The effects of monosex culture and stocking density on survival, growth and yield of redclaw crayfish (Cherax quadricarinatus) in earthen ponds

Sexual dimorphism is apparent in redclaw crayfish, Cherax quadricarinatus, with males typically being larger than females and possessing prominent claws with a distinctive red patch. An experiment was developed to determine if there were advantages to rearing male or female redclaw crayfish at two densities in monosex cultures as opposed to traditional stocking of mixed-sex populations. Juvenile redclaw crayfish (9.6 g average weight) were acquired from commercial suppliers in Mexico. Animals were individually hand-sexed and stocked into 0.02 ha ponds and maintained for 145 days. Treatments were males at densities of 4 or 6 m(-2), females at 4 or 6 m(-2), or mixed-sex at 6 m(-2), used as a control. Each treatment had four replicates. The animals were offered a commercial shrimp diet. The ration was calculated assuming a weekly growth rate of 2 g and a feed conversion ratio of 1.5. At harvest male crayfish were significantly larger than females. In the male ponds, crayfish had a mean weight of 83.6 g while in the female ponds crayfish had a mean weight of 59.1 g. Survival and gross yields were not significantly different among the treatments. Average weight of crayfish in low-density culture (76.8 g) was significantly larger than average weight in high-density (59.3 g) culture. (c) 2005 Published by Elsevier B.V.