The production of hermaphrodites of Atlantic cod (Gadus morhua) by masculinization with orally administered 17-α-methyltestosterone, and subsequent production of all-female cod populations

At two years of age, 3 hermaphrodites and 1 control male were selected on the basis of their plasma ratio of 11-ketotestosterone:estradiol-17β (11KT:E2). The sperm was used to fertilize the eggs of normal females with the aim to produce three all-female and one control population. The sex of the F1 generation was determined at 10 months of age (n = 50 pr group), revealing 100% females in the offspring of all three hermaphrodites, whereas the offspring of the control male consisted of 54.2% females and 45.8% males. These results provide evidence of female homogamety in Atlantic cod.