Commonly, the people who ultimately have the most influence in deciding how many fish there should be in the ocean are industrialists who run the fisheries that profit from these species and the lobbyists working for them. The question they’re asking is a slightly different one: How large do fish populations need to be before they can push quotas back up and start catching more?
The reality is that bluefin tuna are being carefully managed not just so they can continue to exist for their own sake but mainly so they can continue to be hunted. There is an underlying presumption that the ocean provides animals for humans to hunt and eat and, perhaps most importantly, make money from. It’s why organisations like ICCAT exist. In the years since Atlantic bluefin numbers have begun to climb, ICCAT already has been raising the catch limit back upwards, bowing to pressure from industrial fishing nations. Sport fisheries for bluefins, likewise, have reopened in Scandinavia, although with the strict requirement that animals are not to be killed but let go alive—and hopefully that they can survive after their battle on a fishing line. Sport fishers in the UK can now buy licenses to catch bluefin tuna, as long as they fix marker tags on the fish and then set them free, to help assess the size of the stock. In August 2023, the UK government took advantage of its post-Brexit freedom from European Union regulations and unilaterally decided there were already enough bluefin tuna swimming into British waters to justify restarting a commercial fishery.
People are always going to fish and hunt in the ocean, but the future will look very different depending on who gets to make decisions about fishing. Well-run, sustainable fisheries are certainly a better option than allowing industrial vessels to do as they please. The problem is that there is no single definition of sustainability.
The mainstream view of commercial fishing is to run operations to catch as much as possible and maximise profits without causing fish populations to decline. That’s currently the situation with roughly two-thirds of the world’s fisheries. Catches are reasonably stable and could continue that way for years to come. In that sense, these fisheries are sustainable. But those fish are far less abundant than they would be without people catching them. In most species, fished populations are roughly half the size they were before intensive fishing began. That means the ocean could and should contain a whole lot more life than it does today. An alternative view is to think of fish and other sea life not as a resource to profit from but as animals that have their own right to exist.
The notion of sustainability can easily be pulled in different directions and co-opted by those wanting to exploit the seas for profit. Call it the “blue economy” or “blue growth,” stick an eco-label on it, and it’s easy to fall back on the idea that the only true value of the ocean is the money it can generate. That’s one reason talk had begun of lifting the global ban on industrial whaling, a hard-won triumph for the ocean that’s been in place since the 1980s. Since then, many species of great whales have been slowly showing signs of recovery from centuries of intensive exploitation. More humpback whales are returning to the Southern Ocean to gorge on Antarctic krill. Blue whales are swimming around the subantarctic island of South Georgia again. During the commercial whaling heyday in the early twentieth century, as many as four thousand blue whales were killed in South Georgian waters every year. Then, for decades, nobody saw any of these animals there at all. Eventually, blue whale numbers gradually began to climb, and in 2020 scientists celebrated when they spotted fifty-eight of these giants in the area. Nations that were involved in industrial whaling have been let off the hook from causing tragic extinctions. But the current glimmers of recovery are convincing some that the time has come to resume commercial whaling, as if that’s all they can think of to do with these magnificent animals.
Imagine what the ocean could be like if, instead of siphoning off profits to a handful of conglomerates and industry leaders, ambitions for sustainable fishing focused on two things: first, on providing food and livelihoods for people whose income and food security most depend on the ocean and who are most at risk from the climate crisis; and second, on running fisheries and looking after the ocean with the ambition of keeping wild species diverse and abundant, keeping whole ecosystems intact and functioning, and maintaining the countless benefits this brings to all of us alive now and for generations to come.
a Midway along this range, seals at Año Nuevo State Park, a short way south of San Francisco, were fitted with sensors, which revealed their deep-diving, spiralling snoozes.
b The word thunniform comes from their Latin name, Thunnus thynnus.
c 1200 BCE to 470 CE.
d ICCAT is one of around seventeen regional fisheries management organisations (RFMOs), which regulate fishing activities in the high seas. They are set up by international agreements and treaties and take different forms: some focus on particular species; others have a broader mandate. There are five RFMOs around the world focused on tuna.
