore, who leads the Salmon Watersheds Lab at Simon Fraser University in British Columbia and coauthored the new findings. “We can’t just manage for current salmon habitat, we also need to think about how we can manage for future salmon habitat.”

Glacial retreat does pose a threat to salmon in some areas. “It can decrease the air conditioner effect that glaciers have on downstream rivers, so rivers will be getting warmer during the summer,” Moore says. And as glaciers shrink, less seasonal meltwater is available to feed these rivers in summertime. However, when glaciers melt away from valley bottoms they can create new streams. “The rivers will be lengthening as the glaciers will be retreating up the valley, and other work has found that salmon can find and thrive in these newborn river systems,” Moore says.

He and his colleagues investigated how this might play out in the coming decades across a 623,000-square-kilometer (240,542-square-mile) region stretching from southern British Columbia up into Alaska. About 80 percent of the glacier-covered territory in North America’s Pacific mountain ranges fall within the range of Pacific salmon, which support subsistence harvests and fisheries worth billions of dollars annually. 

Led by Kara Pitman of Simon Fraser University, the researchers identified 315 retreating glaciers at the headwaters of existing streams that could create a habitat that salmon would be able to reach. The team then estimated when and where those glaciers would retreat under several climate change scenarios. “The next phase was to use predictions of what the land looks like underneath the ice…[to] imagine the future rivers in these future salmon habitats,” Moore says. 

The researchers calculated that by 2100, Pacific salmon will have access to 6,146 kilometers (3,819 miles) of new streams. Much of this habitat will come from areas with large, low-lying glaciers near the coast, such as the Gulf of Alaska and Copper River.

[Related: Salmon are dying off and your car tires might be to blame]

The team also explored which parts of the aquatic network would provide suitable habitat for the fish to spawn and rear young salmon, based on the expected steepness of the stream channels. They found that about 1,930 kilometers (1,199 miles) of the burgeoning streams could offer gently sloping conditions ideal for the salmon.

As glacier ice disappears, more of the northern landscape will become available to mining and other industries. Forecasting where new salmon habitat is likely to open up may allow researchers to identify areas in need of protection, the researchers concluded.

However, Moore says, this will be a complicated undertaking. He and his team estimated how much potential habitat melting glaciers could create, but didn’t analyze how temperature and other environmental conditions could render new streams more or less inviting for the salmon. 

Another complication is that salmon don’t spend all their time in freshwater habitats; they’re also tied to the sea. “If the ocean is increasingly unsuitable because of the warming that has created new freshwater habitats, that will not lead to more salmon populations,” says Peter Westley, an associate professor in the ​​College of Fisheries and Ocean Sciences at the University of Alaska Fairbanks. Westley is a co-leader of the Salmon Science Network Initiative, which provided funding for the research, but wasn’t involved directly in the current study. “You need both suitable ocean and available and suitable freshwater habitats.”

Moore wants to make it clear that the research doesn’t mean salmon will thrive as Earth warms. Salmon are facing many climate-related burdens, including marine heat waves, ocean acidification, and extreme floods and droughts. “The paper does not suggest that climate change is good for salmon,” Moore says. “It’s possible that these local opportunities might be overshadowed by large-scale declines in salmon populations.”

And even if salmon do move into new areas where glacial ice has waned, there will be consequences for people who depend upon the fish. 

“The shifting distribution of salmon, while good for the salmon, does not address those really stark and pressing societal and cultural issues of the loss of salmon in certain rivers,” Westley says. “That does not help the person that’s on their river and seeing their salmon disappear because it’s too warm.”

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When a reef fish is born, it’s immediately swept out into the open ocean where life is full of uncertainties. But if it makes it out alive and matures from a larva to a juvenile, the reef always calls it back to continue the breeding cycle. 

There are many ways fish scope out a reef to return to. These underwater communities are very noisy places full of vocal marine animals and invertebrates, and given that sound travels far underwater, small fishes are able to tune in to the traffic reports to judge a reef’s quality. Environments that sound good also tend to attract more new animals. 

Healthy reefs have a rich soundscape. “Lots of the invertebrates and the fishes make weird and wonderful noises for all sorts of weird and wonderful reasons. When you take recordings, you hear all these pops and buzzes and trills and whoops,” says Tim Lamont, a marine biology research fellow at the University of Exeter. A degraded reef, on the other hand, has less life milling about and is therefore much quieter. “If you’re in the business of ecosystem restoration, being able to create coral reefs that sound good is a really good thing to be, ” Lamont explains. 

Lamont and his colleagues have been interested in studying the relationship between sounds and underwater life. But it’s by no means an easy process. Oftentimes, it requires a human touch to clean up the background noise in the recordings, annotate the audio, and mark all the distinct sounds. And while there’s been some attempts to automate this task, many technical limits still remain. 

This became evident in a recent collaboration with Mars Inc., which reached out and asked them to use soundscape ecology to monitor the progress of their reef restorations. (The chocolate and pet food corporation has been collaborating with scientists and local communities to rehabilitate damaged coral habitats around the world as part of its larger effort to offset some of its negative environmental impacts. Mars also partly funded this recent soundscape project.) The corresponding study on the effort, published this week in the Journal of Applied Ecology, found that by the sound of it, Indonesian reefs damaged by blast fishing recovered nicely after restoration efforts. 

A new window into ecosystem health

Coastal communities rely on coral reefs for food and more. When these structures fall apart due to human activities like fishing with dynamite, they can have devastating effects on the people that depend on them for a livelihood. Since these reefs have slow natural recovery rates, restoring the coral, which forms the foundation of these ecosystems, could bring back fish and other marine life. But it’s not always so easy to judge whether habitat restorations will take or not. “It’s a different thing to garden a couple of corals than it is to bring back an entire ecosystem,” says Lamont. Outside of checking whether coral regrows, ecologists have to test if the new reefs can support marine life, dampen wave energy, control carbonate budgets, and provide sustenance for coastal communities. 

That’s where soundscape analyses come in. They’re a promising indicator of overall ecosystem diversity because they can detect more critters than images and visual observation; for instance, biologists can hear fishes that are otherwise hidden or are well-camouflaged. Plus, with sound, experts can monitor the habitats around the clock. “There are different things that you can measure about the soundscape,” Lamont says. “You can measure how complex it is, how loud it is, how variable it is through time, or how variable it is at different pitches through frequency bands.”

[Related: What underwater sounds can tell us about the state of coral reefs]

To collect all the necessary data, the team planted underwater microphones, or hydrophones, all around degraded, healthy, and recovered reefs. They recorded what the reefs sounded like at dawn, dusk, midnight, mid-day, during the full moon, and during the new moon for two years. “We wanted to build up a really good picture,” Lamont says. They found that although the restored reefs “didn’t sound identical to healthy reefs, they sounded really similar” and “very different to the degraded reefs.” The planted corals were filled with marine chatter, telling biologists that many critters approved of the construction. 

Sorting and measuring the sounds

Then came the unglamorous part for Lamont’s team: sitting in the sound room and picking apart the layers of knocks, purrs, croaks, growls, and whoops. It’s akin to untangling the individual instruments from a complex orchestral arrangement. 

“This is a very time-consuming science. With this study, I’ve spent months and months listening meticulously through all of these recordings with my headphones,” says Lamont. “It’s pretty mind-numbing at times.”

The team is now trying to automate the process by “getting the computer to do the same job,” Lamont says. But it’s a tough assignment to delegate to machines. Because reef ecosystems are so busy, there’s a lot of background sound that can skew the analysis toward rowdier wildlife. “When you listen to these recordings, you hear a lot of the noise of invertebrates [like] snapping shrimp,” which sounds like crackling static or frying bacon, Lamont says. In fact, these sounds are so loud and prevalent that during World War II, militaries used to hide submarines on coral reefs because the shrimps effectively masked the sound of the submarine. 

Existing computational techniques used to measure soundscapes, also referred to as acoustic indices, are mostly designed for use in terrestrial habitats—like in forests for listening to birds or bats. Still, Lamont sees a lot of similarities between forests and reef communities. For one, different animals seem to be active during certain pockets of time, which can help scientists sort the library of sounds by space, time, and frequency. “We’ve made some attempt to take these indices and apply them underwater,” Lamont says. “But of course, sometimes there are fundamental differences between the types of soundscape you get in different habitats, so they may not work as well.”

[Related: Birders behold: Cornell’s Merlin app is now a one-stop shop for bird identification]

Scientists who study forest soundscapes have come up with creative workarounds for building machine learning algorithms that don’t require setting up recording stations among the trees. Lamont points to a PNAS paper published last July where researchers from the Imperial College London, University of Sydney, and Cornell University used Google’s AudioSet data to train an algorithm to recognize the sound distinctions between individual forests. 

The Google sound compilation, which consisted of a mix of human speech, music, and machine noise, first taught the algorithm to distinguish between various types of noise. Then when the system was applied to forests, it was able to classify the categories of sounds in the forest. The authors wrote that it could one day be used to detect irregular activities like illegal logging and hunting.

Lamont imagines that he could possibly repurpose a similar algorithm to sort through the mountains of ocean sounds he has to analyze. 

The need for cheaper hardware

The other, more classic way to power a useful machine learning algorithm for undersea soundscapes is to collect heaps of data. There are ongoing efforts around the world to build marine soundsets, but the cost of equipment can be a limitation. A high-quality hydrophone with a large memory card, for example, can cost around $3,000.

“They’re often really expensive, which is a bit of an issue if we want more than just well-funded scientists to be able to do this,” says Lamont. In October, he and his colleagues published a study in Ecological Indicators that found that audio from Go-Pro cameras (which cost about $500) were in many cases comparable to the quality of data that they got with a hydrophone. 

[Related: These free-floating robots can monitor the health of our oceans]

“Trialing these lower-cost recordings opens the door for many more people to be involved,” he says. “That would then allow us to collect much more data that would feed into these automated analysis techniques in such a way that we can get useful information [with] low effort.” 

Already, ocean-monitoring technology has come a long way. About a decade ago, hydrophones ran on tape reels and had to be attached to a cable that hung off the side of a boat, where a non-waterproof recording station was housed. Now, they’re completely wireless and can be dropped into a sea bed for weeks or months at a time—until the data needs to be collected. 

“Our ability to take long-term, high-quality recordings underwater is quite a new thing,” Lamont notes. “And that’s partly why we keep discovering all these new things no one’s ever recorded before.” He recalls coming across completely uncanny reef noises as he listened back on the recordings from Indonesia, including the grunt of a soldierfish, the scrape of a parrotfish, and the whoop of a damselfish. But there were some sounds, like a “laugh” that usually occurred at sunrise, that he couldn’t quite place onto a specific species. 

“There’s this fun element of mystery around that,” Lamont says. “There are exciting prospects on the horizon for this field, given how young it is.”

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This story originally published on Saveur.

Up until the 1950s, there were no roads to Comacchio—the sleepy fishing outpost was only accessible by water—so it’s understandable that the Italian town and its people still have an air of superstition when it comes to outsiders. It hasn’t progressed like the more touristy destinations nearby dotting the Adriatic coast (Venice is a two-hour drive north), but travelers prepared to forego some modern luxuries will be rewarded with a trip back in time. That, and a taste of its most delicious export: eel.

Like the curious creature that put it on the map, Comacchio can be tricky to capture. Situated at a delta where several waterways meet the sea, the wetland-rich landscape is reminiscent of a scene out of True Detective—while the inner town could pass for Venice in miniature, with its picturesque network of canals and arched brick bridges.

The locale is perhaps best experienced in September and October, which marks the beginning of eel season, when the doors of the Manufactura de los Marinati (preserving factory) are flung open and visitors can feast on Comacchio’s local “gold.” Sophia Loren famously danced around the space in the 1954 film La Donna del Fiume (“The River Girl”) as hundreds of eels roasted on spits in the background—and the cinematic setting just adds to the impressive meal on offer.

First, an antipasti of fried then pickled anchovy, sardines, and smelt rolls out, followed by penne in a rich mantis shrimp and tomato sauce. Next, fried school prawns and whitebait act as show openers to the star dish: grilled eel on humble polenta. None of this fritto misto gets a drop of lemon juice (my request for the citrus was denied); the flavor is so superior, locals consider it somewhat of an insult to attempt to embellish it further.

