Abstract
Simple SummaryPikeperch Sander lucioperca is a promising candidate for intensive aquaculture. However, controlled reproduction has become the major bottleneck in pikeperch production. To improve and optimize its artificial reproduction, an effective method for hormone treatment is needed. The use of a poly(lactic-co-glycolic acid) microparticle-sustained-release system to administer gonadotropin-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 for hormone treatment in fish.Pikeperch Sander lucioperca is a piscivorous species considered a promising candidate for the diversification of intensive aquaculture. This study aimed to determine the effect of a sustained-release delivery system incorporating mammalian gonadotropin-releasing hormone agonist (mGnRHa) into poly(lactic-co-glycolic acid) (PLGA) microparticles on the sex steroid levels and aspects of artificial reproduction of pikeperch. Fish were divided into four groups and injected with 20 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 was 100% in the PLGA 5 group, significantly higher than in other tested groups. No differences among groups were observed in latency or fecundity. The level of 11-ketotestosterone (11-KT) peaked at 40 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 both PLGA groups showed a reduction in E2 after injection, continuing to decrease until ovulation. A low dose of mGnRHa in PLGA microparticles significantly improves induction of ovulation and results in acceptable reproductive performance, which may positively affect pikeperch production under controlled conditions.
Highlights
Pikeperch Sander lucioperca is the most valuable freshwater fish species for European intensive aquaculture due to its exquisite meat quality, good growth performance, and high market demand [1]
Ovulation rate was 100% in the group treated with 5 μg gonadotropin-releasing hormone analogue (GnRHa)/kg body weight (BW) (PLGA 5) and was significantly higher than rates obtained in other groups
Cumulative ovulation in groups treated with mammalian gonadotropin-releasing hormone agonist (mGnRHa) only and with poly(lactic-co-glycolic acid) (PLGA) 20 was 40%, while no ovulation was seen in the saline-only control group
Summary
Pikeperch Sander lucioperca is the most valuable freshwater fish species for European intensive aquaculture due to its exquisite meat quality, good growth performance, and high market demand [1]. The methods usually used to accomplish this are natural spawning [5] or support of spawning by placing artificial nests (synthetic turf, brushes, coconut mats) inside rearing tanks [6,7,8] These methods have the advantages of minimal handling and labor, but are often associated with low fertilization and with loss of eggs due to spawning outside the nest [8,9]. The techniques do not allow the controlled reproduction of individual fish, often required for breeding programs or triploidisation [10], necessitating stripping for in vitro fertilization It shows advantages, artificial reproduction followed by in vitro fertilization is a challenging process complicated by difficulty in timing of stripping, spontaneous eggs release, post-ovulatory ageing, high broodstock mortality, and variable egg quality [8,11]
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