Crowding female red claw crayfish, Cherax quadricarinatus, under small-tanks hatchery conditions: what is the limit?

Abstract

Previous studies on reproduction in the red claw crayfish, Cherax quadricarinatus, have successfully employed broodstock densities of up to 20 crayfish m −2. This study attempted to increase the density of broodstock in order to intensify production of young in indoor hatcheries. Adult crayfish were stocked in 0.3 m 2 tanks at a 1:5 M:F sex ratio at three densities: 6, 12 and 18 crayfish per tank (corresponding to 20, 40 and 60 m −2). The number of berried females was noted at weekly intervals during 14 weeks. There was no difference among densities in survival rate and percentage of spawning and molting, nor in clutch size (pleopodal egg counts) of females. The results indicated that breeding red claw females are insensitive to crowding over a wide range of densities. They suggest that a broodstock density higher than 60 crayfish m −2 is feasible under indoor hatchery conditions.