1Hokkaido Central Fisheries Experimental Station, Yoichi, Hokkaido 046-8555, 2Graduate School of Fisheries Sciences, Hokkaido University, Minato-cho, Hakodate, Hokkaido 041-8611, Japan
The optimum conditions for inducing triploidy and gynogenesis by cold and pressure shock in barfin flounder Verasper moseri were examined. The sperm of barfin flounder was genetically inactivated by the dose of 10 mJ/cm2 UV irradiation. Triploids were induced by applying cold shock treatment with −1.5°C at 9 min after fertilization for 90 min duration. In this condition, hatching rate relative to the control was 29.2% and triploidy rate was 90.9%. Meiotic gynogenetic diploids were obtained by fertilizing eggs with UV-irradiated sperm and subsequent cold shock (−1.5°C) at 3-9 min after fertilization for 60-90 min duration and pressure shock (650 kg/cm2) at 7 min after fertilization for 6 min duration. Mitotic gynogenetic diploids were obtained by pressure shock (650 kg/cm2, 6 min) and applied at 150-240 min after fertilization.