In December 2007, the Fisheries Laboratory fish farm of Kinki University in Wakayama Prefecture became the first facility in the world to “close the cycle” by breeding Pacific bluefin tuna (hon-maguro) from completely cultured sources. That is, a third generation of fish was bred from two generations of tuna that had never lived in the wild — the first generation having provided the eggs for the second while captive in the net cages, where they had hatched from eggs harvested in the wild.
Meanwhile, Hagen Stehr, chairman of the Australian mariculture company Clean Seas Tuna, claims that Clean Seas is “85 percent there” in its quest to close the cycle for Southern bluefin tuna (minami-maguro). And although leading American tuna companies predict that by 2018 all commercial bluefin will be produced on fish farms, Stehr believes this will happen by 2010 or 2011.
However, Peter Makoto Miyake, a consultant with the Japan-Tuna Fisheries Co-operative, disputes these predictions in crucial respects.
“What the farms are producing at the moment is not bluefin tuna as we know it,” he says. “It’s a different animal . . . the taste is different and so is the appearance.”
Miyake instead advocates the strict enforcement of quotas for capture fisheries and the introduction of a worldwide buy-back program for fishing boats. He argues this would compensate fishermen for leaving the industry and reduce the size of the global tuna fleet — an approach that has been successful in significantly cutting the number of large long-liners worldwide.
Miyake and other experts believe that an immediate 50 percent reduction of TAC (total allowable catch) through such means as quotas, buybacks and the banning of net fishing for bluefin would enable stocks to recover to sustainable levels.
This TAC scheme seems to offer the best chance to save wild bluefin tuna from extinction, since once a species population falls below a certain level, ecological factors tend to prevent it from ever rebuilding. The demise of North Atlantic cod stocks is a stark example of this phenomenon. Bluefin tuna are at present considered to be overexploited and fast approaching such an ecological tipping point.