Salmon: Farmed

Atlantic Salmon, Farmed Chinook

Salmon farming places an indirect stress on the marine environment by utilizing significant quantities of wild fish used in processed aquafeed. Wild fish that are caught for “reduction” to fish meal and fish oil for aquafeeds typically originate off the coasts of South America and the United States, where they represent important components of their surrounding marine ecosystems.

Environmental concerns over salmon farming primarily stem from the fact that farmed salmon are raised in marine net pens, where they are in direct contact with the surrounding marine environment. As a consequence of being farmed in open systems, farmed salmon can escape during storms and routine handling events. There is a growing body of evidence that when salmon farmed within their native range escape they can interbreed with wild conspecific salmon and reduce the fitness of endangered wild salmon stocks. Risk also exists that escaped farmed salmon may become reproductive and establish populations in areas in which they are not native, such as the Pacific.

Salmon farming operations can serve as a vector for diseases and ectoparasites, notably sea lice, which can negatively affect wild salmon. While the literature on disease transfer to wild fish remains somewhat inconclusive, there is significant evidence that sea lice from salmon farms are harming wild salmonid populations, particularly in Europe.

Salmon are farmed in open pens and cages in coastal areas. Waste from most farms is released directly into the ocean. Organic wastes from feces and uneaten aquafeed can accumulate on sediments and affect the benthic species distribution within the immediate vicinity of salmon net pens. Infaunal species diversity is typically lower beneath and down current from net pens with low to moderate flushing rates, though it may be higher in areas with good flushing. Nutrients from salmon operations can also be a contributor to larger regional problems of eutrophication.

Management of salmon farming varies substantially worldwide. However, given the recent scrutiny of the environmental effects of the farmed salmon industry, management practices are generally becoming more rigid in an effort to improve the sustainability of salmon farming. While segments of the salmon farming industry are improving their practices, the environmental impact is still increasing because production has risen more than 400% in the last decade.

Most Atlantic salmon is farm raised. Some chinook and coho salmon are also farmed, so it’s important to ask whether the salmon is “wild” or “farmed”. In the market, there is currently no way to tell which salmon are coming from more-sustainable farms, so for now we ask you to avoid farmed salmon and choose wild-caught salmon instead.

Consumption advisory due to PCBs, dioxins and pesticides.