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fi~us ~ ~U,k~~~~ I ~~~ ABUNDANCE, GROWTH, AND DIET OF CHANNEL CATFISH, ICTALURUS PUNCTATUS, IN THE GREEN AND YAMPA RIVERS, COLORADO AND UTAH Harold M. Tyus and Neil J. Nikirk United States Fish and Wildlife Service, 1680 West Hi hwa 40 #1210, Vernal, UT 84078 University of Washington, Fisheries.Research Institute WH-10, Seattle, WA 98195 Abstract--Channel catfish were widely distributed in 517 km of the mainstream Green and 74 km of the lower Yampa rivers in 1987 and 1988. The fish was most abundant in rocky canyon habitats (average stream gradient >2 m/km), where adult fish comprised 14% of electrofishing and 70% of angling catch. Pectoral spine sections of 364 channel catfish of 27 to 756 mm total length ranged in age from 0 to 22 years respectively, with an average annual growth range of 17 to 53 mm. No difference in growth or condition factor was detected among catfish collected in eight river reaches. Growth of channel D7 l catfish in the Green River basin was judged slow in comparison to other areas of the United States and was attributed, in part, to cold water temperatures, short growing seasons, and elevated summer flow conditions. Channel catfish consumed a variety of food items, but piscivory was limited to larger fish (average length 420 mm). Of 575 stomachs with food (76.2%), 31% contained aquatic invertebrates, 28% contained vascular plant material, 22% contained terrestrial insects, 10% contained algae and detritus, and 8.5% contained fish