Spawning Performance and Sex Steroid Levels in Female Pikeperch Sander lucioperca Treated with Poly(lactic-co-glycolic acid) Microparticles

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English. Simple Summary: Pikeperch Sander lucioperca is a promising candidate for intensive aquaculture.However, controlled reproduction has become the major bottleneck in pikeperch production. Toimprove and optimize its artificial reproduction, an effective method for hormone treatment isneeded. The use of a poly(lactic-co-glycolic acid) microparticle-sustained-release system to administergonadotropin-releasing hormone agonist to pikeperch resulted in acceptable reproductive output.Our results establish the potential of poly(lactic-co-glycolic acid) microparticle as a novel tool forhormone treatment in fish.Abstract: Pikeperch Sander lucioperca is a piscivorous species considered a promising candidatefor the diversification of intensive aquaculture. This study aimed to determine the effect of asustained-release delivery system incorporating mammalian gonadotropin-releasing hormone agonist(mGnRHa) into poly(lactic-co-glycolic acid) (PLGA) microparticles on the sex steroid levels andaspects of artificial reproduction of pikeperch. Fish were divided into four groups and injected with20 μg mGnRHa/kg, 5-day release microparticles encapsulated with 5 μg GnRHa/kg BW (PLGA 5),20 μg GnRHa/kg (PLGA 20), or 1 mL/kg 0.9% NaCl (control). Cumulative percentage ovulation was100% in the PLGA 5 group, significantly higher than in other tested groups. No differences amonggroups were observed in latency or fecundity. The level of 11-ketotestosterone (11-KT) peaked at40 h post-injection, and was sustained during ovulation, in all treated groups. The 17β-estradiol (E2)concentration increased in the mGnRHa-only group immediately after hormone injection, while bothPLGA groups showed a reduction in E2 after injection, continuing to decrease until ovulation. A lowdose of mGnRHa in PLGA microparticles significantly improves induction of ovulation and resultsin acceptable reproductive performance, which may positively affect pikeperch production undercontrolled conditions.