In Comacchio, eels once translated into big business, and excessive stock prompted the development of preservation methods (still used today) to maximize profits. Roasted then cooled, the pieces are placed in a simple brine of vinegar, water, and bay, before being sealed in cans with the original 1950s packaging worthy of design awards. Nowadays eels rule the town for tourism rather than large-scale manufacturing. During the Sagra dell’Anguilla (the annual Eel Festival that kicks off in late September), stalls pop up along the canals selling local delicacies and every restaurant has a special set menu.

At Il Bettolino Di Foce, a destination eatery that stands at the end of a dusty car park under a vast open sky, I meet chefs Mirella and Fillipo. The flat surroundings, a stretch of ramshackle fishing huts and old stone factories where fishermen once lived for weeks at a time, add to the ambience and reflect the locals’ straight-forward approach to preparing their treasured ingredient. “The rich meat needs nothing,” says Fillipo. Oily eel skin develops a beautiful crust when grilled, while the flesh underneath remains moist. Served with polenta, a counterpoint to the fatty protein, and it’s immediately obvious why the combination has never changed.

Another perfect pairing? Wine vinegar. Used to preserve the eel, it’s also featured in the Bec d’Asan—a stew of tomato, onions, garlic, and eel that translates to “donkey’s beak,” an Italian expression for a simple, fast process with great results. Mirella, who has cooked up and down the Adriatic Riviera since the 1980s, holds back on the vinegar when making the dish, but Fillipo, going off the techniques and recipes passed down from his grandmother (herself a locally renowned home cook), insists the stew gets generous splashes of the stuff. And when we start eating it’s clearly warranted; the vinegar permeates the oily flesh and balances out the flavor.

Like most things in Comacchio, residents don’t feel the need to add flourishes or tweak traditional recipes. The original is a classic for a reason. “Cooking here is habitual, nothing inventive, we don’t change anything,” Mirella confirms. That’s reason enough for a visit—just remember to ask for lemon at your own risk!

Head over to Saveur for the best Italian-style eel recipes.

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Fishkeeping is an engaging and calming hobby, perfect for kids and adults alike. Unlike other house pets, their care is relatively straightforward, and confined to a specific space in the home or office. The best fish tank can beautify a space, and keep your fish healthy and happy for a long time.

With the help of an experienced fishkeeper from the Epic Aquarium website, we managed to gather some great fish tanks to get you started.

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This 10-gallon, glass aquarium is the perfect medium—manageable enough for beginners and hobbyists, but sizable enough for long-time fish owners. Fill it with a variety of nonaggressive fish—like neon and cardinal tetras—and cute aquarium decor. For a tank this size you’ll want a filter that turns over 40 to 60 gallons per hour.

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A 5-gallon tank is the best size for a few smaller tropical fish, like guppies, or even cherry shrimp, which can play a useful role as scavengers and algae eaters. This aquarium comes with its own filter, and a low-profile LED light for watching your fish swim around.

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If you want a statement piece for your room, check out Lifegard Aquatics’s 5-gallon aquarium. The angled design makes it even easier to watch little tropical fish dart around. This tank also comes with a full kit of essential fishkeeping items, like a heater, net, LED light, built-in filter with a pump, and algae magnet.

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Vivosun’s aquaponic tank is great for sprucing up the top of your aquarium with a little foliage. This system gives you the best of both worlds—fish waste is an excellent fertilizer, and plants are excellent at cleaning water. It can support hydroponically growing houseplants like pothos and philodendron; herbs like rosemary, basil, and mint; or even salad greens.

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A 1.4-gallon fish tank is ideal for a single betta, a fish that prefers private, tight spaces. A tank this size has a small footprint and is low effort, making it perfect for a bedroom or office, or for kids honing their fish-keeping skills. The tank comes with a built-in filter, an LED light, and two plastic plants.

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There are so many excuses. You won a goldfish at a raffle, but you have a herd of curious cats at home. You got the goldfish in the breakup, but you travel too much to meet its needs. Your kids won’t take care of the goldfish, and anything is better than watching that poor creature suffer.

There are plenty of reasons why people might decide they don’t want a goldfish. If you find yourself hating your fishy friend there are ways to get rid of it other than committing fishicide and sending its soul to the great big fishbowl in the sky. You can give it to a friend, give it to a stranger, but for the love of everything in the ecosystem, do not set it free in your local pond, stream, or any other body of water.

Why, I hear you ask. Why can’t I loose Nemo in a serene wild spot, and let nature take care of the rest? Because goldfish are remarkably adaptive, persistent, and fecund fish that can not only survive in your local pond, but dominate it. Given more space, they grow larger, sometimes up to four pounds. Budling a backward pond and stocking it there can be the perfect solution for your goldfish life.

Michigan’s Department of Natural Resources (DNR) was recently alerted to a small stretch of stream flowing between two lakes that was utterly packed with goldfish. They don’t know exactly how the goldfish got there, and may never know the whole truth, but it’s possible that a few pet goldfish were released into the area and set up house.

There were an estimated 8,000 goldfish in that waterway, and workers with the DNR were only able to remove about half of them—a whopping total of about 450 pounds of goldfish.

While some populations of goldfish have become established parts of the landscape, acclimating by adapting more muted colors, they are seen as a non-native species and a threat to native populations.

“It means they’re taking up all of the resources of fish that should be there,” says Sara Thomas, Lake Erie Unit Manager for the Michigan DNR fisheries division. “Only one or two native fish were found in that stretch.”

Michigan isn’t the only state confronting a goldfish problem. In Minnesota, a nature center is introducing largemouth bass to devour the out-of-control goldfish population. Colorado was debating whether or not to shock invasive goldfish, or scoop them up and feed them to wild fish. And up in Canada, goldfish are thriving in storm ponds, even after being chemically treated.

Long story short: given the opportunity, goldfish will grow forth and multiply. So if you love it, please, please, do not let it go.

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THE NATURAL WORLD is not always a calm place. Every day, animals from the ocean floor to the highest treetops struggle to live, breed, and eat. Their existential endeavors make many of our modern stressors seem placid by comparison. But we still seek out signs of serenity in the wild—and if we press the camera shutter at precisely the right moment, we might just find them.

These images capture flocking birds and schooling fish suspended in smooth, synchronized swirls—twin phenomena of the sky and sea. But while they seem to have complex choreography from behind a lens, avian and aquatic dances follow just one simple rule: If your neighbor makes a move, you follow suit. In both cases, this rote locomotion results in a comforting cluster better able to protect the animals from predation. It also has the potential to produce infinite shapes in the water and air, providing us onlookers with endlessly satisfying displays.

Lots of bird species form flocks, but Sturnus vulgaris​—​the common starling, native to Eurasia but found on every continent save Antarctica—indulges in unusually frequent and lengthy get-togethers known as murmurations.

Fish like these sardines in the Philippines use all their senses to feel out the distance between themselves and their compatriots, which allows them to maintain consistent and precise gaps.

Starlings use their keen peripheral vision to track neighbors’ movements. Research suggests they form murmurations primarily as a means of protection from predators they encounter on their journey down to roost.

These Caranx sexfasciatus in Indonesia are beginning to form a circular school. This common shape minimizes the fraction of the group left exposed to the outer ocean—and the hungry threats that lurk there. 

While individual sardines measure just 6 to 12 inches long, groups of them can collectively stretch out for miles. Aircraft can often spot their wriggling schools from the sky.

Starlings tend to murmurate a bit longer when it’s cold, suggesting they find warmth in numbers. But they flock the longest when an aggressor is actively circling.

This story originally ran in the Spring 2021 Calm issue of PopSci. Read more PopSci+ stories.

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Hagfish are survivors, and they didn’t get that way by being pretty. For the last 300 million years or so they’ve been doing what they do best: secretin’ goo and slippin’ away.

These boneless fish (yes, they are actually fish) are much-studied and much-reviled for their ability to release a stringy, sticky slime that expands quickly to choke predators and clog up gills. They also have loose, flaccid skin that prevents shark teeth from penetrating their muscular bodies.

Biologists are still trying to work out exactly how their famous slime works, though, since it’s something of an engineering marvel. The goop expands rapidly to fill a predator’s mouth, but until recently experts weren’t sure how. A new study published in the Journal of the Royal Society Interface suggests it has less to do with the hagfish themselves and more to do with the water they’re getting attacked in.

Hagfish slime is made up of two key components: mucus and fibers. The mucus bit is pretty self-explanatory, but the fibrous part is a little more complicated. Slime fibers are wrapped up in skeins, which look almost exactly like skeins of yarn (except they’re the width of two human hairs). These balls of fiber unravel, and it’s this motion that helps the goo expand to 10,000 times its previous size in just a few tenths of a second. Previous research had shown that the skeins can uncoil without much outside help, but it’s not like they’re spring-loaded or anything. If left relatively undisturbed they’ll eventually unravel all the way, but it takes much longer—on the order of minutes—than it does during an attack.

Researchers wanted to figure out what makes the skeins expand so much faster under duress. They hypothesized that the movement of the surrounding water—which would be more agitated during a shark attack—helped trigger the uncoiling process, so they started taking a closer look at the skeins under a microscope. Each roll has a loose end, and if you pull on that thread you can unwind the whole thing. But if there’s drag on the skein from water moving around it can all happen much faster. According to their (extraordinarily complicated) models, drag alone can prompt a skein to unravel within a few hundred milliseconds, or even faster if the skein is snagged on a surface like a shark tooth.

The researchers think this all suggests water flow is a necessary part of the equation. So although other factors—like interactions with the mucus component of slime or the salinity of the water—may also impact the speed, it’s the drag that really accelerates expansion.

All of this ingenious evolutionary design has helped hagfish survive mostly as-is for hundreds of millions of years, however revolting they may be to us mammals.

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The story of all land animals begins with a squat-limbed, long-bodied swamp fish. Sometime in the steamy mid-Devonian, a family of those fish followed plants and bugs onto land and became the first tetrapods, or four-legged vertebrates.

But the fossil record from 390 million years ago is so sparse that it’s hard to find clues about who those fish were, or how they evolved. Fossils are few and far between, and there’s a surprising gap: the oldest evidence of tetrapods comes from a set of footprints left in a tidal mudflat that happens to be 15 million years older than the oldest tetrapod fossil. 

A new analysis of that fossil record, published Monday in Nature Ecology and Evolution, suggests that the transition happened in a geological blink of an eye. But surprisingly, it also finds that once the first tetrapods had taken to land, they remained there—mostly alone—for millions more years.

The study reconstructed the family tree of early tetrapods to piece together that critical period. The process is similar to the one virologists use to document the spread and mutation of new viruses, but instead of genetic traits, biologists use physical differences in fossils to map out the process of evolution.

They were also able to incorporate non-fossil data for the first time, like the footprints, to calibrate the model, says Tiago Rodrigues Simões, a postdoctoral fellow at Harvard University’s Department of Organismic and Evolutionary Biology, who led the modelling.

“We were able to incorporate every single phenomenon that is part of evolution,” he says. “It’s not just how species are related, but what is the rate of evolution? How fast were species evolving and dying?”

Four legged animals evolved incredibly fast, the study found, with just six million years separating the first tetrapods from their ancestors. 

[Related: The Sahara used to be full of fish]

On one end of the evolutionary tree were ancestral fish, which, from the outside, basically just looked like fish. It’s only within the skeleton, the researchers say, that the building blocks of terrestrial life become obvious.

“If you look at its fin, you’d say, ‘oh look, there’s a humerus bone’,” says Stephanie Pierce, an evolutionary biologist also with the Department of Organismic and Evolutionary Biology, and the study’s senior author. “If you look behind the pelvic bone, you’d also see a femur.”

Because of that, people tend to focus on the transition from fins to limbs. “But there’s tons of other changes happening all over the skeleton,” Pierce continues. “They’re just really intricate features that most people outside of paleontology aren’t interested in.”

But the study found that the fastest changes happened in the head, where newly terrestrial animals would have had to adapt their eyes, noses, and even jaws to a world above water.

Tetrapods’ eyes migrated from the sides of their heads to the top, while a passage opened up to connect the mouth and nose. They grew collarbones and necks, which gave them extra flexibility to walk and look around. (Fish, Simões says, lifting his shoulders to his ears, “are like Jabba the Hutt.”)

But the rest of the body was also morphing to fight gravity. “It’s not that the skull evolved really fast and the post-cranium evolved slowly,” says Pierce. “The whole body was evolving at rapid speed compared to its fish relatives. It’s just that the skull was evolving even faster.”

In spite of the frenzied changes, the research suggested that there weren’t actually many species of early tetrapods.

