Understanding larval culture requirements of Southern Bluefin Tuna

The primary goal of Clean Sea Tuna Ltd (CST) and the recent Seafood CRC-supported collaborative research projects, is to achieve the closed life-cycle production of Southern Bluefin Tuna (SBT)(Thunnus maccoyii), in order to underpin a sustainable aquaculture industry. There are several known bottlenecks in the hatchery production of bluefin tuna species, initially identified through pioneering research in Japan, largely through Kinki University. These mortality events include: surface mortality in newly hatched larvae, sinking and death on the tank bottom in the live feed stage, cannibalism, weaning, and wall collisions. This research has aimed to address early larval mortality bottlenecks through the live feed stage in tank-based larval rearing. In the 2011 spawning season,fertilised SBT eggs were successfully transferred to Darwin (DAC), Port Stephens (PSFI) and two CST hatcheries in Arno Bay. Investigations of light intensity and live feed type at first feeding resulted in an increase in the incidence of swimbladder inflation in SBT larvae compared to the two previous years’ trials. Urinary calculi, which can be indicative of inappropriate culture conditions, were present at a high incidence in SBT larvae reared in some conditions and were not present in other conditions.