Tag Archives: fish

LED-equipped fishing nets help protect wildlife from unintentional captures

Green light-emitting diode (LED) lights can help protect wildlife from fishing nets, new research reports.

Image credits Paul Lee.

Affixing green LED lights to fishing nets can significantly reduce the catch of nontargeted animals such as sharks, squids, or turtles, according to a team led by researchers from the Arizona State University. The addition of these lights doesn’t impact the quantity or quality of desired catch species (i.e. commercially-available fish), which helps raise confidence that fisheries will adopt the measure. That being said, the installation of these lights comes with a significant upfront cost per net, which many fisheries may not be able to afford.

Beyond practical concerns, however, the findings showcase that it is possible to maintain our current fishing efficiency while insulating species that aren’t desired from capture.

Lights in the deep

Coastal fisheries routinely use gillnets, devices that resemble chain-link fences, to capture fish. These nets are deployed for up to several days at a time and capture virtually every kind of marine wildlife that cannot fit through their holes. Undesired captures (“bycatch”) are tossed overboard once the nets are recovered. These animals experience very high rates of death following this, adding up to significant pressure on marine species such as dolphins and sea turtles. It also impacts the fisheries’ bottom line, as personnel waste time removing these animals from the nets.

In other words, both business and nature lose out from the use of gillnets.

John Wang, a marine ecologist at the National Oceanic and Atmospheric Administration (NOAA), and his colleagues previously designed illuminated nets in order to protect turtles from becoming bycatch, back in 2016. Turtles seem to be particularly good at noticing green light, and these nets cut down on turtle bycatch by 64%. The current study builds on those findings, examining whether other marine animals could benefit from the same idea.

It turns out, they would. The authors worked with small-scale grouper and halibut fisheries in Baja California, Mexico, as the area is known for its large populations of turtles and other large marine species. They deployed 28 pairs of nets, one of each being equipped with groups of green LED lights every 10 meters. The team gauged their efficiency by identifying and weighing the animals each net captured overnight.

Nets outfitted with lights captured 63% less bycatch overall. Per species, they reduced bycatch by 51% for turtles, 81% for squid, and 95% for elasmobranchs (sharks and rays) — the last one being the most “gratifying” result for the authors, as shark bycatch in the Gulf of California is “a huge issue”.

Fish capture was not affected by the lights. However, the LEDs cut down on time wasted by fishermen on hauling and unloading bycatch, and on untangling the nets, by half. The only drawback so far, according to Senko, is the upfront installation costs of the lights: around $140 per net. Some fisheries, especially those in poorer areas such as Indonesia and the Caribbean, simply can’t afford this price per net, they add. The team is toying with using fewer lights and having them be solar-powered rather than battery-powered to reduce some of these costs. Meeting the needs of fisheries is essential for the success of this project, as they are the ones who will decide on using the LED nets or not.

Exactly why some animals seem to avoid lights, and why they do so more than others, is still up for debate. While it is possible that some species’ better eyesight helps them perceive the lights more clearly, it’s very unlikely that this is the cause — any species with sight can see these lights, after all.

The paper “Net illumination reduces fisheries bycatch, maintains catch value, and increases operational efficiency” has been published in the journal Current Biology.

Major aquarium vendor to stop selling fish bowls — they drive fish mad

A major French aquarium vendor has announced it will stop selling the “classic” round fish bowls because they are cruel, driving fish mad and killing them quickly.

The history of keeping fish (either for food or as pets) goes back thousands of years. Oftentimes, fish are kept in tanks or ponds, but at some point, the fish bowl became pretty popular, at least for some species of fish. It’s not clear when the fish bowl was invented, but according to legend, it was first created by Madame du Barry, mistress to King Louis XV in the 18th century. Whether or not this is true, fish bowls became widespread over the next couple of centuries, especially for Betta fish (Betta splendens) or goldfish (Carassius auratus).

Proponents of these fish bowls claim that since these fish cover relatively small habitats, a fish bowl should do for them. But the evidence suggests otherwise.

It’s not just that there’s not enough space for the fish (though that should be enough reason). The shape of fish bowls also creates a poor surface-to-air ratio, and the bowl doesn’t have room for a filter. It also distorts the animal’s field of view and is easy to jump from.

“People buy a goldfish for their kids on impulse, but if they knew what a torture it is, they would not do it. Turning round and round in a small bowl drives fish crazy and kills them quickly,” AgroBiothers CEO Matthieu Lambeaux told Reuters. The company, one of the leading aquarium vendors, announced it will no longer be selling any fish bowls.

In healthy conditions, goldfish can easily live up to 30 years or even more, but in fish bowls, they rarely make it past one year. Germany and a few other countries have banned fish bowls, but most countries (including France and the US) have no legislation on this. Lambeaux said the company worked to educate clients, but at this point, they simply refuse to offer any more fish bowls — although demand does exist. In previous years, the company would sell around 50,000 fish bowls a year.

“It is a French anachronism, that is why we decided to move. We cannot educate all our customers to explain that keeping fish in a bowl is cruel. We consider that it is our responsibility to no longer give consumers that choice,” Lambeaux said. He added that fish need ample space and clean water, that small bowls are driving fish crazy, and anyone considering an aquarium should have at least a minimum of equipment and expertise.

The problem of fish bowls is something people have been aware of for a long time. In a 1902 edition of the Freshwater Aquaria magazine, a commentary noted that “the common glass globe… has nothing whatever to recommend it, except perhaps to those who delight to have their unfortunate captives suspended by a chain from the ceiling in front of the window.” In 1910, botanist Hugo Mulertt noted that “the old-fashioned fish globe is about the worst vessel that can be selected for the keeping of goldfish as pets.” Over a century later, the old-fashioned fish globe still endures.

The welfare of ornamental fish is often overlooked, even though the trade of ornamental fish trade is now a multibillion-dollar industry, with legal trade estimated to be worth between 15 and 20 billion dollarsper year (and a burgeoning illegal industry as well).

Fish have highly underrated cognitive abilities, but as awareness and understanding of fish improves, the case for better welfare for them becomes stronger and stronger, and a movement in this sense seems to be gaining momentum.

The fact that companies are also starting to acknowledge this is encouraging, but overall, this is still just a small step.

Extinct species of fish reintroduced into its native habitat in Mexico

A little river in Mexico is the site of one of 2021’s most heartwarming tales — the reintroduction of a species that had gone extinct in the wild.

Tequila splitfin (Zoogoneticus tequila). Image via Wikimedia.

We often hear stories about animals going extinct, and they’re always heartbreaking. But, every so often, we get to hear of the reverse: a species that had gone extinct, being reintroduced into the wild. The waters of the Teuchitlán, a river in Mexico that flows near a town bearing the same name, can now boast the same tale.

Efforts by local researchers, conservationists, and citizens, with international support, have successfully reintroduced the tequila splitfin (Zoogoneticus tequila), a tiny fish that only lived in the Teuchitlán river but had gone extinct during the 1990s, to the wild.


In the 1990s, populations of the tequila splitfin began to dwindle in the Teuchitlán river. Eventually, it vanished completely.

Omar Domínguez, one of the researchers behind the program that reintroduced the species, and a co-authored of the paper describing the process, was a university student at the time and worried about the fish’s future. Pollution, human activity, and invasive, non-native species were placing great pressure on the tequila splitfin.

Now a 47-year-old researcher at the University of Michoacán, he recounts that then only the elderly in Teuchitlán remembered the fish — which they called gallito (“little rooster”) because of its brightly-colored, orange tail.

Conservation efforts started in 1998 when a team from the Chester Zoo in England, alongside members from other European institutions, arrived with several pairs of tequila splitfin from the aquariums of collectors and set up a lab to help preserve the species.

The first few years were spent reproducing the fish in aquariums. Reintroducing these to the river directly was deemed to be too risky. So Domínguez and his colleagues built an artificial pond on-site, in which the fish could breed in semi-captivity. The then-40 pairs of tequila splitfins were placed in this pond in 2012, and by 2014 they had multiplied to around 10,000 individuals.

By now, their results gave all the organizations involved in the effort (various zoos and wildlife conservation groups from Europe, the United States, and the United Arab Emirates) enough confidence to fund further experimentation. So the team set their sights on the river itself. Here, they studied the species’ interactions with local predators, parasites, microorganisms, and how they fit into the wider ecosystem of the area.

