Dietary Supplementation of Astaxanthin Improves Gonad Development and Reproduction Rates of Female Redclaw Crayfish, Cherax Quadricarinatus

Abstract

Redclaw is a crustacean species with vast potential as a high quality and valuable product that can be cost-effectively grown, however its production is currently limited by hatchery production volumes. Reproductive outputs may be influenced by nutritional inputs, with astaxanthin and cholesterol likely candidates for reproductive improvement. Therefore, the present study examined the effects of nutritional supplementation with either cholesterol (CHOL; 1 g/kg) and/or astaxanthin (AX; 100 mg/kg) for 75 days on ovarian maturation, the frequency of spawning and egg and embryo quality in redclaw crayfish in a 2 × 2 factorial design. The crayfish were housed in 100 L circular tanks, with 6 replicate tanks for each of the four dietary treatments, each containing 7 females (average body weight 61.5 g). Both AX and AX + CHOL supplementation increased ovarian maturation compared to Control and CHOL supplementation alone as evidenced by elevated GSI, and lower HSI. Additionally, the interval to spawning was less (p < 0.05) in crayfish supplemented with AX and AX + CHOL. Moreover, AX supplementation alone resulted in an elevated spawning rate (63.9%, 22.2%, 38.9% and 30.6%, p = 0.005), the mean ± SEM fecundity (10.0 ± 0.13, 7.2 ± 0.36, 8.2 ± 0.16 and 7.7 ± 0.34 eggs/g female, p < 0.001), number of eggs/female (602.0 ± 26.5, 472.4 ± 40.8, 524.1 ± 33.3 and 465.1 ± 26.9 eggs/female, p < 0.001), hatching rate (82.4 ± 1.3, 76.4 ± 3.3, 74.7 ± 1.9 and 74.3 ± 1.8%, p = 0.003) and number of hatched juveniles (504.1 ± 24.8, 318.6 ± 39.2, 404.6 ± 29.2 and 328.7 ± 31.9, p < 0.001) significantly compared to CHOL, AX + CHOL, and Control fed crayfish, respectively. Female crayfish supplemented with CHOL had significantly higher moulting rates (52.8%, 16.7%, 22.2% and 24.9%, p = 0.003) compared to AX, AX + CHOL supplementation and Control diets, respectively. We conclude that a dietary supplementation of 100 mg/kg AX improved the reproductive characteristics in female redclaw, while CHOL supplementation increased moulting rate without improving reproductive output.

Keywords: Broodstock nutrition, Cholesterol, Fecundity, Hatching rate, Juvenile production