7715

• UCREFRP Catalog Number: 7715
• Author: U.S. Fish and Wildlife Service, C. R. F. R. T.
• Title: Bonytail Chub Recovery Plan.
• USFW Year: 1990.
• USFW - Doc Type: \
• Copyright Material: NO

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Present Distribution and Abundance

The bony tail chub now is very rare. In the Lower Basin, individual fish still
are taken occasionally by fishermen in Lake Havasu (W.L. Minckley, pers.
comm.). A few large, old adults also are still found in Lake Mohave, but no
successful reproduction has been documented there. A total of 32 adult
specimens was collected by biologists from Lake Mohave from 1974 to 1987, and
several more were reported by anglers. An additional 16 fish were collected
from Lake Mohave in 1988 and 1989 (P. C. Marsh, pers. comm.).

Recent distribution and abundance of the bony tail chub in the Upper Basin was
described by Holden and Stalnaker (1975), Tyus et al. (1982b, 1987), and
Valdez and Clemmer (1982). Recruitment is apparently nonexistent or extremely
low, with the most recent suspected juvenile bony tails originating only from
the Desolation Canyon (Holden 1978) and Cataract Canyon areas (Valdez 1985).
However, verifying recruitment is difficult due to the uncertainty that exists
in the identification of juveniles.

The bony tail chub apparently was common in the Green River below the Yampa
River confluence after Flaming Gorge became operational in 1962. Charles D.
Vanicek, Utah State University (pers. comm.), stated he could usually catch
adult bony tail chub there during 1964-1966 with the use of gill nets in eddies
or with electrofishing gear, although his analysis (Vanicek 1967) did not
include specimens of sizes less than 200 mm (8 in.) total length (TL) because
of the difficulty in identification. However, Vanicek and Kramer (1969)
reported strong year classes in 1959, 1960, and 1961 based on the capture of
62 bony tails longer than 200 mm (8 in.) TL. Holden and Stalnaker (1975) found
36 adults during a 4-year study of the Upper Basin, 29 of which were captured
in 1968, 3 in 1969, and 4 in 1970. All but two of these were found in the
Green and Yampa rivers within Dinosaur National Monument. No young were
identified during that study. Seethaler et a1. (1976) sampled the Green and
Yampa rivers of Dinosaur National Monument in 1974-1976 and found no bony tail
chub. Holden and Crist (1981) reported one adult 275 mm (11 in.) TL from the
lower Yampa River in 1979. However, no specimens have been reported from
there since (Tyus et a1. 1982b, 1986). Miller et al. (1982) reported no adult
bony tail chub from Dinosaur National Monument in 1981-1983, and Wick et a1.
(1979, 1981) caught no adults and could not distinguish among larval Gila
collected there. Although roundtail chub were found in the Green and Little
Snake rivers in Wyoming during a 1986 survey, no bony tail chub were captured
(Johnson and Oberholtzer 1987).

In other areas of the Green River, two bony tail chub adults were caught in
Desolation Canyon in 1974 (Paul Holden, BID-WEST, and Karl Seetha1er, Utah
State University, pers. comm.). Holden (1978) caught one adult near Jensen,
Utah, and one juvenile in Desolation Canyon in 1977. Service personnel
collected several fish resembling bony tail chub from Gray Canyon in 1980 and
1981 (Tyus et al. 1982a). However, during extensive sampling conducted in
1982-1985 in the Green River and a section of the Yampa River, only one
individual from Gray Canyon was tentatively identified as a bony tail chub from
a total of 523 Gila specimens captured (Tyus et al. 1987).

During the period 1977 through 1983, no bony tail chub were collected from the
Colorado River in Colorado or Utah or from its tributary, the Gunnison River,
in surveys conducted by the Service (Valdez et al. 1982; Miller et al. 1984)

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