Dear EarthTalk: Which are healthier to eat: salmon grown on fish farms, or wild salmon?
—Jay Simms, Madison, WI
According to the National Marine Fisheries Service, 842 million pounds of fish were produced in 1999 by the United States through fish farming, or aquaculture, including 39 million pounds of salmon. Over 50 percent of the world’s salmon is now farmed rather than wild-caught, according to the National Audubon Society. More than likely, the next time you purchase salmon at the supermarket or in a restaurant, it is from a farm.
In a study published by the journal Chemosphere, both wild and farmed salmon from British Columbia were analyzed for toxicity, as were the foods fed to the farmed salmon. The researchers concluded that farmed salmon contained higher levels of polychlorinated biphenyls (PCBs), organochlorine pesticides and polybrominated diphenylethers than wild salmon; the discrepancy was thought to result from the high levels of toxins that were also found in the commercial salmon feed. However, a study by the Canadian Food Inspection Agency determined that the levels of these harmful chemicals in fish feed would not cause fish to exceed the safety standards set in the Canadian Guidelines for Chemical Contaminants and Toxins in Fish and Fish Products.
Though there is not yet conclusive evidence about the toxicity of farmed salmon, what is certain is that salmon aquaculture along the Atlantic coast is causing the population of wild Atlantic salmon to severely decline. According to National Audubon, farms are situated in prime locations where the tide flushes out the area, forcing wild stocks to migrate to less-than-ideal areas. The international organization, North Atlantic Salmon Conservation Organization, is working to increase the population of wild salmon stocks through habitat protection and reclamation.