Walleye Fry Hatching, Diet, Growth, and Abundance in Escanaba Lake, Wisconsin, 1985-1992;Research rept

摘要

We examined the first six months of walleye (Stizostedion vitreum) life over an 8-year period (1985-1992) in north-central Wisconsin's Escanaba Lake to learn how water temperature and diet affect the hatching, growth, and abundance of age-0 walleyes. Walleye eggs incubated for 12-20 days and hatched significantly (P = 0.04) faster in years of rapid spring warm-up. Annual egg mortality varied from 38-81% in covered trays set on walleye spawning reefs and was not found to correlate with water temperature nor spring or summer fry abundance. Within 4-6 weeks of hatching, walleyes townetted offshore ate mostly planktonic Crustacea (especially Daphnia, Leptodora, and cyclopoid copepods), Chaoborus larvae, and some yellow perch (Perca flavescens). The walleye diet then shifted away from zooplankton to include chironomid larvae and pupae, larger insects, and more age-0 yellow perch. Fish increased in the walleye diet during years of high yellow perch abundance.