Fish is our biggest source of Omega-3 essential fatty acids. As consumers, we would like to know how fish acquire methylmercury in their system.
Mercury occurs naturally in the environment, however, fish mainly accumulates methylmercury through exposure to industrial pollution. Mercury from rain, snow, and runoff will accumulate in streams, oceans, rivers and lakes. A chemical transformation aided by bacteria will turn mercury into methylmercury, which can be very toxic. Fish absorb them from water as they feed on the organisms found in the ocean and other bodies of water. The larger and longer living fish feed on other fish throughout their lives, therefore making them the carrier with the highest levels of methylmercury.
As stated within the results of the National Academy of Sciences' study, "Toxicology Effects of Methylmercury (by Committee on the Toxicological Effects of Methylmercury (Author), Board on Environmental Studies and Toxicology (Author), National Research Council (Author), National Research Council(Author), 2000:
"Because of the beneficial effects of fish consumption, the long term goal needs to be a reduction in the concentrations of mercury in fish rather than the replacement of fish in the diet by other foods. In the interim, the best method of maintaining fish consumption and minimizing mercury exposure is the consumption of fish known to have lower methylmercury concentrations."
The King Mackerel, Shark, Swordfish and Tilefish may contain high levels of methylmercury.
Fish considered to have low levels of methylmercury:
Catfish, Lobster, Scallops, Cod, Crab, Ocean Perch, Oysters, Shrimp, Flounder/Sole,
Rainbow Trout, Spiny Lobster, Haddock, Farmed Salmon, Tilapia, Herring,
Wild Salmon, Trout (farmed)
An alternative source of Omega-3 essential fatty acids is to supplement with purified (often called molecularly distilled) fish oil supplements. Omega-3 enriched eggs offer another alternative as well as micro algae-based omega-3 supplements.
Source: http://www.epa.gov/waterscience/fish/advice
