Farming Bluefin Tuna Stirs Hopes — and Fears of Unsustainability

Aquaculture-raised bluefin tuna is now being served in several restaurants in the U.S., encouraging hopes that it may slow the overfishing of the prized sushi species but also prompting criticism that the practice is unsustainable. Researchers from Japan’s Kinki University and Australia’s Clean Seas Tuna Ltd. have succeeded in raising bluefin tuna from hatched eggs and then feeding them in pens using baitfish. The farmed fish, known as Kindai tuna, is now being supplied on a limited basis in the United States. Proponents say it will ease pressure on wild bluefin tuna stocks around the world and is an alternative to tuna “ranching,” which involves netting wild bluefin and fattening them in oceans pens before slaughter. But critics say that raising the great predatory fish from the egg stage is a wasteful and unsustainable practice that requires feeding 12 pounds of wild baitfish to the tuna to produce a single pound of bluefin. Critics also maintain that tuna concentrated in pens generate large amounts of waste that smothers life on the sea floor.