Another one of my favorite! According to a report in Science, factory-farmed salmon*, which is raised on fishmeal and accounts for 80% of the market, has eight times more PCBs than wild caught. The researchers said that if EPA standards could be applied to farm-fed salmon, it would trigger a warning to not consume it at all. In order to protect yourself from PCBs, never eat salmon skin or the layer of fat beneath it. *conditions and practices vary by farm, which can affect the PCB levels.
What is Farmed Salmon? The most commonly farmed salmon is the Atlantic Salmon. Salmon is usually farmed in 2 stages and in some place maybe more. First, the salmon are hatched from eggs and raised on land in freshwater tanks. When they are 12 to 18 months old, they are transferred to floating sea cages or net pens anchored in sheltered bays along a coast. They are fed pelleted feed for another 12 to 24 months, when they are then harvested. Norway produces 33% of the world’s farmed salmon, and Chili produces 31%. The coastlines of these countries have suitable water temperatures and many areas are protected form storms. Chile is close to large forage fisheries which supply fish meal for salmon. Scotland and Canada are also significant producers.
This freshwater favorite has a mild flavor and is very versatile, but unfortunately, the benefits end there. Most tilapia is farm-raised and fed a steady diet of corn which, in turn, affects its nutritional content. Jeffrey Anshel, O.D., F.A.A.O says “Despite what we think, corn is not a vegetable, but actually a grain that has a high glycemic rating. This means that it spikes your blood insulin, which is especially a problem for diabetics. Addionally, tilapia has the highest level of omega-6, the pro-inflammatory fish oils. Omega-6 can exacerbate heart disease, arthritis, asthma, and other overactive inflammatory responses.”
According to Wikipedia, Tilapia from aquaculture (farmed) has been shown to contain more fat and a much higher ratio of omega-6 to omega-3 oils. I’m assuming this is due to their feeding and lack of activity.