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16 r I I I I I I I I I I I I I I I I I I The emigration of stocked Colorado pikeminnow downstream from the target reaches into the Grand Valley reach of the Colorado River or below is possible, considering the precedent at Kenney Reservoir (Trammell et al. 1993). The primary risk associated with such an event would be the potential swamping of the wild genome, particularly in that year class, if the stocked fish survive in propOItion to their abuncl~nce relative to the wild fish. The negative genetic connotations of tIlli circumstance must be considered from the perspective that previous stockings of hatchery-raised Colorado pikeminnow have already occurred in the Colorado and Gunnison rivers, and some survival of these fish to adulthood has been documented. No active monitoring or evaluation of these stockings were performed immediately after their release, so the distribution and survival of t1:is stocked cohort is uncertain but presumed to be low. The presence of traceable, coded wire-tagged fish in association with wild fish as adults many years later confirms their presence in tile population, but their contribution to spawning is unknown. Evidence of stocked fish in the company of resident fish during the summer spawning season cannot be equated to participation in spawning. If the stocked fish have participated in spawning with wild fish, however, the wild genome has already been affected. Regardless, the genetics management guidelines (Williamson and Wydoski 1994) provide stocking gUidelines to compensate for potential swamping impacts and minimize their influence. Similar to .recommendations made by Burdick and Bonar (1997) for razorback sucker stocking, every effort will be made to place Colorado pikeminnow in locations and habitats that will enhance the probability of the fish remaining in the target reach. If the stocked fish leave the target reach regardless, then stocking in that season would be re-evaluated before repeat stocking is conducted. Given past experience, it is unlikely these downstream-displaced fish would survive better than their wild counterparts, but the genetic compatibility of these fish with the wild fish further lessens the potential risk of negative genetic results. What factors, whether environmental, physiologicai or a combination, contribute to dispersal behavior in Age 2-3 Colorado pikeminnow, the upstream dispenal of late-juvenile/early adult Colorado pikeminnow observed by Osmundson et al. (1997), or the selection of home ranges are unknown. Experience with stocking Colorado pikeminnow young-of-the-year in riverine habitat in the San Juan River (Holden 1999) demonstrated no large-scale downstream evacuation similar to that observed in Kenny Reservoir by Trammell et al, (1993). With more rigorous monitoring in place, the opportunity will be present to learn more about the movements, disposition, and ultimate contribution of these displaced fish to the system. The presence of adult populations of Colorado pikeminnow in these river reaches will provide the opportunity to assess factors such as water supply diversions, instream barriers, availability of spawning habitat in associated canyon reaches, larval drift! dispersal mortality, and recruitment with respect to needed recovery actions. Recommendations 1) Razorback sucker, bonytail and Colorado pikeminnow should be stocked into the designated river reaches at the sizes, seasons, and numbers prescribed in Table 1 for 7-9