The Atlantic Salmon Myth: The More We Farm, the More Endangered? | A Reading from a Great Book

Foodthink Says

The Atlantic salmon is a creature of paradox. On the one hand, this fish has become one of the rarest animals in the ocean: very few of us will be lucky enough to see one (or taste it). On the other, fish farming has made it one of the most ubiquitous creatures on the planet. Within a few short decades, aquaculture has transformed what was once a delicacy enjoyed by the few into a global commodity and the most widely traded fish in the world. Perhaps, ten thousand years after humans first raised cattle, pigs and sheep, we have set this fish upon the same path: through farming, this animal now thrives in captivity (underwater fish cages at sea) yet vanishes from the wild. And yet we cannot help but worry about the fate of wild Atlantic salmon. This fish is a natural barometer of the planet’s condition, occupying an unrivalled position. It can transform itself from a freshwater fish into a marine one — and back again. This means that, as it progresses through its life cycle, it travels from inland rivers to the sea, then returns to the rivers. Through the salmon, we can observe the cumulative impact of a whole range of human activities — from deforestation, dam construction and pollution to overfishing and the driving of climate change — on the natural world. This dramatic decline is a clarion call for the changes underway in our land and sea. If we want to save the salmon, we must stop destroying the planet — it is as simple as that.

This fish is elusive, and its life cycle nothing short of miraculous. A female salmon lays roughly 8,000 eggs among the gravel of a riverbed, after which the males race to fertilise them with their milt. Eight weeks later, tiny fry hatch from the golden eggs and, for the next thirty days, live off the nutrients in their yolk sac. Growing from fry into parr, they can leave the shallow, gravel-strewn shallows and venture into deeper, more dangerous waters. In these depths, a salmon must survive for up to three years, finding enough food to reach 15 centimetres in length and developing sufficient muscle before it can finally embark on the great journey out to sea. It must complete thousands of miles of endurance swimming in the Atlantic before it can find abundant feeding grounds in its northern reaches. Thereafter, if it is lucky enough to evade predators and storms, two to three years later it will turn upstream, surmounting every obstacle in its path, back to the gravel stream where it first hatched. There, at the very spot marking both its beginning and its end, it will spawn. Of the original 8,000 eggs, only two will complete this entire life cycle. It is one of the most astonishing processes in the natural world.

To leave their freshwater home and swim into the salt sea, salmon undergo a physical transformation known as anadromous migration. Millions of years ago, as the oceans cooled and became richer sources of food, salmon evolved this biological trait. The process enables the salmon to undergo smoltification: its body becomes more streamlined, its skin turns silver and more reflective, providing better camouflage in the open sea. In the river, salmon are fiercely territorial and highly aggressive; yet as they move into deeper water and join other salmon in a shoal, their temperament grows more docile. In the lower reaches of the river, closer to the sea, the salmon takes one last soak in the water it is about to leave, absorbing its chemical signature. Scientists believe it is precisely this “imprinting” that enables the salmon to find its way home after journeying thousands of feet across the ocean. At the estuary, where freshwater meets the sea, the salmon transforms its gills and alters its breathing to adapt to the new environment, swimming close to the surface. There, it can fill its belly with macrozooplankton — crustaceans, squid, small fish and krill. Yet while hunting other creatures, the salmon itself becomes prey. Its predators include cormorants, sharks, sea lions, seals — and, of course, humans.

This incredible feat of the salmon population takes place across the North Atlantic, spanning more than 2,000 rivers and tributaries in Europe and North America. Atlantic salmon can be found from Norway in the north to Spain and Portugal in the south, from Russia in the east to Canada in the west. Yet wherever they originate, Atlantic salmon ultimately converge on the waters off the west coast of Greenland and near the Faroe Islands to feed. Here, every salmon doubles in size and packs on fat to withstand the cold of the North Atlantic and to build up the energy reserves needed for the return migration.

