The least fecund are sand tiger sharks, which commonly give birth to twins, the winners of a cannibalistic battle that goes on inside their mother. Before they’re born, fertilised eggs hatch into a shoal of tiny sharks, which proceed to eat each other until there are just two left, one in each branch of the pregnant female’s two-pronged uterus. By the time the surviving pups emerge into the ocean, they are so big, between three and four feet long, they have few natural predators. Except now, of course: humans are changing the rules, and sharks are born into an ocean where being big and living a long, slow life is no longer an advantage.

Long before endangered shark species finally blink out and go extinct, their gradual diminishing leaves marks on the environment. Take them away, and it potentially changes the way whole ecosystems work, which is one major reason the future ocean needs more sharks.

The idea that sharks are important for a healthy, functioning ocean generally comes from their position at the top of food chains. A lot of shark species, especially the big ones, are apex predators, primed to have a disproportionate influence over other species—not only the animals they eat but also those further down on the food chain. The disappearance of sharks could set off ripples of change through the rest of the ecosystem.

Keystone predators, the ones that keep entire ecosystems in balance, were first identified in a pioneering experiment carried out in the 1960s. The keystone in question was Pisaster ochraceus, a stout, purple starfish that has a healthy appetite for shellfish. Marine biologist Robert Paine cordoned off areas of shoreline along the rocky northwest coast of Washington State, picked up all the starfish, and moved them elsewhere. Within a few months, in places that were missing the five-armed predators, the local mussel population exploded. Paine watched as the mussels swiftly hogged all the space and outcompeted everything else, mostly other molluscs such as limpets and chitons. He showed that by eating so many mussels and keeping their numbers in check, the predatory starfish allowed a greater diversity of other species to coexist. Lose the predators, and the ecosystem loses its biodiversity. These are the keystones keeping the rest of the ecosystem from collapsing. Paine had picked a good study system to detect these effects, with animals that can be easily moved about and then generally stay put.

Doing a similar experiment with pelagic sharks is impossible; thus, identifying their keystone role is much harder. No scientists have tried excluding sharks from areas of habitat to see what happens. Instead, they’ve tracked the changes that unfold when fisheries deplete shark populations in an area. Some studies have linked a decline in sharks to increases in their prey, including stingrays, octopuses, and moray eels. Whether ripples of change continue all the way through ecosystems—and hence just how important sharks are for the ocean—remains a matter of much debate among shark biologists.

The most controversial investigation into the issue began in 2007, with a study of the shark fisheries off the coast of North Carolina in the United States, where large, predatory sharks, including bull sharks, tiger sharks, and scalloped hammerheads, had been overfished for decades. As populations of these apex predators declined, scientists spotted an uptick in the numbers of smaller sharks and rays. Doing especially well were the three-foot-wide cownose rays, named for their domed heads and straight-lipped mouths, which when they’re crunching on clams bear a passing resemblance to their terrestrial namesake chewing its cud.

While making the most of their new-found freedom from the jaws of larger sharks, the cownose rays were munching their way through the local bay scallops. Here was a ripple of change, kicked off by the loss of apex sharks, cascading all the way down the food chain—just as the science of keystone predators predicts. Authors of that 2007 study made an explicit link between the proliferation of cownose rays and the collapse of a scallop fishery. They made no comment on what, if anything, should be done about this; their job was simply to investigate the ecological changes taking place. But when members of the public caught wind of the study, their reaction was perhaps predictable.

“Save the Bay, Eat a Ray” was the slogan for a campaign that launched after fishers in the Chesapeake Bay decided their oyster harvests were dwindling because cownose rays must be eating them as well. Cownose rays were renamed “Chesapeake rays” to persuade people to eat them; the state of Virginia gave away free ray meat to restaurants to stimulate an appetite for it, and recreational fishers held tournaments to kill as many rays as possible. Like the Florida lionfish, the cownose ray was branded as an invasive species, and people were all too willing to help get rid of it. The truth is, cownose rays are not invaders but are native to the region, and they had been unfairly blamed for changes that were already taking place.