Chapter 7
Rebalancing Seas
The sea was calm, wrinkled just a little by a westerly breeze, and a pair of swans serenely drifted by as I tiptoed into the water, testing the cold. A few fin strokes from the shore, and I was floating on six feet of sea, a garden of seaweeds beneath me—filamentous browns, mossy greens, red tufts, long ruffles of sugar kelp, giant palms of flopped-over oarweed. Crabs raised their pincers as I dived down to look; white, spiny starfish lay still. A shoal of young cod hung among blades of eelgrass. I swam between threads of bootlace seaweed, also known as mermaid’s fishing line, which connected the seabed and the surface, and I carefully watched the tangled tentacles of lion’s mane jellyfish wafting past. A scallop the size of a tea plate sensed my shadow fall across it with a hundred tiny, blue-green eyes, and it squeezed its shells together, leaving a fringe of tentacles sticking out like whiskers.
Sea life thrives in Lamlash Bay because no fishing has been allowed here for years. The bay lies on the eastern side of Arran, a Scottish isle of a little over ten by twenty miles, which packs in mountaintops, rivers, forests, moorland, and sandy beaches. It lies in the Firth of Clyde, a fjordic inlet off the west coast of Scotland that was historically a rich fishing ground. Before the onset of industrialisation, sailing boats used lines and nets to take huge catches of herring, haddock, turbot, and cod. Then, in the nineteenth century, demand soared when railways arrived, and fresh fish could be delivered across the country. More intensive methods of fishing were introduced, including steam-powered trawlers that dragged huge, heavy nets over the seabed. Predictably, the ecosystem was soon overfished, and catches plummeted. In 1889, in a progressive move prompted by scientists and local fishers, the Firth of Clyde was closed to trawlers. The ban stayed in place until 1962, when bottom trawlers and dredgers, now diesel-powered, were allowed into the firth and started catching a species of small orange lobster, known variously as langoustine, Dublin Bay prawn, or scampi. For some time, trawling had been banned within three miles of coastlines, but that restriction was lifted in the mid-1980s, and once again fishing boats could go, more or less, where they wanted. After that, fish catches were heading for terminal decline. Scientists from the University of York, Ruth Thurstan and Callum Roberts, later described the Firth of Clyde as a marine ecosystem nearing the end point of overfishing. Soon there would not be enough animals left for any commercial fishing to be worth the effort.
In the middle of all this lay the Isle of Arran, where the stage was set for a revolution to take place, though the narrative began decades earlier on the other side of the world. In 1962, the same year the Firth of Clyde was opened again to trawling, a marine research station opened in Aotearoa (New Zealand), fifty miles north of Auckland, overlooking the cold waters of Tīkapa Moana (Hauraki Gulf). Valentine Chapman, a seaweed expert from the University of Auckland, suggested the waters bordering the station should be protected so that scientific work could be conducted in peace without fear of fisheries damaging research equipment or catching the study species. The site could be safeguarded from human pressures, allowing scientists to study the sea in a state as untouched as possible and giving them a reference point to compare to other areas. But at the time, Aotearoa had no legislation to allow such a thing to happen.
Reluctant to let the idea drop, Chapman and the research station’s inaugural director, Bill Ballantine, spent six years lobbying politicians, gathering public support, and generating data to support their plans, until finally parliament approved the new Marine Reserves Act. Another six years were needed to protect the coastline on either side of the research station. The Cape Rodney–Okakari Point Marine Reserve, off Te Hāwere-a-Maki, or Goat Island, is modest in size, at two square miles. One of the world’s first no-take marine reserves, it was the first piece of Aotearoa’s coastline to be fully protected, and it paved the way for dozens more that are now dotted around the country and its outlying territories, from the subtropical Rangitāhua (Kermadec Islands) in the South Pacific to Moutere Ihupuku (Campbell Island) in the subantarctic.
Many of Aotearoa’s marine reserves attract scuba divers from around the world, who come to see spectacular underwater life flourishing in the seclusion of protected waters. I visited Tawhiti Rahi (Poor Knights Islands) almost forty years after a marine reserve was established and learned what it feels like to hover in the water and see nothing but faces of countless fish turned to watch me. I saw shoals of demoiselles, small, steely-blue fish flowing through the water as if they had been poured from a jug. A convoy of short-tailed stingrays passed by, each one wider than the space between my outstretched arms and quite obviously one of the world’s biggest species of stingrays. There were sunshine-yellow moray eels poking their heads from between kelp-covered rocks, and finger-length blennies hiding on steep walls blooming with sea anemones. And as if to demonstrate to me that this was a healthy, functioning ecosystem, swift packs of hunting yellowtail amberjacks chased a glinting shoal of koheru, a type of horse mackerel indigenous to Aotearoa waters.
