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<br />002841 <br /> <br />Diversion Dam, An anecdotal account exists of the capture, by angling, of a IS-inch <br />Colorado squawfish, above Glenwood Springs on the Colorado River (Pressey 1968), <br />2) the Upper Colorado River reach and the Gunnison River reach are similar with respect <br />to this carrying capacity based on similar geohydrology and predominating native fish <br />communities based on observed native/nonnative species relative abundance as described <br />in Burdick (1995) and Anderson (1997), <br />3) Depletion and extirpation of adult populations above the barriers occurred as the result <br />of some combination of downstream spawning movements by adults over the barriers, <br />and prevention of upstream dispersal movement and recruitment by late juvenile or adult <br />fish, or return migration by spawning adults. <br />4) As top predator, Colorado squawfish biomass as a percent of the system should be, and <br />would naturally be low (1-2%), <br />5) the Colorado River reach from which biomass estimates in Anderson (1997) were made <br />was at carrying capacity, <br /> <br />Further, the following species interactions and recovery actions are anticipated: <br /> <br />I) Biomass and production in the river system now occupied by common carp and white <br />sucker will be reduced by control efforts, expanding production potential within the <br />native fish prey base for Colorado squawfish. <br />2) With successful establishment of this species,. abundance of other native species may be <br />reduced as a result of predation, <br /> <br />The emigration of stocked Colorado squawfish downstream from the target reaches into <br />the Grand Valley reach of the Colorado River or below is possible, considering the precedent <br />at Kenney Reservoir (Trammell et al, 1993). The primary risk associated with such an event <br />would be the potential swamping of the wild genome, particularly in that year class, if the <br />stocked fish survive in proportion to their abundance relative to the wild fish, The negative <br />genetic connotations of this circumstance must be considered from the perspective that previous <br />stockings of hatchery-raised Colorado squawfish have already occurred in the Colorado and <br /> <br />DRAFT - June 4, 1997 <br /> <br />16 <br />