Fish with larger pre-seasonal oocytes yields lower egg quality in season – A case study of outdoor-cultured domesticated Pikeperch (Sander lucioperca)

Effect of thermal management on vitellogenesis and maturation in indoor-reared pikeperch (Sander lucioperca)

“…Depending on the technological solutions used, this temperature/light regime might have variable success (Hermelink et al 2011;. The period of oocyte growth is important as it is documented that the phenomenon of asynchronous maturation among a common broodstock occurs in this period (Ljubobratovic et al 2020;2022b). Namely, already in the stage of mid-vitellogenesis, it is visible that some of the female breeders grow their oocytes faster than others.…”

“…Namely, already in the stage of mid-vitellogenesis, it is visible that some of the female breeders grow their oocytes faster than others. This could eventually lead to the variable outcome of artificial spawning, reflected in a wide range of ovulation time in a common reproduction batch and high variability in egg quality (Zarski et al 2019;Ljubobratovic et al 2022b). Although such variability in maturation dynamics may provide an evolutionary advantage (Lappalainen et al 2003), it seems that, with an increase in the number of previous reproductive cycles, the maturation dynamic in females from a given broodstock synchronises, leading to a smaller variance in ovulation period and egg quality (Zakes et al 2013;Zarski et al 2019;Ljubobratovic et al 2021).…”

“…Based on thus far published work, it is plausible that two-stage maturation commonly described in many teleosts (Patino et al 2001) is most likely present in pikeperch oocytes. Namely, oocytes reach a certain size that is ready for maturation already in early winter, and further on, oocyte morphology appears to be rather stagnant (Ljubobratovic et al 2021;2022b;2023). Depending on the length of this first maturation phase, the dynamics of the next phase, FOM, may differ (Ljubobratovic et al 2020).…”

“…Depending on the length of this first maturation phase, the dynamics of the next phase, FOM, may differ (Ljubobratovic et al 2020). Likewise, there are inter-and intra-population differences that may lead to differences in FOM dynamics among the individuals of the common population (Zarski et al 2019;Ljubobratovic et al 2022b) as well as between the populations of different origin kept in similar conditions (Khendek et al 2018;Ljubobratovic et al 2023). Finally, the difference in the FOM dynamics can also depend on the postinjection thermal regime applied.…”

“…In the "stable" protocol, breeders, upon wintering, are warmed to spawning temperature (usually 12 °C), hormonally stimulated, and water temperature is further kept stable (Zakes et al 2013;Zarski et al 2019). The latter, the "warming" protocol, has been developed recently; it implies hormonal stimulation at a wintering temperature of 4-6 °C which is then slowly increased to the temperature suitable for ovulation (10-12 °C) (Ljubobratovic et al 2021;2022b). This protocol efficiently reduces the inter-population variation of latency time (LT) -a period from the application of hormones until ovulation.…”