Then, they placed some of the tequila splitfins back into the river — inside floating cages. This step, too, was a marked success, and the fish multiplied quickly inside the cages. When their numbers grew large enough, around late 2017, the researchers marked the individual fish and set them free. In the next six months, their population increased by 55%, the authors report. The fish are still going strong, they add: in December 2021, they were seen inhabiting a new area of the river, where they were completely extinct in the past.

It’s not just about giving a species a new lease on life, the team explains. Their larger goal was to restore the natural equilibrium of the river’s ecosystem. Although there is no hard data on environmental factors in the past to compare with, Domínguez is confident that the river’s overall health has improved. Its waters are cleaner, the number of invasive species has declined, and cattle are no longer allowed to drink directly from the river in some areas.

Local communities were instrumental in the conservation effort.

“When I started the environmental education program I thought they were going to turn a deaf ear to us — and at first that happened,” Domínguez said.

However, the conservationists made sustained efforts to educate the locals through puppet shows, games, and educational materials, and presentations about zoogoneticus tequila. Among others, citizens were told about the ecological role of the species, and the part it plays in controlling dengue-spreading mosquitoes.

The tequila splitfin is currently listed as endangered on the IUCN’s red list.

The paper “Progress in the reintroduction program of the tequila splitfin in the springs of Teuchitlán, Jalisco, Mexico” has been published online by the IUCN CTSG (Conservation Translocation Specialist Group). An update on the project has been published in the magazine Amazonas.

Some fish start Mexican waves to keep themselves safe from predators

New research reports that at least one species of fish engages in similar behavior to sports fans — collective waves.

Kingfisher bird with Sulphur molly. Image credits Juliane Lukas.

It’s not uncommon to see collective — also known as ‘Mexican’ — waves on arenas hosting football (soccer) matches around the world. These involve large groups of fans successively standing up in unison, as a display of solidarity between them and for their favorite teams.

Sulphur mollies (Poecilia sulphuraria), however, do it for a completely different purpose. A new paper describes this incredible collective behavior in the wild fish species, detailing how hundreds of thousands of individuals coordinate, likely to protect themselves from predatory birds.

Stronger together

“At first we didn’t quite understand what the fish were actually doing,” said David Bierbach, co-first author of the study. “Once we realized that these are waves, we were wondering what their function might be.”

The study showcases just how many of the fish partake in such behavior — there can be up to 4000 fish per square meter of ‘wave’, and each can include hundreds of thousands of individuals, according to the team.

Sulphur mollies are small animals, who stand out due to their preferred environment: sulphuric springs whose chemical make-ups make them toxic to most other species of fish.

The team explains that they likely use this living wave behavior as a way to confuse or maybe deter predators, especially birds. Mollies engage in this behavior when a person’s shadow falls on the water as well, further reinforcing this hypothesis. Individual waves last three to five seconds each, but the mollies have been recorded as repeating the behavior for up to two minutes.

The team first had to rule out the possibility that this behavior was random — their experiments showed that the fish would engage in ‘waves’ in a conspicuous, repetitive, and rhythmic fashion in response to stimuli associated with the presence of predators.

Then, they examined whether this behavior had any effect on the predators themselves: it does. The team reports that experimentally-induced fish waves dramatically reduced the frequency of attacks from birds of prey, and doubled the time these birds took between attacks. For one of their predator species (kiskadees, Pitangus sulphuratus), wave patterns also decreased capture probability.

Birds exposed to these wave patterns would switch perches more often than control individuals, suggesting that they may prefer to focus their attention on other prey when confronted with the mollies’ wave behavior.

According to the team, this is the first time a collective behavior has been shown to be directly responsible for reducing a species’ chances of being attacked and preyed upon. It is an important discovery for the study of collective behavior in animals more broadly, they add.

“So far scientists have primarily explained how collective patterns arise from the interactions of individuals but it was unclear why animals produce these patterns in the first place,” says co-author Jens Krause. “Our study shows that some collective behavior patterns can be very effective in providing anti-predator protection.”

Something that the team can’t yet explain is why such behavior helps protect the mollies from attacks. It’s possible that the motions confuse the birds, or perhaps they work as a signal to the bird that they have been spotted, making it consider another target altogether. The team plans to explore these questions in the future.

The paper “Fish waves as emergent collective antipredator behavior” has been published in the journal Current Biology.

Fish like to rub on sharks, strangely enough, and use them as exfoliating soaps

In a somewhat surprising twist, new research finds that fish actually seek out sharks and… rub against them.

Shark. Original public domain image from Wikimedia Commons

What’s the most dangerous animal you’ve ever patted? For most of us, it’s probably a particularly feisty dog. Fish throughout the seven seas, however, put us to shame, it would seem. According to a collaborative research effort led by the University of Miami (UM) Shark Research and Conservation Program at the Rosenstiel School of Marine and Atmospheric Science, fish seek out sharks and chafe against them.

Such behavior is frequent and widespread, the team explains, which suggests that shark chafing could play an important ecological role for sea dwellers.

Dancing with the devil

“While chafing has been well documented between fish and inanimate objects, such as sand or rocky substrate, this shark-chafing phenomenon appears to be the only scenario in nature where prey actively seek out and rub up against a predator,” said UM Rosenstiel School graduate student Lacey Williams, who co-led the study with fellow graduate student Alexandra Anstett.

It’s not the first time we’ve seen fish engage in such behavior, but the study is our first reliable source of data on just how widespread and pervasive this behavior actually is.

The team pooled together underwater photos, videos, and drone footage for the research. In this body of data, they found 47 instances of fish engaging in chafing behavior with sharks. These chafing events took place in 13 different locations around the world and lasted anywhere from eight seconds to five minutes. Multiple species were involved, both in regards to fish and to the sharks being chafed-upon. Twelve different species of finfish were seen chafing against eight species of shark, including the infamous great white sharks. At least one interaction involved silky sharks (Carcharhinus falciformis) chafing on the head of another shark — a whale shark, in this particular case. The single largest group of fish that the team recorded during a single chafing event numbered in excess of 100 individuals.

Another dataset — aerial drone surveys of Plettenberg Bay, South Africa — revealed a further 25 cases of shark-chafing, involving leerfish (garrick, Lichia amia) and a passing white shark.

All of this is fine and well, but obviously leaves a big question unanswered: why would fish intentionally seek out and rub against their predators?

“While we don’t exactly know why it’s happening, we have a few theories. Shark skin is covered in small tooth-like scales called dermal denticles, which provide a rough sandpaper surface for the chafing fish,” said UM Rosenstiel School research associate professor and study co-author Neil Hammerschlag. “We suspect that chafing against shark skin might play a vital role in the removal of parasites or other skin irritants, thus improving fish health and fitness.”

In other words, fish might use sharks for the same purpose we use fancy soaps: exfoliation. Rubbing against sharks likely helps fish remove bacteria and parasites from their skins. Sharkskin is covered in tooth-like scales known as denticles, V-shaped structures that reduce turbulence and drag, allowing them to swim faster and with less effort. Presumably, these same denticles make them very good exfoliators, as well.

The paper “Sharks as exfoliators: widespread chafing between marine organisms suggests an unexplored ecological role” has been published in the journal Ecology.

Climate change is choking the oxygen out of deep water, and it’s putting fish in a double bind

Being a fish was never easy, but a new paper reports that it’s been getting harder over the last 15 years or so. According to the findings, oxygen levels are dropping in the depths of the oceans, forcing fish to move ever closer to the surface.

Image via Pixabay.

New research from the University of California – Santa Barbara and the University of South Carolina is warning us that fish are slowly drowning. Changes in ecology, as well as the effects of climate change on seasonal patterns, water temperature, and its gradient over different depths, have been causing deeper layers of the ocean to lose their dissolved oxygen content. This, in turn, is forcing fish to either move closer to the surface, or asphyxiate.

It may seem like a trivial matter, but this shift is causing wide-scale changes in marine ecosystems and could have a very real impact on the health of the ocean as a whole. It also raises important questions for fishery management and conservation efforts, with the authors underscoring the importance of accounting for this shift with policy to avoid further damaging marine ecosystems.

