Age-0 and age-1 yellow perch diet in southeastern Lake Michigan

Age-0 yellow perch (Perca flavescens) were collected during October 1998 an d age-1 yellow perch were collected during June 1999 from southeastern Lake Michigan off St. Joseph and Muskegon, Michigan, to evaluate diets relative to recent ecosystem changes. Size range of yellow perch examined was 72 to 118 mm. In October at a 15-m site off Muskegon, both Gammarus spp. and Iso poda were found in nearly 71% of age-0 yellow perch stomachs,and accounted for 71 and 26% of the diet by weight respectively. The following spring at the 15-m site (June 1999). Gammarus spp. and Isopoda were only a small part of age-1 yellow perch diet, and Chironomidae and Mysis relicta dominated t he diet. In October at depths of 25 to 35 m, M. relicta, was found in 100 a nd 80% of the age-0 yellow perch containing food off Muskegon and St. Josep h, respectively, and comprised over 96% of the diet by weight. Gammarus spp . Isopoda, and M. relicta were eaten in higher numbers than would be expect ed based on their low abundance in the environment. The high occurrence of Gammarus spp. and Isopoda in yellow perch diet may indicate ongoing changes in the nearshore benthic community.