All this was laid bare in a 2016 study that found flaws in the original sharks-eat-rays-eat-scallops story and pointed out some overlooked facts about the species involved. A drop in predation by large sharks couldn’t have triggered a sudden proliferation in cownose rays because the rays reproduce far too slowly; female rays take eight years to reach maturity and thereafter give birth to a single pup each year. Cownose rays just don’t have the same capacity for rapid growth as Robert Paine had seen among mussels on the rocky shore. More likely, rays increased off North Carolina because they swam in from elsewhere. Cownose rays are known for congregating in the tens of thousands and undertaking immense seasonal migrations. Also, the timing was off. A more careful look at the data showed that the scallop fishery had already been collapsing for a while before the cownose ray bonanza. And besides, cownose rays don’t even eat that many scallops or oysters. Tragically, the legacy of the original research lingers, and cownose rays are still being heavily fished and targeted in fishing tournaments.

Moving on from that sorry study, scientists are still untangling the ways sharks influence their environment. No simple story is emerging of what happens when sharks are gone. The bottom line is that ecology is complicated, especially in the ocean, where water flows and animals restlessly migrate, forming connections that reach far and wide.

There are hints, though, that the largest, most fearsome sharks hold sway over their surroundings without even eating their prey. Fear alone can shape ecosystems. Prowling sharks scare other animals, which alter their behaviour to avoid getting caught. Then, when there aren’t so many sharks around, they no longer need to hide.

This happened at Seal Island in False Bay, a short way east of the Cape of Good Hope in South Africa. Since 2000, marine biologists have been monitoring the great white sharks that come to the island to hunt a huge colony of Cape fur seals. Tourists and wildlife filmmakers would also flock to the bay to have close-up encounters with great whites and watch them leaping into the air as they ambushed seals from below. Then, in 2015, there were suddenly far fewer great whites visiting the bay and far fewer seal attacks. Evidently, life became a lot calmer for the seals. Their anxiety levels dropped, as measured by a drop in the fight-or-flight stress hormones in their faeces, and they began spending more time farther from shore and over deeper water, places that not so long before had been very dangerous.

When great whites left the bay, seven-gilled sharks started showing up at Seal Island for the first time. These smaller predatory sharks, with gummy smiles, used to lurk in the shadows of nearby kelp forests where the bigger, bulkier great white sharks couldn’t easily manoeuvre and chase them.

Great white sharks had been scared out of False Bay by even bigger and more fearsome apex predators. At around the time when the sharks left, orcas began showing up along the South African coast. The marine mammals are not renowned for shark hunting, but these ones adopted a new habit of attacking great whites in packs and eating just their livers, the most nutritious part, leaving the rest of the body untouched. Facing this new lethal threat, many of the surviving great white sharks seem to have fled in fear for their lives, abandoning their former feeding grounds. The arrival of orcas to these coasts is another puzzle of the changing ocean, perhaps linked to fisheries depleting their other prey and forcing these intelligent cetaceans to find alternative sources of food.

The sequence of changes triggered by orcas and great whites in South Africa indicates the magnitude of influence predators can have. It’s possible that these impacts also extend into the surrounding habitats and potentially make ocean ecosystems more resilient to climate change. Shark Bay in Western Australia is aptly named for its large population of tiger sharks, which roam vast seagrass meadows, hunting dugongs and spreading fear through the seascape. The placid, seagrass-munching mammals know they’re in danger when tiger sharks are around and thus behave cautiously; they hold their heads up, keeping a watchful eye, and nibble on the ends of seagrass blades. When the dugongs feel safer, they dig their snouts down into the seabed and rip up whole plants from the roots—a much more destructive feeding pattern for the lawns of seagrasses. With this in mind, marine biologists took the chance to see what might happen to the bay if there were no more tiger sharks. In 2011, Shark Bay was struck by a massive marine heatwave, which caused catastrophic loss of seagrasses, and the dugongs temporarily moved out. In their place, a team of diving scientists, trowels in hand, impersonated dugongs at their most carefree. In some experimental plots, they dug up sea-grasses from the roots, just as dugongs do when there are no sharks in the neighbourhood to watch out for. Other plots they left alone. In the following months, the heat-stricken seagrasses grew back much better in areas the scientists weren’t digging up. This suggests that when heatwaves strike, a decent-size population of tiger sharks could give seagrass meadows the respite they need from overgrazing, by forcing dugongs to stay alert and not uproot the plants.

