Written by Chrystal Moulton, Staff Writer. Significantly higher amount of contaminants found in farm-raised versus wild caught salmon. Also, wild salmon had 2.5 times higher omega 3/6 ratio compared to farm-raised.

The benefits of eating salmon is well known. However, since salmon is a carnivorous fish, it can accumulate chemicals that are toxic and carcinogenic from their prey. In the current study, researchers suggested that eating more than one meal of farmed salmon on average per month could increase their risk of cancer. A total of 459 farmed Atlantic salmon, 135 wild Pacific salmon, and 144 supermarket Atlantic salmon fillets were purchased from 16 cities in Europe and North America (Vancouver, Seattle, Los Angeles, San Francisco, Denver, Chicago, Toronto, New Orleans, Washington, DC, New York, Boston, London, Edinburgh, Paris, Frankfurt, and Oslo). Using these samples, researchers calculated the concentration of omega-3 and omega-6 fatty acids as well as carcinogenic chemicals including: polychlorinated biphenyls, dioxins, toxaphene, and dieldrin.

In the end, researchers found that farmed raised salmon had greater total fat content (average 16.6%) compared to wild caught salmon (averaged 6.4%) (p<0.0001). Average fat content in the supermarket fillets (average 14.4%) was similar to the farm raised salmon. Furthermore, the omega-3 to omega-6 ratio was 10:1 in wild salmon and 4:1 in farmed and supermarket salmon. When comparing concentration of contaminants they found that farm-raised salmon had significantly higher levels of toxaphene (p=0.0089), dioxin (p=0.0002), dieldrin (p<0.0001), and PCBs (p<0.0001) compared to wild-caught salmon. In the end, they found that even though both farmed and wild-caught salmon are good sources of omega-3 fatty acids, the contaminant levels were significantly higher in the farm-raised salmon. Researchers believed that the net benefit of consuming omega-3 from farm-raised salmon is reduced due to the high level of carcinogenic contaminants found in the fish.

Source: Hamilton, M. Coreen, et al. “Lipid composition and contaminants in farmed and wild salmon.” Environmental science & technology 39.22 (2005): 8622-8629.

© 2005 American Chemical Society Published on Web 10/14/2005

 Posted August 15, 2014.

References:

  1. Hamilton MC, et al. Lipid composition and contaminants in farmed and wild salmon. Environ Sci Technol. 2005 Nov 15;39(22):8622-9.