Differences between RAS-reared and wild pikeperch egg quality
Absztrakt
The global consumption of pikeperch (FAO 2012–2016) makes it an important candidate, not only for extensive aquaculture. But, also for the new and improving RAS systems. In the past, pikeperch were farmed in ponds or lakes, but in the last few decades, due to the fast decline in their natural supply, they have been successfully reared in a combination of pond and recirculation aquaculture systems (RAS). However, the production of good gamete quality remains an issue in the aquaculture industry and as such a major bottleneck in pikeperch aquaculture. The use of breeders held in RAS has been a subject of interest and over the years efforts have been made on improving the quality of eggs and larvae obtained from these breeders. The present study was a step further in this direction; which aimed at exploring the rearing conditions by a comparative study of eggs, sperm and larvae obtained from wild pikeperch captured within weeks preceding spawning, and, RAS reared pikeperch prepared for spawning by a photo-thermal induction and nutrition with live prey. Of all the parameters for reproductive performance analyzed, only the latency time and commercial fecundity showed a significant difference between both groups. The latency time of WCF was significantly shorter than its RRF counterpart. Also, commercial fecundity was significantly higher for WCF. Analysis of basic sperm parameters showed significantly higher sperm concentration and cell count for WCF groups. Sperm cell kinematics showed significantly higher VSL, VCL and percentage of progressive sperm of WCF groups. But, a lower percentage of motile sperm cells in the same group although not significant in this case. It is worth noting that although the RRF groups did not significantly differ from their WCF counterparts in terms of reproductive success; factors such as nutrition and handling should be taken into serious consideration for improving the reproductive performance of this group. Also, more emphasis is demanded on the evaluation of reproduction performance, by, examining the larva performance in larviculture. As this study indicated that embryo survival could be inconclusive in determining reproductive success especially on a long term basis.