It was scenes like this that a scuba diver from the Isle of Arran, Dan MacNeish, witnessed when he visited Aotearoa in 1989. He saw for himself what the benefits of strictly protected marine reserves can be, and he met with Bill Ballantine, who inspired him to do something similar. MacNeish’s family goes back generations on Arran, and he had been diving around the island since the 1970s and in that time had seen how dredgers and trawlers were wiping out life on the seabed, leaving behind empty barrens of nothing but gravel and sand. Returning from his Aotearoa trip, MacNeish visited his friend and fellow diver Howard Wood and suggested they could do something to help protect Arran’s waters.
Neither of the pair was a scientist or professional conservationist, and they had no campaigning experience between them, but they set about a tireless crusade similar to the one Chapman and Ballantine launched to establish that first reserve in Aotearoa. For years, MacNeish and Wood worked to garner support in the local community. They understood the power of images to persuade people to care, so they learned how to shoot underwater photographs and videos of the wildlife around Arran, and they visited other, healthier parts of the Scottish seas to document what could be. They found pictures from the recent past of Arran’s anglers and other fishers with huge catches, showing how much more abundant sea life had been just a decade or so earlier. Gradually, more locals came on board as they realised their seas were worth protecting.
All the while, MacNeish and Wood were frustrated that the Scottish government was focused solely on supporting the livelihoods of prawn trawlers in the firth, while ignoring the needs of other people who benefit from the sea—the anglers, tourism operators, shellfish divers, crabbers, swimmers, and snorkellers.
In 1995, the pair set up the Community of Arran Seabed Trust (COAST), bringing on board many other islanders, including members of the fishing community, who were determined to push for better protection of their local waters. The focus for the campaign became plans for a small marine reserve in Lamlash Bay and protecting a critical habitat that grows there. Divers volunteering with COAST found living carpets of pink and purple maerl, a type of seaweed that looks like little coral colonies lying in loose clusters on the seabed. The naturally pulverised remains of these algae, which accumulate limestone in their cells, is what makes the tropical-looking fine white sands on many of Scotland’s beaches. Maerl is legally recognised as a priority for conservation in Scottish seas,a and it’s known to be easily smashed by fishing gear. This meant that COAST could make a case to the government that the maerl beds of Lamlash Bay needed sheltering inside a marine reserve. But the path to protection wasn’t smooth.
Hurdles were constantly thrown up, and members of COAST found ways around them. When the local water board announced plans to build a sewage-outflow pipe into Lamlash Bay directly over the maerl beds, COAST successfully campaigned to have it moved. When a multinational aquaculture corporation planned to open what would have been Scotland’s largest salmon farm right next to the bay, COAST worked hard to have it stopped. When the government dismissed the group’s proposals for a reserve because the surveying divers were amateurs, the team members got themselves fully trained as citizen scientists with the organisation Seasearch and started collaborating with academics.
After thirteen years of forging alliances, gathering data, and drawing and redrawing lines on maps, COAST reached its initial goal, and at midnight on September 19, 2008, Lamlash Bay was closed to fishing, and the marine reserve was designated.
The Lamlash Bay No Take Zone is Scotland’s first highly protected marine reserve, an area where no forms of fishing are allowed. And it’s small, a little over one square mile, roughly the same size as the financial district of the City of London. The idea all along had been to use Lamlash Bay to demonstrate what’s possible and to show how the seabed can recover when it’s left alone, even in small areas. In the years since protection came into force and the dredgers and trawlers have been kept out, biodiversity has increased, and healthy habitats are thriving and covering more of the seabed inside the reserve. There’s now more maerl, as well as more seagrasses, sponges, seaweeds, hydroids, sea squirts, and feather stars, all of which provide shelter for young fish. Lamlash Bay has become a safe haven for bright blue lobsters and king and queen scallops, which are all much bigger and longer-lived inside than outside the reserve. These grand old animals are highly fecund and produce copious offspring that are replenishing populations both in Lamlash and beyond.
In a similar way, Lamlash Bay itself has spawned change beyond its boundaries. In 2016, COAST’s proposal to protect more of Arran’s coastal waters was adopted. Now the Lamlash Bay No Take Zone sits within the boundaries of a larger protected area, which prohibits dredging in almost one hundred square miles of sea around the southern part of the island. Trawling is allowed in only a few places around the periphery. This roughly puts back the protections that had been in place until the Victorian-era three-mile trawling ban was overturned in the 1980s.
