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Cataract Canyon of the Colorado River within 20 miles upstream of the inflow to Lake Powell. This includes two in 1985 (one adult 15 inches TL and one juvenile 2 inches TL), one in 1986 (15 inches TL), and two in 1987 (one adult 11 inches TL, one juvenile 10 inches TL) (Valdez 1985, 1987, 1988). A bonytail was caught by an angler near Wahweap Marina, Lake Powell, in May 1985 (Randy Radant, Utah Division of Wildlife, pers. comm.). Also no bonytail were taken during studies of the San Juan River (VTN Consolidated, Inc. 1978; Platania 1990; Platania and Lang 1992). STATUS This species is very rare. Few individuals have been found in the last decade; recruitment is apparently nonexistent or very low. Like the razorback sucker, it is feared that wild populations of bonytail may soon no longer exist without recruitment of young fish. The recovery priority for the bonytail, discussed in the revised recovery plan for this species, indicates a high degree of threat with a low recovery potential under current habitat conditions. HABITAT REQUIREMENTS The bonytail chub always has been considered a species that is adapted to mainstream rivers, where it has been observed in pools and eddies (Vanicek 1967; Minckley 1973). In reservoirs, the fish occupies an active limnetic niche (Minckley 1973). Spawning of the fish never has been observed in nature, but Vanicek and Kramer (1969) reported that spawning occurred in June and July at water temperatures of about 64°F. Although wild bonytails are old fish, they are still capable of successful reproduction, and bonytail chubs placed in ponds have produced large numbers of young (Buddy Jensen, USFWS, pers. comm.; USFWS 1990x). Although habitats that are required for conservation of the bonytail chub are not well known, the limited data suggests that flooded, ponded, or even inundated riverine habitats may be suitable for adults, especially in the absence of competing nonnative fishes (USFWS 1990a). Riverine Bonytail is considered a big- or mainstream river species. Vanicek (1967) noted that adult bonytail occupied pools and eddies rather than areas with more current. Spawning of bonytail has not been observed in a river, but ripe fish were collected in Dinosaur National Monument during late June and early July suggesting that spawning occurred at water temperatures of about 64°F (Vanicek and Kramer 1969). Vanicek and Kramer (1969) estimated growth rates of bonytail by back calculation of total length based on proportional growth of scales. Fish from the Green River at Dinosaur National Monument were 2 inches total length by the end of their first growing season, 4 inches their second, and 6 inches their third. The largest bonytail handled by Vanicek and Kramer (1969) was 15 inches and 7 years old. 34