Abstract
Tuna aquaculture is currently dependent on the wild capture of juveniles for
production. The development of hatchery technology for the Pacific bluefin and
other tunas would be a major step forward in improving sustainability of their
aquaculture. The present study overviews the technology in the life cycle comple
tion of the Pacific bluefin tuna (PBT) Thunnus orientalis (Temminck et Schlegel)
under aquaculture conditions in Kinki University, and the problems to be solved for
the establishment of tuna hatchery technology. PBT juveniles were wild-caught in
1987 when they were several months old, and reared to maturity. Fertilized eggs
were obtained from these fish in 1995 and 1996, and were used for a mass rearing
experiment. Resulting juveniles (the artificially hatched first generation) were
reared to maturity and spontaneously spawned on 23 June 2002. Over the summer
of 2002, 1.63 million eggs from these fish were used for a mass rearing experiment,
and 17,307 juveniles were produced and transferred to an open sea net cage. Of
these artificially hatched second generation PBT, 1,000 grew to approximately 105
cm TL and 18 kg BW in 24 months. This procedure means the completion of PBT
life cycle under aquaculture conditions which firstly attained among large tuna
species. The problems awaiting solution in PBT hatchery production are their
unpredictable spawning in captivity, to improve survival during the first 10 days
posthatch, to reduce cannibalism in larval and juvenile stages, and to solve collision
problem causing high mortality during juvenile stage.
