DEAR DR. BLONZ: How does fish farming affect the environment? Also, what are the nutritional differences between fish raised on a farm and those caught in lakes, oceans or bays? -- K.B., Springfield, Illinois
DEAR K.B.: The cultivation and raising of fish and water plants for human use, otherwise known as aquaculture, is a rapidly growing form of agriculture. Studies are generally supportive of the raising of fish in water-based pens.
I say "generally" because these systems attempt to take a natural process and reproduce it in a commercial, fixed-location, semi-enclosed system, and such endeavors never work perfectly. Quality control is crucial as farms cope with the inevitable curveballs that nature throws their way. Adherence to safety standards is essential to ensure that the fish are of good quality before they are harvested and sent to market. When things run well, the fish are safe to eat, consistent in quality, and they look and taste great.
The nutritional value of wild-caught and farmed fish tends to be comparable. One exception might be the amount of the oils in the fish, and the "you are what you eat" doctrine applies. Ocean-dwelling fish such as salmon have a leaner diet composed of smaller fish, insects and sea plants. All these can be sources of the compounds that give salmon meat its flavor and color. Those raised on farms dine on controlled diets. Because the genes of the salmon are responsible for its long-chain omega-3 fat production, these levels tend to be comparable between farmed and wild fish. Farmed fish, however, tend to contain more fat per serving.
Keep in mind that based on where they live and feed, even fish in the wild can accumulate toxic compounds. The controlled environment of the farm-raised fish can translate to lower levels of natural toxicants, and studies have borne this out.
Finally, aquaculture can be effective, but there can be no promise of an unlimited supply of fish. Care must be exercised to respect the area's ecology. Overcrowding can quickly turn the effort into a waterborne version of a factory farm. Depending on the location and breeds being raised, there are risks of escaping fish introducing an unnatural species that could interbreed with, or destroy, other area inhabitants. There are also risks of disease transfer, and the problems related to waste disposal and antibiotic use.
No question, fish farms need to operate in an environmentally friendly manner. We, as consumers, can help the system by patronizing those who do it right. Ask at your local fish market, or supermarket counter, where their fish come from. Identify your issues of concern, and let them know that you care. If are unable to get satisfactory answers, take the issue up with the store's corporate headquarters. Your purchasing power can help affect change.
Check out the Marine Stewardship Council (msc.org), Friend of the Sea (friendofthesea.org) and Cleanfish (cleanfish.com) as examples of organizations seeking to foster sustainable aquaculture. As always, it is best to eat a wide variety of foods. Whether caught in the wild or sustainably raised through aquaculture, fish are an important part of any healthful, varied diet.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.