1Nagasaki Prefectural Institute of Fisheries, Nagasaki 851-2213, 2Laboratory of Marine Biology, Division of Marine Bioresources, Department of Animal and Marine Bioresource Science, Faculty of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581, Japan
This study examined the relationship between post-ovulation time and fertilization rates of artificially inseminated eggs of yellowtail, Seriola quinqueradiata. Ovulation was induced by a single injection of HCG (500IU/kg) and occurred between 36 and 54 hours. The fertilization rates of the eggs collected from eleven fish decreased with time after ovulation from 92.5% (0hour) to 16.7% (48hours). The hatching rates of the eggs collected from the eleven fish also decreased, and were 50.3% (peak), 10.6% and finally 0% at 0, 12 and 24 hours after ovulation, respectively. These results suggest that artificial insemination of yellowtail must be carried out immediately after ovulation in order to obtain eggs of good quality.