Farther afield, COAST’s work has empowered other coastal communities to demand a better future for their own parts of the coasts and seas. COAST is showing that the ocean is a public good and should be safeguarded for everyone’s benefit. Any coastal community has the right to healthier seas on its doorstep and can be part of a powerful push for change.
As I made my way back towards the shore of Lamlash Bay, I felt invigorated not just by the cold water and the intricate sea life I had encountered but also by knowing this small piece of sea is being watched and cared for by the people who live on Arran.
On a signboard at the water’s edge, a map marks the no-take zone’s boundaries, starting on either side of Holy Island, a short way offshore, and leading to two points on Arran’s shoreline on either side of the spot where I stood. Since the no-take zone was established in 2008, there have been only a handful of known incursions by fishers into this narrow stretch of sea, all of them seen and reported by local residents. There’s a telephone number on the noticeboard by the bay for anyone to call if they spot suspicious activities. That day, I had no reason to call.
The ability of sea life to heal itself is a powerful and hopeful phenomenon, and sits at the heart of many efforts to undo the troubles humans have let loose in the ocean. More pieces of sea around the world are being cordoned off, and high-profile campaigns are pushing to protect 30 per cent of the ocean by 2030.
The discipline of ocean protection comes with a baffling mix of terminology. There are no-take zones, like the ones at Lamlash Bay, which are also referred to as highly protected marine areas. They are the most stringent, where all damaging activities are prohibited: no coastal developments, no sewage outflow pipes, no fishing, no fish farms, no mining, no aggregate dredging, and no oil drilling or any other form of extraction.
More loosely defined areas include marine parks, marine reserves, marine protected areas, and ocean sanctuaries. These generally carry less strict regulations and often encompass a mix of protection levels. One of the biggest and most complex is the Great Barrier Reef Marine Park in Australia, which is divided into a patchwork of zones covering some 130,000 square miles of coastline, reefs, and islands. Around a third of the park’s zones allow traditional uses by indigenous people as well as scientific research and tourism. Preservation zones, covering less than 1 per cent of the park, are off-limits to members of the public, and only researchers with special permission can gain access. In the general-use zones, fishing is allowed.
Another approach, which is popular in Europe, is to protect parts of the sea to safeguard particular vulnerable habitats or species and to prohibit only the specific activities that impact them. For instance, in parts of Scotland, maerl beds are protected from trawling and dredging. However, if the protections safeguard a species that lives up in the water column, such as the bottlenose dolphin or basking shark, then trawling is often allowed in the protected area, under the misguided assumption that the seabed and the water column above it are ecologically separate, when in fact everything is connected.
All these various protected areas share a similar ethos of trying to help ocean life to be generally healthier and more abundant. Protecting the seabed from physical damage, most importantly by heavy fishing gear such as trawlers and dredgers, can keep habitats in good condition and stop more from being destroyed. And parts of the ocean that are already degraded and depleted can be safeguarded to give sea life a chance to recover, as is happening in Lamlash Bay.
In some cases, the same protected area encompasses both healthy and degraded habitats, with the aim that local regeneration will occur. A hundred miles off Cape Wrath, the most northwesterly point of the United Kingdom, and around three thousand feet down, lie hundreds of thickets of cold-water corals that have been growing there since the end of the last ice age, around ten thousand years ago. Individual corals are estimated to be at least forty-five hundred years old, and unusually for deep-water corals, they’re growing not on firm, rocky ground but on soft humps, known as sand volcanoes, where seawater bubbles up through the seabed. First discovered by scientists in 1998 and named the Darwin Mounds after their research vessel, the RRS Charles Darwin, these coral ecosystems are also rich in many other life forms, including fish, crabs, sea urchins, and single-celled organisms called xenophyophores, which look like basketball-size chunks of honeycomb.
By the time scientists knew about the Darwin Mounds, parts of them had been damaged already by trawling nets dragged over the seabed to catch fish such as orange roughy. A protected area prohibiting trawling was set up in 2003. In 2019, scientists sent an autonomous underwater robot to survey the mounds and found that areas that had been heavily trawled were not yet showing any obvious signs of recovery after sixteen years of protection. The good news is that parts of the Darwin Mounds that weren’t too badly trawled are looking healthy. Coral larvae have settled and are growing into new colonies. For long-lived, slow-growing species such as deep-sea corals, recovery is obviously going to take a long time—all the more reason to protect them before damage occurs.