Since the 1940s, biologists have suspected that “as you modify your body to a whole new environment, those changes would be fast,” explains Simões. The idea went that, since the animal was evolving so quickly to suit its environment, it would also branch off into different body types, and eventually new species. “But that’s not really what we’ve been finding.”

And that helps explain the lack of fossils. “What makes me a little bit sad is that the study showed there were so few species that they weren’t being fossilized,” says Pierce. “Our hope is that we find new fossils that can tell us more of the evolutionary story, but that’s going to be tricky.”

Why exactly the first tetrapods didn’t diverge is still a new question. But, suspects Pierce, it may simply be that they suddenly found themselves living the good life. Tetrapods had found a new niche, and that gave them some evolutionary slack. “You have a little bit of breathing room for a while before it becomes really popular.”

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At nearly 14 inches long, a new tuna-inspired robot created by researchers at the University of Virginia can flap its tail as fast as real tuna (seven times per second), and swim at speeds up to 1.5 mph, or two body-lengths per second. 

In a new paper out in Science Robotics, the team behind this creation breaks down how they made this tuna-like robot—a machine that can tense up or relax its tail joint to move at different speeds. This mechanism has allowed the tuna bot to reach high speeds while also conserving energy, a method that could one day help improve swimming robots and even underwater vehicles. 

Many robotic researchers have been piloting their own robo-fish. “We are different because we study the physics [of actual fish] instead of just mimicking the shape or schematic to build something like a real robot fish,” says Qiang Zhong, a postdoctoral researcher at UVA and the first author of the paper. The team analyzed videos of real tuna to derive the flow physics of its movements, and then used that to inform their design.

Fish use their muscles to not only generate motion, but to adjust how flexible or stiff their tails are to swim efficiently. They can tune their stiffness so they can be as floppy as a piece of paper or as rigid as a branch. This is similar to cars that improve their efficiency by changing gears for different driving speeds.

Tuna have tendons that run through their entire bodies, and when they put force on these tendons, they can stiffen their tails to swim faster. The team tried to emulate this muscle-tendon system with springs and motors. 

“The research we perform is to try to understand the proportion theory of fish,” Zhong says. “We are not just building something that is like a fish, it’s more like we want to take the inspiration from the fish and understand what’s going on here and put this system into anything we want.” 

Their final creation was a simplified robofish with high-frequency actuators (which approximated motion) and a spring system which converted the force of the spring to tail joint stiffness.

Nature as a muse for human-centered machines

The tuna robot is part of a niche family of biomimicry, or biomimetic robots, which are robots that imitate animals. Previous entries have included robots that were influenced by octopuses, manta rays, cheetahs, pigeons, and bats, just to name a few. Increasingly, researchers are looking to nature to provide guidance on how to make better robots. In fact, another group from UVA presented their tuna robot in Science Robotics in 2019.

[Related: Soft manta ray robot glides electrically through the sea]  

Some soft robots can tune their own stiffness as well, through mechanisms like springs, actuators, artificial tendons, and motors. The soft robots with adjustable flexibility are the ones that can change their speeds most smoothly. 

“In other robots, like walking robots, for example, they’ve tried to come up with stiffness tuning mechanisms, so there’s some precedent. We had to think about how we can put it inside a fish,” says Daniel Quinn, an assistant professor of mechanical and aerospace engineering at UVA, and an author on the paper.  

The interest in fish bots in particular, Quinn says, stems from the fact that fish are so maneuverable compared to the best underwater vehicles we have right now; those are pretty clumsy and essentially able to go at one cruise speed in a straight line. “They have control propellers to position themselves, but they’re not really designed to do the loop-de-loops that fish do,” he says. “If you need to leave from a coastal outpost, swim for miles to an oil spill quickly, then slow down and do these tight turns to do some measurements or stand very still—currently our vehicles are very terrible at that kind of multi-modal mission.”

[Related: A fleet of winged underwater robots will patrol the seas for the US Navy]

Additionally, when operating in shallow waters, propellers can very easily get jammed by seaweeds and other marine gunk. Not only would a fish-like vehicle be able to glide through the underwater environment, this system can run at a lower frequency than propellers, so the noise they generate underwater is much lower comparatively. “It’s much more environmentally friendly, especially if you want to do some ocean resource investigation and swim near coral or other fish,” Zhong says.  

The research, in part funded by the Office of Naval Research and the National Science Foundation, could lead to the next generation of underwater vehicles. 

How the tuna is made

The tuna robot is segmented into two parts: a “head” that generates drag and a “tail” that generates thrust. An actuator sits in the front of the tail, and powers it by producing a back and forth motion that reverberates throughout the tail joint. The robot tuna is suspended from a rig and mounted on a platform of air bushings so it could “slide around like it’s on an air hockey table,” Quinn explains. “That means that we can study how this fish is moving around autonomously, but at the same time, we can take very detailed measurements because it’s not completely untethered.” 

Different parts of the fish model (head, tail frame, tail shell, tail joint, tail fin, tail fin connector) were 3D-printed, then assembled. Every part except for the tail joint was 3D-printed in nylon, which is waterproof. Silicone gel was used to seal the gap between the tail frame and shell. The tail joint and tail fin connector were 3D-printed in stainless steel to withstand stress.

The tuna robot is controlled by an automatic, programmed code. That means that the fish could adjust how it swam in real time based on environmental conditions in a closed loop; the tuna was tested in a water channel that’s like a treadmill for the swimming robot. “We just crank up the speed so it’s having to swim faster and faster as the tunnel simulates faster and faster flow speeds,” Quinn explains.  

The team sent the tuna robot on “missions” like a serpentine, 650-feet sprint, where it ramped slowly up from slow speeds to fast speeds. 

Although the end result was impressive, the tuna robot is still only an early iteration of the tech that the team hopes to build. “You can see our tail is still rigid. But the tail on real fish, it’s made of muscle,” Zhong says. “They have almost infinite degrees of freedom.” 

This is one of the key reasons why fish are so pliable. “For our system, right now we are limited. We can’t really generate fancy maneuvers like sea stars or brittle fish. To do that, you need to enhance and improve the degrees of freedom,” he notes. “In the future, we want to use some smart materials like artificial muscles to control the entire tail stiffness. If the artificial muscles are powerful enough, I could extend this to the entire fish. That will make our fish even more like a real fish, and reduce the noise that is generated by the other mechanical parts. That will make our system even closer to a natural system.” 

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In the Processing Plant

One in five people today depend on fish as their primary source of protein, according to the United Nations. And as the world’s population grows, and the quality of diets improves for many of those people (a.k.a. getting access to protein), so does this demand. The demand for salmon, for example, has been increasing an average of 13 percent a year, according to the Norwegian Seafood Council.

Fish populations in the world’s oceans, in contrast, are crashing and burning. More than 90 percent of the world’s fish species are fully exploited or depleted, according to the Food and Agriculture Organization. Of that, 29 percent are overfished at unsustainable levels; the other 61 percent are fully fished, meaning they’re considered sustainable as long as fishing doesn’t increase.

Fish farming, or aquaculture, is one way to try and deal with this situation. I visited one such operation run by Cermaq in Hammerfest, Norway with a few other journalists. Here is how fish farms work today, and how different they’ll look tomorrow.

Norway is the Leader

“We have to do aquaculture,” says Torgeir Neilson, a lifelong Hammerfester and former fisherman who now coordinates Cermaq’s dozens of sea sites. “Some people think we can live off of wild fish we catch in the sea, but we can’t anymore.”

In Norway, the salmon farming industry has been expanding since the 1970s. The northern nation is now the biggest producer of farmed salmon in the world. That may be in part because Neilson says Norwegians are a fish-eating people. He, for example, eats salmon twice a week. But Norwegians are hardly alone in that. People in the rest of the world are big fans of fish as well.

Cermaq is a major player in the global farmed salmon market. They operate fish farms in Norway, Canada, and Chile and produce 137,000 tons of salmon annually, 50,000 of that in Norway. Since 2014, the company has been wholly owned by Mitsubishi. (Yes, the Japanese car company). Their fish are exported whole to more than 25 countries—95 percent of that fresh and the remaining 5 percent frozen.

Raising the Salmon

The Atlantic salmon Cermaq raises are born at freshwater sites and then transferred to sea sites as smolt (young salmon), when they are between 2 and 6 ounces in size. In 2016, the Norwegian operation stocked 8 million fish.

Cermaq, like most of the world’s fish farms, raises its fish in massive, net-like cages, which it places underwater, in fjords. Here the aquatic environment is somewhat similar to the fish’s natural setting, and they are more protected that they’d be in the open ocean.

The salmon are fed fish meal, fish oil, and/or vegetable oil (although the latter leads to lower levels of healthy omega-3 fatty acids in the salmon). The fish require just 12 to 18 months to mature. To keep an eye on their growing salmon, the company keeps underwater cameras in their cages.

The Dønnland

Each cage holds 200,000 salmon. That’s a lot of fish, but Neilson assures me it isn’t crowded. If you look at the volume of the cage, he says, its contents are 2.5 percent fish and 97.5 percent water. “We try to treat them as well as we can,” he says. “I did that when I was fishing, too.”

Processing the Salmon

The fish are transported from the sea sites to a processing plant in Hammerfest with a well boat called the Dønnland. It has a sea lice filter as another layer of protection to keep parasites out. The salmon can stay in the boat for days if needed.

The plant can process 55,000 fish a day, which it sells fresh or frozen. That’s 170 tons, on average.

The waste from the plant is neutralized to lower the pH, and then sold as fertilizer.

Environmental Impacts

Aquaculture presents a number of real ecological concerns. Fish inevitably escape from these cages into the wild, for example, which can mess with wild populations’ genetic pools or interfere with their spawning grounds. Cermaq claims they’ve only had two escapees between 2010 and 2015, but it’s hard to believe that it’s possible to keep track of all 8 million fish at all times.

Fish farms also produce a whole lot of waste, and the chemicals used to treat the fish against diseases can pollute ocean waters. The current limit for these treatments is three per growth cycle.

Prepping the Salmon for Sale

Health Risks

An arguably more problematic issue with fish farms is that of sea lice. These are parasites that can kill fish and transmit bacterial or viral diseases. Whenever animals live at high concentrations in close quarters—people and fish included—lice tend to thrive. The sea is not immune.

The current legal limit for sea lice is 0.25. That means that there can be no more than 1 louse found for every four fish. Once the lice attack a farm, they can spread to nearby farms or to wild populations.

Another disease having a huge impact on salmon farms is Piscirickettsia salmonis, or SRS. This bacterial disease causes lesions, anemia, hemorrhaging, ulcers, and eventually death in fish. This has been a major problem in Chilean salmon farms, though Norway has not felt its effects as acutely.

Just like with livestock operations on land, antibiotics are a major concern in the oceans, too. Vaccinations against certain diseases have helped to drastically reduce the amount of antibiotics used, but SRS, for example, still doesn’t have a viable vaccine.

So how many antibiotics are used for fish in Norway? “It’s very, very little,” Neilson says. “Less than one percent of the total antibiotics in Norway are used on fish.” In fact, he said that antibiotics use for fish farms has been reduced about 99 percent since the 1980s.

Aquaculture Cages Ready for Cleaning

Sustainability Efforts

“There will always be people who are critical of what we are doing,” Neilson says. But Cermaq is working to decrease their environmental impact and health risks in a number of ways. Among their 20-some licenses, they now operate two green licenses, which were recently introduced as an experiment by the Directorate of Fisheries. These licenses are in two of the company’s sites in Alta, two hours south of Hammerfest. Four big changes are involved:

1. Econets: These stronger nets don’t need to be removed and cleaned between generations. Plus they do better job of protecting against both escapees and predators.
2. Lump fish: These small, herring-sized fish live with the salmon and eat sea lice off them. This prevents or reduces the use of chemical treatments on the salmon.
3. Lice skirt: This structure aims to keep lice out of the first few meters down from the water surface, where their infestations are most common.
4. Lights: Green lights are placed underwater during the dark periods in late autumn and early winter to prevent early maturation. Since their maturation is controlled by light exposure, which changes dramatically through the seasons, the lights can delay the onset of maturation until the salmon are ready for harvest. (I could see the clusters of green lights from my plane window while flying from Hammerfest to Tromsø).

Ready for Delivery

The Future of Fish Farms is on Land

As the climate changes, temperatures in the Barents Sea are expected to rise, creating an environment that is hospitable to non-Arctic species of fish not normally seen here. Neilson says Cermaq is not feeling the effects in their sea sites just yet. “It’s the same temperature today as when I started,” Neilson says. Water temperatures have consistently been 50 degrees F in July, August, and September for “as long as I can remember,” Neilson says.

