7984

• UCREFRP Catalog Number: 7984
• Author: Maddux, H. R., L. A. Fitzpatrick and W. R. Noonan.
• Title: Colorado River Endangered Fishes Critical Habitat - Draft, Biological Support Document.
• USFW Year: 1993.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

Interest in Colorado River endemic fishes increased in the 1960's, primarily because of the
rapid disappearance of the fishes in the Lower Basin and new concerns regarding the impacts
of Colorado River Storage Project dams in the Upper Basin. Until the 1950's, the humpback
chub was known only from Grand Canyon (Miller 1946), where the largest population
remains. A number of surveys were made in the Upper Basin in the 1950's and 1960's,
primarily in conjunction with pre- and post-impoundment studies of Flaming Gorge
Reservoir. Humpback chub subsequently were found in the upper Green River (Smith 1960).
Vanicek et al. (1970) reported three specimens from the upper Green River, one each from
Echo Park, Island Park, and Swallow Canyon. Specimens were taken from the lower Yampa
River in 1969 (Holden and Stalnaker 1975b) and one individual was reported from the White
River in Utah (Sigler and Miller 1963). Specimens were collected from Desolation Canyon
of the Green River in 1967 (Holden and Stalnaker 1970). One individual was reported from
the Colorado River near Moab, Utah, in the 1950's (Sigler and Miller 1963) and other
specimens have been collected from the Colorado River above and below Glen Canyon Dam
(Holden and Stalnaker 1970, 1975a; Minckley 1973).
CURRENT DISTRIBUTION AND ABUNDANCE
The largest populations of this species occur in the Little Colorado and Colorado Rivers in
the Grand Canyon, and in the Black Rocks area of the Colorado River. Other populations
have been reported in Westwater and Debeque Canyons of the Colorado River, Desolation
and Gray Canyons of the Green River, and Yampa and Whirlpool Canyons in Dinosaur
National Monument (USFWS 1990b).
The present distribution of humpback chub reported in the Humpback Chub Recovery Plan
(USFWS 1990b) includes the lower 8 miles of the Little Colorado River, Arizona (Kaeding
and Zimmerman 1983; Maddux et al. 1987), the Colorado River in Marble and Grand
Canyons, Arizona (Stone and Rathbun 1969; Suttkus et al. 1976; Suttkus and Clemmer 1977;
Minckley et al. 1981; Kaeding and Zimmerman 1983; Maddux et al. 1987; and USBR
1988), Cataract and Westwater Canyons in Utah (Valdez 1981, 1987, 1988; Valdez and
Williams 1986), and Black Rocks Canyon in Colorado (Kidd 1977; Valdez and Clemmer
1982; Valdez et al. 1982b; Miller et al. 1982c; Archer et al. 1985). Humpback chub also
occur in the Green River in Desolation and Gray Canyons, Utah (Holden and Stalnaker
1975a; Holden 1978; Tyus et al. 1982a, 1982b, 1987), and in the Yampa and Green rivers in
Dinosaur National Monument, Colorado and Utah (Miller 1964; Holden and Stalnaker
1975b; Seethaler et al. 1979; Holden and Crist 1980; Douglas et al. 1989; Karp and Tyus
1990x). More recent intensive research has better defined their distribution include
approximately 13 miles up the Little Colorado River up to Blue Springs (Minckley 1990).
Additionally, concentrations of humpback chub have been collected in the vicinity of
Pumpkin Springs in the Grand Canyon (Valdez and Hugentobler 1993).
In the Lower Basin, the Little Colorado River in Grand Canyon, contains the largest
population of humpback chub and is the main area of humpback chub reproduction in the
Grand Canyon region (Kaeding and Zimmerman 1983). Researchers working on the
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