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<br />002834 <br /> <br />Reach priorities were based on the following considerations: <br /> <br />1) Bony tail will initially be introduced only in the Grand Valley reach of the Colorado River <br />due to a presumed distribution throughout the mainstem Colorado and larger tributaries <br />like the Green River, and a hypothesized need for floodplain habitat This hypothesis <br />has not been adequately tested, but is suggested by the anecdotal evidence (Quartarone <br />1993) of bonytail inhabiting larger riverine habitat like the Colorado River near Moab, <br />Utah, where floodplain habitat was more likely to exist. The logistics of this reach make <br />it more suitable for monitoring survival of stocked fish than the Green-Yampa within <br />Dinosaur National Monument. <br />2) Bonytail were collected from the Green and Yampa rivers near their confluence at Echo <br />Park (USFWS 1987, Vanicek and Kramer 1969), While this site tends to refute the <br />floodplain habitat need hypothesis, bonytail juveniles of the same size collected in <br />previous studies (up to 200mm) should be reintroduced there. <br /> <br />Further, the following species interactions and recovery actions are anticipated: <br /> <br />1) Biomass and production occupied by common caIp in the Grand Valley will be reduced <br />by control efforts, lessening competitive pressure within floodplain habitats, and perhaps <br />enhance expansion of bony tail biomass, <br />2) With successful establishment of an adult bony tail population, general abundance of other <br />native species may be reduced as a result of some competition, <br /> <br />Reintroduction of bony tail into the upper Colorado River Basin has been assessed by <br />several studies (Chart and Cranney 1992, Meyer 1992, Wydoski 1994, Lentsch et al, 1996), <br />Recommendations included the necessity of reintroduction of bonytail in the wild to determine <br />it's ecological requirements, but concerns have been expressed about reintroducing bonytail <br />because of the potential hybridization with the other Gila species, especially humpback chub, <br />While acknowledged as a potential risk associated with reintroduction and establishment of <br />bonytail near existing humpback chub populations (e,g, Black Rocks), this risk appears to be <br /> <br />DRAFT - June 4, 1997 <br /> <br />10 <br />