For CITES to help conserve sharks depends on how well fisheries can be managed so populations don’t continue to spiral into decline. On that score, there’s still a lot of work to do. Less than 10 per cent of the global shark catch is currently well managed within sustainable limits. Some shark species, such as blue sharks, are abundant, reproduce relatively quickly, and are likely candidates for sustainable fisheries—that is, if resources can be devoted to proper monitoring and management. For the more endangered species, including oceanic whitetip sharks, sustainable fisheries will never be a good idea. Their populations are much too small, and even if they do recover substantially, these animals live such long, slow lives that a sustainable fishery would only be able to take incredibly low numbers. So why bother? Better to leave these magnificent animals alone after decades of maltreatment of their species.

A ray of hope recently shone onto the lives of endangered oceanic sharks. A 2023 study of shark fisheries in American waters provided the first compelling evidence that with time and effort, these sharks’ troubles can be reversed, and that they are not doomed to disappear from the ocean. Several decades ago, leading up to the 1990s, fishers in US waters were actively encouraged to catch sharks because it was the general opinion that these wild animals were going to waste as they swam around the seas and could be put to better human use—they were classified as an underutilised resource. In that sense, the shark-catching campaign was a tremendous success. It didn’t take long before this resource was thoroughly utilised and exhausted. In 1993, the US government backtracked and introduced a recovery plan to halt unchecked overexploitation of sharks in the Atlantic. New regulations were strictly imposed by the US Coast Guard and other law enforcement agencies. Limits were introduced on the number of sharks that can be caught. For the most imperilled species, quotas were set to zero. Fishing pressure was reined in. The plan was not just about preventing species extinctions but about reaching for a more ambitious goal of rebuilding populations.

Scientists have compared the situation in US Atlantic waters before and after this protection plan came into force. Using data from Sharkipedia, an open-source database of shark populations, they found that for nine species of large pelagic sharks—the tiburones—the grim, pre-1990s outlook has distinctly improved. Scalloped and smooth hammerheads pulled out of a nosedive and levelled off, and their populations have gradually begun to grow. Declines in tiger sharks and great whites have also stabilised, and their numbers are rising. Great hammerhead populations are steadily climbing as well.

The important message from the northwest Atlantic fisheries is that building a future ocean with more sharks in it is possible. There’s no swift bouncing back for species that spend decades reaching maturity and devote years of pregnancy and egg development to producing a smattering of burly offspring. Even a few decades after shark fishing was restricted in the northwest Atlantic, most of the recovering shark species still have a long way to go to regain their former abundance. But now that they’ve been given a chance, these sharks are slowly, slowly coming back. The same could happen elsewhere, and for many other species, if decisions are made to give elasmobranchs more of their ocean back.

a That’s a 95 per cent decline.

b The IUCN’s Red List of Threatened Species, commonly known as the Red List, has the following categories of threat: Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild, and Extinct. Experts periodically assess the status of species and assign them to these threat categories.

c There are also four threatened species of chimeras, sometimes known as ghost sharks. Together with sharks, skates, and rays, they belong to the class Chondrichthyes.

d This is a fraction of the world’s estimated 2.9 million motorised fishing boats.

e This is certainly an underestimate, as many vessels either don’t carry the automatic identification system or deliberately switch it off while fishing.

f Squatina squatina, one of twenty-two species in the Squatinidae family.

g Lophius piscatorius and L. budegassa, members of the same family as deep-sea anglerfish.

h Squatina oculata and S. aculeata.

Chapter 5 Poisoned Hunters

There she lay on the beach not far from the cold Scottish waters she had called home, one of her flippers pointing at the sky. People had known this female orca for more than twenty years and recognised her by the shape of the white patches behind her eyes and the pale saddle across her black back. This was Lulu.

She was named in 1995 when she first appeared in a pod known as the West Coast Community, a distinct variety or ecotype comprising the last resident orcas in the seas around the British Isles. Around New Year’s Day, 2016, somewhere near the small island of Tiree in the Inner Hebrides, Lulu became entangled in fishing lines. For several days, she dragged the heavy ropes behind her, as they made it exhausting for her to swim and hunt. In the end, Lulu drowned.

