With mercury scares abound, many consumers feel they are making a healthier choice by choosing farm-raised fish over the wild-caught variety. Many are not aware that farm-raised fish have their own problems.
Are there any nutritional differences? We’re glad you asked! FDA statistics on the nutritional content (protein and fat ratios) of farm-versus- wild salmon show that the fat content of farmed salmon is excessively high – 30-35 percent by weight. Wild salmon have a 20 percent higher protein content and a 20 percent lower fat content than farm-raised salmon.
Farm-raised fish contain much higher amounts of pro-inflammatory omega-6 fats and less usable omega-3 fats than wild fish. Normally, we tend to get too many omega-6 fats in our diets and need more of the omega 3s. Balance is key; neither of the fats are "good" or "bad" but "variety" is what you should look for. When a food is eaten that contains high amounts of omega-6 in proportion to its content of omega-3, the omega-6 fats use up certain enzymes that produce a pro-inflammatory condition.
Problem: Farm-raised fish do not spend their lives vigorously swimming through cold ocean waters or leaping up rocky streams. They spend their lives as "couch potatoes," lazily circling in crowded pens fattening up on pellets of fish chow…not the normal life nor feed of the wild variety. For example, farm-raised coho salmon has been found to have approximately 2.7 times the total fat as wild samples.
Antibiotics and Pesticides: Disease and parasites, which would normally exist at relatively low levels in fish scattered around the oceans, can run rampant in densely packed oceanic feedlots. To survive, farmed fish are vaccinated as small fry. Later, they are given antibiotics or pesticides to ward off infection.
PCBs: Research published by the Environmental Working Group [July 30, 2003] indicates that levels of carcinogenic chemicals called PCBs found in farmed salmon purchased from U.S. grocery stores are much higher than levels of PCBs found in wild salmon that they pose an increased risk for cancer.
Synthetic pigment colors in farm-raised salmon: In the wild, salmon absorb carotenoids from eating pink krill. On the aquafarm, their rich pink hue is supplied by canthaxanthin, a synthetic pigment manufactured by Hoffman-La Roche. Fish farmers can choose just what shade of peach their fish will display from the pharmaceutical company’s trademarked SalmoFan, a color swatch similar to those you’d find in a paint store. Without help from Hoffman-LaRoche, the flesh of farmed salmon would be a pale halibut grey. There is debate on whether the canthaxanthin, when added to the fish food, poses any human health risk. Canthaxanthin has been linked to retinal damage in people when taken as a sunless tanning pill. This led the British to ban its use as a tanning agent. It is still available in the U.S.
Wild-caught fish are going to be more nutritious than your farm-raised variety. All of us should try to minimize our exposures to antibiotics, PCBs and pesticides in our environment. Refusing to buy farm-raised fish can be one step in that direction.