Hybridization in Australian freshwater crayfish - Production of all-male progeny

In freshwater crayfish aquaculture high densities can result from uncontrol led reproduction. Hence some farmers manually sex yabbies Cherax albidus an d stock only male crayfish in farm dams or ponds. Although male-only yabby populations produce an estimated 70% increase in gross income, hand sexing is time consuming and prone to error. A hybridization experiment using fres hwater crayfish from the yabby species complex, collected from geographical ly isolated regions throughout Australia, revealed a hybrid between Cherax rotundus females and C. albidus males which consistently produces only male progeny. This has been confirmed in nine crosses of the same two species. The reciprocal cross of C. albidus females x C, rotundus males produces bot h male and female progeny. The consistent production of only male progeny b y hybridization has not been recorded previously for a crustacean.