Oocyte maturation and changes of plasma steroid levels in the wild and cultured pikeperch, Sander lucioperca following hormonal induction

The present study was designed to compare plasma steroid levels and spawning success between wild and cultured female pikeperch, Sander lucioperca after induction of ovulation by different hormones. Two groups of wild-caught (۱۱۸۳.۱ ± ۵۶.۱ g) or cultured (۳۳۷.۴ ± ۲۰.۱ g) fish were treated with human chorionic gonadotropin (hCG; ۶۵۰ IU kg-۱), common carp pituitary homogenate (CPH; ۶ mg kg-۱), luteinizing hormone releasing hormone analog (LHRHa۲; ۱۳.۵ µg kg-۱), and saline solution as control group. The females were injected with those agents as priming and resolving dosages. The blood samples were obtained before hormonal treatment and after ovulation followed by assaying plasma levels of sex steroids (۱۷β-estradiol, testosterone and progesterone) and stress indicators (cortisol, glucose and lactate). The results revealed that all wild-caught females responded to CPH and LHRHa۲, while only ۷۵% of wild-caught females injected with hCG and cultured ones injected with hCG and CPH responded to the hormones and that no cultured ones responded to the injection of LHRHa۲. According to reproductive parameters including the number of eggs g-۱ and working fecundity, no significant differences were found in various treatments. All hormonal treatments exhibited an elevation in cortisol and glucose values in cultured fish after ovulation. In contrast, plasma cortisol levels declined significantly after ovulation in wild groups. The present study displayed that CPH and hCG induce a high reproductive performance and can be recommended to induce the controlled reproduction of either wild-caught or farmed pikeperch. In addition, our results revealed that wild-caught fish are more sensitive in term of cortisol and glucose levels than cultured conspecifics.

Keywords:

Broodstock , Cortisol , Hormonal treatment , Sander lucioperca , Sex steroids