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The traits most useful for identifying juvenile fish (<150 mm TL) were 10 principal anal fin rays and angle of anal fin base extending well onto upper lobe of the caudal fin. The presence of a predorsal hump and subterminal mouth were not helpful for identifying humpback chub juveniles. There was considerable uncertainty in identifying juvenile Gila. However, recent Gila collections from Island Park that were preserved and sent to Dr. Darrel Snyder at the Larval Fish Laboratory at Colorado State University for identification has given us more confidence in our juvenile humpback identification for this study (personal communication, D. Snyder to T. Modde and C. Kitcheyan, 5 October 2001). Adult captures. Electrofishing and angling captured 83 adult humpback chub in Yampa Canyon. The fish were distributed from Laddie Park (river km 17) upstream to Disappointment Draw (river km 72). This distribution was similar to earlier data collected, although previous data showed greater numbers caught downstream (Figure 2). The distribution was very uneven; most fish preferred deep pools and eddies associated with large boulders. The river locations that yielded the highest catches in this study and historically were 0.8 km above Mathers Hole (river km 31), Big Joe (river km 39), Five Springs (river km 43), and Irvings Hole (river km 61). The larger catches at Big Joe, Five Springs, Little Joe, and Irvings Hole were in part the result of camping at these sites and spending more time angling. Angler caught humpback chub averaged 255 mm TL (n = 17) and electrofishing caught fish averaged 244 mm TL (n = 69, includes 3 recaptures). The relative length-frequency offish captured in this study (mean 245 mm TL) compared with historic data (mean 278 mm TL) showed more smaller and fewer large fish (Figure 3). This result may be due to different capture 8