By the time she washed up on the beach in Tiree, the fishing ropes were gone, but the deep wounds they left in her skin remained. Entanglement is generally uncommon for these quick-witted, agile predators. A necropsy revealed a problem that likely contributed to Lulu’s demise. Analysis of chemicals in her body revealed she had been carrying a huge toxic load. The concentration of polychlorinated biphenyls, the pollutants commonly called PCBs, was so high she was one of the most contaminated animals ever found. When they percolate into living bodies, these chemicals interfere with the immune system and brain function, so it’s possible Lulu was too confused to avoid getting snarled in the fishing line and too weak to cope with the added weight once she was entrapped.

PCBs also disrupt hormones and cause infertility, which likely explains another finding of the postmortem. Even though she was at least twenty years old and sexually mature, Lulu had never given birth to a calf. When she died, she left behind eight other members of the West Coast Community, four mature females and four males. The Hebridean Whale and Dolphin Trust has been monitoring the pod since the 1990s, and in that time a calf has never been seen. Lulu’s poisoned body provided evidence that accumulating toxins could be to blame. Since she died, the situation has become even more bleak. Only two orcas from the pod have been spotted recently—both males.

Measuring up to thirty-two feet long and weighing five or even ten metric tons, orcas, also known as killer whales, are the world’s largest dolphins. They occupy every ocean and live long, intricate lives. Tight-knit pods are commonly led by a female, whose children and grandchildren stay with her throughout her life. A recent study found that grandmothers protect their sons from getting into fights with other orcas. The matriarch remains the head of the family into her old age, at eighty, ninety, even a hundred years old and way past her menopause; orcas are one of only five animal species in which females are known to outlive their fertility.^a Grandmother orcas are the wise elders, keepers of expert knowledge of where to hunt, and they call other members of the pod to them with a splash of their tail.

Orcas are supreme hunters, the killers of whales and other marine predators. Distinct populations dispersed across the ocean have evolved to specialise in particular prey. In Antarctica, they hunt for penguins, seals, and young minke and humpback whales; along the coastlines of Patagonia, orcas deliberately beach themselves to grab sea lions. Elsewhere, orcas prey on salmon, herring, and, as seen recently off South Africa, great white sharks.

As cosmopolitan apex predators, orcas are sentinels for the global health of the ocean. It’s revolting but true that the ocean is a dilute mix of just about everything humans make, use, and throw away: raw sewage, farming effluent, spilled oil, pesticides and herbicides, chemical weapons, nuclear waste, mercury that rises from chimney stacks of coal-fired power stations and then rains down from the skies, and so much plastic. Orcas accumulate and concentrate pollutants in their bodies and are often hit the first and the worst as human-made contaminants percolate through the ocean.

The toxic compounds that ended up in Lulu’s blubber were manufactured long before she was born. There are more than two hundred types of PCBs, all sharing a similar molecular structure.^b None occur naturally. They were first synthesised in laboratories in the 1870s and went into mass production in the 1930s, first by the Monsanto Company in the United States, then by other manufacturers in other countries, in particular Russia, Germany, France, and the United Kingdom. These chemicals were widely used in refrigerators and television sets, in sealants, paints, pesticides, herbicides, glues, and lubricants. PCBs were added to coatings on electric cables to stop them from snapping and sprayed onto roads to prevent dust from being kicked up. They were used in carbon paper, floor polish, and false teeth.

From the start, manufacturers knew there were health risks when people working in PCB factories broke out in disfiguring skin conditions. Later studies recognised PCBs as carcinogens and endocrine disruptors and linked them to a plethora of debilitating health conditions. In 1968, in the journal Nature, scientists reported that PCBs were contaminating wildlife and were already widely dispersed in the global ecosystem. Amid spiralling concerns about their impacts on human health and the environment, PCB manufacture was phased out in the United States in the 1970s, and a European ban followed in 1987. But that was already far too late.

Decades have gone by since the last PCBs were made, and still they’re poisoning the planet. The very same properties that made them so appealing for industrial uses now make them especially dangerous. They belong to a larger group of toxic synthetic substances, generally known as persistent organic pollutants,^c among them the insecticide toxaphene, which was used on American cotton crops in the 1960s; chlordane, which was sprayed over termite-infested houses; and the insecticide DDT, which American author Rachel Carson alerted the world to in her 1962 book Silent Spring. All these chemicals are toxic to humans and wildlife, and they’re all tough molecules that don’t easily break down.

