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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />reaches and the lower Duchesne River, and the Larval Fish Laboratory at Colorado State <br />University sampled the Yampa River. About 500 miles of river were sampled prior to and during <br />spring runofffrom late-April through mid-June. About 1,191 hours (149 8-hr days) of boat or raft <br />electro fishing time was expended in all reaches. A substantial amount of effort was also devoted <br />to fyke- and trammel-net sampling of backwaters in the Yampa River. A total of 1,295 Colorado <br />pikeminnow were captured in all passes; 358 from the middle Green River, 256 from the <br />Desolation Canyon reach ofthe Green River, 209 from the lower Green River, 212 from the <br />White River, and 120 from the Yampa River. A total of 140 Colorado pikeminnow were <br />recaptured once and eight individuals were recaptured twice. Size structure and preliminary <br />abundance estimates of Colorado pikeminnow from each reach will be presented. <br /> <br />Kitcheyan, C. <br /> <br />u.s. Fish and Wildlife Service, Colorado River Fishery Project Office, Vernal, ur <br /> <br />Seasonal and Daily Movement Patterns of Colorado pikeminnow in Lodore Canyon. <br />Colorado pikeminnow have been described as having fidelity to a home range and traveling as far <br />as 360 km to one of two spawning sites in the Green River subbasin. Over the last two years <br />(2000 and 2001), data obtained from aerial surveys and telemetry (i.e. data logger and ground <br />surveys) have showed adult Colorado pikeminnow from Lodore Canyon display a great deal of <br />mobility and flexibility in habitat use. Between 2000 and 2001, fourteen Colorado pikeminnow <br />were implanted with transmitters in Lodore Canyon. In 2000, fish emigrated out of the canyon <br />from August to October and did not overwinter in the canyon. An aerial survey found <br />pikeminnow ranging from Horseshoe Bend and extending upstream into the Yampa River. In <br />2001, radio tagged fish began dispersing back into the canyon as early as March and continued on <br />into the month of July. Fish passage by the telemetry logger, above the Yampa River confluence, <br />occurred during midnight and early morning hours. Aerial surveys in the spring and summer, <br />found pikeminnow throughout the canyon and upstream into Browns Park National Wildlife <br />Refuge. Diel observations in Lodore Canyon, concluded pikeminnow were very mobile or <br />remained stationary, occupying an eddy or pool. Two fish displayed a great deal of mobility, <br />moving long distances (i.e. 1.9 and 2.2 km) in the late afternoon. Combined information from the <br />data logger and aerial contacts implied radio tagged fish did not overwinter in the canyon, two <br />fish were located above the Gates ofLodore. Nine other fish were found below the confluence, <br />from the Yampa River extending downstream into the Green River to Horseshoe Bend. Colorado <br />pikeminnow do not appear to be establishing a pennanent residency in Lodore Canyon, but <br />instead use this area opportunistically. <br /> <br />Ross, S. T.1, and T. Modde2 <br /> <br />'University of Southern Mississippi; 2U.S. Fish and Wildlife Service, Colorado River Fishery Project Office, <br />Vernal, UT <br /> <br />Age Determination and Life History Aspects ofthe Roundtail Chub, Gila robusta <br />(Cyprinidae), in the Yampa River Canyon. The Gila complex includes three large, <br /> <br />15 <br />