The Atlantic Salmon Myth: The more farmed, the more endangered? | Recommended Reading

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The Atlantic salmon is a creature of paradox. On one hand, it has become one of the rarest animals in the ocean: few of us are fortunate enough to see (or taste) one in the wild. Yet, fish farming has made it one of the most commonplace animals in the world. In just a few decades, aquaculture has transformed a delicacy once reserved for the few into a global commodity and the most widely traded fish on earth. Perhaps, ten thousand years after humans began domesticating cattle, pigs, and sheep, we have set this fish upon the same path: through farming, the animal breeds in abundance within cages (underwater sea cages), while vanishing from its natural environment. Yet, we cannot help but worry for the fate of the wild Atlantic salmon. This fish serves as a natural barometer for the health of the planet, occupying a unique position. It can transform itself from a freshwater fish to a saltwater fish, and then back again. This means that over the course of its life cycle, it travels from inland rivers to the ocean, and then returns to the river. Through the salmon, we can witness the cumulative impact of human activity—from deforestation and dam construction to pollution, overfishing, and the driving of climate change—on the natural world. The precipitous decline of this species sounds an alarm for the changes occurring on both land and sea. If we wish to save the salmon, we must stop destroying the planet—it is as simple as that.

It is an elusive fish, and its life cycle is even more miraculous. A female salmon deposits around 8,000 eggs among the river gravel, and male salmon compete to fertilise them. Eight weeks later, fry hatch from their golden eggs, spending the next 30 days growing on nutrients from their yolk sacs. Once they grow from fry into parr, they leave the shallow, gravelly reaches and swim into deeper, more dangerous waters. In these deeper zones, a salmon must survive for up to three years, finding enough food to reach 15cm in length and develop sufficient muscle before it can finally undertake the great journey to the sea. It must then complete a grueling endurance swim of thousands of miles to find rich feeding grounds in the North Atlantic. If it is lucky enough to evade predators and storms, it will swim upstream two or three years later, overcoming every obstacle to return to the gravelly stream where it first hatched. There, at the site that marks 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 homes and enter the salt waters of the ocean, salmon undergo a physiological transformation known as smoltification. Millions of years ago, as the oceans cooled and became a richer source of food, salmon evolved this biological trait. This process allows them to ‘silver’; their bodies become more streamlined and their skin turns silver and more reflective, providing better camouflage in the open sea.In the rivers, salmon are highly territorial and aggressive; however, as they move into deeper waters and gather in shoals, their temperament becomes milder. In the lower reaches of the river, as they approach the sea, salmon take one final ‘sample’ of the water’s chemical composition. Scientists believe it is this ‘imprinting’ that allows them to find their way home after travelling thousands of miles across the ocean.In the estuaries, where fresh and salt water meet, salmon adjust their gills and change their breathing patterns to adapt to the new environment, swimming closer to the surface. There, they gorge themselves on large zooplankton, such as crustaceans, squid, small fish, and krill. Yet, while hunting others, they too become the hunted—preyed upon by 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. From Norway in the north to Spain and Portugal in the south, and from Russia in the east to Canada in the west, Atlantic salmon can be found. Regardless of their origin, Atlantic salmon eventually congregate to feed in the waters off the west coast of Greenland and near the Faroe Islands. Here, they grow to twice their original size and put on fat to withstand the chill of the North Atlantic and build up energy reserves for their return migration.

Much of what occurs in the salmon’s life cycle belongs to what Rachel Carson called the ‘ultimate mystery’. We do not truly understand how salmon find their way back (it may be a combination of memory, scent, solar navigation, and the Earth’s magnetic field), nor do we know how they determine when it is time to return. We only know that salmon will migrate at any cost. Near the town of Clohen in County Donegal, Ireland, along the 40-mile stretch of the River Finn, salmon encounter what seems an insurmountable obstacle. Water plunges down a ten-foot waterfall, crashing violently against the hard rock.Salmon swim up from the pool at the base, attempting to leap again and again. Some propel themselves from the surface or the rock face with a flick of their tails in a series of staggered bounds, while others launch themselves high into the air. During this stage, the migrating salmon are still relying on their internal energy reserves. Once they return to the river, they stop feeding entirely, whether it takes days, weeks, or months to reach their birthplace. However, having spent years feeding in the ocean, they are at the peak of their physical powers. Thus, for the predators waiting on the riverbanks—both human and animal—the migrating salmon are at their prime.