To improve and innovate their operations, and to adapt to upcoming changes, Cermaq established the Arctic Salmon Research Center last year. The scientists there aim to come up with more customized food strategies, diversify the geography and species in their sea sites, look into different smolt, and improve the overall health of their fish.

One of the major shifts that Neilson expects down the road is land-based fish farming operations. By isolating closed cages on land, farms can reduce disease and pollution. To be sure, operations on dry ground introduce different challenges. Making space for a massive structure on the shore, for example, is a real problem in many coastal areas.

Cermaq has experimented with these methods already, but their set-up was taken out by a storm. (Yet another risk to consider with these kinds of farms.)

Still, they’re giving it another go. Neilson is convinced the effort will pay off. “This is the future,” he says. “We have to do a lot of research, but we think it’s coming.”

*UPDATE: The FAO fisheries estimates have been updated to reflect the results of a more recent (2014) version of the State of World Fisheries and Aquaculture (SOFIA) report.

Disclaimer: Travel, accommodation, and tours to report this story were paid for by a grant from the Royal Embassy of Norway.

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A boat pulls up to the dock. It’s a long-liner, meaning the owner, an Icelander by the name of Jani, uses long lines and hooks to bring fish up from the seafloor, between 100 and 1,000 feet down. Jani’s boat has 16,000 such hooks, which take two and a half hours to put out and another 8 hours to pull in. All said, he can haul in about 11,000 pounds of fish a night.

I’m on the dock, waiting to see what today’s catch looks like. I’m traveling the northern Norwegian coast with a group of journalists from Denmark, Canada, Germany, Italy, and the Netherlands to see how climate change is impacting industries in the Arctic. Fisheries is our first stop, and here, sustainability is key.

The three workers aboard the small fishing boat went out about 5 PM last night and haven’t slept since. It’s now 9 AM. Most days are 18 hours long, and the workers spend 211 days a year at sea.

The Business of Fish Guts

Jani’s is one of 70 or 80 boats that supply fish to a local filleting company called Tobøfisk. Mostly the company processes cod, but also some haddock, saithe, and a few others, like catfish. The plant is located in the village of Havøysund, population 1,003. On the very northern tip of Norway, the village is alone on an island of only 3 square miles. Tor-Bjarne Stabell, the co-owner of Tobøfisk, says he not only knows everyone in the town, but he knows them well.

Tobøfisk dock

Stabell and his business partner Børge Johansen bought the plant after three bankruptcies and some fishy Russian criminal activity back in the ’80s. Now, between January and June every year, Tobøfisk employs some 300 people around the clock to process 180 to 190 tons of fish a day, most of it cod. Their specialty is fillets.

What’s most interesting about their processing is that it doesn’t produce any waste. They’re unique in this space; while most people just toss their fish waste, Tobøfisk makes money off it in foreign markets. Every part of the fish is used, so an individual cod could end up in pieces in 11 different countries. In fact, Stabell is betting on this supposed waste for the company’s future profits. “In a few years, I feel there is more value than in fillets,” he says.

Tobøfisk has designed a processing line that sorts out the different parts so each can be collected and packaged separately. That took investment as well as vision. Most fish processing plants just seek out the valuable loin and other fillet meat, and they mocked Tobøfisk for saving its garbage. Now, though, the company has developed the infrastructure and tapped into the markets to export these newfound goods.

What Goes Where

Export-Ready

1. Liver is exported to Latvia. The cod liver oil that comes from it is often taken as a nutritional supplement for omega-3 fatty acids.
2. Roe gets used in Norway.
3. Stomach is exported to South Korea.
4. Heads are sent to Nigeria.
5. Skin goes to Canada. Gelatin can be extracted from it.
6. Belly meat is sent to southern Europe.
7. Entrails are kept in Norway. They get ground into fish meal.
8. Tongues go to Spain. They are a delicacy, though after trying them, I must say they weren’t my favorite thing on the fish buffet.
9. Filet meat is exported to the European Union or the U.S. It makes good fish sticks.
10. Carcass goes to Thailand or Vietnam. Perhaps for soup?
11. The loin is the prized cut, and this gets sent to Europe or the U.S.

Fresh Cod Fillets

The Perfect Spot

Since Stabell and Johansen bought the factory, their profit has been on the up and up (with the exception of the financial crisis in 2008/2009). And 2014 was a bumper year.

This is in large part due to Tobøfisk’s location on the Barents Sea. These coastal waters are warmed by the North Atlantic Current, which brings warm water up from the Gulf Stream and keeps the area ice-free year-round. It also makes the water extremely productive, biologically speaking.

According to the World Wildlife Fund, the Barents Sea is the last large cod stock left in the world. The cod run through this area during their annual migration.

“It’s a crazy fish,” Stabell says. A cod eats until it is so full that its stomach looks like a bowl of little fish when you open it up, he says. They can also go months without eating.

Tor-Bjarne Stabell tours the plant

The Future of the Sea

While the global conversation on climate change and fisheries offers mostly gloomy forecasts, Stabell says he isn’t feeling the pressure yet. “They say the temperature has increased,” he says, “but we can’t see it.” So far the Barents Sea has continued to deliver cod to his doorstep, year after year.

Havøysund is experiencing a cold spell now, so the cod have not yet arrived. But Stabell isn’t worried. “When it comes, it comes,” he says, snapping his fingers. “It can be one or two weeks early or late, but it comes.”

He’s an optimist. You have to be, to buy a three-times-bankrupt fish processing plant in a town as small and isolated as his is. Even more so if you’re going to try to adapt your village’s main industry to a changing climate.

Disclaimer: Travel, accommodation, and tours to report this story were paid for by a grant from the Royal Embassy of Norway.

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Lurking in the waters off the coasts of East Africa and Indonesia is the coelacanth—an ancient species of fish that can reach up to 6.5 feet in length. They reside in the ocean’s “twilight zone,” the dimly lit depths 500 to 800 feet below the surface. Little is known about these slow-moving giants. In fact, scientists previously thought they went extinct about 65 million years ago along with the dinosaurs. It wasn’t until the first live specimen was caught in 1938 that scientists realized the marine mammoths were swimming in the deep today.

Scientists have observed very few coelacanths partially due to their mysterious behavior—they spend most of the day clustered together in volcanic caves. The creatures are classified as critically endangered, which means fishing them is prohibited, so very few ever make it up to the surface. However, a study published this month in Current Biology has begun to unravel some of these scaly critters’ secrets. 

The latest study, which was unfunded, found coelacanths live five times longer than once predicted. Prior to this discovery, marine ecologists believed the behemoths lived to the age of 20, which would have classified them as one of the fastest-growing aquatic species. Now, ecologists believe they could reach the ripe old age of 100, a relatively rare feat.

To scientists who know the bizarre creatures, a long lifespan actually isn’t a huge surprise. Characteristics like a slow metabolism, low oxygen extraction capacity, producing small batches of eggs, and ovoviviparity, or when a mother carries eggs within their body until they are ready to hatch all hint at a slow-growing, long-lasting life.

[Related: Animal Crossing’s most elusive fish has a bizarre real-life backstory.]

“That extremely fast growth rate once believed was extremely strange compared to other characteristics [of coelacanths],” Bruno Ernande, a marine ecologist at the French Marine Institute and co-author of the study says. “It was not fitting the picture. So this is why we decided to reinvestigate the age range of coelacanths.”  

Uncovering secret growth rings 

To determine the age of a fish, scientists count growth rings on their scales, much like tallying the rings of a tree trunk. Each ring corresponds to one year of life. 

Past studies observed these growth rings with reflected light, like that found in a flashlight. However, Ernande and his colleagues utilized a more modern technology called polarized light which increases the contrast between the rings. 

In total, the researchers examined 27 preserved specimens across varying ages and sex. The youngest were embryos and the oldest was 84-years-old.

“What we found when we used this different technique is that there were nearly imperceptible rings that originally went unnoticed,” Ernande says. For each bigger, thicker ring, he and his team found five faint ones. “So this is basically how we came to the conclusion that the age of coelacanths was underestimated by a factor of five.” 

Thus, coelacanths may be able to live to the ripe old age of 100, and they don’t reach sexual maturity until their forties to sixties. And the animals don’t just live long lives—the aquatic giants have a gestation period of 5 years, which is possibly the longest of any marine fish and a decent chunk longer than most mammals. 

[Related: ‘Living Fossil’ Fish Has Lungs.]

Ernande says his team is uncertain why every coelacanth specimens deposit bold bands every fifth year. They know it’s not due to environmental factors since the ribbons weren’t uniform across species, but it may have something to do with the five-year cycles of reproduction. However, this is entirely speculative, he says.  

Why age isn’t just a number 

Fishing, channel dredging, submarine blasting, and deep-water port construction, all threaten coelacanths, classifying the creatures as endangered and threatening their 360-million-year run on the planet.  

Plus, species with a slow reproductive rate, such as coelacanths and the great ape, are particularly vulnerable to environmental or man-made changes. While some fish can carry over a million eggs per gestation, Ernande says, coelacanths only carry around 20 on top of being slow to mature and gestate.

“Any accidental or human-caused death takes a very long-time to replace,” Ernande says. 

Understanding the true life span of these living fossils is essential for assessing the demography of the species, which, in turn, can inform conservation policy. 

“There’s a lot more to be discovered about this species,” Ernande says. 

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This story originally featured on Outdoor Life.

For the past couple decades, the fishing industry has been pleading with people to learn how to fish. State game and fish agencies needed the money. Fish needed advocates. The industry needed more customers. Then COVID hit and people started fishing. A lot more people. 

How many more people, exactly, is still being tracked and analyzed, but anecdotes and local data paint a pretty clear picture. The pressure became so intense in some locations that Kirk Deeter, head of communications for Trout Unlimited and editor of Angling Trade magazine, coined some rivers in the West to be “Rivergeddon.” 

His sentiment made national headlines, with the New York Times quoting him in 2020 saying: “The rivers are getting the living snot pounded out of them every day.”

Jeff Kelm, tournament director of the Masters Walleye Circuit, also noticed.

“There’s hardly a boat available. There are no motors available. It’s pretty crazy to be talking to tournament anglers about what they can get ahold of, and often they’re far closer to the industry than your individual civilian,” Kelm says. “We’ve absolutely seen an increase in users on the water and the amount of people at boat launches.”

He’s also had a 10 to 12 percent increase in tournament entries since events could open again after pandemic closures. 

What, exactly, did 2020 look like across the country? Were all waterways flooded with boats, waders, lines and hooks? Are catch-and-release fisheries at risk, as well as catch-and-keep ones? Are fisheries at risk at all, or are seasoned anglers just not used to seeing other people on the water?

Like most questions blanketing a country with countless waters and millions of species, it really depends. After interviews with close to a dozen fisheries researchers and experts, the recent change in fishing pressure is, essentially, a mixed bag.

When reproduction drops, harvest takes a toll

Across the country one main takeaway is that while an increase in fishing pressure could cause issues on fish stocks in both catch-and-release and catch-and-keep fisheries, it could potentially be more troublesome when combined with existing issues like climate change, warming waters, and hurricanes.

Take northern Wisconsin.

Walleye populations in northern Wisconsin have been decreasing since well before COVID and the recent increased interest in fishing. The biggest problem is likely with walleye recruitment, according to Greg Sass, Wisconsin Department of Natural Resource’s fisheries research team leader. 

Natural walleye reproduction has dropped so much that from 1990 to 2000, about 60 percent of northern Wisconsin’s waters were sustained entirely by wild walleye. Now about 35 percent are, and the rest require at least some support from hatchery fish. 

“We don’t have a clear answer, it is likely lots of things,” he says. “The biggest player is climate change, water warming, loss of thermal optical habitat, water clarity, and temperature.”

Overharvest has also played a role in falling walleye numbers. A paper he co-authored in 2019 showed that as harvest rates stayed the same, reproduction rates dropped, leading to a loss in fish numbers. And in 2020, license sales increased another 8 to 10 percent in Wisconsin. 

“From my scientific perspective, it’s something that can be concerning. We have minimum length limits and bag limits, but don’t regulate effort. There is a potential for more harvest in that situation for a species like walleye,” he says. “We will know more down the road, but I would anticipate if there’s more effort out there, there will be more fish caught and harvested.”

