Year-class variation drives interactions between warm-water predators and yellow perch

Abstract

Walleye (Sander vitreus), smallmouth bass (Micropterus dolomieu), and largemouth bass (Micropterus salmoides) are common top predators across many north temperate lakes, but no previous analyses have assessed factors driving their combined impact on mortality of a shared prey, yellow perch (Perca flavescens). We estimated consumption dynamics of walleye, smallmouth bass, and largemouth bass during 3 years that differed in age-0 yellow perch year-class strength and evaluated the relative contribution of each predator to age-0 yellow perch mortality, in Oneida Lake, New York, USA. Habitat-specific diet composition and population densities were integrated with temperature and growth rates to parameterize a bioenergetics model and estimate annual consumption of major diet items. Walleye were the dominant predator in both offshore and inshore habitats, while smallmouth bass and largemouth bass were also important inshore predators. Consumption of age-0 yellow perch by all three predators was positively correlated to age-0 yellow perch year-class strength, but our ability to account for age-0 yellow perch mortality decreased during years when year-class strength was strong. Within each year, predation by the three species accounted for all observed age-0 yellow perch mortality in late summer and fall, but not in the early summer, suggesting other predators in the lake likely predate on the youngest, most vulnerable yellow perch. These results are important for understanding how diverse predator communities can alter the spatial and temporal availability of prey refuges and influence mortality of a shared prey.