Out‐of‐season spawning of cultured pikeperch [Sander lucioperca (L.)]

The aim of this study was to determine the effectiveness of out-of-season spawning of cultivated pikeperch (fish that were reared from the larval stage in re-circulating systems and fed commercial feed exclusively) stimulated hormonally with human chorionic gonadotropin (hCG). The impact of fish age (2+ and 3+) and hormone dosage [200 or 400 IU hCG kg−1 body weight (BW)] on spawning was analysed and expressed as the share of stripped females, commercial fecundity (% BW) and survival of embryos until the eyed-egg stage (EES index). The possibility of utilizing changes in female pikeperch body weight (CBW index) that are observed following hormone injections as an additional indicator for determining maturity was also investigated. The age and hormone dosage were not noted to have a significant impact on the number of stripped females (≥80% on all groups), the latency period (90–100 h), commercial fecundity (11.3–13.3% BW) or the values of the EES index (61–73%; P>0.05). The mean value of EES from the 3+ age group females was higher than that in the 2+ females, and the interaction between the tested factors (fish age and hormone dosage) wasstatistically significant (P 0.05). The regression equations that described the dependence between CBW and the oocyte maturity stage were highly significant statistically, and the determination coefficient R2 assumed a value of 0.76. The most significant increase in BW was related to the oocytes achieving maturity stage III. The BW of pikeperch females with oocytes in this stage was 103% higher than the initial BW. This might be a valuable and useful tool for determining maturity in females of this fish species.