Catch and release can be trouble, too

Data on the number of anglers in Montana hasn’t been processed yet from 2020, but anyone there, particularly in the western half, doesn’t need data to realize that fishing participation has increased. And not just because of COVID.

“The Madison River has been on the rise for several years now, and it is still our most fished water,” says Eileen Ryce, the fisheries chief of Montana Fish, Wildlife and Parks. “Our fishing sites are getting more crowded, and that became very apparent last year. Our facilities were just not able to keep up with demand.”

Anglers struggled with full parking lots, backed-up boat ramps, and people parking on sides of roads and on private land. The issue has become big—and controversial—enough on rivers like the Madison near Bozeman, Montana, that Montana Fish Wildlife and Parks recently created a rule to cap the number of commercial boats on the water. 

As far as harm on actual fisheries, the Madison is an interesting river. Most of the Madison is catch and release only. But catch and release doesn’t necessarily ensure survival. 

Studies across the country, particularly on trout species, have been conducted for years to look at the impact of hooking mortality.

One 2008 paper reviewed previous studies on hooking mortality and found that, across 50 states and dozens of species, mortalities could be more than 30 percent in red drum, smallmouth bass, largemouth bass, and cutthroat trout. Hooking mortalities could be as high as 68 percent in spotted seatrout, bluegills, crappies, and coho salmon. Those figures, however, vary dramatically depending on water temperature, bait type, hook type, how long it takes to land the fish, and how it’s handled after it’s caught. 

Ryce doesn’t yet have data to say if the increase in anglers is hurting trout in the Madison, but she is apprehensive about the possibility.

 “At first it came to us when we were hearing concerns about overcrowding and dissatisfaction, and that’s when we started to look into it,” she says. “And then as the numbers continued to increase, we are concerned about impacts to the population. It is something that we’re looking at closely.”

The biggest worry comes as climate change worsens and river temperatures warm. Cold-water species like trout struggle to survive when waters hit even the high 60s. Add someone pulling a fish out of the water, holding it up to a camera, and struggling to remove the hook? The likelihood the fish survives drops considerably. 

Fisheries officials in Montana have some rules in place to combat warming water mortalities, including limiting anglers to fishing only during morning and night when flows drop to a certain amount and temperatures increase. When it’s hot and dry enough, a river could simply shut down. 

As interest in fishing climbs, and this summer’s temperatures reached the 90s in early June, Ryce is paying attention.

“It’s a combination of stresses we’re concerned about,” she says. “[And] it’s not looking good.”

Read the rest of the article over at Outdoor Life.

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When life hands you lemons, you make lemonade. And when life hands you pearlfish that want to burrow up your anus, you grow teeth on your anus.

The animal kingdom is a pretty weird place, and science writer Matt Simon has made it his job to enlighten you about some of the craziest solutions evolution has come up with to solve life’s challenges. Simon writes the Absurd Creature Of The Week column at Wired, and he’s just finished writing a book compiling all of the grossest, funniest, and most fascinating critters out there.

In this excerpt from The Wasp that Brainwashed the Caterpillar, which goes on sale October 25, we meet the pearlfish. These slender fish dwell near the barren seafloor, where there aren’t a lot of places to hide from bigger fish that want to eat you. The pearlfish’s solution: swim up a sea cucumber’s anus and eat its gonads.

They say home is where the heart is, but for the pearlfish, home is more like where the gonad is. Because to find shelter it wiggles up a sea cucumber’s anus. And lives there. And eats its gonads.

It all begins innocently enough. The skinny, eel-like fish approaches the sea cucumber and gives it a sniff, moving up and down the length of its soon-to-be victim with its body pointed almost vertically. It’s looking for the sea cucumber’s breath, because, well, sea cucumbers breathe through their derrières. If the sea cucumber detects the pearlfish, it’ll hold its breath, sealing its butt like a human holding in a fart. But the sad sack is only delaying the inevitable. At some point it has to breathe, and that’s when the pearlfish strikes.

Once the pearlfish sees its window of opportunity, it has to make one of the toughest decisions in the animal kingdom: whether to enter the sea cucumber’s bum tail first or head first. This, of course, all depends on the size of the orifice (called a cloaca, since it’s used for not just waste removal but also reproduction and breathing). If the opening is big enough to enter head first, the pearlfish goes at it full tilt, jamming its face in and rapidly flicking its tail to fire itself into the sea cucumber. If the opening is too small, the fish first inserts its thin tail, then backs in slowly.

Once the fish is in there it wiggles into what’s known as the respiratory tree, which branches out as tubes on either side of the sea cucumber’s intestines. The sea cucumber breathes by pumping water in and out of its cloaca and into the tree. So not only is the pearlfish enjoying shelter while it’s in there, it’s getting a constantly replenished source of water, and therefore oxygen.

Some species of pearlfish are content sitting there biding their time, safe from predators circling above. Others . . . they get a bit hungry. They’ll start feeding on various parts of the sea cucumber, including the gonads, which isn’t as bad as it sounds. Once the gonads are gone it can grow new ones. The same goes for its other organs: The critter is a remarkable regenerator.

While the sea cucumber can regrow the bits one pearlfish has eaten, another is bound to show up and hack away at its insides once again. In fact, a biologist once found fifteen pearlfish in one poor bastard of a sea cucumber.

And if you thought the fish were ignoring each other’s advances in there, you’ve got another thing coming. Pearlfish also get busy in the respiratory trees, the ultimate indignity after the sea cucumber has itself been sterilized. It takes a tremendous amount of energy and resources to reproduce. If a parasite can figure out how to sterilize its victim, that means more energy is available to support its own shenanigans. Whether sterilization is the pearlfish’s strategy or the gonad happens to be tasty isn’t yet clear. Could be both, really. You’d have to ask a pearlfish.

Drawing of a pearlfish burrowing into a sea cucumber

And pearlfish don’t limit themselves to taking up residence in sea cucumbers. Some species instead invade sea stars, and still others go after bivalves like oysters. Those strategies would appear to be better options, considering the sea cucumber itself is vulnerable, on account of being essentially a tube of meat wandering along the seafloor. But while it may look appetizing, in reality, it’s not, for the sea cucumber has a secret weapon: It disembowels itself to scare away predators.

Admittedly that doesn’t sound like an effective defense at face value, but hear me out. When a sea cucumber feels threatened, the connective tissues that hold its organs in place soften in an instant. Depending on the species, the body wall around either the mouth or the heinie also softens. With everything loosey-goosey, the sea cucumber contracts its muscles, firing its guts through the weakened body wall at one end or the other. The explosion is a kind of surprise that maybe, just maybe, is weird and smelly and goopy enough to scare away predators. And as traumatic as it all sounds, sea cucumbers can regenerate the lost organs in a few weeks.

Interestingly, the pearlfish doesn’t seem to trigger these defenses, and as yet no one is quite sure why. Maybe it’s more energetically cost-effective for the sea cucumber to deal with regrowing gonads than the intestines and all the other ejected bits. So what the pearlfish ends up with is a living, breathing mobile home, which staves off attack by dropping its guts out, like a James Bond car deploying caltrops to slow pursuers. Except the sea cucumber isn’t going to get the girl. You know, on account of missing its gonads.

Adapted from The Wasp That Brainwashed The Caterpillar by Matt Simon, on sale October 25, 2016. Reprinted by permission from Penguin Books, an imprint of Penguin Random House LLC. Copyright © 2016 by Matthew Simon.

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Overfishing our oceans is an obvious hit to biodiversity. You’re simply taking out too many fish.

But a new study published in Nature Communications shows that fishing in general may be depleting the ecosystems of something else – pee.

While it may seem silly, having less pee and other fish waste products can seriously harm the nutrient cycling systems. Pee from most animals contains nitrogen in some form, and nitrogen is an essential building block of life.

Fish also release phosphorus, another important nutrient, through their gills.

Jacob Allgeier, a post-doc at the University of Washington, Seattle, and a team of researchers from throughout the United States, studied nutrient cycles in 43 coral reefs in the Caribbean for four years, specifically looking at what fish can bring to the table.

They collected more than 140 different fish species from the wild, had them sit in seawater-filled plastic bags for a half an hour, and then measured the nutrient contents of the water before and after. They then made estimates of the nutrient levels at different sites based on their findings.

Larger fish, more nutrients

They found that general fishing, where the larger species and those higher in the food chain are caught, is not necessarily hurting the biodiversity like overfishing does. But it does affect the nutrient levels.

“We were not totally surprised that there was such a drastic reduction in fish mediated nutrients, given the degree to which some systems are so heavily fished,” Allgeiers said in an email, as he is currently out in the field, continuing research.

“What was surprising was the way in which fishing was changing the fish communities that lead to the high reductions in fish-mediated nutrients (fish pee) that we found.”

Fishing didn’t reduce the number of species, Allgeiers said. Instead, it removed, “the more valuable, larger and predatory individuals…And those individuals disproportionately supply lots of nutrients through their excretion.”

The findings make sense, as it has been known for decades that coral reefs with stronger fish communities can grow twice as fast as those without.

With the events of coral bleaching via ocean acidification and general overfishing becoming global phenomena, this lack of nutrients can be added to the decline of coral reefs. Allgeiers is already conducting more research, this time studying the nutrient cycles in Pacific coral reefs.

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At first glance, a fang blenny looks completely unthreatening. It’s small, brightly colored, and looks like it would be an adorable backup character in a Finding Nemo film.

Then, it opens its mouth.

Skull of a fang blenny

Yikes.

Fang blennies get their name from their distinct twin fangs, which fit securely into slots in their heads when their mouths are closed. Scary enough. But some fang blennies add a little extra juice to their bite.

In a paper published Thursday in Current Biology, biologists describe the potent venom of these fish, denizens of coral reefs in Australia and around the world. (Not to be confused with the land-dwelling blenny fish.)

Unlike the venom of many other animals, fang blenny’s defensive shots don’t cause pain. Quite the opposite, in fact. Instead, the venom acts like heroin or other opioids, temporarily stunning or slowing a predator before it can enjoy a fang blenny feast.

Lead author Bryan Fry and his colleagues figured this out by oh-so-carefully collecting venom—lifting fang blennies out of a tank, having the fish bite on small cotton swabs, and then popping them back into the water. “They’re not exactly shy about biting,” he says.

Not all fang belnnies have any venom to begin with, and it’s possible not all venomous blennies use the same strange method of attack. The new study only looked at two species. But Fry and his colleagues plan to go looking for other unusual compounds in more members of the venomous genus.

Fry hopes that continued study of these venoms—which are chemically unique—might help develop alternative painkillers in the future, though what form those would take and what conditions they’d be used to treat remains an open question.

While the future of the venom is potentially exciting—and its present is fascinating—the fang blenny’s past is probably the weirdest part of its story.

Fry and colleagues found that long before a genus of fang blennies evolved venom, they had fangs. And instead of using them to scare away other fish, they actually used them to eat.

Their ancestor’s coloring strongly resembles the helpful cleaning wrasse, which cleans the teeth of larger predators. But instead of helping with dental hygiene, the fang blenny’s predecessor would chomp down into the larger fish, tearing off a tasty bite before darting back to safety on the reef.

Now, venom has changed the evolutionary game again. Since predators have started to avoid the bite of the fang blenny, other fish have started to mimic its coloring as a protective camouflage.

What goes around, comes around. Eventually.

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The jellyfish is a fascinating creature. Floating lazily along in the ocean current resembling plastic bags, the gelatinous zooplankton seem to do little more than add a colorful glow to our aquariums and occasionally give swimmers a reason to urinate on each other. But jellies are also efficient hunters, and increasingly, huge nuisances. In some regions, these blobby predators rule the seas—to the extent that they’re killing off other marine life and swarming power plants.

In honor of these majestic, sometimes terrible creatures, here are eight reasons to be awed by jellies:

Click here to enter the gallery

They’ve Been Around Forever

Their Bioluminescence Lets Us See Into Ourselves

They Get Vertigo, Too!

They’re Super Energy-Efficient

They’re Overwhelming The Ecosystem

They Can Take Out A Nuclear Reactor

They Can Be Killer

Oh, And One More Thing

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Mouth agape, revealing rows of small but deadly fangs. A limb-like protrusion extending out of a black, prickly body. This is how beachgoer Ben Estes found a “weird looking” fish on the shores of Newport Beach at Crystal Cove State Park in California last week.

