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The tapeworm (Proteocephaluc ptych~cheilus) was often found in the stomachs of sub-adult and adult Colorado squawfish and is common too in northern squawfish and red shiner in the Columbia River system (Hoffman 19 ). The presence of the bass tape worm (P. amblopletes) reported by Vanicek and Kramer (1969) was not confirmed. Generally, we believe that populations of Colorado squawfish in the upper basin are not being adversely impacted by disease or parasites. The incidence of infection from pathogens observed, although high for Learnaea, is not out of the ordinary of what could be expected in a natural fish population. Humpback Chub Distribution and Abundance The only major populations of humpback chub, Gila cypha, conclusively known to exist in the upper basin are located in Black Rocks (RM 135- 137) and Westwater Canyons (RM 116-124) on the main Colorado River. Incidental captures were recorded from Cataract Canyon; throughout Gray and Desolation Canyons on the Green River; and at the lower end of Cross Mountain Canyon and in Yampa Canyon on the Yampa River. There was also a mixed population of G. cypha, robusta, elegans and a substantial number of intergrades located near Coal Creek in lower Gray Canyon. Another small population of indistinct taxonomy was identified in Debeque Canyon (RM 195-197) on the main Colorado River. The sampling program demonstrated that humpback chub were prevalent in Black Rocks and Westwater Canyons. Catch rates yielded 40 and 18 fish per 10 hr of netting as compared to less than 0.1 fish per 10 hr for all other areas. Disproportionate sampling efforts yielded 167 humpback chubs from Black Rocks and 62 from Westwater Canyon. Of 218 adult humpback chubs tagged with Carlin dangler tags in Black Rocks and Westwater Canyon, 16 were recaptured. All but one of these fish were recaptured within less than 0.5 mi of their initial release site. The exception was a fish that had migrated from Westwater Canyon 14 mi upstream to Black Rocks. The Coal Creek population yielded 70 specimens of various class- ifications. Of these, 52 were tagged and 10 subsequently recaptured in the same area. Aabitat Selection Humpback were very restrictive in the habitat preferred and occupied. The species in all life stages were concentrated in canyon areas of great depths and fast water velocities with redrock, boulder and sand substrates. Microhabitat preferred within these canyons indicated the humpback did not spend a lot of time in the swifter, turbulent waters but preferred the associated slower pools and eddies with velocities of 0 to 3.8 fps but averaging 0.2 to 0.3 fps.