In 2001, fishers discovered the new aggregation forming at Little Cayman’s western end, where none had been seen previously. That year, around seven thousand groupers gathered, and fishers caught some two thousand of them in one week of fishing. The following year, when the remaining groupers came back to spawn, fishers caught another two thousand. At that point, local authorities stepped in and introduced strict regulations on fishing. Initially, a year-on, year-off rule was brought in for fishing the aggregation site, with a catch limit of twelve Nassau groupers per boat per day. The aggregation continued to shrink in size, and in 2003, the regulations were strengthened to a blanket ban on fishing throughout the winter spawning months. Now it’s illegal to catch, own, or sell a Nassau grouper between December and April anywhere in the Cayman Islands. The rest of the year, people are still allowed to catch them, although not using spearguns, and with a daily catch limit of five fish per boat.
As Nassau grouper populations began to collapse throughout the Caribbean, other countries introduced protection measures, but so far only in the Cayman Islands is their recovery obviously underway. The aggregation at Little Cayman is the largest known spawning site for the entire species, and it’s growing.
Diving scientists have been conducting yearly surveys, measuring individual fish with laser dots projected onto the sides of their bodies and tagging them to see how often they come back to spawn and to estimate the total size of the population. Over the course of fifteen years, the numbers of Nassau groupers at Little Cayman has gradually increased—not a smooth and consistent recovery, but over time the population has tripled in size, returning to an abundance approaching that before the fishing spree began at the start of the century. There are also signs of recovery at a spawning site on the nearby island Cayman Brac.
The Nassau grouper is one of many coral-reef fish species that congregate in huge numbers to spawn and have historically been targeted, overfished, and extirpated. The message from the Cayman Islands is that recovery of these endangered populations is possible, but it takes commitment, patience, and time.
A lot of ocean animals are in trouble because humans are overexploiting them to the point that the survivors can’t replace the lost ones fast enough. Without human interference, wild species are killed and eaten by other animals, and while populations naturally fluctuate, in general a balance is struck between predators and prey so that neither explodes nor collapses. Humans add to the predation pressure, and as long as they are not too greedy, prey populations can keep pace and maintain themselves. And if the numbers of targeted prey animals begin to dwindle, there are simple steps to take to avoid their extirpation. Reduce the number that are hunted, fished, and extracted, and populations should recover and restore.
At times, this has happened rather by chance. A little over a century ago, on beaches along the Pacific coast of California and Mexico, commercial sealers crept up on northern elephant seals as they were lined up like so many giant, furry sardines, the titanic, fifteen-foot-long males fighting each other, raising their bulbous-snouted heads and bellowing at the sky. While the seals were trying to mate and rear their young, sealers killed them for their blubber to render down and burn in oil lamps. The slaughter only stopped when there seemed to be no more seals to kill, and the species was presumed to be extinct. Then, in 1892, scientists from the Smithsonian Institution visiting Guadalupe Island, 150 miles off the coast of Mexico, found nine elephant seals alive and well. The species wasn’t extinct after all—but the scientists didn’t help the situation. Presuming the seals were on their way out anyway, they killed seven to take back to the museum.
In the following decades, more scientific expeditions went to Guadalupe Island and found the elephant seals were still not quite gone, and they carried on catching them. Some seals were kept alive and displayed at public aquariums, where generally they died after a year or two. More were killed and stuffed for museum exhibits. Fortunately for the seals, the commercial trade in blubber was moving on as fossil fuels were replacing animal fats and oils, so pressure from sealers was reduced. Despite scientists showing up now and then to grab more seals, their numbers gradually began to increase. In July 1922, when a survey counted 264 elephant seals on Guadalupe Island, the species was finally deemed worthy of protection. That same year, it became illegal to hunt elephant seals in Mexico, and soon after in the United States.
An American zoologist from the San Diego Natural History Museum, Laurence M. Huey, went on several trips to Guadalupe and witnessed the early days of the seals’ recovery. In 1930 he wrote: “Let us trust that it may continue, that again this largest of all seals may inhabit its former hauling grounds and prevent at least one black deed from entering the annals of man’s wanton destruction.”
Huey would surely have been happy to know that elephant seals have continued to make a good recovery. All that was needed to save the species was for people to stop hunting them. Now, to see a northern elephant seal no longer requires a boat trip to Guadalupe Island. At certain times of year, along California State Route 1, the highway that skirts the Pacific Ocean, drivers can call in at several beaches and watch elephant seals snoozing on the sand. The total number of northern elephant seals, ranging from Castle Rock in Washington State to Isla Natividad off Baja California Sur,a is now estimated to be in the region of two hundred thousand.
