Polyploidy Induced by Heat Shock in Rainbow Trout

Polyploidy was induced in rainbow trout Salmo gairdneri when fertilized eggs were immersed in 36 C water for 1 minute. Triploids were produced if the eggs were treated 10 minutes after fertilization; tetraploids were produced by treatments 5 hours after fertilization. Sterile triploid trout and salmon potentially could grow and survive better than normal fish at sexual maturation. Heat-shock techniques also should be useful in the production of gynogenetic diploid trout and salmon for biological studies and breeding programs.