But the issues of sustainability that have plagued some wild species have also become more prominent on the farm. Ultimately, the ecological impact of aquaculture depends on the species being raised, how they're raised and where the farm is located.
Trout, catfish and tilapia are raised inland in sustainable water supplies where wastes are carefully controlled and cannot contaminate coastal waters or the wild supply.
Salmon are cultivated in net pens usually situated in coastal waters. In the United States, Canada, Chile and other developed nations, salmon farmers must abide by laws that protect the surrounding seas from wastes, so country of origin sourcing and sustainable practices should be key to purchasing decisions.
Clams, oysters and mussels are raised in special beds or on ropes suspended near the shoreline. Harvesting these shellfish does little to disturb the ecosystem. And as they grow, they filter plankton from the water for their food supply and can actually improve water quality.
Shrimp farms run by certain producers in the United States and Mexico use re-circulating closed-water systems and tanks, thus eliminating contamination by waste products; others use inland ponds and treat the wastes internally. Several shrimp farms, including one in Ecuador, have also received organic certification. But generally, shrimp farmed in Asia and Latin America are not as ocean-friendly. Check with your supplier to make sure you're getting sustainably farmed shrimp.