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11 Larger, more predacious channel catfish may experience difficulty in capturing fish in the Green and Yampa rivers. Only the largest individuals contained fish remains (average TL = 392 mm, n = 28) and whole fish were found only in 12 stomachs (average TL = 446 mm). Fish species identified in stomach contents included channel catfish (n = 9), suckers (n = 2), sculpin, Cottus sp. (n = 1), and speckled dace, Rhinichthys osculus (n = 1). Our inspection of stomachs could have missed partially digested larvae or postlarvae, but some stomachs (n = 4) contained fish eggs. Although some of the fish containing fish remains no doubt consumed the prey, the presence of large fish bones, including vertebrae, in relatively smaller-sized channel catfish indicated that many of the catfish were scavenging. The presence of large carp scales in 10 individuals but no other fish parts, suggests some scale-feeding behavior, as reported for marine catfish by Szelistowski (1989). Piscivory only in larger catfish contrasts with other studies reporting piscivory by smaller (50 to 200 mm) individuals (reviewed by Carlander, 1969). The low incidence of piscivory we found may have been due to low prey availability or other factors such as temperature or turbidity regimens. High turbidity may limit the ability of channel catfish to capture fish as prey, and turbidity effects on catfish suggested by Davis (1959) and Lynch and Lemons (in litt.) may also apply to the Green River, in which the sediment load fluctuates from 19 to 66,000 mg/1 and the suspended load from about 110 to 1,700 mg/1 (Remilliard et al., 1988). Layher and Maughan (1985) reported optimal water clarity for channel catfish as <30 mg/1 (reported in Jackson Turbidity Units). The variety of bottom foods in many channel catfish stomachs (miscellaneous food category includes such camp garbage as rice, corn,