Tuna Conservation

Beleaguered Bluefin

Experts warn that without concerted efforts to reduce overfishing and restore depleted stocks, tuna stocks will continue to decline. Bluefin tuna in particular are prized by sushi chefs and the high demand for these fish has taken its toll in the Atlantic, Pacific and Southern Oceans.

Bluefin tuna are slow to mature and many fisheries are catching young bluefin tuna that haven’t had a chance to reproduce. Bluefin are also highly migratory, which means many nations, including the U.S. and Japan, need to cooperate on management plans to maintain global populations. Unfortunately, this hasn’t happened, though there were signs of progress for Pacific bluefin in late 2010, based on an agreement by the Western and Central Pacific Fisheries Commission. In the Atlantic, the bluefin tuna fishery is managed through the International Commission for the Conservation of Atlantic Tunas.

In addition, bluefin are often caught with longlines that are up to three miles long, with thousands of hooks. These result in large bycatch, including threatened or endangered sea turtles, contributing heavily to the decline of some of these species.

Bluefin tuna ranching is also becoming common, where small bluefin are brought from the wild and fattened in open net pens. This further depletes bluefin stocks, and uses large quantities of fish as feed. Closed lifecycle aquaculture is also being developed, where bluefin are raised from egg to adult in captivity. But this has many of the same issues as ranching, notably the large amount of forage fish required as feed. All types of bluefin are on the Seafood Watch "Avoid" list.