Thousands of tuna, their silver bellies bloated with fat, swim frantically around in netted areas of a small bay, stuffing themselves until they grow twice as heavy as in the wild. Is this sushi's future? Tuna raised like chickens or cows? As the world's love affair with raw fish depletes wild tuna populations, long-running efforts to breed the deep-sea fish from egg to adulthood may finally be bearing fruit. Though the challenges are daunting, the potential profits are huge. By the end of this year, an Australian company says it will begin selling small amounts of southern bluefin tuna hatched in its fishery. A Japanese firm breeding the more prized Pacific bluefin tuna hopes to start sales in 2013 and ship 10,000 fish by 2015. Whether tuna farming will become viable on a large scale remains an unanswered question. Tuna are much harder to rear than the widely farmed salmon and shrimp. They are large and need room to swim. They only spawn under certain circumstances. In some experiments, fewer than 1 percent of the babies survive. And those that do eat so much that they could wipe out other fish species. The bulk of the tuna farmed today isn't bred from eggs; it is caught in the sea and fattened on farms, which does nothing to save nature's dwindling stock. Atlantic bluefin, found in the Atlantic Ocean and the Mediterranean, is disappearing so rapidly that Monaco is pushing to list it as an endangered species at an international meeting in Qatar in March. The US says it will back the proposal. Separately, the International Commission for the Conservation of Atlantic Tunas recently slashed the quota for next year's catch by about a third to 13,500 tons, a move criticized by environmentalists as not going far enough. No wonder Japan's biggest seafood company, Maruha Nichiro Holdings Inc., is bullish on tuna. Maruha operates several tuna farms, including one in Kumano, a small coastal city in western Japan. Here, in a small bay, the fish live in netted sections mostly 50 meters by 80 meters, smaller than a football field. “For years, everyone assumed it was impossible to breed tuna on farms,” says Takashi Kusano, a general manager who has worked for 20 years on cultivating tuna. “Tuna remains forever a mystery.” Japanese consume 80 percent of the world's Atlantic and Pacific bluefin tuna, the two species most sought after by sushi lovers.
