Reconstruction of Yellow Perch (Perca flavescens) Cohorts from Examination of Walleye (Stizostedion vitreum vitreum) Stomachs

Abstract

Number of young perch (Perca flavescens) consumed by walleye (Stizostedion vitreum vitreum) in Oneida Lake was determined from analysis of feeding chronology and digestion rates. Young perch were ingested between sunset and sunrise and digestion rates were estimated from the decrease in weight of perch in stomachs during the day. Walleye prédation began in late June and by October the number of young consumed ranged from 17,940 to 242,900 ∙ha⁻¹ in 1971–73. Concurrent studies indicated an additional 590 to 56,130 young were eaten by adult perch.Minimum population of young perch in June was calculated by adding to the number of young that survived to fall, the number consumed by walleye and adult perch. Populations reconstructed in this manner approximated independent estimates of the pelagic population in June. Mortality of young perch was apparently attributable to predation by percids and reconstructed populations accurately portrayed seasonal trends in abundance of young perch. Key words: predation, walleye, yellow perch, digestion, mortality