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of 206 fish in 1975 to no fish between 1989-1992 (Burdick 1992). During 1993, three adult razorback suckers were captured in the upper Colorado River (Pfeifer, 1993, Personal Communication). The razorback ¦ sucker has also declined dramatically in the Green River from an estimated 948 fish (95% confidence interval, 758-1,138) between 1980- 1988 (Lanigan and Tyus 1989) to an estimated 543 fish (95% confidence interval, 393-693) in 1991 (T. Modde, 1993, Personal Communication). 2. Bonvtail. The bonytail was assigned "Priority 2" among the four endangered fishes because this species is nearly extirpated from the upper basin and the possibility of using upper basin bonytails for broodstock development is very remote.. Only single specimens are collected at irregular intervals in the upper basin. Several of the last confirmed captures of suspected bonytail included a single specimen from the Black Rocks Canyon in 1984 (Kaeding et al. 1986), two adults and three juveniles from Cataract Canyon during 1985-1987 (U.S. Fish and Wildlife Service 1990a), and one bonytail adult from the Colorado River about four miles upstream of its confluence with the Green River in 1993 (F. Pfeifer, 1993, Personal Communication). d h among t e The habitat of the bonytail is the most poorly understoo four endangered fishes. Reintroduction efforts may be in vain if suitable habitat is no longer available to this species in the upper basin. Therefore, the ecological requirements of this species should be determined through restoration stocking in selected river reaches of the upper basin. Program protocol has been developed to bring bonytails captured in the upper basin into captivity for broodstock development. The primary 1 reason for this protocol is to preserve the remaining upper basin, bonytail gene pool. However, biologists in the upper basin realize that the probability of obtaining sufficient wild bonytails for broodstock development is low. Presently, it appears apparent that broodstock development for the upper basin will be limited to Lake Mohave stock from a broodstock that is maintained at the Dexter National Fish Hatchery and Fish Technology Center in New Mexico. The 1 Utah Division of Wildlife Resources has the responsibility to develop a restoration stocking plan for bonytail in Utah waters. The Colorado Division of Wildlife will develop a similar plan for Colorado waters in the upper basin. A survey for bonytail will be conducted in Lake Powell during 1994 using methods developed in the lower basin (E. Wick, Personal Communication, 1994). If these surveys are successful in collecting upper basin bonytail, they will be compared with Lake Mohave stock using appropriate genetic analyses. Dexter is the primary refuge for the bonytail but the species is also maintained in refuges at Palm Lake, at Hassayampa'TNC Preserve near Wickenburg AZ, and at the Golf Course Pond at Arizona State University, Tempe. 3. Humpback Chub. The humpback chub was assigned "Priority 3" among the four endangered fishes because the stocks are considered to be stable but may be at catastrophic risk of immediate. Humpback chub stocks are small, localized populations that occupy relatively short, deep canyon reaches of the Colorado, Green, and Yampa rivers. Most 15