Effects of Diet on Growth and Survival of Larval Walleyes

Abstract

Abstract The effects of diet quality on larval walleye (Stizostedion vitreum vitreum) growth and survival are described. The cyclopoid copepod Diacyclops thomasi consumed larval walleyes within 10 min at dense copepod concentrations and within 1 d at lower densities (500 organisms/L). At initial feeding, larval walleyes consumed both copepods and cladocerans 500-1,100 μm total length. Postlarva-II walleyes fed four different diets (minnow larvae, brine shrimp, and two size grades of zooplankton) for 6 d averaged 4.00 mg, 3.48 mg, 2.23 mg, and 1.92 mg (dry weight), respectively. No appreciable differences in survival (70-85%) were observed on these diets. During the first 3 weeks of life, the survival of walleye larvae at optimal conditions of diet, temperature, light, space, and density was 71% (range, 52-87%). The combined influence of higher water temperatures and smaller food organisms stimulated initial feeding 3 d sooner than previously reported for larval walleyes. Sufficient food and higher temperatures may be factors in suppression of cannibalism. Artemia sp. may be the best choice of a first food, because brine shrimp support high growth and survival of larval walleyes and do not prey on the larvae as do some copepods.