Even with so many odds stacked against them, elasmobranchs have yet to suffer from extensive recent extinctions, although there are several species that haven’t been seen in a long time. The Red Sea torpedo, a species of ray that sends electric shocks through the water, was originally named in 1898 and hasn’t been reported since, despite biologists making a concerted effort to find one. The lost shark was last found in the wild in 1934. Both species are classified on the Red List as Critically Endangered (Possibly Extinct). Meanwhile, the Java stingaree was a dinner-plate sized ray that was only recorded once, in 1862, in a fish market in Jakarta, Indonesia. Following more than twenty years of searching fish markets for another specimen, and studying the highly-industrialized and heavily-fished seas of the region, in 2023 a team of scientists declared the species extinct.

There are also cases of sharks and rays that were thought to be vanishingly rare and restricted to a minute part of the ocean, which have, with more careful examination, proven to be more widespread and certainly not beyond hope. One species recently pulled out of obscurity is the angelshark.^f So named because of its outspread wings, it sits and waits, pressing its flat, six-foot-long body against the seabed and nestling in the sand, hiding from passing prey. But angelsharks haven’t been able to hide from trawl nets dragged over the seabed, and consequently, they’re one of the most endangered of all the sharks.

Overexploitation of angelsharks was well underway in the nineteenth century, when fisheries across the northeast Atlantic and the Mediterranean were catching them. The sharks were intentionally targeted for their meat, their oily livers, and their skin, used to make into leather. In southeast France, on the Mediterranean coast, La Baie des Anges (the Bay of Angels) was named after all the angelsharks that used to be caught there. Angelsharks were a common catch around UK coasts, although the British didn’t know they were eating sharks because the meat was sold under an alternative ecclesiastical name, monkfish. And seafood consumers had no clue when angelsharks became overfished and disappeared from the menu. Fishers swapped them for two species of shallow-water anglerfish,^g which they used to throw away but then started keeping and selling under the same name, monkfish, as still happens today. Apparently, nobody eating monkfish noticed the switch. The demise of angelsharks didn’t even show up in fishery records but was lost amid the species substitution, because catches under the generic category of monkfish didn’t decline. By the 1980s, the once-common angelsharks had almost disappeared. On rare occasions when one was caught in a fishery, it was considered a novelty and if still alive placed on display in an aquarium.

For years after fisheries depleted them across much of their range, one place became renowned as the last stronghold for angelsharks. In the Canary Islands, the Spanish archipelago two hundred miles west of Morocco, divers were having regular encounters with the mottled, flattened sharks. Thanks to decades of a trawling ban and swirling, food-rich waters, the Canary Islands population was doing well. But this wasn’t the only place where angelsharks were still living.

It took a groundswell of action and collaboration between scientists, fishers, anglers, divers, and other ocean-goers to raise the profile of these overlooked sharks and show they still exist elsewhere and are well worth protecting. Local knowledge has been pivotal in building accurate maps of angelshark distributions. Researchers met and spoke with people living along coastlines in Europe to hear their stories of catching or seeing angelsharks; newspaper archives have turned up photographs of anglers posing with this unusual-looking species; a network has been set up so members of the public can report angelshark sightings.

A 2020 study gathered all this information together and showed that the angelshark’s range is not as restricted as people had feared. There are still some locations where its presence is highly uncertain. It’s possible the species has been lost from the North Sea, along the Iberian Peninsula, and south to the Moroccan coast. Elsewhere, angelsharks don’t occur in large numbers, but they do live along the coasts of Algeria, Tunisia, Libya, and Israel; in the Adriatic Sea off the Italian and Croatian coasts; and off Corsica, Cyprus, Greece, and Turkey. In addition to the Canary Islands, other important strongholds for angelsharks are the Irish and Celtic Seas. Along the coast of Wales, scientists are now searching for genetic clues left behind by angelsharks. Seawater contains a soup of DNA fragments from sloughed-off skin cells, scraps of mucus, and faeces. It’s now possible to take water samples, extract the DNA snippets, and work out which species they came from. This environmental DNA, or eDNA, doesn’t last long and soon breaks down, so when angelshark DNA shows up in samples of Welsh seawater, it means one must have swum by in the past few days. In 2021, a diver filmed a young, live angelshark underwater, a first for British waters and a sure sign that female angelsharks are using the Welsh coast as pupping grounds. And in July 2023, an angelshark was spotted near the city of Brighton off the south coast of England.