The poet Seamus Heaney loved fishing from a young age, and he used to fish for salmon east of the Clohen falls in County Donegal. He described seeing their shimmering silver bodies, blue-green scales, and torpedo-like heads as they broke the surface, fighting their way back to the waters of their birth. Heaney’s poem, ‘To Salmon’, was published in 1969. At that time, the total population of wild Atlantic salmon was around 10 million. Today, that number is less than 2 million. By contrast, another species—the Sockeye salmon (which shared a common evolutionary ancestor with the Atlantic salmon 20 million years ago)—still returns to its natal rivers by the tens of millions. This makes the drastic decline of the Atlantic salmon all the more terrifying. Fifty years ago, half of every million salmon that left their rivers for the Atlantic successfully returned to spawn in their homeland and complete their life cycle. Now, only 30,000 can do so. Although the world is trying to uncover the cause, we still cannot fully explain why Atlantic salmon have suffered such a precipitous drop. For any species, when numbers fall this low, the future becomes precarious. Some marine scientists believe that wild Atlantic salmon could truly face extinction.

The primary feeding grounds for Atlantic salmon are located off the west coast of Greenland, where thousands of salmon from various rivers congregate. Today, these waters have become targets for industrial fishing. In the 1970s, large Norwegian fleets were catching between two and three million salmon annually—potentially more than the total number of salmon in the world today. It was not until the 1980s that an international agreement was reached to halt this unrestrained plunder. Now, most commercial salmon fishing has been prohibited; in Ireland, only a handful of fishermen with long-standing licences are permitted to fish at river mouths. Net fishing has also declined significantly in Scotland, the UK, and Norway. Yet, salmon numbers continue to fall. There are serious problems in our rivers and oceans.

Ken Whelan, Ireland’s most authoritative salmon scientist, believes that changing ocean temperatures are a major potential factor. “In some of the areas where salmon feed, the plankton have disappeared,” he says. Meanwhile, new fish species have appeared off the south coast of Ireland. “Warming waters have attracted Triggerfish from the Caribbean and Sea Bream from the Mediterranean, which compete with salmon for food. The ocean is changing, and salmon are among the victims.”

Herein lies the paradox. While wild salmon numbers are dwindling, the total population of Atlantic salmon is increasing rapidly. It is estimated that at any given time, there are approximately 400 million salmon in fish pens along the Norwegian coast alone. The number of salmon in just ten of these giant pens exceeds the total number of wild salmon in all the world’s rivers, streams, and the Atlantic Ocean. As wild salmon decline, farmed salmon are thriving. Some believe the two are linked.

The majority of the world’s farmed salmon come from a handful of Norwegian companies, including Lerøy Seafood Group and SalMar, the largest of which is Mowi. Mowi operates farms in the waters of Norway, the Faroe Islands, Scotland, Canada, and Ireland, producing nearly a quarter of the global consumption of salmon. Mowi’s global operations even extend Atlantic salmon farming to the Chilean coast south of the equator. I had the opportunity to visit Mowi’s operations from start to finish on the west coast of Scotland. At the hatchery, I saw newly hatched fry, their eyes still tightly encased in egg membranes. Mowi has 25 farms in Scotland; at one of them, I saw hundreds of thousands of salmon swimming in endless circles in the pens, with the occasional fish breaking the surface in a leap. “I entered this industry as an environmentalist,” Ian Roberts, a Mowi manager, told me during the tour, “I wanted to stop fishermen from catching the last of the wild salmon from the sea, so I provided them with an alternative.” He arrived at this conclusion because, in recent decades, much of the growing global demand for fish has been met through aquaculture. More than half of the seafood consumed by humans now comes from aquaculture.