Exploring yellow perch diets in Lake Michigan through stomach content, fatty acids, and stable isotope ratios

Describing food web structure through either direct or indirect diet analysis is often a fundamental step in elucidating ecosystem dynamics and developing resource management goals. The present study examines spatial trophic connections in an opportunistic forager, juvenile yellow perch (Perca flavescens), through the concomitant use of stomach content, fatty acid profiles, and stable isotope ratio methods. During September 2010, yellow perch were collected at nine coastal locations representative of Lake Michigan's habitat heterogeneity. The three diet assessment methods revealed differential levels of spatial diet heterogeneity. In general, yellow perch relied on pelagic prey more along the eastern shoreline, and over rocky substrates within each shoreline grouping. Conversely, high benthivory was noted in yellow perch from sandy substrates and western locations. Intra-population spatial diet dissimilarity may be common yet over looked among other species within large systems. We further advocate the concurrent examination of chemical ecological tracers (e.g., stable isotopes and fatty acid profiles) and stomach contents to investigate diet patterns of predators.