Induction of diploid gynogenesis in Atlantic salmon and rainbow trout using irradiated sperm and heat shock

Three experiments were carried out to investigate the possibility of producing inbred lines of Atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdneri) by gynogenesis using irradiated sperm and heat shock. In experiment I, tolerance of eggs to heat shock was investigated. In experiment II, eggs were inseminated with irradiated sperm and effects of temperature level, duration of shock, and time from insemination to heat shock were investigated. Heat shock administered for 10 or 20 min during the first 30 min after insemination increased the frequency of gynogenetic fry. Time from insemination to heat shock did not influence the results. The highest frequencies of gynogenetic fry were produced when Atlantic salmon and rainbow trout eggs were heat shocked at 24 and 26 °C, respectively. In experiment III, eggs from albino rainbow trout (recessive homozygote for a depigmentation gene) were inseminated with irradiated sperm from wild-type coloured males and heat shocked. All fry produced in this experiment were of the yellow albino phenotype. It is concluded that induction of diploid gynogenesis by heat shock is a rapid and practical method of producing high numbers of inbred lines in Atlantic salmon and rainbow trout.