Angelsharks remain highly endangered, but conservationists, now armed with a much better idea of where these animals live, are putting together plans to protect them. These plans also include two similar-looking relatives, the smoothback and sawback angelsharks,^h which share a similar range along European and African coasts but have lost a lot of ground to fishing and habitat destruction.

It won’t be an easy task bringing back more of these rare, flat sharks to an ocean that’s still intensively fished. Angelsharks are protected in British and EU waters, where it’s illegal to cause them deliberate harm or to keep them when they’re caught in fisheries, but trawlers are indiscriminate and will keep catching them. Conservationists are working with fishers to help them find ways of safely handling angelsharks and carefully untangling them from nets and lines, to give them a better chance of surviving once they’ve been let go.

In the Canary Islands, Greece, and Turkey, recreational scuba divers are looking out for angelsharks and reporting when and where they see them. Their input is helping scientists to identify places that are especially important—the parts of the seabed where angelsharks go to feed, find mates, and give birth—and that need urgent protection from fishing. In this way, angelsharks are also acting as so-called umbrella species, helping to protect other species that share their habitats.

Angelsharks almost slipped away from the ocean decades ago, but now they are making a comeback, thanks in large part to the everyday people who are spotting them in the wild and becoming their champions. Most people will never catch sight of the ocean’s wandering sharks, such as an oceanic whitetip, hammerhead, or thresher. Swimmers, divers, and anglers along the world’s coasts have a much greater chance of an enchanting encounter with one of these serene angelsharks lying quietly on the seabed.

A lot is changing for elasmobranchs, and not all of it for the worse. At the turn of the twenty-first century, there was very little international attention on their plight. Fisheries were catching as many sharks as they wanted with no limits. The trade in shark fins was freewheeling without scrutiny. Popular Western culture was plagued by lingering fears of shark-infested waters, stirred decades earlier by the movie Jaws, and sharks still were not looked on kindly in the public eye.

Gradually, these stereotypical beliefs shifted, and alternative views of sharks started to become more mainstream. Scientific studies helped with this, uncovering new details of the nuanced, intelligent lives of sharks. Early breakthroughs in the field of shark intelligence were made in the 1950s by American biologist Eugenie Clark, who showed that these fish are not mindless killing machines but are capable of learning and have good memories. She kept lemon sharks in open sea pens and successfully trained them to push a target with their snout, which rang a bell and released a piece of food. The sharks stopped feeding through the colder winter months, but as soon as spring arrived and the water warmed, they remembered precisely what to do and swam up to the target to get their food.

More recently, scientists working at the Bimini Biological Field Station in the Bahamas tracked young lemon sharks marked with coloured tags. From atop a tall tower set in shallow lagoons of a mangrove inlet, researchers watched through binoculars and noted down the individual movements of each shark cruising around the shallows. Often, they saw the same two, three, or more sharks swimming together. Some sharks stayed in the same groups throughout the whole two years of the study, evidently preferring their mutual company to that of any other sharks in the area.

Young sharks also make close acquaintances under controlled laboratory conditions. Given the choice, they prefer to stay close to sharks they’ve met before rather than strangers. These social networks likely help sharks learn from each other, passing on knowledge on how to find food and avoid predators.

New ways of thinking about why sharks matter have also been coming to the fore. It’s long been known that shark ancestry can be traced back at least four hundred million years. That evolutionary heritage has come into focus with the advent of new genetic techniques that allow scientists to decode their genomes and learn about how elasmobranchs have been evolving their own unique ways of doing things. Sequencing the DNA of great white sharks, for instance, identified the genes that allow their wounds to heal swiftly, an important attribute for a species whose courtship involves a lot of biting. If great white sharks, or any other species, went extinct, millions of years of their unique evolutionary information would be lost that could have all sorts of applications and uses in the human medical world.