More than a million metric tons of PCBs were manufactured between 1930 and 1993, and roughly 80 per cent of them still exist today. While it is possible to safely destroy PCBs by incineration at very high temperatures, there are massive stockpiles of them in old buildings, electrical equipment, bridges, ships, and landfill sites. As infrastructure crumbles and poorly managed rubbish dumps leach contaminants, more PCBs get into soils and waterways and eventually end up in the ocean. Another route to the ocean is through the air. The toxic molecules evaporate and get blown around the atmosphere before raining down on land and sea.

Once in the ocean, PCBs make their way into ecosystems by sticking in thin layers to the outside of phytoplankton and zooplankton, which then bestow their toxins to plankton-eating animals and on through the food web. PCBs are not readily shed back into the ocean but stay stored inside living cells and tissues, accumulating over an animal’s lifetime, until they’re passed on to the next predator or scavenger that comes along.

Even the deepest parts of the ocean are turning into a toxic soup. PCBs bind to organic particles of marine snow that drift downwards and feed multitudes of animals in the water column and on the deep seabed. The toxins are showing up in dangerous levels in the bodies of deep-sea shrimp and fish, in vampire squid that float in the twilight zone, in anemones and sea lilies, and in sea cucumbers that roam the abyssal seafloor. In the extreme depths of the Mariana Trench, between five and six miles down, sandhopper-like crustaceans called amphipods have levels of PCBs in their bodies fifty times higher than crabs living in paddy fields fed by the Liao River, one of the most polluted waterways in China.

PCBs and other organic pollutants are highly soluble in fats, which is why aquatic mammals with thick layers of blubber are at especially high risk. Seals, porpoises, beluga whales, narwhals, and polar bears have all been found with highly contaminated blubber, often way above thresholds that are known to suppress the immune system and interfere with reproduction.

Dolphins around the coasts of Europe live in small and declining populations that are producing few calves or none at all, a likely upshot of the toxins the adults are carrying in their bodies. In a study of male harbour porpoises around Britain, the more PCBs they’ve absorbed into their bodies, the smaller their testes and the lower their fertility. For decades, California sea lions have been dying of cancer at one of the highest rates found in any wild species. The disease is triggered by a herpes virus and made much worse by chronic exposure to organic pollutants, including DDT that was dumped in the ocean off California in the 1960s and PCBs that washed from the urbanised and industrialised coastline. Pollutants from industry and agriculture play their parts in the demise of endangered Yangtze finless porpoises in China and Ganges River dolphins in Nepal, India, and Bangladesh.

Even before they’re born, seals and cetaceans inherit a toxic load from their mothers via the placenta. Newborns then suckle on rich, fatty milk, which delivers yet more of their mother’s toxins. This is one likely reason Lulu the orca became so very contaminated—she wasn’t getting pregnant, giving birth, and feeding her calves. Normally, reproductive female orcas become less contaminated over time because they repeatedly pass on the pollutants to their offspring. Lulu just kept accumulating toxins.

A trio of traits makes orcas some of the most contaminated animals of all: they live a long time, they have a lot of fat, and they’re top-level predators. Orcas that feed the highest up the food chain are especially at risk from the magnified toxins. Around Iceland, orcas that hunt for seals and porpoises have been found to have PCB levels in their blubber almost ten times higher than orcas that eat only fish.

To get a handle on just how much of a threat PCBs are for orcas globally, a group of scientists simulated the species’ possible future in a toxic ocean. They compiled available data on the PCB concentrations in the blubber of orcas around the world and compared these to levels that are known to impact their immunity and reproduction. The team then built a computer model to predict how each population might change over the next hundred years, whether it would likely increase, stay roughly the same, or decline.

The model predicted that within a century, more than half of the world’s orca populations could collapse. Orcas suffer from such chronic exposure to PCBs that their immunity is weakened and reproduction impaired to the point where they may struggle to maintain their numbers. If adult orcas fail to rear offspring year after year, their populations will gradually dwindle and blink out, as already seems to be happening to Lulu’s West Coast Community off Scotland.

