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t upstream from the Price-Stub Irrigation Diversion Dam (Burdick 1992). This stock declined rapidly and the razorback sucker is extremely rare in the upper Colorado River at the present time. About 600 razorback suckers are in Etter Pond along the Colorado River near Debeque, Colorado (B. Ehnblad, 1994 personal communication). These fish were progeny from few pazents (presumably, 1 female and 2 males) and contain a high frequency of a flannehnouth sucker allele (Huth 1993; Dowling and Minckley 1994; Philipp 1994). Bonytail: The interim management objective for adult bonytail estimated population size in the upper Colorado River basin is 4118 (± 817) per population (Lentsch et al 1998). The bonytail is considered extirpated in the Upper Basin. The bonytail was common in the Green River below its confluence with the Yampa River after Flaming Gorge Dam became operational in 1962 (LJ.S. Fish and Wildlife Service 1990x; Vanicek 1967). During a four year study of the upper basin (Holden 1973), 29 adult bonytails were captured during 1968, three in 1969, and four in 1970 in the Green River at Dinosaur National Monument. No young bonytail were collected during 1968 and 1970 by Holden (1973). During another study in I the Green and Yampa rivers of Dinosaur National Monument between 1974 and 1976 (Seethaler et al. 1979), no bonytail were collected. One adult bonytail (279 rnm TL) was reported from the lower Yampa River in 1979 (Holden and Crist 1981). No bonytail were captured from the Green River in Dinosaur National Monument during 1981-1983 (Miller et al. 1982). U.S. Fish and Wildlife Service personnel collected one suspected juvenile bonytail in 1987 (Tyus and Karp 1989). The bonytail broodstock at Dexter National Fish Hatchery, New Mexico was developed from five pairs of bonytails collected from Lake Mohave between 1976 and 1981 (Minckley et al. 1989). Six additional bonytail from Lake Mohave were added as broodstock with the progeny of the original coatings in 1988. Minckley et al. (1989) state that the genetic heterozygosity for these bonytail was comparable to mean values reported for other western North American cyprinids and that the broodstock was considered suitable producing captive-reazed fish for reintroductions into suitable wild habitats. No bonytail stocks were identified in the upper basin because no aggregations of this species exist at the present time. Humpback Chub: The interim management objective for adult humpback chub estimated population size in the upper Colorado River basin is 4796 (± 1317) per stock (Lentsch et x11998). Yampa River Stock This humpback chub population estimate is approximately 600 adults and probably stable. The humpback chub population in the Yampa River exhibits lazge variation in phenotypes. Desolation-Gray Canyon Stock This humpback chub stock is probably stable and composed of a relatively small number offish based on collections by Holden and Stahiaker (1970), Tyus et al. (1982), Chart (1993). Black Rocks Stock The humpback chub stock in Black Rocks Canyon is apparently stable and is modest in size (Archer et al. 1985, 1986; Valdez and Clemmer 1982; Kaeding et al. 1990). An estimate of the population in Black Rocks-Westwater canyons is approximately 7,000 adults. Westwater Canyon Stock This stock is considered to be small but stable and self-sustaining (Valdez and Clemmer 1982; Chart 1994, personal communication). 11