The bitter joke among fisheries scientists is that the Japanese are engaged in a dual project of turning all available knowledge and energy to the farm-rearing of bluefin tuna while simultaneously expending all available effort to catch every wild example.
In August 2006, they succeeded in one of those aims: Hidemi Kumai and his team at Kinki University managed to raise fry born in captivity to adult size and them have them breed successfully. Because of the complexity of their life cycle, it is a considerable achievement.1 These are valuable fish, with the record holder having sold for $180,000 in Tokyo. The three largest fishers of bluefin tuna are the United States, Canada, and Japan.
This is good news for those who enjoy bluefin tuna sashimi, though they should probably be hoping that the rearing process can be scaled up to commercial levels. According to the US National Academy of Sciences, present day stocks are only 20% of what existed in 1975.2 Some sources hold existing bluefin stocks to be just 3% of their 1960 level. Present stocks are only 12% of what the International Commission for the Conservation of Atlantic Tunas has designated as necessary to maintain the maximum sustainable yield for the resource. Within another fifty years, it is quite possible that wild bluefin tuna will no longer exist.
2 National Academy of Sciences. National Research Council. An Assessment of Atlantic Bluefin Tuna. Washington DC National Academy Press, 1994.
Also discussed on my blog: http://www.sindark.com/2006/08/06/tuna-farming/