At greatest risk and most contaminated today are orcas living offshore from the industrialised regions that produced and used the most PCBs, including Japan, North America, and Europe. PCBs have also blown far and wide in the atmosphere, contaminating orcas in places where the chemicals were never used, from Greenland and the Faeroe Islands to the Ross Sea in Antarctica. No place is out of reach of these toxins.

Decades-old PCBs are not the only toxic threat to orcas and other marine life. A new chapter is opening in the chemical pollution of the planet and its ocean. When PCBs were phased out, the chemical industry, overseen by negligible regulation, developed new substances to take their place. Just like PCBs, these tend to be large, complex organic molecules that don’t occur in nature. Many are clustered in groups sharing similar chemical formulas, which have tough, waterproof properties; long, unpronounceable names; and horrible acronyms. One group that’s causing huge concern comprises the polyfluoroalkyl and perfluoroalkyl substances, or PFASs, which—just like PCBs—persist and accumulate in human bodies and the environment. They’ve been widely dubbed “forever chemicals”^d because they’re practically indestructible. It will take centuries for them to break down,^e and they’re everywhere, in fire extinguishers, smeared on non-stick cookware, sprayed on waterproof hiking jackets and snowsuits, added to stain guards for armchairs and school uniforms, and used as grease-proof coatings in pizza boxes, carry-out containers, and sandwich wrappers.

It’s no surprise at all that forever chemicals already pervade human lives. We breathe them in, absorb them through our skin, eat and drink them. A study in the United States revealed they contaminate the drinking-water supplies of at least two hundred million people. Experts suspect that forever chemicals are likely in the blood of every human on the planet, even unborn babies. And these chemicals are incredibly dangerous. Even tiny amounts increase the risk of cancer and are linked to a growing list of other serious health problems including birth defects, kidney disease, and liver damage.

Of course, these chemicals are also showing up everywhere in nature. They’re spraying into the atmosphere when waves crash on beaches and melting out of Arctic sea ice. They’ve been found in plankton, manatees, sea otters, and polar bears.

Truly daunting is the fact that forever chemicals are a messy mix of unregulated, unmonitored substances. There are at least fourteen thousand different types. The majority remain untested for their precise toxic thresholds, and for some, no method is available to detect their presence in the environment. So far, only two have been widely restricted for their dangerous toxicity. One of them, known as C8,^f was the subject of a long legal battle by US lawyer Robert Bilott, who unearthed evidence that chemical giant DuPont had continued to produce the chemical and contaminate water supplies long after knowing its toxic effects. Hundreds of millions of dollars in compensation have been paid out to people in contaminated communities, although the payouts apparently are not steep enough to persuade major players in the chemical industry to behave any differently. Like a stuck record, DuPont and another chemical manufacturer, Daikin, have known since 2010 about the dangers of another forever chemical^g used in food packaging, but hid the findings of their studies from the public and regulators, as revealed in an investigation by the Guardian.

There are, however, signs that the flow of forever chemicals into our bodies and the environment could be diminishing. In the United States, numerous state laws have banned forever chemicals in food containers and cookware. In California, forever chemicals aren’t allowed in clothing or cosmetics. Firefighting foams, which badly pollute local watercourses, are banned across much of the United States and Australia. Other countries, including Aotearoa (New Zealand), are considering similar restrictions on certain uses. Companies are also stepping up. One of the world’s biggest producers, 3M, has pledged to end manufacturing forever chemicals by the end of 2025. At a federal level, however, the US is not taking such bold moves. Regulators at the Environmental Protection Agency keep on changing their definition of what constitutes a forever chemical. In 2023, their view narrowed even further, excluding thousands of substances that won’t be regulated and instead the industry will be allowed to continue manufacturing and profiting from them.

What’s needed most urgently is a decisive ban on all forever chemicals, all in one go. This avoids the same loophole that’s been used many times before, when manufacturers replace one chemical from this dangerous group with a slightly different one that’s likely just as damaging, if not worse. And there’s a chance the European Union could lead the way in this bold move. In February 2023, the influential European Chemicals Agency proposed a ban on the production, sale, and use of the entire group of chemicals.