Helping ocean life to recover is relatively effortless when commercial industries have given up hunting threatened species and moved on to something else, as the sealers did. It’s much harder to find ways of killing fewer animals when they’re still in high demand, but it can be done. In October 2020, off the coast of Cornwall, where England dips its foot into the North Atlantic, surfers witnessed, for a few brief, implausible moments, a massive fish leaping from the sea. The giant bluefin tuna jumped again and then a third time, as if to say, “I am here. We are back.” For decades, the spectacle of bluefin tuna had been missing from British waters. They had been gone for so long, most people had no idea they were ever there.
Commonly growing to between six and ten feet long, Atlantic bluefins are the biggest of the three bluefin-tuna species. The other two live in the Pacific Ocean. They all look like they’ve been cast from polished steel into a teardrop shape, painted indigo along their back, and given an elegant, crescent tail, and pectoral fins that fold away into slots in the sides of the body to improve streamlining while cruising at high speed. As they swim, bluefin tuna keep their body stiff and push their tails from side to side, in the classic thunniform style.b To breathe, they open their mouths and let water flow over their gills, supplying oxygen to the ruby-coloured muscles that power their long-distance endurance swimming.
Bluefin tuna in the Atlantic were being fished as long ago as the Stone Age. In a cave on the Rock of Gibraltar, archaeologists have found prehistoric remains of bluefin-tuna bones dating back more than twenty-two thousand years, which could have been left there by Neanderthals. Perhaps early hominids didn’t fish for bluefins but scavenged them from beaches after pods of orcas chased them onto shore. Farther to the east and thousands of years later, during the Mesolithic, on the small island of Levanzo near Sicily, people painted images in a cave that look a lot like bluefin tuna. Dated to around ninety-two hundred years ago, this is the earliest reliable evidence that people had started fishing for bluefins in the Mediterranean. To go to the trouble of painting them, people must have thought these fish were important.
Commercial fisheries for bluefin tuna got underway across the Mediterranean during the time of the Phoenician civilization and the Roman Empire.c People caught bluefins in traps and beach-seine nets, preserved them in salting factories, and traded them in earthenware amphorae. Bluefins were one of the species that ancient Romans processed into the flavour-enhancing condiment garum, by laying out leftover trimmings, intestines, and blood to ferment in the sun. In fishing settlements from Turkey to Morocco, coins were minted with bluefin-tuna designs.
Archaeological remains show that bluefin tuna were also caught for millennia in the waters of northern Europe, and there, during the early part of the twentieth century, fishing effort increased. Fishers had known about the enormous tuna that swam into the region each year as they chased after smaller forage fish, like herring and mackerel, the same shoals that fishers themselves were after. In the early 1900s, in Øresund, the narrow strait between Denmark and Sweden, Danish fishers used bluefin tuna as scouts, following them to find and catch shoals of needle-shaped garfish. In the 1920s, Norwegian fishers complained about bluefin tuna ruining their nets by grabbing for any stray fish while the catches were being hauled in.
Herring fishers occasionally caught bluefins in their nets and traps and soon realised they could sell the huge fish for a good price. A photograph from 1910 of a German fish auction hall shows a dozen bluefins lined up on the floor waiting to be sold. Around the same time, fish markets in the northern French town of Boulogne sold bluefins that fishers caught over Dogger Bank in the North Sea. Canning factories began opening in Denmark and Norway to process the growing catches of bluefins.
While commercial fishers looked to profit from bluefin tuna, sport fishers also turned their attention to these giants. A Danish sport fishery for bluefins opened in the 1920s. In 1928, one fisher single-handedly caught sixty-two tuna in the Kattegat sea.
The Tunny Club opened in 1930 in the coastal town of Scarborough in northern England. Members of the aristocracy and movie stars, including John Wayne and Errol Flynn, motored offshore in search of bluefins in the oceanic equivalent of big-game hunting parties in Kenya and India. Men and women strapped themselves into reinforced harnesses and hooked bluefins on enormous rods, often with a team of professional fishers on hand to help reel in the catches.
A silent film from 1933 documents one such trip as people wrestled with the wildly thrashing fish. “And so closes a perfect day,” the caption card reads on-screen, followed by a shot of at least eight enormous tuna lying dead on deck, outsizing and outnumbering the smiling people on board. That same year, a UK record-breaking bluefin tuna was caught, weighing 851 pounds, almost twice as heavy as a mature male Bengal tiger.
Sport fishing for bluefin tuna also became popular in the western Atlantic along the US coast. Small bluefins were being caught along the coast as early as the 1850s. When stronger tackle was developed in the 1900s, anglers began battling larger animals. American author Ernest Hemingway was a big fan of hunting bluefins in the Bahamas.
