Intraspecific variation in clutch and brood size and rate of development in the yabby, Cherax destructor (Decapoda: Parastacidae)

The cultured freshwater crayfish Cherax destructor Clark has the largest distribution of any freshwater crayfish species in Australia. This study presents preliminary data on intraspecific variation in reproductive traits of C. destructor obtained from three populations under indoor hatchery conditions. Clutch size, measured as pleopodally attached eggs, and brood size, measured as newly independent juveniles, were positively correlated with crayfish weight. ANCOVA indicated significant differences between populations and between clutch and brood size. Based on size adjusted means, clutch size ranged from 360.6 to 593.4 and brood size from 311.4 to 384.5. Average brood size was 22.6% lower than average clutch size. Development time also differed amongst populations and was negatively correlated with temperature. Temperature adjusted mean development time ranged from an a minimum of 33.4 days to a maximum of 42.2 days. A strong inverse relationship between clutch/brood size and development time further highlighted the extent of life history differences amongst the crayfish populations. The implications of the increasing evidence for significant intraspecific variability within commercial species of Cherax in relation to aquaculture research and sustainable aquaculture are discussed.