Swimming out of breath

“This study finds that oxygen is declining at all the depths we surveyed: from 50 meters to 350 meters,” said lead author Erin Meyer-Gutbrod, assistant professor at the University of South Carolina, “and so fish seem to be moving up to shallower regions to get to an area where the oxygen is relatively higher.”

The findings are based on 15 years’ worth of recordings, surveys, and measurements. These included measurements of dissolved oxygen in samples of water taken at varying depths, of temperature, salinity, and surveys of the average depth at which certain fish species tend to congregate. A total of 60 different species of fish were encountered often enough during these 15 years to be statistically relevant and included in the study.

Data was collected on a yearly basis, every fall, from 1995 through to 2009. The team focused on three reef features between the Anacapa and Santa Cruz islands in Southern California. These were the Anacapa Passage area, with an average depth of 50m, a seamount known as the “Footprint”, at around 150m, and the “Piggy Bank”, with an average depth of around 300m. During the surveys, the team identified all fish species that came within two meters of the submarine or were visible and within two meters of the seafloor. They also estimated the length of each individual fish.

During this time, they saw depth changes in 23 species. Four of these shifted towards deeper waters, while the other 19 moved towards the surface in response to low oxygen conditions (as shown by analysis of water samples).

The team explains that surface waters tend to be better oxygenated (have higher levels of dissolved oxygen) due to surface motions such as waves continuously mixing gases into the top layer of bodies of water. Over time, as waters mix, this oxygen also finds its way lower along the column of water. However, the team explains that warming climates make for warmer surface waters, which increases the buoyancy of these layers compared to those deeper down, reducing their ability to mix. This process is known as ocean stratification.

In addition to this, warmer water has a lower ability to dissolve and hold oxygen compared to colder water, so there’s less of this gas being mixed into the ocean to begin with.

In the end, this means less oxygen makes it to the bottom layers of water. Although salinity and temperature gradients along the column of water also influence the extent of vertical mixing, the team reports that both remained relatively constant over the study period. In other words, the trend towards lower oxygen levels seen at the study site is primarily driven by climate-associated changes in surface water temperatures. That being said, the other factors can’t be discounted completely either.

“A third of [the 60 fish species’] distributions moved shallower over time,” Meyer-Gutbrod said. “I personally think that’s a remarkable result over such a short time period.”

The team acknowledges that their study only included a relatively small area, but it did include a wide range of depths, which was the ultimate objective of the research. This narrower area actually helps reduce confounding factors, they explain, since it allowed for most conditions (apart from depth) to be constant across all the survey areas.

“Other scientists have used lab experiments to show that fish don’t like low oxygen water,” Meyer-Gutbrod said, “but what nobody’s ever done is just return to the same location year after year to see if there’s actually a change in the distribution of fish stemming from a change in oxygen over time.”

In closing, the authors explain that this trend can have quite severe negative impacts on marine ecosystems, and indirectly, on all life on Earth. Fish are simply forced to move away from their optimal depths, which will eventually result in them being pushed out entirely out of several ecosystems. According to co-author Milton Love, a researcher at UC Santa Barbara’s Marine Science Institute, we could even see a point in which species are forced into depth ranges that they simply cannot survive in.

They also cite previous research showing that many fish species also cannot tolerate high water temperatures, and are migrating towards lower depths. In the end, these factors can leave many species in an impossible situation — where they cannot breathe if too low, and can’t bear the heat if too close to the surface.

In the end, even if we start working to redress climate change right now, meaningful progress will take quite a lot of time. Until then, policymakers need to recognize and react to the pressures faced by fish species and issue regulation that protects them as best as possible, or risk wide-ranging ecological collapse in the world’s oceans.

“If you throw your net in the water and you get a ton of fish — more than you’re used to getting — you may think, ‘Oh, it’s a good year for the fish. Maybe the population is recovering,'” Meyer-Gutbrod said. “But instead, it could be that all the fish are just squished into a tighter area. So you could have fishery regulations changing to increase fish allowances because of this increase in landings.”

The paper “Moving on up: Vertical distribution shifts in rocky reef fish species during climate‐driven decline in dissolved oxygen from 1995 to 2009” has been published in the journal Global Change Biology.

Some fish are warm-blooded — and it lets them swim faster

Most fishes are ectothermic — or cold-blooded — which means they rely on environmental temperatures for thermoregulation. However, some have developed an evolutionary advantage to regulating their own body temperatures, such as sharks and tunas. This has intrigued scientists for decades, curious about the differences between different types of fish.

Now, a new study by marine biologists offers answers to this big puzzle.

A white shark (Carcharodon carcharias) swimming at the surface with a biologging package attached to dorsal fin. This package records temperature, swimming speed, depth, body movement and video footage.

Researchers from Trinity College found that while warm-blooded fish can swim faster, they don’t live in waters spanning a broader range of temperatures. This means they are just as vulnerable to changing global temperatures as their cold-blooded relatives. 

“Scientists have long known that not all fish are cold-blooded. Some have evolved the ability to warm parts of their bodies so that they can stay warmer than the water around them, but it has remained unclear what advantages this ability provided,” Lucy Harding, lead-author of the research article, said in a media statement. 

Endothermy (warm-bloodedness) is the ability to conserve metabolically derived heat through vascular countercurrent heat exchangers, and elevate the temperature of specific internal tissues, such as muscle and eyes. It’s a very rare ability, with only about 35 species of marine fishes (less than 0.1% of all known fish species) are known to exhibit it. 

Various hypotheses have been raised over the years to explain the ultimate driver of endothermy in fishes. These include that endothermy enables thermal niche expansion, facilitates elevated cruising speeds, allows for more effective perception of thermal gradients, increases metabolic rates and facilitates increased rates of gonadal growth. But this is maybe the first time convincing evidence has been found to support one of these hypotheses.

With a team of researchers, Harding decided to look further at whether warm-blooded fish can swim faster and live in a broader range of temperatures – making them more resilient to the effects of climate change. They collected real-world data from wild sharks and bony fish, as well as using information from existing databases. The researchers attached bio-logging devices to the finds of the animals they caught. This allowed them to gather information such as water temperatures encountered by the fish in their habitats; the speeds at which the fish swam for most of the day; and the depths of water the fish swam in. A total of 16 species were tagged, four endotherms and 12 ectotherms, and the data were compared between the different species. 

The results showed that warm-blooded fishes swim approximately 1.6 times faster than their cold-blooded relatives, but they didn’t live in broader temperature ranges. This suggests that they are as sensitive to ocean warming as all other fish in the sea, or perhaps even more so. The findings can now help future conservation efforts for these animals, co-author Nick Payne said in a statement. 

“The faster swimming speeds of the warm-blooded fishes likely gives them competitive advantages when it comes to things like predation and migration. With predation in mind, the hunting abilities of the white shark and bluefin tuna help paint a picture of why this ability might offer a competitive advantage,” Payne said. 

Climate change has been steadily warming the ocean, which absorbs most of the heat trapped by greenhouse gases in the atmosphere, for over 100 years. This warming is altering marine ecosystems and having a direct impact on fish populations. Many fish are sensitive to temperature and can survive only in specific temperature ranges, which puts them at great risk as oceans become hotter and hotter.

The study was published in the journal Functional Ecology. 

Fossil Friday: private collector wanted a dinosaur skull, but got a huge, fossilized bony fish lung

Researchers at the University of Portsmouth have run into the fossilized remains of an ancient bony fish — the coelacanth — out of sheer luck. Or bad luck, depending on who you’re asking.

The original slab as purchased. The coelacanth ossified lung in close proximity to a series of associated, but disarticulated wing elements of a large, but indeterminate pterosaur. Image credits University of Portsmouth.

In a break from our traditional story path for Fossil Friday, there won’t be much talk about anything being ‘unearthed’ today. That’s because the fossil in question is part of a private collection from a London aficionado. It was identified as having belonged to a species of coelacanth by Professor David Martill, a paleontologist from the University’s School of the Environment, Geography and Geosciences, after he was asked to take a look at the specimen and determine its origin.

Although the discovery is quite exciting from an academic point of view, the collector was (reportedly) less than thrilled: they wanted a pterosaur skull, but got a bony fish.