Meanwhile, the story of PCBs is still being told, and how it ends is going to depend on how nations deal with the legacy of these toxins. The Stockholm Convention on Persistent Organic Pollutants, which came into effect in 2004, bans their production globally and sets targets for phasing out their use by 2025 and cleaning up stockpiles by 2028. Many countries signed on to the convention but are likely to miss those targets. The United States has produced and used more PCBs than any other country (on average, more than four pounds per person), and billions of dollars have been spent on clean-up efforts. In 2001, General Electric was forced to pay to dredge New York’s Hudson River and remove PCB-laced toxic wastes the company had dumped over decades. But the United States isn’t party to the Stockholm Convention and has set no binding national deadlines for finishing the clean-up. Canada and the Czech Republic, showing it can be done, have already safely disposed of most of their stocks of pure PCBs and dealt with PCB-contaminated materials by actions like stripping out sealants and transistors from old apartment blocks and skyscrapers.

In the ocean, the phasing out of PCBs has been taking time to show an effect. Animal populations, such as the beluga whales of the Beaufort Sea on the fringes of the Arctic Ocean, are just as contaminated as they were decades ago. Pollutants in the bodies of striped dolphins in the Mediterranean dropped but then levelled off, and they remain worryingly high. And some species are gradually improving, as more of the chemicals already in the environment have settled into seabed sediments and new pollution is subsiding. The Franciscana dolphin, small and rare with a long, slender snout, lives along the coast of Brazil and regularly gets caught and dies in gill nets. Scientists have been measuring the persistent organic pollutants in the bodies of these dead dolphins and since 2000 have tracked a fall in their contamination.

It’s not often the case that reducing pollution is the single action that saves a species or a population in the ocean, because multiple threats exist. The more immediate problems may be overhunting or habitat destruction, but chronic exposure to pollutants weakens an ecosystem already stressed and depleted. Undoing the problem of pollution can give wildlife a much better chance of recovering and replenishing, allowing more young to survive and numbers to grow.

That is happening in the Baltic, a sea notorious for its troubled environmental history. For decades, this brackish sea that winds around the Scandinavian peninsula had suffered from overfishing, overhunting, and the pollutants pouring in from the nine surrounding industrialised countries. In the early twentieth century, a swift collapse of a whole suite of top marine predators occurred. Grey, ringed, and harbour seals and harbour porpoises were all vanishing and headed towards local extinction, as were cormorants and white-tailed sea eagles. The fish these birds hunt were depleted, and their bodies were tainted with DDT and PCBs. Very few large animals remained swimming in and flying above the Baltic. But the ecosystem was not too far gone. With hunting controlled, overfishing reined in, and chemicals banned, a dramatic revival began. Levels of PCBs in ringed and grey seals, as well as in the eggs of white-tailed sea eagles, have been steadily dropping since the 1970s, and now far more chicks and pups are surviving, raising the populations of birds and seals.

The fishing nets and ropes that tangled around the tail of Lulu the Scottish orca are the kinds of large plastic debris in the ocean that have gained a great deal of public attention and concern, and for good reasons. It’s heartbreaking to see animals harmed by the trash that ends up in the seas, whether it’s a seal with a plastic ring cutting into its neck, a sea turtle with bundles of plastic bags stuffed in its stomach, or dolphins drowned in ghost fishing nets that break away and drift by themselves, still pointlessly catching and killing wildlife. But there’s mounting evidence that an even greater danger is posed by an invisible smog of minute plastic particles that contaminate every part of the global ocean.

Recent estimates indicate there are between 82 and 358 trillion microplastic particles afloat in the ocean, each measuring less than one-twentieth of an inch across and cumulatively weighing as much as 4.9 million metric tons—roughly twice the weight of all the African elephants alive today. This plastic burden will get worse in the future, not just because plastics will keep getting dumped into the ocean but from the breakdown of the larger plastics already there, creating a toxicity debt that will linger for decades to come.

