Not so long ago, Atlantic salmon was an abundant wild species. Born in the rivers of northeastern United States and Canada, after a couple years in freshwater they embarked on an epic migration, navigating 2,000 miles across the Atlantic to feed and mature off western Greenland. Millions of salmon travelled up to 60 miles a day, fending off predators and feeding on zooplankton and small fish. When the time came, instinct and the earth’s magnetic fields led these magnificent fish back to spawn in the precise rivers of their birth.
Today, wild salmon are an endangered species, gone from most rivers in the U.S. There are many culprits, from polluted waterways and habitat destruction to overfishing and climate change. In the last 20 years, however, a new threat has emerged: floating feedlots on the ocean known as open-net salmon farms. The $20-billion-a-year farmed salmon industry is the world’s fastest growing food producer, and it has made farmed Atlantic salmon the most popular fish on dinner tables North America. But at what cost?
This new fish is an industrialized imposter that risks our health and damages our planet. Farmed salmon are bred to grow fast in cages so crammed that they are rife with parasites and disease. The fish eat pellets of fishmeal, vegetables, and animal byproducts; they are doused regularly with pesticides and antibiotics.
We spent more than two years investigating the global salmon farming business and the multinational companies that control it for our book, Salmon Wars. We interviewed scientists, physicians, fishers, activists, and those in the business of aquaculture. We read academic studies, court papers and previously undisclosed investigative files. We identified and tried to answer three critical questions swirling around farmed salmon.
First and most important, is eating farmed salmon healthy?
Doctors recommend salmon for protein, nutrients, and heart-healthy omega-3 fatty acids. The American Heart Association suggests consuming at least two servings of fish a week. But they rarely spell out the kind of salmon you should eat or warn of the dangers.
Many experts and scientific studies cast doubt on the blanket claim that salmon should be part of a healthy diet when the fish comes from open-net farms. Some farmed salmon may be safer than other types, but consumers rarely have enough information to make that choice. Labels are unlikely to disclose that the salmon was farmed, let alone identify the chemicals used to raise it. The U.S. Department of Agriculture doesn’t even have definition for organic salmon.
“It is confusing, and I suspect there is willful confusion out there,” Dr. Leonardo Trasande, a professor of environmental medicine at New York University, told us. “We know that every fish is a trade-off between omega-3 content and toxic content like PCBs. From the perspective of salmon in general, the balance favors consumption of that fish. Now the challenge here is that I can’t tell which salmon is farmed the right way or the wrong way.”
As early as 2004, scientists found levels of polychlorinated biphenyls, a probable carcinogen known as PCBs, seven times higher in farmed Atlantic salmon than in wild salmon. More recent studies found high levels of other chemicals and antibiotics in farmed salmon. Researchers at Arizona State University discovered increases in drug-resistant antibiotics in farmed seafood over the past 30 years, leading to concerns about increased risk of antibiotic resistance in humans. Toxins often wind up in salmon flesh and accumulate in people who eat the fish.
Some studies warn that a single meal per month of farmed Atlantic salmon can expose consumers to contaminant levels exceeding standards from the World Health Organization. The risk is greatest for infants, children, and pregnant women because of the potential harm from contaminants to developing brains.
Seafood Watch, an independent guide to fish consumption affiliated with the Monterey Bay Aquarium, recommends avoiding most farmed Atlantic salmon because of excessive chemical use and disease. Nutritionists generally recommend eating wild salmon over farmed salmon.
Second, is farmed salmon sustainable?
Salmon farmers often advertise their fish as sustainable and naturally raised. These assertions are deceptive.
Salmon are carnivores. Fish meal and fish oil from anchovies, sardines, mackerel, herring, and other small forage fish comprise 25 to 30 percent of most salmon feed. Fully a quarter of the fish harvested from the world’s oceans winds up in feed for aquaculture and pets. To meet growing global demand for salmon, huge trawlers pillage the fisheries off the coast of West Africa and Peru, robbing subsistence fishers of their livelihood and increasing food insecurity.
“You take the food from the plates of people in West Africa to feed the people of Europe and the United States and other countries,” Dr. Ibrahima Cisse of Greenpeace told us.
Salmon farmers argue that they fill the need for protein as the global population grows. Depleting fisheries in low-income countries to provide an unsustainable fish for richer countries sets a dangerous precedent.
Efforts to develop alternative protein sources are under way in university laboratories and start-ups. So far, there is no end in sight for the industry’s exploitation of small fish.