Induced out-of-season and seasonal tank spawning and stripping of pike perch (Sander lucioperca L.)

Abstract

Nine trials were carried out on the induced propagation of pike perch in out-of-season as well as in the natural reproduction period. From January till May, periodically, 16–20 pairs were transported to the hatchery, and acclimated to 15–16°C. The following hormonal treatments were used to induce reproduction: carp pituitary homogenate (CP) and human chorionic gonadotropin (hCG) alone or in combination; gonadotrop-releasing hormone ‘Ovurelin’ (D-Phe6-LH-RH) alone or with metaclopramid (MTC); and ‘Ovopel’ [containing des-Gly10-(D-Ala6)-LH-RH-ethylamide and MTC]. The effects of daylight regime, water temperature and the length of the pre-spawning conditioning period on the reproduction performance were determined. From the 130 hormonally treated pairs, 122 either spawned in tanks or were stripped. There were no differences in the ovulation rate between out-of-season (93%) and seasonal (91%) propagation. The developmental stage of the eggs correlated with the latency period, which significantly declined from January till April. The latency period was the shortest in fish treated with hCG and, secondly, with CP. The germinal vesicle migration did not proceed without hormonal treatment, although in some trials breeders were kept at the spawning temperature for 1–2 weeks. The results demonstrate that the pike perch can be successfully induced to spawn about 3 months earlier than its natural spawning season, which allows a significantly prolonged yearly supply of fry.