Influence of thyroxine on spawning performance and larval development of Sterlet sturgeon Acipenser ruthenus

This study set out to examine the effects of thyroxine (T4) on reproductive success of female Sterlet sturgeon broodstock and subsequent growth and development of the larval offspring. Fish received four intraperitoneal injections of coconut oil (controls), 1 mg T4/kg body weight (BW) in coconut oil (T1) or 10 mg T4/kg BW in coconut oil (T10) over a 170-day treatment period. Ovulation was induced by intramuscular injection of luteinizing hormone-releasing hormone (LHRHa2). Fish in the control group ovulated quicker and had higher fecundity than the fish in experimental groups. Oocyte diameter was highest in the T10 group. Hatching rate in the control group was lowest among the groups. Larval survival at 3 days post hatch in T10 group was 92.2% and was highest among the treatments. Larval survival and the specific growth rate were greater in T10 than in the other treated groups. The T4 concentrations in unfertilized eggs, pre-larvae and post-larvae were higher in the T10 group than the others. These results showed the maternal injection of T4 has stimulatory effects on larval hatching rates, survival, and growth which make it a valuable treatment in sturgeon aquaculture.