Reproductive management and gamete quality in pikeperch (Sander lucioperca)

Abstract

Reproduction of temperate fish species is regulated by external and endogenous signals. It was hypothesized that the manipulation of environmental cues, as often practiced in aquaculture, may interfere with endogenous signals affecting the reproductive success. In an integrative study, (I) an array of commonly studied parameters associated with egg quality, (II) the effect of year-round reproduction and broodstock characteristics on egg composition and development and (III) predictive biomarkers were evaluated in 41 egg batches of commercially reared pikeperch (Sander lucioperca). Fertilization, embryo survival at 24, 48, 72 h and hatching rate were used to assess developmental potential. Substantial variability in developmental rates could be explained (47.1% fertilization; 58.2% 24 h, 47.0% 48 h, 43.9% 72 h survival; 46.6% hatching; 88.9% hatched larvae) by fecundity, maternal length, egg size and specific fatty acids (polar 20:5(n-3), 15:0, 18:0). The inherent oocyte composition exerted the highest influence during early development until 48 h. Fatty acid profiles were identified as major integrative parameters affecting oocyte development and being associated with other egg features, especially egg cortisol content, as well as fecundity and maternal traits (spawning history and time, female length). Other parameters had no direct effect (cortisol, prohibitin2 mRNA) or only a weak impact (egg dry weight content). Conclusively, female length, rather than endogenous zeitgeber, spawning history (first-time versus successively stripped) and time of spawning negatively influenced egg quality. An optimal maternal length of ~65 – 70 cm was associated with high fecundity and egg quality. In turn, specific egg characteristics can be used to predict the developmental potential of the oocytes.