Growth, gonadal development and sex ratios of meiogynogenetic diploid sea bass

Gynogenesis showed little effect on general physiology and gonadal development in sea bass Dicentrarchus labrax. Meiogynogenetic fish showed well-developed gonads indicating low occurrence of developmental imbalances even after gynogenesis induction in this species. In addition, the proportion of sexes of meiogynogenetic sea bass was similar to the diploid controls in two independent trials, which did not deviate significantly from a 1 : 1 male : female sex ratio. Even considering some environmental influence on sex differentiation, as has been previously demonstrated, the fact that the proportion of sexes was similar between gynogenetic and control diploids essentially eliminates the possibility that in the sea bass the females are the homogametic sex. Although the mechanism of sex determination of this species still remains unknown, even after gynogenesis induction, the genetic mechanism of the ZW/ZZ type could probably operate in the sea bass.This research was supported by EC grantNo. AIR2-CT93-1543 and by CICYT grant No. AGP94-1321-EC to S.Z. A.F. wassupported by a grant from the Government of Valenci