Observations on growth, sexual maturity and spawning performance of pond-reared Penaeus merguiensis.
This 12-month preliminary study investigated the development of sexual characters, primary sexual maturity, ovarian maturity and spawning performance of pond-reared Penaeus merguiensis in relation to culture conditions in south-east Queensland, Australia. Post-larvae of P. merguiensis were produced and cultured in two 60-m3 tanks during the first 14 weeks. Before winter, they were harvested and stocked in three different overwintering facilities: a 200-m2 covered pond, two 60-m3 outdoor tanks and a 15-m3 indoor, recirculated tank at a stocking density of 10 individuals m2. The development of sexual characters was found to be similar to that reported previously in wild P. merguiensis. Males matured at younger ages and smaller sizes than females. Overall, the average size at primary sexual maturity of pond-reared P. merguiensis was 23.1 mm carapace length for males (possessed spermatophores) and 29.3 mm for females (being impregnated). Water temperature and the availability of natural food strongly influenced prawn growth, maturity rate and their subsequent spawning performance. Growth, maturity rate and spawning performance of prawns in the covered pond were significantly higher than in the other overwintering facilities. Prawns started mating at 6-7 months, reached full ovarian maturation and spawned as early as about 8 (peaked at 9-11) months from hatching, producing high fecundity and viable larvae. There was a strong relationship (P < 0.001) between prawn size and fecundity. The results of this study suggest a potential for using pond-reared broodstock P. merguiensis for hatchery production and for domestication or selective breeding programmes.