Domestication of silver perch, Bidyanus bidyanus, broodfish

Abstract

ABSTRACT. Most breeding programs for the Australian native freshwater silver perch, Bidyanus bidyanus, are based on fish originally captured from natural populations. However, over the last 20 years, there has been a dramatic decline in the distribution and abundance of silver perch in the wild and the species now has the conservation status of “vulnerable.” Unless broodfish can be domesticated a serious shortage is imminent. The aims of this study were to determine the age and size at sexual maturity and the reproductive performance of silver perch reared in captivity. Fingerlings (mean weight, 4.0 g) from a hatchery were stocked into an aerated 0.32-ha earthen pond at a density of 22,000 fish/ ha for 12 months, harvested, and restocked at 10,000 fish/ha for a further 2 years. The fish were fed a formulated diet containing 35% crude protein. No fish were mature at 1 year of age; at 2 years, most males (93%; total length, 304.0 mm, weight 412.7 g), but no females were mature; and at 3 years, most females (97%; 316.4 mm, 549.6 g) were mature. Three-year-old fish injected with 200 IU/kg human chorionic gonadotrophin spawned viable gametes. High fecundity (mean 139,286 eggs/ kg), fertilization rates (84.5%) and hatch rates (76.8%) demonstrate that broodfish can be domesticated and the life cycle of silver perch can be closed. The use of domesticated broodfish will eliminate reliance on wild populations and provide a basis for future hatchery production and selective breeding programs.