9678

• UCREFRP Catalog Number: 9678
• Author: Tyus, H. M. and C. A. Karp.
• Title: Habitat Use and Streamflow Needs of Rare and Endangered Fishes
• USFW Year: 1990.
• USFW - Doc Type: Flaming Gorge Studies - Draft Consolidated Report Preliminary.
• Copyright Material: NO

Colorado squawfish. Hendrickson and Brooks (1987) noted predation by yellow
bullhead, Ameiurus natalis, and largemouth bass, Micropterus salmoides, on
young Colorado squawfish stocked into the Verde River, Arizona. Osmundson
(1987) noted predation by largemouth bass, green sunfish, black crappie, L.
nigromaculatus, and black bullhead, A. melas, on young Colorado squawfish in
gravel pits near the Colorado River and indicated that predation by channel
catfish may have occurred. In addition, Coon (1965) reported channel catfish
predation on Colorado squawfish in the Dolores River.
Humpback Chub
Humpback chub occur in several canyon-bound, turbulent sections of the
Green River basin, including the lower portion of the Little Snake River and
Yampa, Whirlpool, Desolation and Gray canyons (Holden 1978; Tyus et al.
1982ab, 1987; Karp and Tyus, in review; M. Moretti and E. Wick, pers. comm.).
Survey studies conducted prior to and following closure of Flaming Gorge Dam
indicated that all three forms of Colorado chubs were locally common in the
Green River; bonytails and roundtails in upper Green River above Ouray, Utah;
humpbacks in Desolation and Gray canyons and historically in Flaming Gorge
basin of upper Green River (Smith 1960; Holden 1978; Vanicek 1967; Seethaler
et al. 1979). Although intensive netting and electrofishing efforts in the
Green River mainstream by USFWS and Utah Division of Wildlife Resources
biologists yielded over 500 chubs (Miller et al: 1982; Tyus et al. 1987; M.
Moretti, pers. comm.), status of humpback chub in that system is not well
understood, due in part, to confusion with specific identification of some
individuals (Tyus et al. 1987; Rosenfeld and Wilkinson 1989; M. Moretti, pers.
comm.).
More intensive studies .are needed to further elucidate the systematics of
the Colorado River chubs and to determine their habitat needs in the Green
River basin. The morphological variation that occurs in some areas of sympatry
may be induced by recent habitat change (Valdez and Clemmer 1982). Thus, the
presence of intermediate forms in altered systems (e.g., Green River, Colorado
River) and the paucity of such forms in unaltered rivers (e.g., Yampa River,
Little Colorado River) suggests that natural riverine environments are
important for recovery of the humpback chub. The following paragraphs
summarize information on habitat use of humpback chub in Yampa Canyon because
this information is unknown for the Green River. We presume habitat use and
needs are similar throughout the Green River basin.
During the spring and early summer, adult humpback chub were most often
collected in shoreline eddy habitats created by large boulders and rapids in
Yampa Canyon (N=130; Karp and Tyus, in review). Three adult fish, one a ripe
male, were collected in Whirlpool Canyon. Juvenile fish were most prevalent in
smaller eddies in shoreline runs. Humpback chub were observed feeding at
various levels within the water column, consuming such terrestrial insects as
ants and Mormon crickets (Tyus and Minckley 1988; Karp and Tyus, in review).
There is some indication that humpback chubs in Yampa Canyon exhibit short-
distance, localized movements, and display some fidelity to specific eddy
habitats (Karp and Tyus, in review).
Adult humpback chub were captured in DNM in association with 18 other
fishes, but were most commonly captured with roundtail chub and the
introduced channel catfish when angling (Tyus and Minckley 1988; Karp and
Tyus, in review). Channel catfish comprised about 35% of the angling catch in
habitats from which humpback chub were collected (Karp and Tyus, in review)
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