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.