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I I I I I I I I I I I I I I I I I I I 2-3 2.3 River Flows Estimated flows in Cataract Canyon during this investigation varied from a high of 21,985 cfs on July 25 to a low of 6,330 cfs on August 26, 1985. Flow estimates were provided by USSR River Forecast Center in Sal t Lake City, Utah. Each estimate is based on recorded flows at the Green River gauge near Green River, Utah and the Cisco gauge on the Colorado River near Cisco, Utah. Flows for each day and general river conditions for the 6 trips are presented in Table 2-3. 2.4 Sample Gear Ten distinct fish sample gears were used during the 6 Cataract trips (Table 2-4). Each gear type was designed to sample certain habitats Of' certain size fishes, and may have been used with greater intensity during some tri ps. The sampl e gears used on each tri p and the number of sampl e efforts are presented in Table 2-5. Electrofishing was used regularly on all trips, although the number of sample efforts was reduced on tri ps 2, 3, and 6 because of high and/or' turbid water conditions. Gill nets and tru.el nets were al so used with regularity, but heavy debris in the river on trips 2, 5 and 6 restricted their use. Attempts were made to float a tru.el net fixed between largE! bra 11 es in the center river channel duri ng tri ps 2 and 3, but thi s gear had 1 ittl e success. Seines were al so regul arl y used on each tri p; the small.. mesh l/16-i nch mesh was used most frequently on tri ps 2 and 3 to capturE! newly-hatched fish, and the 1/4-inch mesh seine was used on trips 4, 5, and 6 to capture the young-of-year after a m>onth of growth. Drift nets WerE! used during trips 2, 3, and 4 to capture drifting larval fishes.. Unseasonably warm spring temperatures apparently caused early reproduction by most fishes in Cataract Canyon, and these drift nets had limited success because the program was initiated too late in the season. long-handled dip nets and hand-held kick screens (Mundo nets) were al so used to capture small fishes in habitats too small and shallow for other gears.