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1 <br /> <br />Longitudinal analysis of capture data for large-bodied fish was accomplished by <br />assigning samples collected in Lodore Canyon to one of the four 8-km reaches described above. <br />Incidental electrofishing data collected just upstream and downstream of Lodore Canyon were <br />not included in this analysis. Capture data for each species in each reach were represented as <br />percent community composition. Longitudinal shifts in size distributions of common species <br />were analyzed by comparing length frequency histograms among reaches. <br />We derived alength-weight relationship for Colorado pikeminnow captured in the Green <br />River, Lodore Canyon by regressing fish weight as a function of fish TL. We then compared <br />predicted weight of Colorado pikeminnow captured in the study area to that in the proximal <br />Yampa River (Hawkins 1992). <br />Water temperature data collection and modeling.-Low water temperature in the <br />regulated reach was thought to preclude reproduction by some native fishes. However, little was <br />known about rates of downstream warming of Flaming Gorge Dam releases in summer during <br />either the post-1978 period or after flow re-regulation in 1992. Therefore, continuously <br />recording thermographs were set in the Green River in early June in upper and lower Browns <br />Park, and in lower Lodore Canyon in 1994 and 1995. Additional data temperature data were <br />collected at a middle Browns Park station at Browns Park National Wildlife Refuge (BPNWR, <br />pers. comm., G. Smith, U. S. Fish and Wildlife Service, Denver, Colorado). <br />We used water temperature, air temperature, and discharge data collected in 1994 and <br />1995 to build empirical regression models (sensu Matuszek and Shuter 1996) to predict water <br />temperature at upper Browns Park (Swinging Bridge, RK 610.7), lower Browns Park (Lodore <br />boat launch, RK 585.2) and lowermost Lodore Canyon (RK 555.9) during summer. The models <br />were restricted to the period from 1 June to 30 September because reliable temperature data were <br />available then and summer water temperatures were the only ones likely to effect a reproductive <br />response by Green River fishes. Models were developed at each site so that warming rates and <br />relative effects of air temperature and discharge could be compared among approximately <br />10 <br />