Effect of Starvation on Survival Rate and Body Composition of Artificial Pacific Bluefin Tuna Thunnus orientalis Juveniles

The effect of starvation on Pacific bluefin tuna Thunnus orientalis (PBT) juveniles was investigated according to two stages, weaning stage (0.8±0.2 g) at 25 days post hatching (dph) and transportation stage (3.8±1.2 g) at 36 dph. The juveniles were then transferred (0 h) into each tank from the mass production tank. Starved PBT juveniles were collected from one random tank at 3, 6, 9, 29 and 93 h (25 dph), and 12, 24, 36, 48, 60 and 72 h (36 dph). The survival rate of 25 dph remained above 80% until 78 h: moreover the standard length and weight were increased until 9 h of starvation. However, the survival rate of 36 dph rapidly decreased to 42% at 48 h, and the standard length and weight were gradually decreased until the end of starvation. Whole body lipid and glycogen were rapidly consumed initially and moreover, the protein and energy contents were gradually and steadily decreased during starvation in both experiments. When compared to the linear regression analysis between energy consumption and starvation time, there was a statistical difference between the experiments (P < 0.05). These results suggest that energy mobilization differs between the weaning (25 dph) and transportation stages (36 dph). Further, it is assumed that the juveniles are more sensitive to starvation at 25 dph.