Estes alerted state park rangers and lifeguards to his find, who in turn alerted the California Department of Fish and Wildlife. “I knew it was an unusual find,” Estes told the Guardian. “I have never seen a fish that looked like that before.”

The bizarre sea creature turned out to be a 18-inch female Pacific Footballfish, a species of anglerfish similar to the notorious one-time villain from Finding Nemo. As shown in the movie, each anglerfish has a fleshy, long dorsal fin called an illicium that extends in the front of the mouth. The bioluminescent bulb on the end of the illicium emits light to attract unsuspecting prey. 

Pacific Footballfish ordinarily dwell in the pitch-black depths of the deep sea, as far as 3,000 feet below the surface, according to a Facebook post from Crystal Cove State Park.  Authorities haven’t yet determined how the monstrous fish died. But they were surprised its body managed to stay so intact while coming all the way up to the surface. It’s not unheard of for deep-sea dwellers to occasionally make their way to our beaches. But it’s still very rare.

[Related: Five animals you shouldn’t take relationship advice from (and one you should)]

John Ugoretz of the California Department of Fish and Wildlife told the LA Times that, as of Monday morning, the fish was frozen at Crystal Cove State Park. State officials were still determining where the specimen would ultimately end up. He told the Guardian that it will likely be transferred to the Natural History Museum of LA County. The museum has just three others in its collection, but none are as well preserved. 

“Seeing this strange and fascinating fish is a testament to the diversity of marine life lurking below the water’s surface in California’s [marine protected areas],” reads the post from Crystal Cove State Park. “As scientists continue to learn more about these deep sea creatures it’s important to reflect on how much is still to be learned from our wonderful ocean.”

Correction: An earlier version of this article stated that the Pacific Footballfish was not a rare species, when in fact it is indeed rare. We regret the error.

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This story originally featured on Field & Stream.

Everyone should spend a week paddling in a canoe—if not every year, at least once in their life. There’s no better way to get to know someone than being stuck in the same boat for days on end, and it’s been the boat of choice for hunters and anglers for centuries. There are paddling routes all across the world, and many in your backyard. Some will challenge you as a paddler, while others can help you and your family relax.

After a few trips under your belt you may end up falling in love with canoe tripping. You’ll know it’s too late if you find that your belt has been replaced by an NRS cam strap.

This is not a definitive list. There are too many gorgeous places to paddle and not enough time, but these North American canoe trips are a good place to start.

The elements of a great canoe trip

A canoe trip is flexible. You can float lazily down a river, chatting with your friends, or you can suffer through a hellish portage in the snow for days on end. It can be whatever you want. I will say that a grueling portage helps to make a trip memorable. The same goes for tricky weather, exciting rapids, and killer fishing conditions. Oh, and bugs.

Tandem paddling and tough portages can bring you closer or make you start whacking each other with your paddle. Make sure your paddling crew works well together. Carry an extra paddle in each boat in case you break or lose your main paddle, and make sure everyone wears a life jacket. Explain the route carefully before you start so everyone knows what to expect.

Always make sure to have a warm, dry change of clothes when you get into camp. No matter how gnarly it gets on the water, a toasty pair of socks waiting for you at the end of the day can help you get through it. A big bag of trail mix (the kind with M&Ms) in each boat helps, too.

If you’re worried about navigating your route, or just want some help on the water, hire a guide or outfitter.

1. Northern Forest Canoe Trail, New England

A group of friends and I paddled the first two sections of the Northern Forest Canoe Trail (NFCT) a few years back, and I’ve been itching to go back to complete the rest. I’ve also paddled section 12, the famous Allagash River, in Maine. The beauty of the NFCT is that I can keep picking these trips off section by section, or choose to paddle all thirteen sections at once to cover the entire 740 mile route like an AT thru-hiker. The trail starts in Old Forge, New York, and finishes in Fort Kent, Maine. The NFCT covers 23 rivers and streams, 59 lakes and ponds, and 65 portages (a little more than 70 miles) and is the longest inland water trail in the United States. This is as classic as canoe country paddling gets, with the trail following traditional Native American travel routes.

2. Boundary Waters Canoe Area Wilderness, Minnesota

More classic canoe country, the Boundary Waters Canoe Area Wilderness has more than 1,200 miles of paddling routes. At 1 million acres in size, you can spend a month in the backcountry of northeastern Minnesota and still barely scratch the surface. There are thousands of lakes and streams and you can spend your nights at one of over 2,000 designated campsites. Bring smores, you’ll want to watch the stars all night long.

3. Okefenokee National Wildlife Refuge, Georgia

A canoe can be just as at home down in the swamp as in the North Woods. Paddle through the black swamp waters of Georgia’s Okefenokee National Wildlife Refuge to watch colorful birds and curious alligators. A photographer friend, Chris Funk, has been telling me to paddle the Okefenokee for years. “It’s a place that is so wild; man tried to tame it and failed,” he says. “The beauty of that place burns deep in the hearts of the folks that visit those black waters.”

4. Buffalo National River, Arkansas

The standout character of my time on the Buffalo National River in the beautiful Ozark region of Arkansas was the smallmouth bass. Even the smallest bass I caught that week were feisty as hell and brilliantly colored. There are many route options for paddlers looking for a multi-day float, with a total of 132 river miles beginning in the town of Ponca. Head there for the fishing, but make sure to enjoy the tall bluffs on this scenic river.

5. Green River, Utah

If north country whitewater or alligator swamps aren’t your speed, paddle one of the best flatwater routes in the country on the Green River in Utah. Start in the town of Green River and paddle 120 miles to the confluence of the Colorado River. Most people can complete the trip in three to five days, but make sure to plan time to hike the surrounding country. The giant rock formations of Labyrinth and Stillwater Canyons will keep you awestruck.

6. Tuolumne River, California

Designated a Wild & Scenic river in 1984, California’s Tuolumne River starts in the High Sierra mountains and runs for 62 miles before it enters the Stanislaus National Forest. Besides the gorgeous views, like lush meadows between glacially carved canyons, there’s also a chance for serious paddlers to test their skill. Starting From Lumsden Bridge to Wards Ferry, a series of tricky rapids run one after another for 18 miles. If you’d rather run it than portage it, this may be the route for you.

7. Noatak River, Alaska

On a list of the best canoe trips in North America, of course you have to include one within the largest undisturbed watershed on the continent: the Noatak River in Alaska. You have almost 400 miles of river to plan your route on, but if you’re going to paddle the whole thing (why not, right?), a good place to put in is Kotzebue. There’s also the option to split it up and come back again year after year. It is after all a clear, Arctic river with serious fishing and great wildlife like bear, sheep, caribou, and musk ox.

8. Wabakimi Provincial Park, Ontario

With more than 1,200 miles of some of the best wilderness canoeing routes in the world, Wabakimi Provincial Park must be explored over a lifetime. You just have to keep going back. There’s plenty of action for whitewater paddlers, chances to explore the park’s long cultural history of indigenous communities, and of course the fishing. Fly-in lodges put their clients on giant walleye and northern pike, but spending a week (or more) there in a canoe means you’ll have first dibs at all the best spots.

9. Nahanni River, Northwest Territories

Spend two weeks in the backcountry of Canada’s Northwest Territories on the classic Nahanni River. This river features Virginia Falls, a waterfall nearly twice the height of Niagara Falls. It also takes paddlers through some of Canada’s deepest river canyons and leads them past hot springs and other unique geological features. This river is so legendary that the United Nations declared the Nahanni River first World Heritage Site in 1978.

10. The Bowron Lakes Circuit, British Columbia

Paddle along the western slopes of the Cariboo Mountain Range in Bowron Lake Provincial Park. The Bowron Lake Canoe Circuit is world-renowned among paddlers, connecting 72 miles of lakes, waterways, and portages through the wilderness. You can spend 10 days paddling the whole circuit, or just paddle two to four days on the west side of the circuit.

Remember, sometimes the portages between each lake are the best part—at least they are later when you’re talking about them to your coworkers back in the real world.

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3D movies are a love-hate experience. You absolutely adore the feeling of something plummeting out of your screen so close you think you can nearly touch it, or the whole thing completely freaks you out. Either way—the only way it works is being able to use both of our eyes at the same time to capture the image and perceive its illusory depth.

But as a new study shows cuttlefish experience this phenomenon as well. When equipped with little 3D glasses and placed in front of a screen with a 3D movie of a shrimp passing by, they actually tried to grab it with their tentacles.

These new findings are laid out in a study in Scientific Advances, and it demonstrates more than just a cuttlefish’s ability to “hunt” virtual prey—it show’s that their vision systems are capable of stereopsis or “binocular vision”.

Binocular vision is the way that the brain uses images from both of our eyes to create a perception of depth. Humans have this ability—it’s how we know when something is about to smack us in the face, or if we need to reach out to grab something. For a while, it was thought that only primates and people could manage this because of our front-facing eyes. But it turns out that quite a few other creatures judge distance this way as well.

One other invertebrate, the praying mantis, evolved this way, as proven in their own tiny 3D glasses study from about a year ago. A cuttlefish is another complex invertebrate, so author Trevor Wardill, an ecology professor at the University of Minnesota had the idea of using them to further figure out stereopsis.

“To be fair when we proposed the project … they thought it was a little bit crazy,” Wardill says of first proposing the project to his partners at the Marine Biological Laboratory in Massachusetts. “They did not really expect it to work, but we were pretty convinced that we should try.”

The initial act of getting cuttlefish to willingly wear the glasses without trying to take them off and actually watch the screen was tough enough, Wardill says. This process required gluing velcro to the top of its mucus-covered body, placing the glasses on their heads, and keeping the creatures happy and distracted enough to not mess with them (or ink all over the experiment).

But when the animals finally focused on the screen, creating an illusion of depth that can only be seen when using binocular vision, they accurately “hunted” the shrimp on screen.

“Putting little glasses on a slimy, tentacled invertebrate may sound both adorable and funny, but it’s actually an amazing accomplishment,” says Kate Thomas, a visual ecologist and postdoctoral researcher at the Natural History Museum in London who was not involved in the study.

This illusion of depth is created by using two different colored images that are seen through the two different lenses, which the brain then calculates the distance between. Even though cuttlefish are colorblind, the colored filters in the glasses send the accurate color from the monitor to the right eye. They only see the image in each eye as a variety of greyscale intensities, Wardill adds.

Strangely enough, most animals with stereopsis have “yoked” eyes—meaning they look at the same thing at the same time. Cuttlefish’s eyes move separately, except for the moment they notice their prey.

The cuttlefishes weren’t great at “yoking” their eyes, Wardill says, but they still were able to hunt. It’ll take more investigation on what the cuttlefish’s eyes are actually doing to see how they use cues and spacial information to capture their meals.

Their lack of yoked eyes is not the only thing that’s different about a cuttlefish’s stereopsis. The study found that critters can also detect the distance from an “anticorrelated” stimulus, where the image seen in each eye was completely the opposite of the other (think black on white in one eye, white on black on the other).

Humans need the brightness in each image to match up in order to tell distance, so the contrast in this kind of stimulus makes it tough for us to perceive. But the teensy brain of a praying mantis can see depth in these stimuli easily.

This study demonstrates convergent evolution, Thomas says, as these creatures are so far off the evolutionary pathway from humans, but are in some ways similar to us. “I think it’s fascinating that an animal more closely related to a clam than to us has not only evolved eyes similar to ours, but also processes images from those eyes in a similar way to produce depth perception.”

Though they’re interesting results, they shouldn’t be super surprising—and they actually make a lot of sense in the context of the cuttlefish’s daily needs. Binocular vision makes predation easier, Wardill says, since you can see your prey in front of you without moving around or making a bunch of attempts to capture a meal. After all, a cuttlefish probably wouldn’t be catching very many shrimp if it was continually scaring them off.

If anything, Wardill says, it was more surprising that the animals kept their glasses on.

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Some people need a cup of coffee to really get moving. For jellyfish, a jolt of electricity apparently does the trick. Scientists have implanted tiny controllers in live jellyfish that use electric pulses to direct the animals’ movement. With the electrical aids, the animals swam at nearly three times the speed of normal jellies while expending only twice as much energy. The prosthetic didn’t injure the animals, and the researchers hope to use the turbocharged jellyfish to explore the world’s seas.

“What we’re hoping this technology can do is provide our first window into what’s happening in the majority of the ocean,” says John Dabiri, a mechanical engineer at the California Institute of Technology, who published the findings January 29 in the journal Science Advances.

