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 nanoparticlesh 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.
A ship passing within a few hundred yards will commonly cause orcas to end their foraging dives. Presumably, they intuitively understand that when so much other noise is raging around them, trying to hunt with intricate beams of sound is pointless. Females are especially sensitive and halt their hunts more often than males, likely because they have offspring to look out for. Nonstop disturbances while they’re trying to forage could mean females go hungry and struggle to produce enough milk for their young.
Compared to the lingering legacy of toxic chemicals, a much simpler solution for noise pollution can be implemented. When ships slow down, they immediately quieten down. Trials of voluntary reduced speeds in parts of the Salish Sea have successfully reduced the background volume in orcas’ foraging grounds. When ships passing through are slower and quieter, orcas spend more time hunting and feeding.
A few Southern Resident orcas haven’t experienced the growing volume and toxicity in the ocean because they were taken away from it. In 1964, a young male from the community was the first orca to survive in captivity for more than a few days. Collectors had planned to kill him and use his carcass as a mould to sculpt a replica for the Vancouver Aquarium, but amazingly the orca survived, even after the harpoon fractured his skull and damaged his brain. Mistaken for a female, he was given the name Moby Doll and put on public display in a sea pen off a beach in Vancouver for just one day, and thousands of people came to see him. From then on, out of the public eye, his keepers struggled to work out what to feed him, and after three months in captivity, Moby Doll died. His short life was enough to demonstrate that it was possible to keep orcas in captivity and, more importantly, that the public was keen to watch them.
After that, around one-third of the Southern Resident community was captured and sold to aquariums and theme parks, including a young female originally known as Tokitae. She was around four years old when she was taken from her family in 1970 and sent to Miami Seaquarium in Florida. Tokitae was trained to leap and do stunts. For performances she was renamed Lolita and paired up with an older male from the same community called Hugo. For a decade, Tokitae and Hugo were kept together and performed tricks for the crowds twice a day in the smallest orca aquarium tank in the United States.i They mated many times, but Tokitae never gave birth to a live calf. Hugo died in 1980 after incessantly ramming his head against the side of the tank. Thereafter, Tokitae was kept in isolation from her species. She was the last Southern Resident orca in captivity.j
During the time of Tokitae’s confinement in the Florida aquarium, the tide turned against keeping orcas in captivity. A watershed moment came in 2013 with the release of the feature-length documentary Blackfish. It told the tragic story of Tilikum, an orca captured in Iceland and then sent to SeaWorld in Orlando, Florida, where he killed several trainers, his aggression symptomatic of post-traumatic stress disorder induced by a captive life. The film triggered public outcry, attendance at SeaWorld slumped, and the American public became disenchanted with the unethical spectacle of confined, performing animals.
For decades, campaigners pleaded for Tokitae to be released from captivity and returned to her native waters. Among the most passionate advocates for her return were members of Washington State’s indigenous Lummi nation, who have cultural and spiritual ties to the Southern Resident orcas, known to them as qwe’lhol’mechen, the people beneath the waves.
In March 2022, Tokitae was retired from public shows. A year later, Miami Seaquarium finally agreed to release her. The plan was for Tokitae, or Sk’aliCh’elh-tenaut, as the Lummi people know her, to be flown to the Pacific and transferred to an open-water enclosure in the Salish Sea, then perhaps one day allowed to swim free. There she would have found out how much her home waters had changed since she was taken away. She would have sensed the tang of unfamiliar chemicals in the seawater and in the fish she ate. She would have heard how noisy and crowded these seas had become. She might have heard calls she remembered from more than fifty years ago and known that her community was somewhere nearby. She may have even recognised the sounds of the elder female orca who is still alive in the wild and likely is her mother. And it’s possible Tokitae would have mourned the orcas from her community who are no longer there, the ones who like her were sold into captivity. But Tokitae never made it home. On August 18, 2023, she died while still in the same concrete tank she had been held in for fifty-three years at Miami Seaquarium. She was fifty-seven years old.
A few days later, hundreds of people gathered at Jackson Beach Park on San Juan Island, in the heart of the home waters of the Southern Resident orcas. Mourners laid flowers on a totem that in 2018 had been taken from the Salish Sea to the Seaquarium and back, and they listened to some of Tokitae’s last calls recorded shortly before she died. Lummi dignitaries and elders asked those present to remember not just Tokitae but the rest of her family, the seventy-five remaining members of the community who are struggling to survive in the wild.
While humans have turned them into captives and spoiled their world, orcas have shown they are capable of great madness and also great sadness. In July 2018, an orca known as Tahlequah was the first member of the Southern Resident Community to give birth to a live calf in three years. But the newborn lived for only a half hour. Why it died so soon, nobody knows for sure, but polluted waters were likely at least partly to blame. Neonate orcas have washed up on beaches in other places, and scientists have tested their bodies and found them loaded with PCBs and other dangerous chemicals. After her baby died, and for the next seventeen days, Tahlequah carried the small body with her as she followed her pod on what became a thousand-mile funeral cortege. Each time the dead calf began to slide into the deep, Tahlequah swam down and brought it back to the surface, balancing it on her nose. She was grieving, orca experts widely agree, and wasn’t ready to let her calf go.
It’s not too anthropomorphic to imagine that orcas can feel sorrow for their changing ocean, as they watch their calves dying far more frequently than before and grieve the lost ones. And some orcas, maybe, are witnessing their ocean changing around them and getting angry about it.
