Alcalase enzyme treatment affects egg incubation and larval quality in pikeperch (Sander lucioperca)

Although egg de-adhesion has been the subject of research in pikeperch of late, the possible effect of this technological procedure on larval viability under intensive rearing conditions has not yet been evaluated. The aim of the present study was to evaluate the effect of the Alcalase enzyme on egg incubation and larviculture success compared to a commonly used procedure with milk and kaolin clay suspension. Preliminary research was conducted in order to find the minimal exposure time of eggs in Alcalase enzyme solution for the total elimination of adhesiveness. Further on, stripped eggs from three females were divided into two equal portions, and each portion was treated according to the abovementioned procedures. Efficiency of the procedures was evaluated and compared through egg incubation and larviculture. Alcalase-treated eggs exhibited significantly shorter incubation time (121 ± 12 h vs. 157 ± 10 h), hatching period (16 ± 7 h vs. 48 ± 21 h) and lower embryo survival (82.5 ± 2.4% vs. 87.7 ± 1.4%) with a significantly higher hatching rate (98.5 ± 1.0% vs. 72.0 ± 35.3 %). The larviculture yielded significantly lower production efficacy in eggs treated with Alcalase manifested as the share of larvae with an inflated swim bladder in the total number of stocked eggs (5.8 ± 2.4%) compared to larvae hatched in eggs treated with milk and kaolin (20.1 ± 11.9%). The Alcalase enzyme treatment reduced the incubation time and diminished the larval performance; therefore, its application in eggs of pikeperch should be reconsidered.