Abstract
Redclaw, Cherax quadricarinatus, is a tropical freshwater species, endemic to Northern Australia and is a promising species for global aquaculture development. However, the commercial expansion of redclaw is hindered by low female fertility. Our aim was to investigate if pre-exposure of female redclaw to males can induce spawning and enhance reproductive performance. The study was conducted in two phases: A dissociated phase (111days) where crayfish, were either isolated (Control, n = 36) or were exposed to either 6 (6M, n = 36 females) or 12 (12M, n = 36 females) males suspended in the uppermost row of a vertically arranged, recirculation system; an associated phase (34 days) where females were maintained at a sex ratio of 1M:1F. During the dissociated phase, the spawning rate was less in the control compared to the 6M group but similar between the 12M and other groups (2.8%, 22.2%, and 13.9%, respectively; p=0.048). However, the moulting rate was greater in the control compared to the 6M and 12M groups (22.2%, 5.6%, and 5.6%, respectively; p=0.034). During the associated phase, there were no significant differences in spawning rate, mean days to spawning, hatching rate, and moulting rate between treatments. The mean number of eggs produced during the associated phase was >30% greater in the 6M and 12M groups compared to the control group. We conclude that pre-exposure of female redclaw to males in a dissociated, vertical recirculation system, increases spawning rate during the dissociated phase, improves egg production, and has the potential to increase hatchery productivity.