Improved Seed Production of Goldstriped Amberjack Seriola lalandi under Hatchery Conditions by Injection of Triiodothyronine (T3) to Broodstock Fish

Survival of the seed of goldstriped amberjack Seriola lalandi was consistently enhanced by intramuscular injection of triiodothyronine (T₃) to the broodstock fish at a dose of 20 mg/kg body weight. Survival rates at the time of transfer to net cages (35 d after hatching) were 2.6–5.0% for the T₃ treatment while only 0.3–2.1% for the control. Survival rates 36 mo after hatching was estimated to be 12 times higher in the T₃-treated group (1.1%) than in the control (0.09%). T₃ concentration in newly spawned eggs increased from control levels of 0.3–1.0 ng/g to 68–127 ng/g 2 d after injection and subsided with successive spawns. T₃ concentration in the treated larvae was about 360 times higher than in the control upon hatching (29 np/p vs 0.08 ng/g), but became indistinguishable from the control 6 d after hatching. These results indicate injection of T₃ to the broodstock of S. lalndi to be of practical value in aquaculture of the species.