July 31, 2003

PCBs in Farmed Salmon: Contaminated fish meal

Contaminated fish meal

In 2001 about 80 percent of the farmed salmon consumed in the U.S. was imported from Canada and Chile (44 and 36 percent, respectively). An estimated 11 percent was raised domestically, and the remaining nine percent came from Norway, the U.K, China and 28 other countries (NMFS 2002).

These fish are fed from a global supply of fishmeal and fish oil widely traded between countries and manufactured from small pelagic, or open sea, fish including Peruvian anchoveta, Icelandic herring, menhaden from the Gulf of Mexico, Norweigian capelin, and sand eels from the North Sea. Iceland, Peru, Chile, and Denmark lead the world in production of fishmeal and fish oil (Tibbetts 2001). The global movement of fishmeal is illustrated by data on U.S. imports and exports of fishmeal: in 2001 the U.S. imported 51 million kilograms of fishmeal from 16 countries, and exported 108 million kilograms to 40 countries (NMFS 2002).

In three independent studies scientists tested 37 fishmeal and fish feed samples from six countries, and found PCB contamination in nearly every sample (Jacobs 2002, Easton 2002, and CFIA 1999). Although the data are too limited to carry statistical significance, PCB concentrations in fishmeal were highest on average in the Scottish samples, followed by samples from Canada, the United States, Russia, Iceland, and Peru, in order of decreasing levels. PCBs build up in salmon at 20 to 30 times the levels in their feed and surrounding environment (Jackson et. al 2001), so even low concentrations of PCBs in fishmeal can become a concern for human health.

In June 2003 the National Academy of Sciences issued a landmark study calling for broad changes in farming practices and human eating patterns to reduce human exposures to PCBs and other dioxin-like contaminants (DLCs) in the food supply, noting that because of the “intensive management approach” of the fish farming industry, even low levels of PCBs in fishmeal can accumulate in fish tissues.

Further, the Academy found that for fishmeal derived from the Atlantic Ocean and Gulf of Mexico, levels of PCBs and other DLCs are uncontrollable, stating that “...there is presently no known intervention that can lower the DLC levels in these fish,” raising the importance of the farmed salmon industry identifying clean feed sources for their product. The Academy recommended that the government conduct studies to find the distribution of PCBs and other contaminants in animal feed; and that the government, in collaboration with the animal production industry, identify ways to reduce contaminated fats as a component of feed, restricting the use of feed obtained from areas known to have high pollution levels (NAS 2003).


  • National Marine Fisheries Service (NMFS). 2002. Foreign Trade Information. The Fisheries Statistics & Economics Division.. Import and export statistics available online at http://www.st.nmfs.gov/st1/trade/index.html.
  • National Academy of Sciences (NAS). 2003. Dioxins and dioxin-like compounds in the food supply: Strategies to decrease exposure. NAS Institute of Medicine, Food and Nutrition Board, Committee on the Implications of Dioxin in the Food Supply. The National Academies Press. Washington, D.C.
  • Tibbetts, John. 2001. Aquaculture: Satisfying the global appetite. Environmental Health Perspectives. 109(7).