Meanwhile, industrial fisheries in northern Europe were inventing more efficient ways of catching bluefins on an industrial scale. People started shooting them one by one at the surface with harpoon rifles. In Norway, fishers experimented with a new type of fishing gear, laying out a great loop of net to engulf an entire shoal of tuna in one go. At first, these early purse seines didn’t work well because the muscular fish shredded the nets when they were trapped. By the 1950s, Norwegians had developed sturdier nets and mechanical winches to drag them back on deck, and the new industry snowballed. In 1949, there were forty-three boats in the Norwegian tuna fishery. A year later there were two hundred, making it Europe’s biggest bluefin-tuna fishery.
As technologies advanced and fishing intensity increased, so did catches of bluefin tuna—but only to a point. By the early 1970s, bluefin fisheries in northern Europe had collapsed, and the species disappeared from Skagerrak, Kattegat, and Øresund, from the Norwegian and North Seas.
Elsewhere, fishing for bluefins continued. Purse-seine fisheries opened along the US eastern seaboard. Japanese longliners entered the Atlantic, taking bluefins while targeting yellowfin and albacore tuna for canning.
A major turning point in the Atlantic came in the 1970s, when a new appetite for bluefins took off. American anglers were catching bluefins but mostly not eating them, because the meaty flavour didn’t appeal. Often the giant fish were thrown away or sold to pet-food factories. However, Japanese businessmen spotted an opportunity. The market in electronic devices, like cameras and personal radios, was booming with major exports from Japan to the United States. Rather than returning to Tokyo with empty cargo planes, Japanese airlines began filling up on cheap frozen tuna. This wasn’t a traditional ingredient in Japanese cuisine, but tastes were changing. During the Second World War, American imports of meat to the Pacific, including processed Spam, had introduced Japanese people to meatier flavours, priming them for bluefin tuna.
A trend for bluefin sashimi caught on in Japan, and it became embedded within the food culture. Today, at showcase fish auctions each New Year, sushi magnates bid millions of dollars for individual bluefin tuna. This is mostly a marketing stunt aimed at stirring interest among consumers, and prices are less extortionate the rest of the year, but still, there’s enormous demand.
The 1990s saw a swift rise in bluefin fishing across the Atlantic. In the Mediterranean, fisheries started using small aircraft to spot tuna shoals from the air and send in fishing vessels to scoop them up in giant purse-seine nets. A new technique emerged of catching younger tuna to rear in giant cages at sea, fattening them up before shipping them to Japan. Within a few decades, the wild populations of Atlantic bluefins had shrunk by at least half, and as the fishing frenzy continued, the species urgently needed protecting.
By then, an organisation responsible for regulating bluefin-tuna fishing already existed, the International Convention for the Conservation of Atlantic Tunas (ICCAT).d Its remit was to assess the tuna populations and set quotas that would prevent the species from being overfished. But amid the bluefin crisis, ICCAT soon earned itself an appalling reputation. A panel of expert scientists reviewed the organisation’s performance and declared it to be an international disgrace. Environmental campaigners called it the International Conspiracy to Catch All Tunas.
In 2006, a recovery plan was introduced aimed at making the fishery sustainable by 2022. Scientists at ICCAT advised that the only way the population could recover was to limit the catch to no more than 15,000 metric tons of bluefins per year. But as happened repeatedly, ICCAT ignored the recommendations and set the catch limit at 29,500 metric tons. The actual catch, including estimates of illegal and unreported fishing, was more than double that.
In 2009, the stakes were raised. Environmentalists were piling on the pressure to protect the Atlantic bluefin tuna. A campaign was launched to add the species to the Convention on International Trade in Endangered Species (CITES). An Appendix I listing would prohibit all international trade, placing bluefin tuna alongside such famously endangered species as the giant panda, Asian elephant, and tiger.
Despite meeting the necessary criteria for a CITES listing, the proposal was rejected—but the message of bluefin endangerment had finally got through. Decision-makers at ICCAT listened at last to their scientific advisers and late in 2009 agreed to cut the quota to 13,500 metric tons.
A little over a decade later, there are signs that the tuna recovery plan is working. Atlantic bluefin tuna are no longer vanishing in droves from the seas; their numbers seem to be tentatively increasing, and they are beginning to show up again in their former haunts.
Off the west coast of Ireland in the Celtic Sea, and in the English Channel, fishers, scientists, surfers, and wildlife tour operators have started witnessing spectacular giant fish leaping from the sea. They’ve seen the water boiling where shoals of bluefins were swimming near the surface. Divers and underwater photographers have seen bluefins hunting tight, swirling bait balls of silvery fish.
