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1 I I I I I I I I I I I I I I I I I I -..I This stocking plan requires the propagation of fish over seven years for bonytail, eight years for razorback sucker and nine years for Colorado pikeminnow. These time frames allow for the recruitment and full maturation of the desired three adult age groups, and permit assessment of their reproductive success and juvenile fish survival for three years. For razorback sucker, stocking is proposed for two reaches of the Colorado River from Rifle to Debeque and Palisade to Stateline, and in the Gunnison River from Hartland Dam to Redlands Dam. Within Czapla (1999) and Wydoski (1995), these three reaches are all included within the range of one genetic population of razorback sucker for the Upper Colorado River subbasin. For Colorado pikeminnow, stocking is proposed in two rivers-the Colorado River from Rifle to Debeque and the Gunnison River from Hartland Dam to Redlands Dam. The Colorado and Gunnison river reaches are included together as part of the range for one genetic population of Colorado pikeminnow in the Upper Colorado River subbasin (Wydoski 1995, Czapla 1999). Bonytail is proposed for stocking in the Yampa River in Dinosaur National Monument and in the Colorado River within the Grand Valley reach. Due to this species extirpation in the wild, the Recovery Program Genetics Management Plan identifies only one captive genetic stock, from which all restored populations must be derived. For all three of these species, the size of fish to be stocked represents the estimated size of fish after the second growing season for razorback sucker and bonytail, and the third growing season for Colorado pikeminnow. This approach is consistent with recommendations made by Burdick and Bonar (1997) for stocking razorback sucker. For all three species, the size at stocking also represents the sizes at which the fish may be PIT tagged prior to stocking. It is recommended that PIT tagging be used on all fish stocked. The cost for PIT tags will range from $5,000 to $45,000 per stocked population per year based on 1,340-12,000 fish and $3.75/tag. The cost of PIT tags alone will be $161,700/year if all plants of all three species are made annually. Monitoring would require the implementation of population estimate protocols (see Osmundson and Burnham 1996) for adult fish in each river reach. The target objective of stocking for each of the three species is to meet the abundance criterion with the presence of at least three adult age groups surviving in each river drainage basin. For razorback sucker, these age groups are 5-7; for bonytail, age groups 4-6; and for Colorado pikeminnow, age groups 7-9. The cumulative survival and abundance of these age groups is desired to achieve the population objective in the river. Using monitoring to evaluate survival and abundance post-stocking, subsequent numbers of fish stocked may have to be increased or decreased. The presence of an adult, multi-year-class population in the target river reaches is desired to further determine spawning and reproductive success, and the effects of limiting environmental factors that may be influential. The persistence of a potentially long-lived, stocked adult population would thus contribute to recovery of subsequent self-sustaining wild populations of these species in these river reaches. Stocking of humpback chub in Colorado is not anticipated at this time but may become necessary to augment existing small populations. This species is characteristically associated with canyon-bound river habitat, which dictates where stocking would occur. Within the two canyon 5