Abstract

Photoperiod and temperature were found to have a significant influence on spawning rate of mature redclaw crayfish, Cherax quadricarinatus. Average monthly spawning rates ranged from 15% with less than 12 hours of light to over 35% with more than 12 hours of light. Peak spawning occurred with day lengths of 14 hours. Spawning rates increased as temperature increased from 22°C to 30°C. Peak spawning could only be maintained tor about three months. No differences in spawning rates were found at broodstock densities of 10, 15 and 20 m^-2 at a sex ratio of 1M:1F or at sex ratios of 1:1, 1:3 and 1:5 ( male to female) at a density of 10 m^-2. Females with newly spawned eggs had an average of 10 eggs per gram of body weight. By day 21, at 28°C, eggs had reached the eyed stage and egg number had decreased to 7.8 eggs per gram of female body weight. Hatching rate was 95% resulting in an average of 7.3 hatchlings per gram of body weight. Using late stage eggs, the relationship between egg number and female body size was linear and described by the equation, Y=-5.7478 + 7.7593 X, r² = 0.92, tor females ranging from 40 to 190 g.

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