Over time, these materials can accumulate in the sediments on bay bottoms and result in the release of gases such as ammonia and hydrogen sulfide, which are toxic to fish. In addition, some fish farmers routinely use antibiotics to control disease, and this may encourage the evolution of antibiotic-resistant bacteria. Anti-fouling agents and other pesticidal chemicals can pollute water and harm other organisms. Some fish farms, particularly in developing countries, use hazardous chemicals developed for land agriculture, such as the insecticide Sevin, which kills crustaceans, and the herbicide 2,4-D, which kills aquatic plants. Effects on Wild Fish and Ecosystems Aquaculture can also permanently alter the composition of wild fish populations and aquatic ecosystems.
Fish farms can be extremely leaky.
The escape or release of fish from aquaculture facilities can pose ecological concerns. Escaped or released fish of nonnative species may establish populations in the wild, displacing native fish or otherwise altering natural ecosystems. And if large numbers of native cultivated species escape or are released, their interbreeding with wild fish may alter the genetic makeup of wild populations in significant, undesirable ways. Special Risks of Coastal Fish Farms Coastal aquaculture operations, particularly in developing countries, can cause social and economic as well as environmental harm. Many large commercial shrimp farms in Asia and Latin America have destroyed coastal mangrove forests to make room for their operations.