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' Habitat data (water depth, velocity, temperature, and substrate type) <br />were recorded at each humpback chub capture location. Depth was measured <br />with a wading rod; water velocity was classified as low or high, upstream <br />or downstream, to differentiate eddy habitat from shoreline runs; and <br />gross substrate type was described from visual and manual examination. <br />Temperatures were obtained with hand-held thermometers. River flows were <br />daily averages recorded at the U.S. Geological Survey gauging station at <br />Deerlodge Park, Yampa River (Figure 1). Stream gradient was obtained from <br />U.S. Geological Survey stream profile map. <br />We did not attempt further quantification of water velocities used by <br />humpback chubs because the water was turbid and we could not accurately <br />determine the point location of a particular capture. Secondly, the fish <br />were primarily captured in habitats in which water currents swirled in <br />both upstream and downstream directions and preliminary efforts with a <br />flow meter yielded a wide range of positive and negative velocities <br />depending on exact location of recording device. <br />Data Analyses <br />Capture data were summed by gear (i.e., angling or electrofishing) <br />and by river reach (i.e., Yampa, Whirlpool, and Split Mountain canyons) <br />and catch per unit effort was calculated by dividing total numbers of fish <br />captured by total effort. Trammel netting effort was not quantified <br />because its use was limited due to harmful effects of this technique on <br />chubs. Angling in 1986 were not included in catch per unit of-effort <br />estimates because numbers of fishes other than humpback and roundtail <br />chubs were not recorded. Angling efforts in September 1989 also were not <br />included in these estimates. <br />6