Diet Overlap of Age-0 Walleye and White Bass in Lake Poinsett, South Dakota

Abstract

ABSTRACT White bass (Morone chrysops) and walleye (Stizostedion vitreum) coexist in several of the large glacial lakes in eastern South Dakota. We collected age-0 white bass and walleye in Lake Poinsett monthly from July through September of 1996 to assess the extent of diet overlap using Schoener's index (Cxy). Age-0 white bass increased from a mean length of 51 mm in July to 131 mm in September, while walleyes grew from 79 to 134 mm during the same period. Both species initially fed on zooplankton in July; however, diets diverged in later samples. Age-0 white bass primarily consumed zooplankton through September; prey fishes constituted a progressively greater proportion (by number) of age-0 walleye diets. Benthic macroinvertebrates did not make up a substantial portion of the diet for either fish species. Thus, diet overlap between age-0 white bass and age-0 walleye was initially high in July (Cxy = 69), but declined through September (Cxy = 36).