Use of Spatial Resources by Fishes in Grayrocks Reservoir, Wyoming

Relative abundance of fishes in different habitat types and sampling areas of a reservoir in eastern Wyoming was assessed with experimental gill nets during summer 1989. Seven of 12 species captured in the gill nets were numerous enough to enable statistical evaluation: quillback (Carpiodes cyprinus), common carp (Cyprinus carpio), walleye (Stizostedion vitreum), gizzard shad (Dorosoma cepedianum), shorthead redhorse (Moxostoma macrolepidotum), channel catfish (Ictalurus punctatus), and yellow perch (Perca flavescens). All seven species were significantly more numerous in samples from littoral and offshore bottom areas than in samples from offshore surface areas throughout the summer. Common carp and walleye were significantly more abundant in the upstream portion of the reservoir throughout the summer, whereas quillback, gizzard shad, shorthead redhorse, and channel catfish were more abundant in the upstream portion during early summer.