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 neglected. In this study, we report primary sex ratio data obtained from 13 families of C. destructor obtained from intra- and intersubspecific crosses within and between C. destructor destructor and C. destructor albidus. Intrasubspecies crosses and the intersubspecific cross between C. destructor albidus males and C. destructor destructor females generated 1:1 sex ratios suggesting a simple chromosome-based sex determination mechanism in these crayfish. However, the reciprocal intersubspecific cross between C. destructor destructor males and C. destructor albidus females produced aberrant sex ratios 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 findings are difficult to interpret, however, they do suggest that the mechanism 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.