Old fish

“The collector was mightily disappointed he didn’t have a pterosaur skull, but my colleagues and I were thrilled as no coelacanth has ever been found in the phosphate deposits of Morocco, and this example was absolutely massive!” explains Professor Martill.

“The thin bony plates were arranged like a barrel, but with the staves going round instead of from top to bottom. Only one animal has such a structure and that is the coelacanth — we’d found a bony lung of this remarkable and bizarre-looking fish.”

The fossil corresponds to a fish that’s similar in size to a great white shark of today and is the largest fossil of its kind to ever be discovered by accident. Although they’ve been swimming around since the dinosaurs were still roaming the Earth, coelacanths are still alive to this day, although they are quite rare and rarely seen. They’re also quite endangered.

The collector bought this fossil thinking it could have been part of a pterodactyls’ skull. Professor Martill instead found that the specimen was composed of numerous, thin bone plates, not a single piece, as you’d see in a skull. Prof. Martill worked together with Dr. Paulo Brito of the State University of Rio de Janeiro, a leading Brazilian paleontologist, to study the fossil. Brito, an expert on coelacanths and their lungs, admitted to being ‘astonished’ at how large this specimen was.

It has been embedded in a block of phosphate with a plaster backing, and everything was then coated in lacquer — this, the two explain, caused the fossils to take a brown hue. It was found next to a pterodactyl specimen (which is probably why the collector thought it was part of that animal). Although they turned out to be completely different species, this does help give us a rough estimate of when the fish lived: around 66 million years ago, in the Cretaceous era.

The lung specimen and its likely position in a mawsoniid coelacanth.
Image credits University of Portsmouth.

Following an initial investigation of the specimen, its owner offered to give the researchers the remains of the bony lung off the slab, which they accepted. Later, they removed the lacquer using specialized equipment (mostly dental tools and fine brushes) to enable more thorough research on the fossils.

The very large size of the lung belonging to this animal suggests that it was a very, very big individual during its day — around five meters in length, the team reports. This is much larger than the coelacanths of today, which grow to around two meters in length, at most.

“We only had a single, albeit massive lung so our conclusions required some quite complex calculations,” Professor Martill explains. “It was astonishing to deduce that this particular fish was enormous — quite a bit longer than the length of a stand-up paddleboard and likely the largest coelacanth ever discovered.” 

The fossil will be given back to the Moroccan government, the owner explains, and will most likely be added to the collections in the Department of Geology at Hassan II University of Casablanca.

The paper “A marine Late Cretaceous (Maastrichtian) coelacanth from North Africa” has been published in the journal Cretaceous Research.

Fish have been eating plastic since the 1950s. And it’s getting worse

Every day, fish around the world’s ocean eat microplastics — small, barely visible pieces of plastic that are formed when larger plastic objects like food containers break down into smaller bits. This has been going on for a while, but researchers weren’t exactly sure how long.

Now, researchers at the Loyola University Chicago looked at the guts of freshwater fish preserved in museum collections. They found that fish have been eating microplastics since the 1950s and that the concentration in their guts has only increased over time. 

Image credit: Flickr / Peter Corbett

“For the last 10 or 15 years it’s kind of been in the public consciousness that there’s a problem with plastic in the water. But really, organisms have probably been exposed to plastic litter since plastic was invented, and we don’t know what that historical context looks like,” Tim Hoellein, co-author of the study, said in a statement.

Previous studies have shown that eating microplastics can cause aneurysms and reproductive changes in fish, as well as affect the cognitive performance of hermit crabs and weaken the physical performance of mussels. There’s also evidence of microplastics travelling up the food chain and having potential effects on humans. We’re not sure just how bad microplastics are, but they’re almost certainly not good for you.

Hoellein and his team wanted to understand how microplastics have built up in the ocean over the past century and what that meant for the fish of the past. They realized the best place to go was Chicago’s Field Museum, where around two million fish specimens are preserved in alcohol and stored in an underground collection.

They focused on four species in particular: largemouth bass (Micropterus salmoides​), channel catfish (Ictalurus punctatus), sand shiners (Notropis stramineus), and round gobies (Neogobius melanostomus). The four of them have records dating from 2017 back to 1900. The researchers also collected fresh samples of the species for the study.

“We would take these jars full of fish and find specimens that were sort of average, not the biggest or the smallest, and then we used scalpels and tweezers to dissect out the digestive tracts,” Loren Hou, the paper’s lead author, said in a statement. “We tried to get at least five specimens per decade.”

To actually find the plastic in the fishes’ guts, the researchers treated the digestive tracts with hydrogen peroxide – a substance that breaks down the organic matter but leaves plastics intact. Then they also used microscopes to identify the materials with suspiciously smooth edges that might be indicative of microplastics. 

The findings showed that the amount of microplastics in the fishes’ guts increased significantly over time as more plastic was manufactured and built up in the ecosystem. There were no plastic particles before mid-century. But when plastic manufacturing was industrialized in the 1950s, the concentrations skyrocketed. 

While the researchers didn’t look at how eating these microplastics affected the fish, they wanted over digestive tract changes and increased stress — as seen in previous studies. They hope their findings will serve as a wakeup call to change our relationship with plastic and argued the purpose of their work is to contribute to solutions. 

“Microplastics can come from larger objects being fragmented, but they’re often from clothing. Whenever you wash a pair of leggings or a polyester shirt, tiny little threads break off and get flushed into the water supply. It’s plastic on your back, and that’s just not the way that we’ve been thinking about it,” said Hoellein in a statement. 

The study was published in the journal Ecological Applications.


This fish will give you dental nightmares — meet the sheepshead fish


Lovely set of dentures right there. Could use some brushing, though. Credit: VA Institute of Marine Science (VIMS).

We’re used to seeing all kinds of wacky and crazy-looking animals in the wild. The sheepshead fish is no exception, boasting some incredible dentures that bear an uncanny resemblance to those of humans — incisors and molars included.

This isn’t Photoshopped

Common to North American coastal waters, from Cape Cod, Massachusetts to the Gulf of Mexico, the sheepshead (Archosargus probatocephalus) can be seen around rock pilings, jetties, mangroves, reefs, and piers. Most of all, they thrive in brackish waters.

It can grow up to around 91 cm (35 inches) in length and weigh up to 9.6 kg (21 lbs).

Bunch of sheepshead convicts. Credit: MENTALBLOCK_DMD; FLICKR

Bunch of sheepshead convicts. Credit: MENTALBLOCK_DMD; FLICKR

It’s sometimes referred to as the “convict fish” due to the black vertical stripes over its body — a nickname which the sheepshead apparently takes very seriously since it’s often seen stealing bait.

A baby sheaphead fish showing off his still growing teeth. (c) Texas Parks and Wildlife Department

A baby sheepshead fish showing off its still growing teeth. Credit: Texas Parks and Wildlife Department

The sheepshead, as you’ve most likely noticed, has sharp incisors sitting at the front of the jaw, and molars set in three rows in the upper jaw and two rows in the lower jaw.

Like humans, it makes proper use of these dentures to suit its omnivorous diet consisting of small vertebrate and invertebrate animals, as well as plants.

Its hard and sturdy molars are used to crush the shell of its prey and actually become stronger depending on its environment. If a sheepshead fish lives in a shell-rich environment it will grow larger and stronger teeth than another sheepshead fish.

“There was a significant correlation between increased force production and increased durophagous [shell-crushing] habit. Studies such as this one speak directly to the relationship between maximum functional potential and actual patterns of resource use,” notes L. P. Hernandez from the Museum of Comparative Zoology at Harvard University and P. J. Motta from the Department of Biology at the University of South Florida in a 1997 issue of the Journal of Zoology

It has a psychedelic cousin

The sheepshead is part of an entire family of wacky fish. The Sparidae family includes species that engage in various forms of hermaphroditism, either from male to female, the reverse or unisex. However, the sheepshead is very confident of its sexuality from birth and doesn’t change its sex.

The Salema porgy (Sarpa salpa), another Sparidae fish, has been known for its psychedelic properties for millennia. Some aristocrats from the Roman Empire would sometimes use this fish to get high. The Romans had a rather peculiar sense of partying, however, since the Salema porgy gives you one hell of a trip –  hallucinations and terrifying nightmares that can last for several days.

