第1卵割阻止によるヒラメの雌性発生2倍体の誘起と飼育特性

抄録

The following results were obtained from the experiments to find optimum conditions for induction of gynogenetic diploids in hirame Paralichthys olivaceus by suppression of the lst cleavage, and to clarify their survival and growth rates. Induction of gynogenetic diploids by suppression of the lst cleavage was achieved by adding hydrostatic pressure of 650kg/cm² for a duration of 6min at 60min after insemination, but the induction rate was low (2.7-5.3%). Genotypes of gynog-enetic diploids induced by suppression of the lst cleavage from female whose genotype in TDH isozyme was heterozygous, separated into 2 homozygous types. Since genotype of IDH isozyme in gynogenetic diploids induced by retention of the 2nd meiosis was heterozygous, induction of homozygous hirame has been easily identified. However, thier survival rates were very low, growth rate was not good, and coefficient of variations of total length was relatively large in gy-nogenetic diploids.