Much of what happens in the salmon’s life cycle belongs in Rachel Carson’s “ultimate mystery“. We do not truly know how salmon find their way back to migrate — it may be a combination of memory, scent, solar navigation and the Earth’s magnetic field — nor do we fully understand how they judge when to make the return journey. All we know for certain is that salmon will migrate at any cost. Near the town of Cloonheen in County Donegal, Ireland, along the 40-mile River Finn, the salmon encounters a seemingly impassable barrier. Water plunges over a 10-foot waterfall, crashing violently against the hard rock below. The salmon swims upstream from the pool beneath the falls and tries again and again to leap. Some fish fling themselves off the water or the rock face with their tails, bouncing up in stages, while others soar skyward in a single magnificent leap. At this stage, the migrating salmon is still drawing on its energy reserves. Once back in the river, whether it takes days, weeks or months to reach its birthplace, it will not feed again. Yet the salmon, having fed in the sea for years, is at the peak of its powers in every respect. And so, for the predators waiting on the riverbank — humans and animals alike — the returning salmon is at its very finest.

The poet Seamus Heaney loved fishing from a young age, and he cast his line for salmon east of the Cloonheen Falls in County Donegal, Northern Ireland. He recalls seeing salmon with their gleaming silver bodies, blue-green scales and torpedo-shaped heads, bursting through the surface as they drove themselves toward the waters where they were born. Heaney’s poem To Salmon, from an Angler was published in 1969. At the time, the total wild Atlantic salmon population stood at around 10 million. Today, that figure is fewer than 2 million. By contrast, another species — Pacific sockeye salmon (which diverged from the same evolutionary group as Atlantic salmon some 20 million years ago) — still returns in their tens of millions to the rivers of their birth. It is precisely this contrast that makes the catastrophic decline of the Atlantic salmon so terrifying. Fifty years ago, half of every million salmon leaving their rivers for the Atlantic successfully completed the return migration, spawning in their home waters and completing their life cycle. Today, only 30,000 salmon achieve this. Though the world strives to understand what has happened, we still cannot say with certainty why the Atlantic salmon has suffered such a precipitous decline. For any species, once numbers dwindle to this extent, the future becomes a precarious one. Some marine scientists believe that wild Atlantic salmon could genuinely face extinction.

The principal feeding ground for Atlantic salmon lies off the west coast of Greenland, where thousands of salmon from different rivers converge. Today, these waters have become a target for industrial fishing. In the 1970s, Norway’s vast fleets could catch two to three million salmon a year — more than the entire global salmon population today. Not until the 1980s was an international agreement reached to halt the indiscriminate plunder. Nowadays, most commercial salmon fishing has been banned, and in Ireland only a handful of historically licensed fishermen may cast their nets in the estuaries. In Scotland and the rest of Britain, and in Norway, net fishing has also declined sharply. Yet the salmon numbers keep falling. Something is seriously wrong in our rivers and seas.

Ken Whelan, Ireland’s foremost salmon scientist, believes that changes in ocean temperature are a major contributing factor. ‘In parts of the salmon feeding grounds, plankton has disappeared,’ he says. Meanwhile, new fish species have appeared along Ireland’s south coast. ‘The warming waters have brought Caribbean triggerfish and Mediterranean sea bream, which compete with the salmon for food. The sea is changing, and the salmon is one of its victims.’

And so the paradox emerges. While wild salmon numbers are falling, the total population of Atlantic salmon is rising rapidly. It is estimated that at any given moment, around 400 million salmon are confined in fish cages off the Norwegian coast. The salmon in just ten of these enormous cages alone outnumber the entire wild salmon population of every river, stream and stretch of the Atlantic Ocean in the world. As wild salmon dwindle, farmed salmon flourish. Some believe the two are linked.

The vast majority of the world’s farmed salmon comes from a handful of Norwegian fish-farming companies, including Lerøy Seafood Group and SalMar, the largest of all being Mowi. Mowi operates farms in Norwegian waters as well as in the Faroe Islands, Scotland, Canada and Ireland, and its output accounts for nearly a quarter of global salmon consumption. The company’s global operations even extend Atlantic salmon farming to the coast of Chile, south of the equator. I had the privilege of touring Mowi’s operations from start to finish on the west coast of Scotland. At the hatchery, I watched freshly hatched fry with their eyes still sealed tight within their eggshells. Mowi owns 25 farms in Scotland, and at one of them I saw hundreds of thousands of salmon swimming ceaselessly in circles inside a covered pen, now and then breaking the surface in a leap. ‘I entered this industry as an environmentalist,’ one of Mowi’s managers, Ian Roberts, told me as he showed me around the farm, ‘I wanted to stop fishermen taking the last wild salmon from the sea, so I offered them an alternative.’ He came to this view because, in recent decades, the growing global demand for fish has been met largely through aquaculture. More than half of the seafood humans consume now comes from fish farms.