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I I I I I I I I I I I I I I I I I I I SUMMARY OF FINDINGS 1IIIIIIIIIIIII,I:llilillll:111111111L1II7,.,:,$,',',_,','.','.p.',.,'....,.....,:.E..,........,.,.,C,.,.,.,C,.,:,1,.,.,.,~,.,.,.,.,.,.,:,.,.,.,CA,..,.,.,.,.,.,p,.,.,:,.,.,.,.,.,N,.,.,.,.,.,.,~,.,.,., .,.,.,.,...I,.,$,....,N,.,.,.,.,H,....,....:....,:.$,:.:,..W,....m..,....,.. '.1&.11.1~:illllll:lI1I,IIII::~:.: {)}f?~rr~~~~r~~~~ff}tr:::[(?)U~r~~~~~~~Ui:r~~rj)U)){))Yf)frrnff( .. .. -. ... , -." - ;.;-:-:.:.:.:-:.:.::::::::;.::::=:::::::::::::::::=:::::::::;:::::::::::::::::::::::::::::::::::::::::;::::::=::: =::::::::::::;::::::::::::::::::::.;.:::...:-. .... :.;...:.:-:-:.:-:.:-:..-:.;-:-;-;.:-:.;-;.:-.-..:-:.:.......:-:...;.:.:-:...;.:.:.:.:.:.....:...:.;.:.:.;-:-:.:.;.;.:-;.:.;.;.:-::::::::::=:::::=;::=:::=::::::::::::::::::::: ,:,:,',:,",:-:-:,:- :,;-:,;.;,:,:,:,:,;,:.:-;.',-.",-'" .:.:.:-:.:.:-;-:.;-:.;.:-:.:.:.:.:.:.:........... Thirty-one species of fish were found in the lower 50 miles of the Colorado and Green Rivers, and the 16 miles of the Colorado River from their confluence to Lake Powell from 1985 to 1988. This included 23 non-native and only 8 native species. Of the eight natives, six were endemic to the Colorado River Basin; Colorado squawfish, humpback chub, bonytail, razorback sucker, roundtail chub, and flannel mouth sucker. The other two native species were not endemic; bluehead sucker and speckled dace. .............. ... ,..... .-.....................-..---.. ................................ .......................-.-.--.. ............................ ................ ........ ...-..---.............. .....-.................. . . . . . . . . . . . . . . - . . . . . . . . . . . .......................... .....-.-............................. ................................... .....P.............................. ............................ -....... .. :;:::::::::::::;:;::::;:::::::;:::::::::::::::;:;::;:::;:::::::.;.;-..;.:........... :::::::,:::::::;:~p~~!ty~sPE~~~..!.g~!'!!!Eg..m~:lCHT8YOFiu~:..:,.'C??':;. :::::::::::::::::;:;:::;:::::::;:::::::::::::::::;:::::::;:;::::::::::::::::::::::::=::, ::::=::::::::::::::::::::::::::::::::::::::::::::;:;;;;::;:::;:::;:::::;:::: .. :::::;:;::::::::: :::::;:::::::::::::::::::::;::;::;:.::: :-:-:-:.:.:.:-;.:.:.:::.:.:::::::::::.::::::::::::::::::;:::::;::::;::: ...... ..... :::::::::::::::::::::::::::::::::::::::::::::::::::: .. .......................... . ...... .................... Over 95 percent of the fish captured during this investigation were non-native while only 5 percent were native. Five species jointly accounted for 90 percent of the catch: red shiner, sand shiner, channel catfISh, carp, and fathead minnow. Red shiners alone made up about 50 percent of the fish in all samples while sand shiners composed about 21 percent. ... ............... .-.... .............................. . .. ...... ...........:::::. ..... ........:.:.:.:.:;::;::;}:.:.:.;.:.:.:.:.;.:.:.:.:.:.:.:.:. .. :.:.;.:.:.;.:.:-;.:-:::::::.; ... ...... ::::::::::::;:::::;.::::::::;::::::::.;...............:...... .......:.:. ... .............:.:.:.:.:.:............ .... .... ..";.;"):;:, .:::::{At.t:{~OUfl::OF?:reI:5:,bbt09Ab<):'atVea.A1N$TEIVI::::::: ................ ............................. .. .. ...::i:i;i:::;.:::::i::."..,!:!:!:::!!!!!!:!!:!!!I~!:!:~$fl~l:iil'I!~_~',.::>:::::..;...............:...............:...:.....:.........:.;.;;...:...;.::.;...;.......;...;.:.;........;...;.:.;. ............:.:. i/.:: .... .........................................:.....:.:...:.:.:.:.:.:.:.:.:.'.:.:.:.:.:.:.:.:.:.;.:.:.:.:.:.:.;.:.:.:.:.:-:.:.:.:.:.:.:.:.'.:.:.:.'.:.:.:.:.:.:.'.:-:-:.:.:.:.:.:.:.:.:.:.:.'.;.:.:.:.:.:.:. :.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.....:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.;..:.:.:.:.:-...::-.::::.-.:::.-.:.:.-.'.-.. All three federally Iist.ed endangered species and the one federal candidate for Iist.ing were present in the Cataract Canyon Study Area The total numbers of these endangered species made up only 3% of the total catch from 1985 to 1988. Colorado squawfish were found in each of the fIVe regions of the st.udy area, but were most. numerous as young-of-the-year (YOY) in the lower 50 miles of the Green River. Of the 4348 Colorado squawflSh captured, 4161 were YOY, 175 were juveniles, and only 12 were adults, including two that were previously tagged and released by the U.S. Fish and Wildlife Service 120 and 172 miles upstream in the Green River. Humpback chub were found in the 16-mile reach of Cataract Canyon closely associated with rocky, talus shoreline habitat and eddies next to deep, swift currents. Of 108 humpback chub captured, 11 were larvae, 19 were YOY, 56 were juveniles, and 22 were adults. Suspected bonytail were also captured in the 16-mile whitewater reach of Cataract Canyon, often in close association with humpback chub. The 14 suspected bonytails included 1 YOY, 7 juveniles, and 6 adults. Only 1 adult razorback sucker was captured during this investigation on a large alluvial cobble bar at the mouth of Salt Creek on the Colorado River, 3.6 miles upstream from the confluence. vii