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1 <br />1 <br /> CONCLUSIONS <br /> <br /> The existing flow regimen of the Yampa River is critical for the survival <br />I of extant populations of Colorado squawfish, <br />-~, humpback chub, and razorback <br /> sucker in the Green River Basin. These nar•• ~^1 a^^-?i rions should be protected <br />i <br /> <br />unless more definitive stream flow needs can ~ <br />be Quantified for all indigenous <br /> rare and endangered fishes. Our recommendat ions were based on empirical field <br /> <br /> data because outputs from analytical models could not be interpreted. Flow <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br />recommendations produced by physical habitat simulation models must be <br />employed only in conjunction with a program that ~_isa_s empirical data to <br />validate the outputs. <br />The distribution, abundance and habitat use of the rare and endangered <br />fishes in the upper Colorado River is inextricably associated with the biology <br />of approximately 42 species of non-native fishes introduced into the system. <br />Competition and predation b_y non-native fishes may significantly reduce <br />stocks of rare and endangered fishes. Habitat use by non-native competitors <br />and predators must be evaluated in conjunction with all flow recommendations <br />for the native fauna. <br />Work in progress on mainstream Green River by BR and FWS should be <br />evaluated for potential application to the Yampa River. This includes use of <br />aerial photographic mapping of sensitive habitats with different flows, <br />studies of species interactions, and trophic relationships. <br />47 <br />