White bass (Morone chrysops) and walleye (Stizostedion vitreum) coexist in
several of the large glacial lakes in eastern South Dakota. We collected ag
e-0 white bass and walleye in Lake Poinsett monthly from July through Septe
mber of 1996 to assess the extent of diet overlap using Schoener's index (C
-xy). 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 per
iod. Both species initially fed on zooplankton in July; however, diets dive
rged in later samples. Age-0 white bass primarily consumed zooplankton thro
ugh 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 ov
erlap between age-0 white bass and age-0 walleye was initially high in July
(C-xy = 69), but declined through September (C-xy = 36).