Food Consumption of Walleye (Stizostedion vitreum vitreum) and Sauger (S. canadense) in Relation to Food Availability and Physical Conditions in Lake of the Woods, Minnesota, Shagawa Lake, and Western Lake Superior

Abstract

Measurement of walleye (Stizostedion vitreum vitreum) daily food consumption rates and prey density in Lake of the Woods, Minnesota, Shagawa Lake, and western Lake Superior showed a general relationship exists between the two variables. Daily food consumption increased from 1 to 3% of body weight at prey densities up to 400 mg∙m−3. Abundance of age 0 yellow perch (Perca flavescens) in Lake of the Woods, Minnesota, and Shagawa Lake resulted in much higher prey densities and daily food consumption to 4% of body weight. In Lake Superior where walleye fed exclusively on rainbow smelt (Osmerus mordax), prey density did not exceed 300 mg ∙m−3 and daily food consumption averaged less than 2.5% of body weight.Hourly food consumption by walleye changed in response to variation in prey availability and light intensity. Night feeding predominated during July and August when walleye fed on pelagic age 0 yellow perch. Feeding appeared to be continuous or crepuscular during June and September when larger demersal prey fish or invertebrates were eaten. Food consumption declined when prey concentrated near aquatic macrophytes and under conditions of high light intensity. Walleye daily food consumption was not influenced by a change in temperature from 20 to 15 °C.Daily food consumption of Lake of the Woods, Minnesota sauger (Stizostedion canadense) averaged less than walleye and was influenced by wave activity and prey density. Demersal prey was utilized by sauger throughout the 24 h-day. Key words: Percidae, food consumption, behavior, feeding, walleye, Stizostedion vitreum vitreum, sauger, S. canadense, light