Recent refinements of pikeperch artificial reproduction methodology at NAIK HAKI

Uroš Ljubobratović¹, Géza Péter¹, Zoltán Horváth², Ferenc Demény¹, András Rónyai¹

¹NAIK Research Institute for Fisheries and Aquaculture, H-5540 Szarvas, Anna-liget u. 35.
²H&H Carpio, H-7814 Ócsárd, Kossuth u. 7.

Abstract

The main aim of the research was to improve the method in such way to bring it closer to farmers’ possibilities, thus at the same time to be practical and successful. In order to estimate the ovulation day, monitoring of final oocyte maturation is being done on a daily basis. Main improvement which made this methodology applicable is the suture of genital papilla in order to prevent spontaneous ovulation, what was the most critical point of the whole procedure. Further on, in order to reduce the chance of over ripening of ovulated eggs and with it reduce the frequency of ovulations checks and fish handling, the work on hormonal preparation and ovulation temperature took its share in the research. Therefore, instead of earlier used gonadotropins, we are presently using salmon gonadoliberin analogue, in forms of single injection, or in form of priming and resolving injection. Likewise, instead of earlier used temperatures of 14-16 °C, presently we are expecting ovulations on 10-12 °C. These improvements lead to significant reduction of the labour, finally performing ovulation checks every 6 hours. Instead of stripping and collecting in syringe, presently we are collecting milt with catheter avoiding possible contamination with urine, on such way improving the sperm quality and fertilisation success. Finally, we developed rather simple and reliable egg de-adhesion method with milk and kaolin which leads to high embryo survival and rather natural way of hatching. Using our own feed-eating broodstock, our methods are producing reproductive success of 40-80% larvae from dry eggs amount during the period from January to mid-April. Since this year we are working on the synchronisation of ovulation using priming on the low temperatures and first trials are pointing to the highly promising procedure. Our recent new research field is spawning induction in totally controlled conditions, which should be main topic in the following period.