Development of techniques for the large-scale rearing of the larvae of the Australian freshwater fish golden perch, Macquaria ambigua (Richardson, 1845)

Abstract

Experiments were conducted over four consecutive breeding seasons. Golden perch, Macquaria ambigua, larvae (total length, 5.0 mm) held at 23� to 25�C, commenced feeding on crustacean zooplankton (<350 pm in length) five days after hatching, at age D6 (D1 = day of hatch). Zooplankton density had a significant effect (P < 0.01) on the survival of larvae in 70-L aquaria. A delay of only two days to age D8 in initial feeding significantly reduced (P < 0.01) survival, and larvae not offered zooplankton until D10 did not commence feeding. There was a positive linear relationship (r2 = 0.98) between survival in earthen ponds (0-57.6%) and the volume of small zooplankton sampled from the ponds at stocking, but survival was not affected by larval stocking density (32-365 m-2) or length of the culture period (28-53 days). A mean survival of 44.6% in ponds that were left dry over winter and then stocked 10-14 days after filling, was significantly higher (P < 0.01) than survival in ponds stocked only 2-5 days after filling or in ponds inundated during winter. Survival, growth and production were not significantly different among ponds fertilized with inorganic fertilizer (NPK) alone or in combination with lucerne hay or poultry manure. Larvae grew at rates of 0.5-1.1 mm day-1, production rates were up to 153 kg ha-1 and a maximum number of 271 000 juveniles were reared in a 0.3 ha pond. Approximately 3 × 106 golden perch are produced annually at hatcheries in eastern Australia using techniques developed during this study.