Effects of Water Temperature, Density, and Sex Ratio on the Spawning Rate of Red Claw Crayfish Cherax quadricarinatus (von Martens)

Effects of water temperature on red claw crayfish Cherax quadricarinatus spawning rates was evaluated for 3 mo at 22, 26 and 30 ± 1 C. A 20/m 2 stocking density and a 1:2 M: F sex ratio was used. Spawning rate increased as temperature increased, with 30 C providing the highest spawning rate ( P < 0.05). Effects of stocking density and sex ratio on the reproduction of red claw crayfish were also evaluated at densities of 10.15 and 20/m 2 , with a sex ratio of 1:1, and at three sex ratios (1:1. 1:3 and 1:5 M: F) at a density 10/m 2 . Water temperature was maintained at 28 ± 1 C and photoperiod was maintained at 14L: 10D for 6 mo during the density and sex ratio experiments. Spawning rates were not significantly different ( P > 0.05) within the three stocking densities at a sex ratio of 1:1, nor were they different ( P > 0.05) for the three sex ratios at a density of 10/m 2 . Results revenled that densities as high as 20/m 2 and sex ratios of 1 male to 5 females can be used to increase spawning per tank. Also, high temperature (28 ± 1 C) and long day lengths (14L: 10D) can be utilized to stimulate peak spawning rates, but high spawning rates cannot be maintained for more than about 3 mo.