The global impact this is having on ocean life is complex and poorly understood, but already it’s obvious that the smaller the plastic particle, the greater the harm it can cause. Microplastics enter ocean food webs when they are eaten by zooplankton and small fish. Copepods, flea-size crustaceans, are among the most abundant zooplankton. They create water currents with their flickering legs and antennae that draw particles towards their mouths. If they taste an inert plastic particle, they will sometimes spit it out, but not if it’s mixed in with their phytoplankton food, in which case they swallow the whole lot together. Once in the guts of these tiny animals, microplastics can build up and stop them from feeding. Microplastics also interfere with the gut microbiome, the mix of microbes that are essential for an animal’s healthy immune function and nutrition; even their behaviour can be affected by plastic-induced changes in their microbiome.

Laboratory studies suggest that much of the microplastic fish swallow is excreted in their faeces within a week, which should limit the harm they do. However, microplastics break down and get even tinier, entering the size range of nanoparticles^h and raising the likelihood they will stay in the body and accumulate in tissues. Nanoparticles can get inside living cells and pass from the gut into the blood system and then distribute all around the body and into the brain. They can alter expression of genes and elicit inflammatory immune responses.

In addition to their direct impacts, plastic particles also act like Trojan horses, bringing other dangerous substances inside living bodies. Chemical additives are used to manufacture plastics that are tough, flexible, and flame-retardant, and many are known to be toxic, such as bisphenol A (BPA), commonly used in water bottles and food cans. Plastic debris also picks up toxic molecules from the ocean, including PCBs and other persistent organic pollutants, adding to the flow of these chemicals into food webs. Another concern is that microplastics can carry pathogenic bacteria and viruses.

Thousands of ocean species have been found with microplastics inside their bodies, either eaten directly or passed to them from their prey. Plastic-contaminated animals are entering the human food chain, creating potential health risks, especially for coastal communities reliant on seafood for their nutrition. In the wild, the animals likely at greatest risk from microplastic pollution are baleen whales, which filter and strain small prey from seawater using bristles inside their enormous mouths. A 2022 study calculated the microplastic load picked up by whales when they visit the California coast each year to feed. Data from tags fixed onto diving whales showed they mainly forage between around 160 and 820 feet down, which overlaps with a zone containing ten times more microplastics than the surface. The whales don’t filter microplastics directly from seawater but mostly consume them via their diet of krill and fish, such as anchovies, which they eat in colossal quantities. A fin whale can take in close to six million plastic particles every day. A blue whale consumes more than ten million particles per day, cumulatively weighing as much as ninety-six pounds. Over the course of the four-month feeding season, each blue whale likely consumes more than a billion plastic particles. Owing to its krill-rich diet, the biggest animal that ever existed is being contaminated by infinitesimal flecks of synthetic materials because krill crush the microplastics into even smaller nanoparticles when they feed. And the Pacific waters off California where this study was conducted are by no means the most contaminated in the world ocean. Baleen whales elsewhere are likely consuming even more plastic, and they will continue to do so as long as plastic debris keeps entering the ocean.

For decades, humans have been transforming the ocean homes of whales across the globe, introducing a potent mix of chemical pollution and many other threats. One of the most endangered populations of orcas, known as the Southern Resident Community and made up of three distinct pods, lives along the Pacific coast of the United States and Canada, where fewer than eighty individuals remain. Its members are expert fish hunters and depend on Chinook salmon as their main source of food. Declines in Chinook, especially the fattiest spring migrants heading inland to spawn, are making it harder for the orcas to find enough food. The orcas’ bodies are contaminated with pollutants, including PCBs and 4-nonylphenol, a chemical used in paper, textile, and detergent processing, and commonly found in toilet paper, that escapes into the environment via sewage treatment plants. Furthermore, the habitat of these orcas has become increasingly noisy. Southern Residents spend the summer months in the Salish Sea, a busy inland waterway bordered by major Canadian and US port cities, including Seattle, Vancouver, and Victoria, and crisscrossed by international shipping lanes and ferry routes. The underwater roar of engines masks the orcas’ repertoire of pulse calls, jaw clacks, and bellows. Whirling propellors create streams of cavitation bubbles that collapse and pop at the same frequency as the echolocation sounds that orcas use to hunt. These highly sonic animals have trouble communicating with each other and hearing echoes bouncing off their prey while subjected to a din roughly equivalent to a lawnmower thundering past.