The humble jellyfish might not have a brain, but it does have the impressive distinction of being the most energy-efficient of all swimming animals. “Some of that goes to their evolutionary heritage of being the first animals to learn to swim some 500 million years ago,” Dabiri says. Jellyfish move by contracting and relaxing their bells; these pulsating motions create donut-shaped swirls of water called vortex rings that propel the animals forward without much effort on their part.

Before outfitting jellyfish with exoskeleton-like attire, researchers first built soft, flexible robots that mimic the marine animals’ swimming motions. However, the robots demand much more energy than real animals do and are typically tethered by a power cord. Dabiri has also teamed up with researchers at Harvard University to build a less power-hungry jellyfish out of rat heart muscle cells. They could control the artificial jellyfish by contracting the muscle cells, but the delicate robot couldn’t function outside the lab.

Dabiri and his colleague, Nicole Xu of Stanford University, decided to harness the power of real jellyfish instead. The animals feed themselves, so only a little extra energy would be needed to control the prosthetic device. They’ve also colonized every part of the ocean—from the arctic to tropical waters, and from the sea surface to the depths of the Marianas Trench.

“They’re already operating in that domain that we’d like to explore,” Dabiri says. “The trick then is how do we give them a brain so we can tell them where to go and when?”

They implanted microelectric controllers in live moon jellies, a species that is common in both the wild and in aquariums around the world. The team expected that the jellyfish outfitted with prosthetics would swim more quickly than regular jellyfish. “What was more surprising was that they’re more efficient at swimming at those higher speeds,” Dabiri says. Relative to their size, the hybrid jellyfish demanded between 10 and 1,000 times less power than other aquatic robots.

In the wild, moon jellies probably don’t need to tap into these dormant powers of propulsion, Dabiri says. The average jellyfish isn’t actually trying to travel from one point to another; its efficient swimming motions are mainly useful for catching prey. If jellyfish can draw food into their waiting tentacles from the surrounding water using these leisurely strokes, there’s no need to hustle.

Life in the fast lane didn’t seem to harm the jellyfish either. The animals have no central nervous system or pain receptors. Jellyfish do secrete mucus in stressful situations, but Dabiri and Xu didn’t observe the moon jellies engaging in this slimy behavior during the experiments. And when they removed the implants, the jellyfish went back to swimming normally.

Eventually, Dabiri plans to fit sensors on the jellyfish so scientists can send them on voyages into the depths of the ocean. The remotely operated vehicles that currently explore this dark, cold realm typically only have enough juice to last for 12 to 24 hours of traveling. “There is a lot of life in deeper waters that we simply aren’t able to observe,” Dabiri says.

The enhanced jellyfish could also collect valuable information about the ocean’s climate. Dabiri envisions the animals roaming seas around the world, outfitted with sensors to measure key variables such as water temperature, salinity, acidity, or oxygen levels. The jellyfish could even gather data about the microbes that inhabit different parts of the ocean.

Before the jellies can be deployed on these missions, the researchers will need to figure out how to guide the animals in different directions. They’re currently experimenting with sending electric pulses to different parts of the jellies’ bodies to make them turn. By making the muscles on one side of a jellyfish contract at a time, Dabiri says, they can prompt the animal to change course or even make a U-turn.

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This story originally featured on Sportfishing Magazine

Thanks to a burgeoning conservation ethic, many saltwater anglers choose to release their catches. Others do so because of fishery-management rules, or because it’s required in tournament regulations. As a result, anglers release many, many saltwater fish every year. But just how many?

In my home state of Georgia, anglers released more than 1 million red drum during 2018, according to the Marine Recreational Information Program. For the entire United States, that number climbs to 18 million redfish released. The MRIP estimate for the number of released fish of all species during 2018 is an astounding 605 million.

While we optimistically believe that most of these fish survive, the reality is much more complicated.

Multiple factors, often combined, determine the fate of a released fish, such as how the fish was caught and handled, the fish’s environment, and ecological conditions—including predation. These interactions are unique to each species and situation.

Given the importance of the angler in this complex interaction, biologists and regulators have expended much effort to develop guidelines for catch-and-release fishing. These angling best practices, when used, markedly increase post-release survival. For many years, these methods remained simple and were based on common sense, such as handling a fish with wet hands.

Today, after hundreds of studies evaluating the effects of everything from hook type to handling devices, these best practices have evolved. The studies validate the benefits of some well-known techniques yet reveal that some methods and behaviors are more harmful than once believed.

The Point of the Matter

Hooking injury is considered a primary cause of post-release mortality. Ideally, a fish should be hooked in or around the immediate area of the mouth—lip, tongue, jaw hinge—or just inside the oral cavity. Most lures with single or treble hooks achieve that outcome. However, treble hooks also can injure a fish’s eye or result in foul-hooking.

Conventional J hooks, when used with natural or synthetic scented baits, can be swallowed deeply into the throat or digestive tract. Pulling on a hook lodged in such a location can cause injury to the heart, liver, gill arch, kidneys, stomach and intestines. Attempts to remove the hook only increase the severity of such injuries.

Research backs up the long-standing belief that removing hooks that are not easily accessible in the mouth region should be avoided. The Florida Fish and Wildlife Conservation Commission, in its guidance for fishermen, references an agency study that showed four of 12 deep-hooked snook died when anglers removed embedded hooks, compared with zero mortality when leaders were cut and hooks left intact. Fish can dislodge, expel or simply render a hook inert, especially if it’s made of a material such as bronze, which degrades quickly from the combined effects of salt water and the fish’s body chemistry.

Happily, the number of deep-hooked fish has declined dramatically in recent years due to the revival of an ancient hook design. When rigged and used properly, circle hooks penetrate the lip or jaw-hinge area, causing minimal anatomical damage yet producing a strong connection point. Furthermore, studies show that inline circle hooks—those having the point aligned with the shaft—prove most effective at reducing deep-hooking.

In a 2007 South Carolina Department of Natural Resources study, researchers compared the performance of a J hook, an offset circle hook and an inline circle hook used on subadult red drum. Inline circle hooks attached in the jaw, tongue or inside of the mouth area in 90 percent of the fish. Offset circle hooks resulted in mouth- or jaw-hooking 80 percent of fish, and J hooks, 60 percent. Inline circles also generated the lowest rate of subadult mortality: 2 percent. Researchers found similar results with adult red drum, where the circle hook performed better than the J hook.

Despite these conservation benefits, circle hooks don’t work in every angling situation. When J hooks are needed, anglers should opt to use the smallest size—in length, width and wire diameter—to minimize fish injury. They should also consider barbless versions because removing a barbed J hook usually takes longer, thereby increasing handling time.

Time Matters

Fish lead active lives chasing prey and escaping predators. At the same time, they must adapt to varying extremes in their environment. Every species has its physiological tolerances, but those tolerances have limits.

Once a hooked fish starts resisting, a stress response begins that can interfere with normal respiration and alter the fish’s body chemistry. The longer the duration of the stress response, the more likely there will be long-term or permanent negative effects.

A 2010 Florida study compared several stress-indicator blood-chemistry parameters in subadult and adult tarpon caught on hook-and-line gear with that of tarpon resting at a holding facility. Experimental treatments included holding the hooked fish vertically versus horizontally, and exposing them to ambient air for 60 seconds compared with leaving them in the water. In this study, the duration of time between hooking and landing had more effect than handling time and method on stress-indicator levels.

A fight of even short duration can exhaust a fish, impairing its ability to evade predators and carry on with life as usual. Research has shown that a significant source of postrelease mortality in tarpon and bonefish is shark predation. The time needed to recover full function varies from species to species and can be greatly influenced by factors such as water temperature.

Holding a lethargic fish in the water with its head into the current can help accelerate its recovery. Once the fish resists, release it.

The take-home message: Choose tackle that allows you to bring the fish to hand in the least amount time yet provides for the enjoyment of successfully angling the fish. When I target adult red drum, I plan to have them to the boat in five minutes or less. If you choose to use light tackle for large fish, do so with the recognition that you’re consciously increasing the chances that the fish will perish.

Landing Gear

Once anglers subdue fish, they have a responsibility to release them in the most expedient manner. Some species can be more sensitive to the effects of handling than others.

In contrast to the 2010 study on tarpon, mentioned above, a 2016 Virginia Institute of Marine Sciences study showed that removing white marlin from the water and exposing them to air had a more pronounced effect than fight duration on postrelease survival for that species. Research also has revealed that warm air can quickly dry delicate gill filaments, causing them to become nonfunctional.

If you choose to bring a fish into the boat before release, preferred options include the use of hands to lip grippers to landing nets—never gaffs. Wet, gloved hands or a handheld wet towel can effectively control small- to medium-size fish such as seatrout and bonefish but can be inadequate for larger, more vigorous animals. When using hands, always keep the fish in a horizontal position supporting its weight, and avoid any contact with the gills and eyes, which can be easily damaged.

Lip grippers, such as the BogaGrip, have steadily grown in popularity, but their design often tempts anglers to support the entire weight of the fish vertically. Research has shown that doing so can cause debilitating injury to mouth parts, internal organs and skeletal structure, especially for larger fish. When using grippers, support the fish’s weight with a hand under its abdomen.

A 2009 Australian study of barramundi (20 to 40 inches in length) handled with lip grippers provides some perspective. Researchers lifted 10 fish vertically without any additional support—all the fishes’ weight was supported by the mouth parts. Eleven were lifted in a horizontal position with a hand supporting the belly of the fish. Lifting fish using grippers without support increased the severity of mouth injury and altered the alignment of vertebrae, which did not return to normal for three weeks.

Landing nets, used frequently for small- to medium-size species, offer many advantages such as reducing fight time, controlling fish movement to allow for hook removal and preventing the fish from being dropped. Yet landing nets also can potentially harm fish by removing the protective mucus layer, dislodging scales and damaging fins.

Recognizing this, most net manufacturers offer a knotless rubber model, some with the further modification of a flat bottom to prevent fish from rolling in the net and damaging fins. Another study of barramundi in 2008 showed that a landing net of this design resulted in significantly less fin damage and abrasions when compared with a traditional knotted net.

Pressure Drop

Many species most prized by saltwater anglers live near the ocean bottom, sometimes in extreme depths. Granted, we usually pursue them as table fare, so catch-and-release is not typically the targeted outcome. But in today’s world of restrictions on size, quantity and season, releasing reef fish has become part of our new reality—as are the challenges of ensuring postrelease survival for an animal pulled up from 20 fathoms.

Species such as snappers and groupers have air bladders, which allow them to make fine-scale adjustments in their buoyancy. However, when we rapidly pull these fish from the seafloor to the surface, an uncontrolled expansion of their air bladders can cause barotrauma.

Most anglers know the symptoms: bulging eyes, stomach protruding from the mouth, a distended abdomen, and lack of equilibrium when returned to the water. When released, these fish can’t submerge, which makes them easy pickings for predators. In addition, prolonged barotrauma causes irreversible anatomical damage and extended physiological stress, often leading to death.

For many years, anglers have been advised to treat barotrauma in a fish by venting—puncturing its air bladder with a hollow needle. However, venting causes injury, creating additional stress and an opportunity for infection. If you choose to vent, be sure to do it properly. There’s no doubt venting beats simply discarding a fish with severe barotrauma, but there’s a better way.

Several devices on the market now allow anglers to lower the fish to depth, allowing it to recompress, alleviating the effects of barotrauma (visible and nonvisible). Additionally, these devices return fish to an environment of optimal conditions while hopefully bypassing some of those hungry predators. Collectively known as descending devices, these products have proved to increase postrelease survival in bottomfish.

In a 2015 Gulf of Mexico study, red snapper returned to the seafloor with a descending device fared better than fish that were vented or untreated. Survival rates for descended fish rose during summer, when sea-surface temperatures exceeded those at the seafloor. Research has also shown the benefits of descending devices for Pacific rockfish, reef fish in Australia and even walleye in freshwater lakes.

Descending devices hold such great promise for improving bottomfish survival that the South Atlantic Fishery Management Council has requested the National Marine Fisheries Service make a rule requiring anyone who possesses or is fishing for snapper-grouper species have such a device on board. If approved by the Secretary of Commerce, this requirement will go into effect sometime in 2020.

Choice or Law?

Fishery management and catch-and-release fishing succeed only when a high percentage of released fish survive. Thanks to years of study and on-water experiences, we now have angling best practices that, when followed, maximize survival chances. The quandary becomes whether to mandate the use of some or all of these angling best practices or to rely solely on voluntary compliance. Not surprisingly, angler opinion is divided.