The sheepshead fish, however, is perfectly edible and a quick google search reveals hundreds of recipes. In fact, the sheepshead is highly sought after by restaurants, thanks to its fine white flesh and mild palatable taste

Fish motions could help us identify their personalities

New research says that you can, in fact, judge a fish by their cover. Or at least by the way they swim.

The three-spined stickleback (Gasterosteus aculeatus). Image credits Gilles San Martin.

A research team with members from Swansea University and the University of Essex reports that the subtle differences in how each fish moves around can be used to determine its overall personality. We still don’t know if the findings translate to humans, or if such an approach can be reliable over the long term, but it’s an interesting place to start from.

A bat of the fins

“These micropersonalities [motions] in fish are like signatures — different and unique to an individual,” explains Dr Ines Fürtbauer, a co-author of the study from Swansea University. “We found the fish’s signatures were the same when we made simple changes to the fish tanks, such as adding additional plants.”

We know that the animal kingdom is quite rich with personality types, in species ranging from ants to apes. Quite like you’d see in humans, animals can be shy, energic, bold, or sedentary. The current paper shows that the same is true with fish.

However, something new that the researchers have found is that we can look at the tiny idiosyncrasies of how fish swim around to learn more about their personality. They recorded 15 three-spined stickleback fish as they went about their day in a tank with two, three, or five plastic plants, in fixed positions. Later, high-resolution tracking was used to chart their movements. The team used this to measure different parameters for every individual including how often they turned and how often they stopped and started moving.

Each fish had distinct and very repeatable movement patterns, so much so that the team could reliably identify the animals based on how they moved. The authors also note that there is a correlation between behavior and movement patterns. Fish which spent more time moving, took more direct approaches, and didn’t “burst travel” very often tended to travel and explore more of the tank, and were also more likely to spend time in open water.

“Our work suggests that simple movement parameters can be viewed as micropersonality traits that give rise to extensive consistent individual differences in behaviors,” says Dr Andrew King from Swansea University, lead author.

“This is significant because it suggests we might be able to quantify personality differences in wild animals as long as we can get fine-scale information on how they are moving; and these types of data are becoming more common with advances in animal tracking technologies.”

It’s not to say that these patterns remain constant, however. The team used a static layout in the experimental tank, and only observed the fish for a short time. We also don’t know if changes in the environment would change their movement patterns or behavior. As such, the next step should be to observe animals’ motion “over longer periods and in the wild will give us this sort of insight and help us better understand not only personality but also how flexible an animal’s behavior is.”

However, it is possible these signatures change gradually over an animal’s lifetime, or abruptly if an animal encounters something new or unexpected in its environment. Tracking animals’ motion over longer periods — in the lab and in the wild — will give us this sort of insight and help us better understand not only personality but also how flexible an animal’s behavior is,” says Dr Ines Fürtbauer, a co-author of the study from Swansea University.

The paper ““Micropersonality” traits and their implications for behavioral and movement ecology research” has been published in the journal Ecology and Evolution.

Living fossil fish has 62 copies of a “parasite gene” humans share too — we have no idea how they got there

The capture of a ‘living fossil’ fish off the coast of South Africa in the 1930s is now helping us understand one of the more exotic ways evolution can happen — interspecies genetic hijacking.

A model of Latimeria chalumnae, one of two known species of coelacanths. Image via Wikipedia.

Coelacanths are one of the oldest lineages of fish in existence today. They’re so old, in fact, that they’re more closely related to the ancestors of reptiles and amphibians than modern-day fish. We first encountered them as fossils from the Late Cretaceous (some 66 million years old), and naturally assumed they must’ve died off by now. However, the capture of a live African Coelacanth (Latimeria chalumnae) fish in 1938 showed that it was actually still living in the deep oceans, and had hardly changed compared to its fossilized relatives.

But we should never judge a fish by its scales, as new research explains that the species did in fact gain 62 new genes around 10 million years ago. The most interesting part is how — these didn’t appear spontaneously in their genomes but are ‘parasitic’ DNA gained through encounters with other species.

Genetic stowaways

“Our findings provide a rather striking example of this phenomenon of transposons contributing to the host genome,” says Tim Hughes, senior study author and a professor of molecular genetics in the Donnelly Centre for Cellular and Biomolecular Research at the University of Toronto.

“We don’t know what these 62 genes are doing, but many of them encode DNA binding proteins and probably have a role in gene regulation, where even subtle changes are important in evolution.”

Coelacanths have earned the moniker of “living fossils” because they share so much of their anatomy with the fossilized specimens — in fact, they’re pretty much identical from a physical point of view. But the current findings showcase how gene transfer between species (through elements known as transposons or “jumping genes”) can shape evolution and, perhaps, even alter the genetic trajectory of entire species or lineages.

Transposons are genes that use a self-encoded enzyme to recognize themselves. This enzyme can then cut them out of the genetic strand and paste them in somewhere else. Sometimes, this process can interact with the cell division process and generate new copies of the transposon.

Still, nothing lasts forever, and eventually, the information describing the enzyme degrades. At this point, the transposon can no longer move throughout the code, but it’s still there and acts like any other gene. If it confers some kind of advantage to the host organism, it can be selected for over time through evolutionary processes and become part of their genetic lineage. Coelacanths aren’t by any means the only animals we’ve seen such ‘parasite’ genes in, but they do have a very high number of such genes.

“It was surprising to see coelacanths pop out among vertebrates as having a really large number of these transposon-derived genes because they have an undeserved reputation of being a living fossil,” says graduate student Isaac Yellan who spearheaded the study.

“The Coelacanth may have evolved a bit more slowly but it is certainly not a fossil.”

The team was actually studying counterparts of a human gene, CGGBP1, in other species. We knew that this was a legacy of a particular transposon in the common ancestor of mammals, birds, and reptiles. During their work, the team found CGGBP-like genes in some but not all fish species they studied, and one type of fungus. Worms, molluscs, and most insects had none. But the Coelacanth (whose genome was sequenced in 2013) had 62.

As a common ancestry was out of the question, the team concluded that these transposons entered various lineages at various times in history through horizontal gene transfer. We don’t exactly know where they came from, but one known documented source of such transfers are parasites. This would also explain why the gene was introduced in the fish’s genome several times.

We still don’t know what these genes do. Lab experiments showed that the protein they encode binds to unique sequences of DNA, so they could be involved in gene regulation, like their human counterpart. Their origin however is still a mystery.

Given the extreme rarity of living specimens — the only other living species ever found, Latimeria menadoensis, was discovered in 1998 after being pulled by a fishing boat and winding its way into an Indonesian market. These two species split before the genes were introduced.

The paper “Diverse Eukaryotic CGG Binding Proteins Produced by Independent Domestications of hAT Transposons” has been published in the journal Molecular Biology and Evolution.

Algae-farming fish domesticate shrimp to improve their farms

Longfin damselfish. Credit: Griffith University.

Domestication changed human history forever. Judging from mitochondrial DNA, scientists believe that the dog was the first animal to be domesticated nearly 14,000 years ago from wolves. Later, came farm domestications, including animals such as sheep, goats, pigs, and cattle. But humans aren’t alone in this game.

According to a fascinating new study by Australian researchers, longfin damselfish (Stegastes diencaeus) have domesticated mysid shrimp (Mysidium integrum), whose feces is a good fertilizer for the algae that the fish farms.

“Domesticator-domesticate relationships are specialized mutualisms where one species provides multigenerational support to another in exchange for a resource or service, and through which both partners gain an advantage over individuals outside the relationship. While this ecological innovation has profoundly reshaped the world’s landscapes and biodiversity, the ecological circumstances that facilitate domestication remain uncertain,” the authors wrote in their study published in Nature Communications.

“Mysids passively excrete nutrients onto farms, which is associated with enriched algal composition, and damselfish that host mysids exhibit better body condition compared to those without,” they added.

When researchers at Griffith and Deakin Universities first observed this behavior during dives to coral reefs in Belize, they almost couldn’t believe it. It wasn’t some fluke or misunderstanding either, as subsequent lab tests confirmed that damselfish were indeed in a domesticator-domesticate relationship with the shrimp.

Mysid shrimps benefit from the protection provided by damselfish and, in turn, improve the condition of the farmer, the damselfish. Credit: Griffith University.

