Artificial fertilization and generating families for a selective breeding programme of large yellow croaker (Larimichthys crocea)

Large yellow croaker is an important marine aquaculture species in China. The aim was to determine an appropriate protocol of artificial fertilization for family construction in the breeding programme based on two trials. In trial 1, luteinizing hormone-releasing hormone A(3) (LHRHA(3)) was injected once, with a dosage of 2 mu g/kg for females and 1 mu g/kg for males. The latency time was in the range of 30-34 h. The maturation stage was checked by extracting a few eggs with a Pasteur pipette. The fertilization rate and hatching rate were 27 and 52%, respectively. The percentage of females with spawning difficulties was 30%. In trial 2, the females were injected LHRHA(3) twice: with a first dose of 0.8 mu g/kg and a second dose of 2 mu g/kg, at an interval of 10 h, whereas the males were still injected once. The latency time was in the range of 29.5-35 h, determined by only observing courtship behaviour of males. The females with spawning difficulties decreased to 10%, and the fertilization rate and hatching rate also improved to 41 and 62%, respectively.