Growth and survival of Lake Hallwil whitefish (Coregonus sp.) larvae reared on dry and live food.

Abstract

Two commercial dry diets and live zooplankton were tested as initial food for larvae of Lake Hallwil whitefish (Coregonus sp.) in comparison with a reference food type (Anemia nauplii). The ability of the larvae to switch from dry diet to live zooplankton was also investigated. After three weeks of feeding, the diets in all experimental tanks were changed to live zooplankton caught in Lake Hallwil and larvae were fed for another three weeks. Mean total length and dry weight of the Artemia-prefed larvae at the end of the experiment were 18 mm and 3 mg at 5 °C, and 30 mm and 23 mg at 13 °C. Dry-diet prefed larvae were 15 mm and 1.5 mg at 5 °C, and 25 mm and 12.5 mg at 13 °C. Zooplankton-prefed larvae reached 17 mm and 2.5 mg at 5 °C, and 27 mm and 19 mg at 13 °C. Overall mortality varied between 5 and 45 %. Larvae fed live zooplankton suffered less mortality than those fed dry diets. Feeding conditions during the first three weeks after hatching affected larval growth: After the switch to zooplankton diet at the end of the third week, slower growth of Artemia and dry-diet prefed larvae was recorded. We conclude that the dry diets tested give satisfactory rearing results, but zooplankton is still the best diet for mass rearing of whitefish.