The researchers found that the mysids are attracted to the odor of the damselfish, but are repelled by the smell of predators. The mysids also don’t seem to be attracted to non-farming fish nor the algae itself.

When the shrimp were around, the quality of the algae and the health of the fish improved. In return for the shrimp’s fertilization of their farm, the fish actively protect the mysids. The researchers found that outside the algae farms, other fish tried to eat the shrimp, but inside the farm under the watchful eyes of the damselfish, predators didn’t come close.

“This is not unlike the series of theoretical steps underpinning the domestication of animals by our own ancestors via the commensal pathway, where animals who were attracted to human settlements were subsequently domesticated by ancient humans,”  Dr. William Feeney from Griffith University’s Environmental Futures Research Institute and co-author of the new study, said in a statement.

“It is generally food scraps or shelter that are thought to have attracted animals to humans.”

The domestication of other species was long considered to be uniquely human. While we know of ants that have domesticated fungi, finding examples of animal domestication by species other humans has proven elusive thus far. So, in many ways, seeing another species performing its own domestication may tell us much about how we first domesticated familiar species like cats, dogs, and chickens.

“This study highlights the important role that protection from predators also plays in domestication, with mysids shrimp quickly consumed by other predators when the damselfish farmer wasn’t present,” Feeney said.

“It reveals the fascinating insights into domestication by humans that can be gained by examining relationships between non-human organisms.”

Let more big fish sink — it can help tackle climate change

Leaving more big fish in the sea can reduce the amount of carbon dioxide (CO2) released into the Earth’s atmosphere, according to a new study. Researchers found that when a fish dies in the ocean it sinks and thus sequesters all the carbon it contains, making it a previously not considered opportunity to tackle climate change.

Credit Flickr Stephan Downes

More than 60% of the countries that signed the Paris Agreement on climate change committed to including nature-based solutions in their climate programs. These are actions that protect or restore ecosystems to counter the negative effects of shifts in climate. But so far, most of these solutions haven’t considered the ocean.

In particular, the potential role of marine vertebrates has received little attention, even though they can store carbon through several mechanisms. For example, fish modify nutrient limitation and promote the sequestration of carbon in vegetated coastal habitats, while coastal predators protect this blue carbon stock by limiting grazing.

The role of fish as direct carbon sinks via carcasses deadfall has only been speculated on. Yet, marine fisheries have depleted most fish stocks relative to preindustrial levels, thereby removing massive amounts of blue carbon from the ocean when fisheries catches were landed, processed, and consumed, therefore emitting atmospheric CO2.

A team from the University of Montpellier in France focused on the capacity of the fish to sequester carbon in the deep sea after their death. They hoped to estimate how catching large fish from the ocean may have affected this carbon sequestration potential.

They used global fish catches data since 1950 to estimate the spatial and temporal dynamics of the blue carbon extracted from the ocean and released into the atmosphere as a result of fishing. They also estimate the extent to which fishing remote unprofitable areas in the high seas contributes to CO2 emissions.

The study showed ocean fisheries have released at least 730 million metric tons of CO2 into the atmosphere since 1950. An estimated 20.4 metric tons of CO2 were released from fisheries in 2014, equivalent to the annual emissions of 4.5 million cars. The researchers found that the carbon footprint of fisheries is 25% higher than previous industry estimates.

“Fishing boats produce greenhouse gases by consuming fuel,” Professor David Mouillot from the James Cook University, co-author of the study, said in a statement. “And now we know that extracting fish releases additional CO2 that would otherwise remain captive in the ocean.”

Mouillot explained that when fish die, they sink fast and as a result, most of the carbon they contain is sequestered at the bottom of the sea for millions of years. They thus act as carbon sinks. It’s a natural phenomenon, which is now being disrupted by industrial fishing across the globe. Fishing gets subsidized by governments, which makes even remote fishing in the Central Pacific and the South Atlantic profitable (despite the high quantity of fuel needed to reach them).

For the authors, the data supports more reasoned fishing. They called for limiting or preventing blue carbon extraction at least on the unprofitable areas of the high seas while managing all fisheries to maintain long-term viability and productivity of fish stocks. This would reduce CO2 emissions from fuel and rebuild fish stocks.

“The annihilation of the blue carbon pump represented by large fish suggests new protection and management measures must be put in place, so that more large fish can remain a carbon sink and no longer become an additional CO2 source,” said Gaël Mariani, the study’s lead author. “And in doing so we further reduce CO2 emissions by burning less fuel.”

The study was published in the journal Science Advances.

Climate change is destabilizing marine food webs

Climate change could starve out the oceans, finds a new study from the University of Adelaide.

Image credits Susanne Pälmer.

Man-made climate change is a threat to all life on the planet whether it flies, walks, swims, or crawls. That being said, individual types of ecosystems will feel the heat at different times, and in different ways.

Sadly for us, marine ecosystems will be among the first. The oceans have always had a special connection to life — this is where it spawned. Even today, ocean ecosystems are the linchpin of life, supplying food, oxygen, and recycling essential nutrients for us landlubbers.

Marine ecosystems, the new paper reports, are in for a rough time. Increased average temperatures and higher CO2 atmospheric content threaten to push the food webs maintaining marine ecosystems beyond their breaking point.

Storms a-brewing

“Healthy food webs are critical for ecosystems so that the world’s oceans can continue to provide an important source of food for humans,” says lead author Professor Ivan Nagelkerken, from the University of Adelaide’s Environment Institute.

“Greenhouse gas emissions are affecting the health and persistence of many marine species because of increasing seawater temperatures and CO2 levels. Our research shows that ocean warming reshuffles species communities; the abundance of weedy plant species increases but the abundance of other species, especially invertebrates, collapses.”

The researchers modeled a coastal ecosystem consisting of three habitats that are predominant in the Gulf St. Vincent, Adelaide, where the South Australian Research and Development Institute (SARDI) maintains a site. They then observed how higher temperatures and ocean acidification would impact these areas.

All in all, the ‘trophic pyramid’, which is a schematic of who eats who in an ecosystem, would grow at the base and the top, but contract in its middle layers. This “unusual profile” most likely describes a “transitory state” before a collapse, Nagelkerken explains. After this collapse, marine food webs will be “shortened, bottom-heavy”, meaning they will house much fewer species, and most of them will be plants or plant-eaters. In marine food webs, fish are generally the top predators (and, as such, the highest on the pyramid).

Trophic pyramids show how energy and nutrients flow in an ecosystem; to be sustainable, they need to be triangular in shape, with many species at the bottom (thereby concentrating energy on this level). As each species feeds on the level below, this energy is moved up the pyramid. If the lower levels aren’t abundant enough, everything above them falls apart (goes extinct, or close to).

“Where food web architecture lacks adjustability, ecosystems lack the capacity to adapt to global change and ecosystem degradation is likely,” says collaborator and co-author Professor Sean Connell from the University of Adelaide’s Environment Institute.

“Marine food webs that are not able to adapt to global change show all the signs of being transformed into a food web dominated by weedy algae. Even though there were more plants at the bottom of the food web, this increased energy does not flow upwards towards the top of the food web.”

While things don’t look encouraging now, the team says that future emissions of carbon dioxide are only going to make the problem worse.

Unless some species quickly adapt to the new conditions, ocean ecosystems are likely to become much less abundant in the future. The species we most rely on economically and for food are exactly the ones that are at risk of collapse.

“An ecological tipping point may be passed beyond which the top of the food web can no longer be supported, with an ensuing collapse into shorter, bottom-heavy trophic pyramids,” says Professor Nagelkerken.

“This will weaken the health and sustainability of ocean ecosystems unless species are capable of genetic adaptation to climate stressors in the near future.”

The paper “Trophic pyramids reorganize when food web architecture fails to adjust to ocean change” has been published in the journal Science.

This parasite can eat the tongue of a fish and then take its place

Rice University biologist Kory Evans started his Monday like any other day, expecting it to be largely uneventful. He was wrong.

His day was about to change when he started scanning the head of a fish, which is not uncommon in his work. But what was uncommon what was inside the fish’s head. A crustacean had eaten and replaced the tongue of the fish.

Credit Kory Evans


The crustacean in case is an isopod, also known as tongue biter or tongue-eating louse, and it sucked the blood from the tongue of the fish, releasing an anticoagulant maintain the flow of blood even as there’s almost nothing left of the tongue. But that’s just the opening act — it gets much worse.

