Whether fish is farmed or caught free, the process of getting delicious seafood onto the plates of consumers is rife with problems. Open sea fishing has severely depleted wild fish stocks, and as a result, roughly half of the seafood sold in the United States is farm raised, rather than caught in the open waters, according to NPR. But like most commercial agriculture, the aquaculture (fish farming) industry struggles with problems of inefficiency and environmental impact. The practice of confining thousands of fish to relatively small pens makes it necessary to use pesticides and antibiotics to prevent the spread of disease. Since aquaculture facilities are usually located in the ocean, discharges of fish waste, cage materials, and pesticide chemicals can damage surrounding ecosystems and threaten wild fish populations. Escapement is also a problem, as escaped fish from these facilities compete with native populations for food.
Furthermore, fish need to be fed, and the question of how to feed farm-raised fish presents yet another challenge, particularly when it comes to carnivorous species such as salmon and tuna. As Food & Water watch points out, farmed fish are often fed with wild species such as krill, with the effect of further threatening wild fish populations by depleting vital elements of our oceans' ecosystems. It's a system that's woefully inefficient: to raise one pound of farmed tuna, for example, 15 pounds of wild fish are converted to feed, according to chef Dan Barber -- wild fish, some argue, that could be used to feed humans instead.