A preliminary study of primary sex ratios in the freshwater crayfish, Cherax destructor Clark

Although Cherax destructor is the principal cultured freshwater crayfish in Australia many aspects of its general biology and genetics have been negle cted. In this study, we report primary sex ratio data obtained from 13 fami lies of C. destructor obtained from intra- and intersubspecific crosses wit hin and between C. destructor destructor and C. destructor albidus. Intrasu bspecies crosses and the intersubspecific cross between C. destructor albid us males and C. destructor destructor females generated 1:1 sex ratios sugg esting a simple chromosome-based sex determination mechanism in these crayf ish. However, the reciprocal intersubspecific cross between C. destructor d estructor males and C. destructor albidus females produced aberrant sex rat ios with three of four families being consistent with a 3:1, male to female , ratio and the fourth family consistent with a 100% male brood. These find ings are difficult to interpret, however, they do suggest that the mechanis m of sex determination may differ between the two subspecies and stress the need for further research in this field. The implications of these results in relation to the aquaculture of C. destructor are discussed. (C) 1999 El sevier Science B.V. All rights reserved.