Spontaneous spawning of Atlantic bluefin tuna Thunnus thynnus kept in captivity.

The fact that the captive BFT broodstock spawned spontaneously in 2010 is something that has never previously happened in aquaculture facilities far from the BFT natural spawning areas and this, therefore, shows that (a) the fish have reached an important degree of domestication as a result of their stay at the experimental farm for several years and (b) the conditions present in the area are sufficient to allow completion of the reproductive cycle. The spontaneous spawning in cage R1 in 2010 was longer in duration (26 days) but smaller in fecundity (48 million eggs) than in 2009, when 15 individuals of this cage were administered GnRHa. Moreover, the spawning in 2009 was more regular.