Culture of sunshine bass, Morone chrysops x M. saxatilis, fry in tanks with zooplankton cropped from ponds with a drum filter.

摘要

Sunshine bass, M. chrysops x M. saxatilis, fry were stocked at 20 fry/litre into 260-litre tanks when 4 days old (3.93 mm) and harvested 21 days later. Zooplankton were fed to the fry at rates of 10, 20, or 30 plankton/ml once per day with three replicates of each treatment. Zooplankton were collected with a drum filter from ponds managed to maximize rotifer densities at the time of filtration. The zooplankton were retained by a 60-鎚 mesh filter but passed through a 150-鎚 mesh. Beginning at age 9days, fry were also offered a ?50-鎚 microencapsulated, 50% protein fry feed at 1 g/2.4 hour. Mean survival rates at harvest were 3.1, 14.2 and 24.3% in low to high feeding treatments. Fry from the 30 zooplankton/ml treatment survived at a significantly higher rate than fry from the 10 zooplankton/ml treatment. Average total lengths of fry were 8.24, 8.15 and 7.66 mm and were inversely related to survival with fish from the 30 zooplankton/ml treatment, having significantly smaller fry than the other treatments. Use of a drum filter appears to be a practical way of cropping appropriately sized zooplankton for use in sunshine bass fry culture.