Study on embryonic development and early growth of triploid and gynogenetic diploid left-eyed flounder,Paralichthys olivaceus (T. et S.)

The early effects of chromosomal manipulation of eggs and sperm on the yields of triploid and gynogenetic diploid larvae ofParalichthys olivaceus were investigated Triploidy was achieved by cold shocking fertilized eggs at 0–2°C for 45 minutes duration 5 minutes after, fertilization, and the induced triploidy rates were 31.2%–50% and the relative hatching rates were 53.3%–99%. Gynogenetic diploids were obtained when eggs were inseminated with irradiated sperm and cold shocked at 0–2°C for 45 minutes duration 5 minutes after fertilization. The induced gynogenetic diploid rates and the relative hatching rates were 94%–96% and 48.5%–68.5% respectively. The embryonic development of the triploid experimental group and of the gynogenetic diploid experimental group was delayed at first compared with the control group. But from the gastrula stage, it was not delayed anymore. There were no significant differences in the growth of the triploid experimental group larvae and the control group larvae, and in the growth of the gynogenetic diploid experimental group larvae and the control group larvae according to Student’s t-test (α=0.05). The relationship between the early growth of the triploid experimental group larvae and that of gynogenetic diploid experimental group larvae was also studied.