More people than ever are embracing a new fondness and compassion for sharks, seeing them as graceful, efficient, and important animals. Members of the public are joining scientists in campaigns to make the ocean a less dangerous place for sharks. Even victims of shark attacks are advocating for their conservation and are convinced the ocean will be a better place with more sharks in it. This is arduous work because of the slow lives of elasmobranchs and the slow pace of international negotiations, but gradually the situation is improving, and there are hopeful signs that sharks and their kin can make a comeback.

Back in 2009, the Pacific island state of Palau banned targeted shark fishing from all its waters, an area of more than two hundred thousand square miles. This was the world’s first shark sanctuary. It was followed by more than a dozen others. Several countries, including French Polynesia and Kiribati, have territories covering more than a million square miles of ocean, which they declared off-limits to shark fishing. Most of these countries have major tourism industries, and the income generated by visitors keen to encounter wild sharks was deemed to be more significant than revenues from fisheries catching sharks. Now, more than 3 per cent of the global ocean is technically a shark sanctuary, where it’s illegal to deliberately catch and sell sharks and in some cases rays too.

More than a decade after many of these sanctuaries were declared, it isn’t entirely clear how well they’re helping shark populations to rebuild, chiefly because very little data have been generated. In most places, nobody knows how many sharks were there before the sanctuaries were set up or how many are there now. The best indication comes from a survey of scuba divers’ opinions, which suggests countries with sanctuaries are seeing less drastic declines in sharks compared to elsewhere. In general, shark meat and fins are not often seen openly on sale in countries with shark sanctuaries. Sharks were already well protected in some of these countries before sanctuaries came into force. In the Bahamas, for instance, commercial longlining had been banned for years when the shark sanctuary was declared. The sanctuary did, however, prevent a new fishery from opening that would have begun exporting shark fins.

While these sanctuaries might seem like a shark utopia, only commercial fishing for sharks is prohibited within many of them, and other fisheries continue to catch a lot of sharks and then dump them over the side because it’s illegal to keep them. A 2023 study used satellite data to track the operations of longline vessels and estimate how many sharks are caught and killed within the boundaries of eight shark sanctuaries in western and central parts of the Pacific Ocean. Close to three hundred thousand large pelagic sharks were likely caught in a single year (2019), and more than one hundred thousand of them died, including blue sharks, silky sharks, thresher sharks, and oceanic whitetips. Until the death toll from longliners can be reduced, these areas will offer sharks little sanctuary.

Other than the shark sanctuaries, most marine reserves have been set up without elasmobranchs in mind. Globally, the average size of an individual reserve is roughly the same as that of Central Park in New York, which is woefully small for protecting animals that can roam great distances and migrate across entire ocean basins. And when it comes to protecting sharks and rays, a lot of marine reserves are not at all well enforced. In the Mediterranean, catches of endangered elasmobranchs are higher inside reserves than in places with no official protections at all.

While poorly patrolled marine reserves are struggling to make a difference for sharks, more focused measures are helping to protect specific parts of the ocean that are important for endangered and rare species, including some spots that have been discovered rather by chance. In 2019, British marine conservationist Chris Rickard spotted on social media a photograph of a giant egg case, the size of a football, and he instantly knew it must be the egg case of a Critically Endangered flapper skate. It had been pulled up by a scallop fishing boat off the west coast of Scotland, in cold waters of the Inner Sound of the Isle of Skye, and Rickard persuaded the skipper to take him back there to have a look. He dived down to the seabed and saw forty flapper egg cases, each one with a wriggling embryo inside. The following year Rickard went back again, accompanied by fellow marine conservationist Lauren Smith, and together they counted more than one hundred giant egg cases nestled on the seabed. They had found a flapper skate nursery.

It wasn’t far from the spot where the female flapper skate had been hauled on the deck of a fishing boat and laid the egg that hatched a year and a half later. Maybe that pregnant skate had been caught on her way to the seabed nursery. Rickard and Smith instantly understood the importance of this egg-laying habitat. Very little is known about the breeding habits of these rare animals, making this a major finding for the species. And it was obvious the flapper skate egg cases were at tremendous risk of being scraped up by trawlers and dredgers while they gestate for eighteen months on the seabed.

