Effect of gonadotropin hormonal stimulation on out-of-season propagation success of different year classes of indoor-reared pikeperch (Sander lucioperca (L.))

Three trials of hormonally induced out-of-season spawning of cultured pikeperch were performed. Two preparations containing human chorionic gonadotropin (hCG) (groups Bg-4 and Pl-4) were applied in experiment I. Injections of preparations containing hCG either alone (group P1-3) or in combination with pregnant mare serum gonadotropin (PMSG) of different producers (groups Sr-3 and Pg-3) were applied in experiment II. Spawning effectiveness was determined for four age groups (2+ to 5+) of pikeperch stimulated with hCG (groups Pl-2–Pl-5) in experiment III. The females from all the experimental groups were stimulated once with a single dose of hormone at 300 IU kg^?1 body weight (BW). Females from the control group were injected with a 0.9 % solution of NaCl (group C). The working fecundity (CF; % of BW), latency time (LaT; h), and eyed-egg survival (EES, %) were determined. No progress in oocyte maturation was noted among the females from group C. Significant differences were noted in LaT, which was lower in group Pl-3 than in groups Sr-3 and Pg-3. The youngest fish (2+) matured significantly more slowly and exhibited significantly lower values of the CF and EES indexes in comparison with older fish (LaT 102 vs 75–80 h; CF 5.4 vs 10.4–11.2 % BW; EES 47 vs 70–77 %). The hormonal preparations used had a positive impact on the ovulation and spermiation of the cultured pikeperch. No improvement in the effectiveness of out-of-season spawning was noted when combined preparations of hCG and PMSG were used.