Regulations are gradually being put in place to protect the most vulnerable parts of the deep ocean. Bottom trawling on seabed deeper than a half mile has been banned in European Union waters of the northeast Atlantic since 2016 to safeguard fragile coral and sponge reefs growing on underwater mountains. An additional six thousand square miles of habitat was protected in 2022, when that lower limit for trawling was raised up to thirteen hundred feet. Much damage has already been done by decades of unrestricted deep-sea trawling, but these measures should begin to turn things around.
Elsewhere, pre-emptive steps are being taken to protect parts of the ocean from future impacts. Among the biggest marine protected areas is the Ross Sea in Antarctica, one of the most significant areas of largely intact ocean ecosystems left on the planet. Despite being incredibly remote, more than two thousand miles south of Aotearoa and reaching within two hundred miles of the geographical South Pole, this sea has faced growing pressure from industrial fishing fleets pushing into its icy waters to catch krill and Antarctic toothfish. Between them, krill and toothfish are staple foods for many other Ross Sea animals, including emperor penguins, Antarctic petrels, and Weddell seals. The Ross Sea is also the exclusive home to the world’s smallest orcas, known as type C, which grow to only twenty feet long. Until recently, scientists weren’t sure what this population of orcas feeds on. Then, when marine-mammal expert Regina Eisert was working at the ice edge in the Ross Sea, an orca swam right up and head-butted the waterproof camera she had lowered into the water on a pole. The orca opened its mouth and revealed a large, chewed tail of an Antarctic toothfish. Eisert was convinced the orca had done this on purpose, like a cat presenting a dead mouse to their owner. It proved that type C orcas eat toothfish, and further studies have shown these fish constitute more than a third of their diet. This means the Ross Sea region Marine Protected Area is critical for protecting the food source of this unique population of marine mammals.
Setting up the protected area in 2017 had taken years of difficult negotiations among all the nations that are part of the Antarctic Treaty, since no single nation can lay claim to Antarctica and its surrounding seas, and all members must agree on regulations. Several countries with major fishing interests supported the protected area only when the original plans were reduced in size by almost half, down to 420,000 square miles, and when concessions were made to allow fishing in some areas. Holding out until the end were Russian officials, who agreed to the plans after a sunset clause was introduced. The Ross Sea was given an initial period of thirty-five years of protection.
The boundaries of marine protected areas drawn on maps are chiefly there to show the people running fisheries where they can and can’t legally operate, but obviously those lines don’t exist out in the ocean, and marine organisms are oblivious to the designations. This leads to another of the potential benefits of ocean protection. Within protected waters, animals have a chance to live longer, grow bigger, and produce more offspring, as is happening among the scallops and lobsters of Lamlash Bay. But they don’t all stay inside the no-fishing zone. Mature animals may have home ranges bigger than or straddling boundaries of protected areas, or they may embark on seasonal migrations that lead them into more distant waters. What’s more, their young likely drift and swim away to start their own lives elsewhere, replenishing surrounding seas.
Conservationists and fisheries scientists refer to this as spilloverb and generally see it as a good thing, using it as a major argument for protecting more of the ocean. Stop fishing in some places, and catches overall should improve because fish populations will be healthier and more productive. Even if fishers lose out in the short term when they’re denied access to parts of their normal fishing grounds, the theory suggests that catches in nearby areas could soon outweigh the losses. Several studies confirm that protected areas work beautifully within their boundaries, boosting the abundance and diversity of species inside compared to outside. It’s much trickier to detect the spillover effect, in part because the ocean is so endlessly complex and dynamic. It also takes time for depleted populations to recover enough for spillover to be noticeable, and many parts of the sea haven’t been protected for long enough. In the United States, for instance, most marine protected areas are less than twenty years old.
While scientists are still busy debating whether spillover is a general effect that will occur more widely in the coming years as protected areas mature, some hints of it are occurring. In the northern Channel Islands off the California coast, there are now more spiny lobsters hunkered on the seabed both inside and a short distance outside a series of ten-year-old no-take zones. In Aotearoa, the effect of one small no-take zone was measurable much farther away. One in every ten juvenile sea bream occurring in waters up to thirty-five miles away is born within the protected waters of the reserve.