Government entities, conservation groups and the marine industry invest vast sums of money and effort in promoting angling best practices. In some jurisdictions and fisheries, these government entities mandate the use of some types of tackle and gear or disallow certain activities.

For example, circle hooks must be used for billfish, sharks, reef fish, and striped bass in some areas and situations. Federal regulations prohibit marlin or sailfish from being removed from the water, if the fish won’t be kept. Florida law also forbids anglers from removing tarpon over 40 inches from the water.

Whether by choice or legal mandate, anglers have the responsibility to use best practices and to advocate their use to others. This might mean changing behaviors and postponing the catch of the next fish for the benefit of the one in hand. After all, a fish that survives after release is a potential future catch. And we are always looking forward to that next catch.

Tagging Tales

Determining the postrelease survival of fish caught on hook-and-line gear can be daunting. The study methods themselves—taking blood samples, marking, handling, confinement—can mask or amplify the effects of the catch.

Ideally, the fish should suffer the least amount of additional stress and be released into the same environment from which it was caught as quickly as possible. Oh, and yes, the scientist must be able to determine if the fish remains alive or dies during a minimum of 24 hours—and, ideally, for weeks, if not months.

This was once thought impossible, but not anymore, thanks to technological advances in batteries, microcircuitry and satellite communications. Acoustic telemetry and pop-up satellite archival tags (PSATs) have revolutionized scientists’ ability to document the fate of hook-caught-and-released fish.

In a 2015 North Carolina study, researchers used externally attached acoustic tags to document the fate of scamp, snowy grouper and speckled hind caught from depths of 200 feet and treated with a descending device. Previous knowledge suggested that any fish brought up from those depths perished. However, this study reported a 50 percent survival rate after 14 days, showing that recompression can increase postrelease survival in deepwater species.

Read Next: U.S. Senators Cassidy and Jones Introduce DESCEND Act Companion

PSATs have been used in multiple studies of billfish and tunas, species that are notoriously difficult to study with conventional methods. One such project using these tags on juvenile bluefin tuna revealed almost 100 percent postrelease survival, and concluded that the recreational catch-and-release troll fishery for school-size Atlantic bluefins does not represent a significant source of fishing mortality.

Best Practices

For more information about properly releasing fish, consult these resources:

fishsmart.org

releasense.org

myfishcount.com/bestpractices

fisheries.noaa.gov (search “catch-and-release best practices”)

myfwc.com (click on “saltwater fishing,” then “fish handling”)

About the Author

Capt. Spud Woodward retired in 2018 after 34 years with the Georgia Department of Natural Resources serving in various positions from senior biologist to division director. He is the vice chairman for the Atlantic States Marine Fisheries Commission and a member of the South Atlantic Fishery Management Council.

The post Releasing a caught fish isn’t as simple as tossing it overboard appeared first on Popular Science.

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For years, snorkelers in mangrove forests around the Florida Keys, Caribbean, and Micronesia have reported a bizarre and unpleasant phenomenon. Despite being careful not to touch the jellyfish littering the seafloor below, swimmers sometimes feel a stinging sensation that seems to come from the water itself. After encountering stinging water while studying the jellies, scientists sought to get to the bottom of these prickling shores.

To their surprise, they discovered that mucus secreted by these jellyfish is filled with tiny, wriggling cell masses that allow them to fire stinging substances from a distance. The researchers reported the newly identified structures, which they dubbed cassiosomes, on February 13 in the journal Communications Biology.

“It was really one of the most shocking days in my history as a scientist,” says co-author Cheryl Ames, an associate professor of applied marine biology at Tohoku University in Sendai, Japan. “The mucus was really visible when you were down there snorkeling around and diving, but we didn’t know what was in the mucus that was making us feel stingy.”

This group of jellies, known as upside-down jellyfish, is a bit unusual. They don’t drift through the water, capturing prey in their long, trailing tentacles like their cousins. Instead, they lie on the ground and, with the help of stubby arms, they wave about all day in mangrove forests, seagrass beds, and other coastal habitats. Upside-down jellies get some of their nutrients from the symbiotic photosynthetic algae living inside their cells. However, they also feast on brine shrimp, nematodes, and other hapless creatures snared by the clouds of mucus they pump into the surrounding water. “It’s like dropping a ball of saliva while it’s still stuck to your lip and then being able to suck it back in,” Ames says.

The first mention of this floating mucus dates back to 1908 when a zoologist named H.F. Perkins at the University of Vermont saw tiny, mobile organisms in the mucus of upside-down jellyfish that he declared were parasitic larvae. For more than 100 years, their true identity remained a mystery and snorkelers, naval divers, and jellyfish keepers in aquariums were baffled by stinging water. Ames and her colleagues experienced the zinging sensation on the parts of their faces and necks that weren’t covered by protective gear while collecting upside-down jellyfish specimens in the waters off the Florida Keys and Caribbean.

“You get a little sting and you think, ‘okay, I can handle this,’ but it doesn’t go away because you’re in the water,” she says. “It gets to the point where you’re like, ‘I’m out of here,’ especially as the tide is going down and your face gets closer and closer to this humongous bed of upside-down jellyfish.”

She and her team decided to feed captive jellyfish a plankton snack, “liberate” some of the mucus attached to their bodies, and stick it under a microscope. Within the mucus, the researchers spied hundreds to thousands of tiny, gyrating masses propelling themselves about, killing any brine shrimp they bumped into and moved on. “They were passing through like a Roomba…just covering every single bit of that mucus area,” Ames says.

When they examined these cassiosomes under higher magnification, they saw that the structures were popcorn-shaped balls made from an outer layer of nematocytes (the stinging cells typically found on jellyfish tentacles) and thin filaments to push them through the mucus, all surrounding an inner core filled with symbiotic algae. After being plucked from their slimy homes, the cassiosomes survived for 10 days in a petri dish.

The researchers also observed that the cassiosomes were created in spoon-shaped appendages along the frilly arm-like appendages surrounding the jellies’ mouths. The animals would then release them into the water like “potent little grenades.”

It remains to be seen how common this weaponry is among jellyfish. After discovering cassiosomes in the upside-down jellyfish Cassiopea xamachana, Ames and her colleagues also found the structures in four closely related species. A more distant relative, the moon jellyfish, didn’t have any cassiosomes.

Going forward, Ames and her colleagues will continue their search for cassiosomes in other species. By identifying which jellyfish carry these tiny weapons, they hope to alert snorkelers, military divers, and aquarium staff who handle jellyfish so they’ll know when to take extra precautions.

As irritating as stinging water might be, though, it’s all part of a thriving mangrove ecosystem. “If the jellyfish are there, then the water is healthy and it’s a great place to enjoy,” Ames says. “Just show up well-protected.”

The post Upside-down jellyfish lob tiny grenades to kill prey appeared first on Popular Science.

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For February, we’re focusing on the body parts that shape us, oxygenate us, and power us as we take long walks on the beach. Bony bonafide bones. These skeletal building blocks inspire curiosity and spark fear in different folks—we hope our stories, covering everything from surgeries and supplements to good old-fashioned boning, will only do the first. Once you’ve thoroughly blasted your mind with bone facts, check out our previous themed months: muscle and fat.

Humans may have perfected sex (or at least made the most earnest efforts to try), but we definitely didn’t invent it. So who did? Sexual reproduction is around 2 billion years old, but the way bacteria swap genes isn’t really what we mean when we talk about the birds and the bees, and ancient red algae that relied on ocean currents to sweep their sperm cells to receptive partners doesn’t sound much sexier. (David Attenborough makes a valiant attempt, however.)

The earliest evidence of organisms doing it like they do on the Discovery Channel comes in the form of fossils from some 385 million years ago. Delightfully and totally coincidentally named Microbrachius dicki, these antiarch placoderms—a long-extinct group of armored fish—swam around what are now Scotland and Estonia. This particular species was discovered by geologist Robert Dick in the 19th century, and the genus is so named for the “little arms” of bone found poking from their bodies. But Dick might have been slightly scandalized by the placoderm’s modern claim to fame: In 2014, researchers reported in the journal Nature that specimens of M. dicki showed clear and distinct male and female sex organs.

The male skeletons show protruding, L-shaped tubes of bone similar to cartilaginous “claspers” that modern sharks and rays use to deliver sperm. The female skeletons, conversely, feature pairs of genital plates for the proto-penises to lock into. But with seemingly no flexibility to these external sex organs, M. dicki wouldn’t have boned quite like we do (or even like sharks and rays do) today. Instead, they would have had to ease themselves into place so the fixed angles of their claspers and genital plates matched up.

“They did it sideways, square dance style,” Flinders University paleontologist John Long told National Geographic in 2014.

Talk about sexy dance moves. Here’s an artist’s interpretation of how it all could have gone down:

It wasn’t a straight evolutionary shot from square dancing bony fish to the wonderfully colorful spectrum of sexual activity animals enjoy today. The placoderm’s predilection for copulation was just a bit of brief sexual experimentation; fish would later lose the ability to fertilize eggs internally. Only a few regained the trait in a new fashion further down the evolutionary timeline, setting the stage for sex as we know it to emerge.

But before Tinder and Netflix and chill, there was the humble M. dicki getting it on in the only way it knew how: Awkwardly, and with a lot of bones.

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When you think of the Sahara, seafood probably isn’t the first thing that springs to mind. For thousands of years, this massive desert stretching across North Africa has been home to just the scant few animals adapted to life in hot, arid land.

But during the Holocene, the Sahara was lush—and full of fish.

A study published last week in PLOS One reports that out of 17,551 faunal remains found in the Takarkori rock shelter in the central Sahara, 80 percent were fish. That’s a pretty stark difference from the dry desert we think of today.

“Southwestern Libya is presently an inhospitable place—it is among the most arid locations in the Sahara—so it is really extraordinary,” says Kathleen Nicoll, a professor of geography at the University of Utah who was not involved in the study.

The fossil record also shows swimmers seeing a decline over the years as the area’s climate changed. Remains from the earliest dates are made up of around 90 percent fish species, but by around 5,000 years ago aquatic animals made up less than half of the population. By then, only small, hardy fish built to outlast shallow waters and high temperatures remained.

Savino di Lernia, an author of the study and the Director of the Archaeological Mission of the Sapienza University of Rome, has been working in Libya since 1990. He says that around 12,000 years ago, shifts in monsoon patterns brought rain to the region. With increased rain grew waterways that connected to Lake Chad in the south and the Nile River in the north, possibly opening up a passage for these fish to reach the central Sahara in such quantities.

Marks found on the fish remains show evidence of other residents: The humans who munched on them.

“I was personally surprised by the fact that fish were a type of staple food, even during neolithic, pastoral times,” di Lernia says. Eventually, many of those people would become sheep and goat herders.

Around 5,000 years ago, the climate changed dramatically. Due to changes in the atmosphere caused by Earth’s position while orbiting the sun, monsoon seasons changed rapidly, and the rain that kept the Sahara green virtually vanished, says study author Andrea Zerboni, a geoarchaeologist at the University of Milan.

“The whole region underwent a dramatic landscape change. Some areas abruptly shifted into a hyperarid desert,” he says.

Some scientists in the field, including di Lernia, think that people could have helped trigger this climate change by switching over from hunting and gathering to pastoral lifestyles. Zerboni and Nicoll published a paper in 2018 outlining the overlap of increased herding, soil erosion, and monsoon pattern change. Grazing caused soil erosion and mobilization of dust, which Zerboni says amplified the area’s aridification.

But not everyone is sold on the idea that humans helped dry up the desert. In fact, another 2018 paper argued that the shift toward pastoralism might have kept the area green for longer than it otherwise would have stayed.

For Nick Drake, a professor of physical geography at King’s College London who was not involved in the new study, the story of the drying Sahara is one of resilience—something we can learn from as we face the mounting pressure of human-caused climate change.

Drake says the people of Germa in Libya looked to technological fixes from all over the world, tinkering with Persian irrigation systems and trying out both Roman horses and Arabian camels as transportation options. That ingenuity allowed them to persevere and even flourish during the massive climate switch—adapting and surviving for thousands of years before being swept up in other empires. The fish and fauna of a wetter period may have been gone, but their society continued.

Innovation is key to keeping our societies alive in the face of a changing climate, Drake says. With developments like renewable energy technologies, he remains hopeful that we can take a page out of Germa’s book.

“The chances are, we’re going to innovate,” he says, “and you can see that happening now around the world.”

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