Then, the isopod takes the role of the tongue in the mouth of the fish.

The discovery was done by Evans, who works at the Department of BioSciences at Rice University in Houston, Texas, when digitizing the X-rays of the fish skeletons. He posted the images of the finding on Twitter, joking about the whole situation. “Mondays aren’t usually this eventful,” Evans joked in the tweet.

There are around 10,000 known species of isopods and a surprisingly large number of them have adapted to eat tongues: about 380 go after the tongues of specific fish. It’s not entirely surprising since isopods are one of the most morphologically diverse of all the crustacean groups, coming in many different shapes and sizes and ranging from micrometers to a half meter in length. About half of the known species of isopods live in the ocean.

Masquerading as a tongue

The specific type that Evans encountered enters the body of the fish through the gills, attaches to the tongue and starts to feed.It grabs the tongue with its seven pairs of legs and takes out the blood until the organ drops off.

But that’s just the start. Having already taken out the blood from the tongue, the parasite acts as a functional tongue for the fish, taking its place and feeding on its mucus. The link between the two can go on for years, with cases reported of fishes outliving their parasites, according to researcher Stefanie Kaiser. Not much is known about how these isopods reproduce, but the most common theory is something to behold. Researchers believe that juveniles that first attach to the gills of a fish become males. As they mature, they become females, likely mating on the gills of fish.

Speaking with Live Science, Evans said he made the discovery as part of his current research, which involves scanning a family of coral reef fishes called wrasses.

He aims at creating a 3D X-ray database of skeletal morphology of the fish group and then share it with researchers from around the world.

Credit Kory Evans

“I compare skull shapes of all these different fish to each other, that requires placing landmarks — digital markers — on different parts of the body,” Evans explained. He looked into the mouth cavity of one specific wrasse, a herring cale (Odax cyanomelas) from New Zealand, and found something strange.

“It looked like it had some kind of insect in its mouth. Then I thought, wait a minute; this fish is an herbivore, it eats seaweed. So I pulled up the original scan, and lo and behold, it was a tongue-eating louse,” he said, explaining that wrasses are actually a very strange fish with a second set of jaws on their throat.

It’s like being in the movie Alien, Evans said. Some wrasses known as parrotfish even have mouths so strong that they can bite through the coral. The slingjaw wrasse, for example, can launch its jaws forward up to 65% the length of its head in order to catch evasive pray.

Migratory freshwater fish declined 76% since 1970

The populations of migratory freshwater fish species have drastically declined by 76% on average since 1970, according to a new report. Most of this damage is linked to human-made impacts such as hydropower, overfishing, and pollution.

Europe was the most affected region, with a 93% plunge.

Credit Peter Harrison. Flickr (CC BY 2.0)

Issued by the World Fish Migration Foundation and Zoological Society of London, the Living Planet Index is the first major report to look to the status of freshwater migratory fish on a global scale. The researchers looked at data from 1,406 populations of 247 species, the largest data set to date, but with still significant gaps (especially for regions outside Europe and North America).

The results are concerning.

“Catastrophic losses in migratory fish populations show we cannot continue destroying our rivers. This will have immense consequences for people and nature across the globe. We can and need to act now before these keystone species are lost for good,” Arjan Berkhuysen, Managing Director of the World Fish Migration Foundation, said in a press release.

Latin America registered an 84% average fall, followed by a 59% plunge decrease in Asia-Oceania, the report showed. Data was too limited in Africa to establish a reliable trend. Meanwhile, North America registered a less dramatic drop of 28%. The reason why things are not as bad in North America is largely the removal of dams — most of the damage there was done before the 1970s, researchers note.

In addition to playing an important environmental role, species such as salmon, trout, and the Amazonian catfish are vital to the food security needs of the world. They support the livelihoods of millions of people around the world, the researchers explain, while also working to keep the rivers, lakes, and wetlands healthy by supporting a complex food web which again — millions of people rely on.

Habitat degradation, alteration, and loss account for approximately half of the threats to migratory fish, according to the report. Wetlands are essential habitats for migratory fish species, but, globally, wetlands are disappearing three times faster than forests, while dams and other river barriers block fish from reaching their mating or feeding grounds and disrupt their life cycles.

Over-exploitation, such as unsustainable fishing and accidental by-catch account for around one-third of the threats to these populations. Populations are also threatened by the impacts of the climate crisis as changes in temperature can trigger migration and reproduction, causing these events to happen at the wrong time, and therefore misalign reproduction.

“Migratory fish provide food and livelihoods for millions of people but this is seldom factored into development decisions. Instead, their importance to economies and ecosystems continues to be overlooked and undervalued – and their populations continue to collapse,” Stuart Orr, WWF Global Freshwater Lead, said in a press release. “The world needs to implement an Emergency Recovery Plan that will reverse the loss of migratory fish.”

The way forward

Image credits: Jon Flobrant.

While the situation is bleak, the analysis showed that sustainable management strategies can have a positive impact on migratory freshwater fish. These include habitat restoration, dam removal, setting up conservation sanctuaries, species-focused management and legal protection. In the US, for example, many dams have been removed over the last few decades and the dam removal movement is growing. In 2019 alone, over 900 upstream river miles were reconnected through dam removal projects, improving habitat and biodiversity in rivers, and their resilience to a changing climate. This is beginning to happen in Europe, as well, as the environmental downsides of hydro dams is becoming apparent.

The report argued dam removal has significant positive environmental impacts, is cost-effective, and supports job creation. Several case projects around the world have shown migratory fish populations can come back quickly in response to dam removal and nature-like solutions.

For example, back in 2016, The Penobscot River Restoration Trust partners completed a river restoration in the Penobscot River in Maine, opening up over 3,200km of habitat and removing two dams that blocked fish migration.

The following spring, the river herring numbers grew from a few hundred to nearly 2 million.

“Rivers and migrations are the connective tissue of our planet – and migratory fish are bellwethers for not just rivers, but for the countless other systems they connect, from the deep sea to coastal forests. Losing these fish means losing so much more,” Jeffrey Parrish, Global Managing Director for Protect Oceans, Land and Water at The Nature Conservancy, said in a press release.

The authors called upon the global community to protect free-flowing rivers and guide basin-wide planning by addressing existing threats, adhering to ongoing conservation initiatives and water protection laws, investing in sustainable renewable alternatives to the thousands of new hydropower dams that are planned across the world. Without this, river environments will continue to degrade.

There are many ongoing initiatives around the world supporting the recovery of migratory fish species and freshwater biodiversity in general. For example, researchers and NGOs recently presented the Emergency Recovery Plan, listing a set of measures to transform the management and health of rivers, lakes and wetlands for the benefit and health of freshwater biodiversity.

Eating fish may protect the brain from air pollution and white matter shrinkage

Credit: Pixabay.

Older women who ate more than 1-2 servings of fish or shellfish per week had greater volumes of white matter than those who had a low intake of fish. The findings suggest that omega-3 fatty acids, which can be easily sourced from fish and shellfish, may counteract the effects of air pollution on the brain.

Previous research has shown that omega-3 fatty acids relieve inflammation and help conserve brain structure in aging individuals.

Omega-3 also reduces brain damage due to neurotoxins such as lead and mercury. However, many toxins found in noxious fumes and other air pollution can also have a neurodegenerative effect on the brain. Could omega-3 offer protection against air pollution too? This is what researchers at Columbia University set out to investigate.

“In previous studies, fish oil reduced the brain damage caused by exposures to various environmental neurotoxins, including lead, organic solvents, and methyl mercury. PM2.5 exposure (particulate matter smaller than 2.5 microns) is a risk factor for cognitive decline and reduced brain volumes. But, no study has examined whether fish oil offers similar protection against PM2.5 exposure. Thus,  we started this investigation in the Women’s Health Initiative Memory Study (WHIMS) study. We found that higher blood omega-3 levels attenuated the toxicity of PM2.5 exposure on white matter volumes in elderly US women. Similar protection was seen for dietary intakes of omega-3 and non-fried fish,” Ka He, a researcher at Columbia University in New York and lead author of the new study, told ZME Science.

For their study, 1,315 women with an average age of 70 and no prior history of dementia at the start of the study, had to fill in a questionnaire about their diet, physical activity, and medical history.

