MILESTONE 2: Environmental Sustainability and Food Security

Background: milestone 2The presence of PCBs (polychlorinated biphenyls) and mercury in both wild and farmed salmon is a concern that some translate as a significant issue for all aquaculture operations.


  • The most recent research shows that the levels of PCBs in wild and farmed salmon are virtually the same at about 1/200th of the FDA tolerance. These levels pose no health risk to consumers, according to leading public health organizations worldwide.
  • The levels of PCBs in other foods, such as butter, are higher than in either wild or farmed salmon.
  • With wild or farmed salmon in particular, public health organizations note that any potential risk is outweighed by health benefits of omega-3 fatty acids and other nutritional factors.
  • It is easier to limit fish intake of PCBs in aquaculture (by controlling PCBs in the diet) than it is to limit such intake in the wild. Aquaculturists now monitor PCB levels in the fish oil and fish meal components of fish feeds. For this reason, it is likely that that PCB levels in farmed fish may soon be lower than those in wild fish.
  • Overall, levels of PCBs in all foods have declined about 90 percent since PCBs were banned in the late 1970s.
  • It is widely believed that mercury (methylmercury) is absorbed by single-cell ocean plants (phytoplankton) and is then concentrated as it moves up the food chain (a process known as bioaccumulation). Larger, longer-lived, carnivorous fish tend to have the relatively higher concentrations.
  • Mercury levels in wild fish are down slightly or the same as they have been since the 1970s, according to a 2005 U.S. House of Representatives Resources Committee report. New efforts such as the EPA’s Clean Air Mercury Rule are likely to reduce mercury emissions.
  • Like all farmed animals, cultured fish are given controlled diets. By testing for mercury in feed, fish farmers can better monitor and minimize mercury intake in their fish.
  • In Australia, farmed tuna have been extensively tested for mercury and, as a result, have been re- moved from the mercury advisory list. Further testing may provide a better sense of the actual risks weighed against the widely acknowledged, proven health benefits of eating seafood.

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Next page: MILESTONE 3: Preventing Escapement Impacts