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I I I I I I I I I I I I I I I I I I I RESULTS Summary of Fish Collections A total of 28 species of fish, representing 10 families, were captured in the Cataract Canyon Region in 1987 (Table 4). This list is similar to that reported for collections in the region in 1985 and 1986 (Valdez 1985, 1987), except that two suspected adult bonytail were reported in 1987, as well as an adult razorback sucker. Also, an adult kokanee salmon was captured in upper Lake Powell in 1987 and one was captured in 1985 at the same location. As a percentage of total catch, the most common species of fish captured in 1987 were red shiner (52.70), channel catfish (11.70), common carp (9.40), sand shiner (6.23), and fathead minnow (5.05). These five non-native species made up 85.08% of the catch. Of the 28 species reported, 20 are non-native (exotic), and only 8 are native or endemic to the Colorado River system (Tyus et ale 1982). As a percentage of total catch, the ratio of non-natives to natives was 87.22 to 12.41 (0.37% were not classified, since a glass vial was broken in shipment to the LFL). The endangered species (Colorado squawfish, 4.17%; humpback chub, 0.09%; and bony tail 0.01%) made up 4.27% of the total catch. It should be noted that some non-native species (striped bass, threadfin shad, bluegill, and kokanee salmon) were caught below Cataract Canyon, in an area where riverine habitats are inundated by Lake Powell. If only the species caught above the inflow of Lake Powell are considered, there were 16 non- native and 8 native species. It is also noted that some species normally considered non-riverine (black crappie, largemouth bass, green sunfish, walleye) were captured in quiet backwaters within Cataract Canyon. The complete data set, as total numbers of fish captured in each sample by gear type, and the associated habitat information, are presented in Appendix A. A copy of this complete data set has been provided to BOR on a computer diskette in dBASE 111+ format. Fish Collections by Gear with CPE Statistics A summary of all fish sampling efforts with the type of gear used is presented in Table 5. An effort was made to expend similar effort during each of the eight sample trips for electrofishing, gill and trammel nets, and seining. Drift netting for larval fishes was conducted only on trips 2, 3, and 4. Other gear types were used as condi tions allowed. Summaries of fish species collected by life stage and CPE for each of the principal gear types are presented in Tables 6-18, on pages 30-38 of this report. Catch rates were computed as described in the methodology section for each species by each sample and then averaged. 11