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4-3 The nearest capture of an adult humpback chub to the project site was an individual captured by G. Kidd in 1977 (Kidd 1977), about 2.5 miles downstream of the site. The next nearest capture of an adult was in August of 1979 at river mile 143.9 (Valdez et al. 1982), about 44.3 miles downstream of the site. The nearest capture of juvenile humpback chub was an individual captured in July of 1980 at river mile 139.8 (Valdez et al. 1982), about 48.4 miles downstream of the site. Young-of-the-year humpback chub are recorded only from the two population locales of the species in the Upper Colorado River; Black Rocks at about river mile 135 and Westwater Canyon at about river mile 125. The chances of fish from these populations moving upstream into the JH-1 project area are remote, as indicated by radiotelemetry studies at Black Rocks (Valdez and Nilson 1982). Individuals defined as 'intergrades' were captured in 1980 and 1981 at Beavertail Bend, river mile 195.5, (Valdez et al. 1982), about 7.3 miles upstream of the JH-1 site. These intergrades are either geomorphs of the Gila complex or the result of a gene pool arising from hybridization of ~ cypha x ~ robusta. As intergrades, these fish do not receive protection from the Endangered Species Act. Individuals recognized as this intergrade were also captured during this investigation near the JH-1 site (see RESULTS). No fish identified as humpback chub were captured or seen during this investigation, and so the current known distribution of the species as it affects this project remains as stated above. 4.4 Bony tail . The bony tail is the least known of the native Colorado River fishes. It was 1 isted as 'endangered' on April 23, 1980 by the U.S. Fish and Wildlife Service. Few individuals have been recently captured in the Green River, and the species was thought to be extinct in the Upper Colorado River ~~