Bluefin Tuna Aquaculture
Tuna “ranchers” believe that their operations take pressure off wild tuna populations because the tuna fishermen get a better price for their catch and therefore need to fish less intensively. But because many populations of Atlantic bluefin are considered severely over-fished, critics of the industry say that these ranching operations are adding to an excessive hunt that is steadily pushing some populations toward commercial extinction. They say that the fish being caught for ranching are not necessarily counted against international quotas that are set to conserve the species.
Blue fin tuna ranching is also being done in Mexico, targeting populations of the smaller-sized Pacific blue fin that are thought to be in better shape that their Atlantic cousins. But given that the overall hunt for tuna throughout the Pacific is steadily growing, many marine biologists believe that it's only a matter of time before Pacific populations are over-exploited. Another issue again centers around the fact that these top predators are fed enormous volumes of forage fish, which critics say can have negative impacts on marine ecosystems and may involve health risks to humans due to the accumulation of toxics like dioxins and PCBs. In a world where fish populations have been steadily declining, they say this form of aquaculture consumes far more fish protein than it creates.