Bluefin tuna are also coming back to Nordic seas. Animals of a similar size to ones seen and caught in the 1960s are once again migrating along the Norwegian coast. But there have been no signs of tuna returning to the English coasts of the North Sea. It’s possible the 1930s sport fisheries took out all the biggest fish, the ones that put up the best fight. These older animals—bluefins can live for forty or fifty years—would have passed on their knowledge to other tuna of the best feeding grounds. But without those ocean elders, new generations of bluefins may have no way of knowing that the waters of the North Sea are worth visiting.
There’s no practical way to count exactly how many bluefins are swimming around the Atlantic, and it’s hard to know for sure how the species is doing. Fisheries scientists base their quota recommendations on stock assessments, which estimate a population size based on various available data, including how many tuna the fisheries are catching. There’s a lot of uncertainty in models like this. For instance, ICCAT scientists manage bluefins as two separate stocks, on the eastern and western sides of the Atlantic, although satellite tagging studies show that some tuna swim all the way across the ocean, and there is some mixing between eastern and western populations. Nevertheless, there are good signs that compared to past decades of crisis, these are now relatively good times for Atlantic bluefin tuna. In 2021, the species was moved off the Red List of Threatened Species. Even though experts don’t have a clear idea of just how the entire population is changing, they cautiously think there’s no immediate risk of Atlantic bluefin tuna going extinct.
It’s not all good news for tuna, though. While eastern Atlantic bluefins appear to be on the rise, the western population that spawns in the Gulf of Mexico has been in continual decline for the past forty years. But because those western tuna constitute only a small part of the total population, the species as a whole is still considered to be out of trouble.
The warming ocean adds another layer of complexity to the picture of recovering tuna. There are natural fluctuations year to year in tuna abundance and their prey, likely linked to the climate. One theory for the return of tuna to Scandinavian waters is that a 2003 heatwave in the Mediterranean allowed a large portion of tuna larvae to survive. When these young tuna matured in the 2010s, they started showing up as adults in feeding grounds off Norway.
Bluefin tuna are also going much farther north than they used to, some crossing the Arctic Circle and reaching as far as Svalbard, only five hundred miles from the North Pole. They’ve also recently been seen for the first time in the seas around Greenland. Bluefins are likely following shoals of mackerel, which are expanding their range north as the ocean warms. Big, old tuna can survive in these cold waters by virtue of their size; this biological feat, known as gigantothermy, allows the tuna’s large muscles to generate a lot of heat, which is held in their bodies via a network of blood vessels around their gills, keeping their vital organs warm and their vision sharp in their golf ball–size eyes.
Other tuna species also seem to be doing better than they have been in recent times. The southern bluefin tuna, previously classified on the Red List as Critically Endangered, was upgraded to merely Endangered in 2021. Albacore tuna is now thought to be out of jeopardy. Likewise, the bluefins’ sister species, the yellowfin tuna, is on a path to recovery, although it is still being badly overfished in the Indian Ocean. In early 2023, the Indian Ocean Tuna Commission (the region’s equivalent of ICCAT) voted to phase down a controversial technique used for catching tuna. Fish aggregating devices (FADs) are clumps of plastic netting and lines that fishers set adrift in the ocean to attract sea life that come in to seek shelter. Tuna then show up to hunt the smaller fish. Fishing vessels encircle the whole lot in huge seine nets, catching everything there, including juvenile tuna, sea turtles, sharks, and dolphins. New measures proposed by a dozen Asian and African nations include a reduction in the number of FADs each vessel can deploy and a seventy-two-day period each year when the devices are banned, all in the hope of allowing yellowfins and other ocean life forms to recover. A short while after the vote went through, the European Union, which runs the largest tuna fisheries in the Indian Ocean, announced it was exempting itself and would not comply with the new ruling.
The future of many species that roam the open ocean depends on the precarious balance of international diplomacy. Disagreements are raging over bluefin tuna too. Turkey has repeatedly lodged objections to the catch limits set by ICCAT and has decided it is allowed far higher bluefin quotas in the Mediterranean, claiming they represent the country’s historic share of the catch. If other countries decide to follow suit and adopt similar tactics, the scientific advice could become powerless, and Atlantic bluefin populations could once again be in danger of collapse.
Even with such ups and downs, it’s not too soon to celebrate the recovery of bluefin tuna or Nassau grouper or any of the other species that still exist in the ocean when they could so easily have already disappeared. To pull any species back from the brink of extinction, rather than carelessly or deliberately push it over, is a promising step in the right direction.
Such victories may yet be only a slight return to healthier, more abundant ocean life, compared to what it once was, and recent progress must be maintained. We also need to determine where to set our sights next. What can we aim and hope for? How many tuna, or grouper, is the right number? How many is enough?