Working with local fishers and conservation groups, Rickard and Smith spread the word and remarkably quickly got the response they hoped for from the Scottish government. Within six months, the Red Rocks and Longay Urgent Marine Protected Area was announced, banning all fishing from the area for an initial period of twelve months across the entire area where the egg cases had been found. It was a bold and swift move. The site was deemed to be so vulnerable, it was even made off-limits to scuba divers in order to leave the female skates and their eggs in peace. In February 2023, a larger, permanently protected area came into force.

Sharks are also beginning to gain protection while they’re on the move. Advances in satellite-tracking technologies are showing that elasmobranchs don’t wander the ocean at random, but they intelligently navigate along predictable routes, often through waters belonging to many nations and out into the high seas. This makes international cooperation critical for conservation plans. In November 2021, the presidents of Ecuador, Panama, Colombia, and Costa Rica announced they were joining up and expanding existing marine reserves to create a huge, protected corridor between their countries. For hundreds of miles through the eastern Pacific, from the Galápagos Islands along a chain of deep seamounts to Cocos Island and on to the mainland of Central and South America, multiple endangered species migrate back and forth in a wide stretch of ocean. Giant manta rays; tiger, silky, hammerhead, and whale sharks; and green and leatherback sea turtles all follow the same path. Now that those four countries have agreed to work together, the next big challenge will be keeping long-range industrial fisheries from operating in this wildlife superhighway.

Efforts are also being made to cut down the killing of endangered sharks by industrial fisheries. Since 2010, tuna fisheries in the Atlantic have been banned from keeping and selling any oceanic whitetip sharks they catch. In 2011, a zero-retention regulation was brought in that requires fishers to release oceanic whitetips that get caught on their lines or in their nets. Other endangered species are similarly required to be set free. But zero retention does not translate to zero deaths. Some sharks can survive relatively well after they’ve been released, including blue sharks, the species most commonly caught by longliners. However, many sharks don’t survive the ordeal of an encounter with a longline because they suffocate. It’s not true that all sharks need to keep swimming in order to breathe; there are those, angelsharks included, that lie on the seabed and actively suck in water to oxygenate their gills. But pelagic sharks, such as oceanic whitetips, typically breathe by opening their mouths as they swim and letting oxygen-rich seawater pass right over their gills, a process known as ram ventilation. They can’t do that when they’re caught and tangled on a fishing line.

Even if sharks survive the ordeal of being caught, how long they can live after they’ve been released from a longline is another question. A 2021 study conducted in waters off Florida showed that some species are reasonably robust. Scientists tagged the sharks with accelerometers, a shark version of a digital fitness-tracking device, and monitored their movements following release. After being caught on a longline hook, only three out of every hundred tiger and sandbar sharks died within twelve hours of being set free. Other species didn’t do as well. The accelerometers showed that many of the blacktip sharks and spinner sharks swam around erratically before sinking to the seabed and lying very still. For those sharks, the trauma and physiological stress of capture proved too much, and they soon died.

There are also proven ways of cutting down the number of sharks caught on longlines. The straightforward step of adjusting the depth where lines are set can make a big difference. For instance, in the Indian Ocean, fisheries that target marlin catch most sharks on lines set below five hundred feet. When lines are set in the top three hundred feet of the sea, the same number of marlin tend to be caught, but far fewer sharks end up getting snagged. Switching the type of bait can also be effective, as happened when a swordfish fishery in Hawai’i swapped squid bait for fish and started catching a third fewer blue sharks.

Much research has focused on developing technologies to deter sharks from biting lines and hooks. Pulsed electrical fields, emitted by small electronic devices fixed onto the snoods of longlines, seem to do the trick. Without causing any lasting harm, these seem to briefly overstimulate the electrical sensors on a shark’s snout, so it swims away. Sea trials in a small-scale bluefin-tuna longline fishery in the Mediterranean reduced the already very low catches of blue sharks even further. Illuminating gill nets with LEDs also reduces the number of sharks being caught, presumably because it helps them to see the nets and avoid swimming into them. For now, it’s debatable how well any of these measures will scale up to the large fisheries that catch the most sharks, chiefly because it will be expensive for fishers to buy the devices.

Making relatively minor adjustments to fishing gear, and legally requiring the release of endangered species, are pragmatic measures that can help ameliorate the death toll of sharks, but they deflect from a deeper question. Given that industrial fisheries dominate the ocean and intrude on the global territories of so many endangered sharks, should we really be longlining at all?