Off the coasts of Spain and Portugal, orcas have been behaving strangely of late. This is another highly endangered group, made up of at most thirty-nine animals. They visit the Strait of Gibraltar each year to feed on Atlantic bluefin tuna that swim into the Mediterranean to spawn. The orcas give chase until the exhausted tuna can swim no more. Some orcas have also learned to save their energy and pick off tuna from fishing lines in a local fishery. Then, in 2020, some of these tuna-hunting orcas began deliberately ramming into boats. Dozens of sailors have reported seeing groups of orcas swimming up behind their yachts and then slamming their bodies against the vessel repeatedly, for up to two hours at a time. The orcas bring the boats to a sudden halt and turn them in circles. Often their final act is to snap off the rudder, leaving the boat without steering. In most instances, the skipper and crew have radioed for assistance and a tow back to shore, but on several occasions, boats were rammed so badly they sank, although with no harm to the people on board.
This previously unseen behaviour has continued in Iberian waters, and scientists remain mystified as to why it’s happening. Many experts are keen to avoid labelling these as calculated attacks or projecting human-centric motivations on the orcas. Some think it could have been started by a few curious and boisterous orcas, and then others joined in until the situation got rather out of hand. The plot thickened in June 2023, when orcas from a different group, two thousand miles to the north of Gibraltar, repeatedly rammed into a yacht off the Shetland Islands of Scotland. How and why they developed a similar habit is yet another mystery. It’s possible highly mobile orca pods have been swimming long distances and passing on the idea of messing with boats, or the Scottish orcas could have started doing it all by themselves. And it’s possible one day they will all just stop. Orcas are known to pick up new habits, then drop them just as quickly. In the 1990s, one orca pod began killing fish and carrying them around on their noses; after a while, they stopped. Boat bumping could just be the latest vogue that started among the Gibraltar orcas and is catching on elsewhere.
But it’s not out of the question that something more complicated is going on. Several of the orcas involved in this unusual behaviour, the unruly ringleaders, were found to have recent injuries, likely from collisions with boats travelling at speed. These orcas may have finally grown fed up with living in a busy shipping lane and figured out how to deliberately slow boats down, targeting yachts because they’re easier to take on than larger craft.
a The others are short-finned pilot whales, belugas, narwhals, and humans.
b PCB compounds contain two rings of carbon atoms with multiple chlorine atoms attached.
c Organic in the chemical sense, meaning these are molecules that contain carbon atoms bonded to each other and to hydrogen atoms.
d In December 2023 the phrase “forever chemical” was added to the Oxford English Dictionary, a historical record of the English language that notes first use and meanings of words.
e One reason PFASs are so tough is because they contain carbon-fluorine bonds, one of the strongest chemical bonds in existence.
f C8 refers to the chain of carbon atoms in the structure of this chemical, perfluorooctanoic acid, or PFOA.
g This one is called 6:2 fluorotelomer alcohol, or 6:2 FTOH.
h Nanoparticles are between one and one thousand nanometres in size; there are more than twenty-five million nanometres in one inch.
i Their concrete tank was eighty by thirty-five feet and twenty feet deep; Tokitae measured twenty feet long.
j At time of writing, fifty-four orcas from other communities were kept elsewhere in captive conditions.
PART THREE
OCEAN REVIVAL
Chapter 6
Restoring Seas
In the Caribbean Sea, roughly halfway between Havana, Cuba, and Kingston, Jamaica, lies the island of Little Cayman. At ten miles long and a mile wide, it’s the smallest of the three Cayman Islands. Known best, perhaps, as a tax haven, these islands are also a haven for fish. During the winter months, when the moon is full, the sea off the western end of Little Cayman fills up with Nassau groupers. For most of the year these large predatory fish, one to two feet long, live solitary lives on the coral reef that fringes the island. But they know, when the time comes, to gather—maybe they sense the strengthening pull of the spring tide, or they notice the moon shining down—and they set off, intently swimming towards the same destination. On the outer shelf of the reef, in an area roughly the size of London’s Trafalgar Square, thousands of groupers congregate. The milling shoal can become so dense no water can be seen between fish. Then, a secret signal goes out, and a dozen or more groupers at a time pinch off from the group and rush towards the surface, aiming for a spot in the water above their heads. Their bodies form a brief, shivering huddle, and a second later they split apart, leaving behind a cloud of eggs mixing with sperm. This is how new groupers are made.
Flocking together in large shoals most likely boosts each grouper’s chances of reproducing successfully. Fish and their fertilised eggs are generally safer in numbers and less vulnerable to predators, which can’t possibly eat every last one of them. Timing is key for these events, coinciding with the strongest tides so the fertilised eggs are swept offshore, away from the reef and the many hungry animals that live there. After a month spent afloat at sea as tiny larvae, growing and learning to swim, juvenile groupers are ready to return to the reef.
Aggregations like this are now a rare spectacle, but they used to occur across the Caribbean. The first scientist to publish an eyewitness account of an enormous Nassau grouper spawning aggregation was C. Lavett “Smitty” Smith, curator of ichthyology at the American Museum of Natural History. In 1972, he visited Cat Bay in the Bahamas and reported seeing at least thirty thousand and perhaps as many as one hundred thousand groupers coming together to spawn.
On reefs and atolls in many Caribbean countries, Nassau groupers would periodically migrate to their spawning grounds, at the same places and times year after year, some of them swimming for hundreds of miles to get there. However, the predictable timing of these events made them easy targets for fishers. Nassau groupers used to be the mainstay of fisheries in the region year-round, but the biggest catches were taken from aggregation sites during the brief spawning seasons. As a result, breeding populations were run down until their numbers were so low the adult fish no longer showed up to spawn. Nassau grouper aggregations shrank, then one by one, they blinked out.
That’s what happened in the Cayman Islands. Several historic spawning grounds were wiped out, including one at the eastern end of Little Cayman that formed until 1993; then the fish stopped coming, and so did the fishers. But the Nassau groupers were not entirely gone. They have long lifespans, up to at least thirty years, and they can wait out many seasons without spawning, and then come together again when conditions suit them.
