The global demand for fish has caused widespread overfishing in the wild fishery and commercial fishing markets. As a result fish farming, also known as aquaculture, is offering an alternative solution to the increasing market demand. This alternative does not come without controversy however, and there are many issues associated with farmed fisheries.
Most notably is the diet of some salmon species which in the wild partly consists of an intake of anchovies and menhaden. These ordinarily carnivorous diets are being replaced by vegetable-derived proteins in the fish farms, and some experts speculate that vegetable-derived oils have not successfully been incorporated into the diets of carnivores. These vegetable-derived diets are being tied in with higher levels of toxins (PCB’s, dioxin, etc.) than wild fish.
Polychlorinated biphenyls (PCB’s) are mixtures of chlorinated compounds. They have been used as lubricants in transformers, capacitors, and other electrical equipment because they are good insulators. The manufacture of PCB’s was banned in the U.S. in 1979 because of evidence they build up in the environment and can cause harmful health effects. However, these toxins exist in the environment, and are absorbed by fish from contaminated sediments in their food. Farmed salmon contains more fat than wild, and it is in this fat that the PCB’s are stored and remain there for extended periods of time.
Additionally, farmed fish are kept in concentrations not seen in their wild ecosystems. This has been affiliated with several forms of pollution. Given the tight living quarters, the fish rub against each other and their cages damaging their fins and tails and becoming sickened with various diseases and infections. The level of stress this causes is also evident in the taste of these fish.
Fishermen near these fish farms are often cited as complaining about the effects of the natural habitat these farms create. High concentrations of feces can affect local waterways. The resultant bacterial and algae growth strips the water of oxygen, reducing or killing off the natural marine life. Once an area has become too contaminated, the fish farms simply move to new, cleaner areas.
Although fish farms are helping supply the world with food, they are also creating health concerns, effecting natural ecosystems, and hindering recreational and commercial fishing areas. Salmon production is just one example of the issues concerned with fish farms, there are other popular species that have similar repercussions. Before purchasing seafood, be sure to check into the production methods to ensure a healthy and environmentally safe product.