Most notoriously, sharks are exploited for their fins, for use as an ingredient in traditional Asian soups. The fins themselves have little taste, but when dried, shredded, and boiled, they give the broth a sinewy, chewy texture that is highly regarded among diners who pay top prices for this luxury food. The brutal practice of cutting off fins from sharks at sea, then dumping the bodies back in the ocean, has been widely outlawed. Known as finning, it’s horrendously cruel when performed on live animals and encourages overexploitation of populations, because fishers keep the sharks’ fins without taking up space in their holds with the bodies, which generally have a lower market value or no quota to legally bring them back to land; shark fins are also much easier to hide. Over the past twenty years, dozens of countries have introduced laws that require any landed shark bodies to be accompanied by a certain weight of the fins on the same vessel, or they must have their fins still naturally attached, as is the case in US waters, India, Colombia, Brazil, Taiwan, and elsewhere; while in Oman and South Africa, sharks can only be legally sold whole. Finning is now illegal on EU vessels operating anywhere in the ocean. Since 2019, Canada has banned the import and export of detached shark fins, and the UK’s Shark Fins Act was passed into law in June 2023, banning the trade into and out of the country of shark fins and any product containing them, such as canned shark-fin soup.

There have also been advances in controlling the trade in shark meat and fins under the aegis of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Known best for banning trade in wildlife products like elephant ivory and tiger bones, this global body also regulates trade in species that are not deemed to be on the very brink of extinction but are heading that way. In 2002, the basking shark and whale shark were the first elasmobranchs to be added to CITES, and they were joined by the great white shark in 2004. It took another decade of tireless work by campaigners before several more endangered elasmobranchs were listed, including the manta ray, great hammerhead shark, and oceanic whitetip shark. Except for the incredibly rare and endangered sawfish (a type of ray), in which trade is banned, all the other elasmobranchs were placed in Appendix II of the convention, which allows a certain level of trade. Permits required to engage in trade certify that consignments of these species are legal and traceable and do not threaten their survival in the wild.

This should, at least in theory, help to reduce impacts of shark fishing, because fins and meat can be legally traded only if they’re proven to come from sustainable fisheries. Providing that proof is the big challenge—even knowing which species are being traded was a long-standing problem. Once a fin was detached (legally or otherwise), dried, processed, and trimmed, it was almost impossible to work out by eye which species it came from. Genetic tools have transformed the monitoring ability of the fin trade, allowing regulators to accurately identify shark species from the DNA in their dried fins. Scientists in Hong Kong, the main hub in the international fin trade, have been conducting routine surveys, visiting seafood vendors once a month and purchasing small bags of trimmings—the pieces snipped off fins to neaten them for sale. They found that many CITES-listed species were still being traded in huge numbers and not always accompanied by the necessary permits.

A turning point came in 2022 with the release of another study showing that species in the fin trade are inordinately threatened with extinction. The study identified eighty-six elasmobranch species in the trade, of which sixty-one were listed in the IUCN’s Red List of Threatened Species. The study warned that most sharks in the trade are being caught in fisheries lacking good management, and that without better controls, a wave of species extinctions was likely.

That study was very well timed, and later in 2022 it proved highly influential at a landmark meeting of CITES in Panama, where the biggest-ever vote passed in favour of sharks. The entire guitarfish family, comprising thirty-seven species of sharklike rays whose fins are highly valued, was added to CITES Appendix II, as were several hammerhead shark species. Also listed was the entire family of requiem sharks: the fifty-four species, all close relatives of oceanic whitetips, of which include lemon, spinner, blue, and copper sharks, along with whitetip and blacktip reef sharks. These additions mean that around 90 per cent of all sharks in the fin trade are now CITES-listed.

The next step will be for countries to enforce these new trade regulations, which should be easier now that superfast DNA tests can identify illegal shipments that don’t have the required permits. Results from DNA sequencing used to take a week or longer to come back from the lab, which is no use to customs officers in most countries, as they can impound suspected illegal consignments for only a day or two. Now a mobile shark DNA lab can be taken to a container of shark fins at a port, and customs officers can conduct a far simpler test and within a few hours identify the species.