Effect of long-term exposure to high temperature on survival, growth and reproductive parameters of the redclaw crayfish Cherax quadricarinatus

The effect of temperature on survival, growth and reproductive parameters of Cherax quadricarinotus from a stage of early sexual differentiation to a stage of sexual maturity was investigated. Growth performance was expressed as specific growth rate (SGR) and growth increment (GI), while reproductive performance was evaluated in terms of the gonadosomatic index (GSI), mean oocyte diameter (MOD), proportion of mature vs. immature testicular lobes and structure of the vas deferens. The experiment consisted of males and females exposed separately to two treatments (water temperature at 27 and 30 degrees C) during a 360-day period. Survival was similar between treatments for each sex and between sexes for each treatment. Female growth, GSI and MOD did not differ between treatments. High temperature induced spawning in at least 20% of females. This treatment negatively affected growth of males, but they showed higher GSI and a greater proportion of mature testicular lobes, thus indicating an accelerated spermatogenesis. At 27 degrees C, males grew more than females from an approximate size of 15g. confirming previous results about the differential growth of both sexes. We conclude that the long-term exposure to 30 degrees C is favorable for ovary maturation and spawning in females, but it clearly affects male somatic growth and consequently, the yields of culture. Both results are especially useful for the species culture in tropical countries. The effect of this water temperature on male reproductive performance deserves further research. (c) 2010 Elsevier B.V. All rights reserved.