“Elderly people are in higher risk of cognitive decline and neurodegeneration, compared to younger adults. Increasing evidence in elderly populations supports that ambient air pollution, including PM2.5 exposure, may be a novel environmental risk factor for cognitive impairments. Therefore,  we identified the WHIMS cohort as a well-characterized and geographically-diverse population unique for our research questions with comprehensive data on omega-3, PM2.5, and MRI scanning,” He wrote in an email.

From their dieting data, the researchers calculated the average amount of fish each woman consumed on a weekly basis. This includes broiled or baked fish, canned tuna, tuna salad, tuna casserole, and non-fried shellfish. Fried fish and shellfish were not taken into account due to research showing deep-frying destroys the omega-3- fatty acids.

Blood was also drawn from the subjects in order to measure the amount of omega-3 fatty acids in their red blood cells. Based on their omega-3 fatty acids serum content, the participants were divided into four groups.

In order to assess air pollution exposure, the women’s home addresses were compared to three-year average measurements of air pollution in their respective areas.

Finally, all participants underwent brain scans with magnetic resonance imaging (MRI) in order to measure the structural health of various areas of the brain, with a focus on white matter and the hippocampus (the part of the brain responsible for storing and processing memory).

After adjusting for age, education, and other environmental factors, the team of researchers found that the women with the highest levels of omega-3 fatty acids in their bloodstream also had a greater volume of white matter when compared to those with the lowest levels. The average difference in brain volume between the two groups was 7 cubic centimeters.

Additionally, women with the highest levels of omega-3 fatty acids in the blood showed greater hippocampus volumes.

It’s important to note that the findings uncovered an association between brain volume and eating fish. This correlation does not prove any cause and effect relationship, although the researchers have some ideas.

“White matter may be a novel target of PM2.5 neurotoxicity. On the other hand, omega-3 protects the cells responsible for the production and maintenance of myelin in the white matter. They can also help resolve local inflammation and promote remyelination in the white matter, thereby facilitating white matter repair. Therefore, high levels of omega-3 may alleviate myelin damage and the subsequent white matter abnormalities induced by PM2.5 exposure,” He said.

It’s also not a good idea to stock up on all the fish products you can find in the supermarket. Many species of fish — several of which end up on our plates — are displaying increasing levels of methylmercury, a very toxic substance. This is why it’s better to consult with your doctor before going all-in on a fish diet.

“Future laboratory studies may elucidate the underlying mechanisms, and clinical trials may demonstrate the effects of fish oil supplementation as one of the critical strategies for preventing PM2.5-induced neurotoxicity. Since environmental pollution is unavoidable, these findings provide helpful insight regarding how healthy diet could reduce the adverse effects of air pollution on cognitive decline and neurodegeneration,” He concluded.

The findings were reported in the journal Neurology, published by the American Academy of Neurology.

Fossil Friday: ancient squid caught in stone while munching on a fish

We’ve talked yesterday about how behavior doesn’t fossilize, and that is true — most of the time. Some extremely rare finds, such as this fossil discovered in the 19th century, can be the exception to that rule.

Despite its age, the fossil wasn’t analyzed properly until now.

A close-up image of the fossilized fish with the squid arms around it.
Image credits Malcolm Hart / Proceedings of the Geologists’ Association.

It was discovered in Jurrasic-aged rocks off the coast of England and captured the oldest known case of a squid-like creature attacking prey. The event took place almost 200 million years old and the fossil is currently housed within the collections of the British Geological Survey in Nottingham.

Fish for dinner

“Since the 19th century, the Blue Lias and Charmouth Mudstone formations of the Dorset coast have provided large numbers of important body fossils that inform our knowledge of coleoid paleontology,” says Professor Malcolm Hart, Emeritus Professor in Plymouth and the lead author of a study analyzing the fossil.

This, however, is a most unusual if not extraordinary fossil as predation events are only very occasionally found in the geological record. It points to a particularly violent attack which ultimately appears to have caused the death, and subsequent preservation, of both animals.”

The team identified the attacker as a Clarkeiteuthis montefiorei with its prey belonging to the herring-like species Dorsetichthys bechei.

The particular position of the attacker’s arms suggests that what we’re seeing is an actual predatory event, and not a quirk of fossilization, according to the team. They believe this specimen hails from the Sinemurian period, between 190 and 199 million years ago, which would make it the oldest fossil of its kind by about 10 million years.

The attack doesn’t seem to have been a pleasurable experience for the fish at all: the team explains that the bones in its head were apparently crushed by the squid.

The complete specimen (squid on the left, fish on the right).
Image credits Malcolm Hart / Proceedings of the Geologists’ Association

The authors believed that the attacker, too, bit off more than it could chew. The fish was likely too large for it to successfully bring down, or got stuck in its jaws. The unfortunate pair eventually killed each other by the looks of it, and found their way to the bottom of the ocean where they fossilized.

Another possible explanation is that the Clarkeiteuthis brought its prey down below in a display of ‘distraction sinking’, behavior meant to discourage other predators from attacking, or possibly just to hide from them. It’s possible that the squid swam into a body of low-oxygen water, where it suffocated.

The findings have been presented at the virtual event EGU2020: Sharing Geoscience Online this week in the “Life and Death in the Jurassic Seas of Dorset, Southern England” session. They will also be published in the journal Proceedings of the Geologists’ Association.

A new model developed to estimate how ocean acidity evolves over time

A new mathematical model developed at the University of Colorado at Boulder could allow us to accurately forecast ocean acidity levels up to five years in advance.

A pteropod shell submerged in seawater adjusted to an ocean chemistry projected for the year 2100. It dissolved in 45 days.
Image credits NOAA.

Ocean acidification is driven by CO2 gas in the atmosphere, levels of which are increasing sharply due to human activity. The acid in question is carbonic acid which, although a relatively weak acid, can impact the health and wellbeing of marine life by messing with their metabolism and calcification processes (i.e. with their ability to form and maintain shells).

The authors hope that their model can be used to insulate coastal communities from the economic and nutritional impacts of ocean acidification while helping researchers and policymakers develop adequate conservation methods for marine environments.

Not the acid we were looking for

“We’ve taken a climate model and run it like you would have a weather forecast, essentially — and the model included ocean chemistry, which is extremely novel,” said Riley Brady, lead author of the study, and a doctoral candidate in the Department of Atmospheric and Oceanic Sciences.

The team says that their model is the first to allow for acidity predictions over such a long time period, as previous attempts could only reliably predict up to a few months of data.

For the study, the team focused on the California Current System (CCS), which is one of the four major coastal upwelling systems in the world, running from the tip of Baja California in Mexico all the way up into the Canadian coast. The CCS supports fishing grounds that yield around a billion dollars in fishing catches every year in the U.S. alone. It’s also particularly vulnerable to ocean acidification, the team explains, as it pushes deeper waters (which acidic and denser, so they settle near the bottom) to the surface. The extra acidification we’re causing could push its fragile ecosystems over the edge.

The team used a climate model developed at the National Center for Atmospheric Research to generate ‘forecasts’ for past changes in acidity levels and compared those to real-world data — finding that they fit recorded changes very well. Another advantage this model has over localized ones that it can factor in events with global effects, such as El Niño.

However, while the results were quite exciting, our ability to deploy such models is still limited. These tools still require an immense amount of computational power, data, manpower, and time to implement and run, so they can’t really be used around the clock to generate acidification forecasts.

But we do know that they would be useful. It’s estimated that around 30% to 40% of the CO2 emissions from human activity are absorbed by the world’s waters and react to form carbonic acid, which makes them more acidic. The effect is only going to increase in the future, and researchers are expecting that large swaths of the ocean are going to become completely corrosive to the shells of certain organisms within decades.

“The ocean has been doing us a huge favor,” said study co-author Nicole Lovenduski, associate professor in atmospheric and oceanic sciences and head of the Ocean Biogeochemistry Research Group at INSTAAR.

But now, “ocean acidification is proceeding at a rate 10 times faster today than any time in the last 55 million years.”

Communities who rely on ocean resources for food or tourism will undoubtedly be affected by acidification, the team notes.

The paper “Skillful multiyear predictions of ocean acidification in the California Current System” has been published in the journal Nature.