7340

• UCREFRP Catalog Number: 7340
• Author: Valdez, R. A.
• Title: Status of the Distribution and Taxonomy of the Humpback Chub,
• USFW Year: 1980
• Copyright Material: YES

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STATUS OF TIlE DISTRIBUTION AND TAXONOMY OF
Gila cypha IN THE UPPER COLORADO RIVER

by

Richard A. Valdez, Ph.D.

Colorado River Fisheries Project
U.S. Fish and Wildlife Service
764 Horizon Drive.
Grand Junction, Colorado 81501
[phone] ext 370 FTS (8) 323-0370

ABSTRACT

New populations of the endangered humpback chub, Gila cypha, were encount-
ered in habitat assessment studies by the Colorado River Fisheries Project of
the U.S. Fish and Wildlife Service in 1979-80. These are located in Westwater
Canyon and Cataract Canyon, Utah. A third new population is indicated in
Debeque Canyon, but since the individuals of this population lack some of the
pronounced features of the species, taxonomic veri~ication is still pending.
A fourth population, encountered by other investigators in 1977 in Black Rocks,
Colorado, was also studied. No estimates of population abundances are pre-
sented. Taxonomic studies on individu~s of each population continue in order
to more clearly distinguish Q. cypha, Q. robusta, and G. elegans, and to sub-
sequently facilitate their identification afield.

INTRODUCTION

The humpback chub (Gila cypha Miller) is one of the most bizzare riverine
fishes in North America. Having evolved in the tUlbu1ent, silt-laden waters of
the Colorado River, it is North America's most recently described large fish
species (Miller 1946). Gila cypha is closely allied to and sympatric with the
roundtail chub (G. robusta)and the bony tail chub (Q. elegans). These three
species make up the Gila complex, a group of Colorado River fishes with such
species variation and overlap that systematic studies continue in order to
more clearly delineate the species. Gila cypha, and Q. elegans were designated
endangered in 1967 and 1980, respectively, and are protected by The Endangered
Species Act of 1973. The conflict between the well-being of these fishes and
water uses is a significant environmental issue in the United States today.

This presentation is a product of the Colorado River Fisheries Project
(CRFP) of the U.S. Fish and Wildife Service. The investigation is an assess-
ment of the habitat of endangered native Colorado River fishes; Colorado squaw-
fish (Ptychocheilus lucius), humpback chub, and bony tail chub. The project is
funded by the U.S. Water and Power Resources Service, Bureau of Land Management,
and Fish and Wildlife Service. The study is concentrated in (1) the Little
Colorado River of the Grand Canyon, Arizona, (2) the Green River between Split
Mountain and Turk's Head, Utah, and (3) the Upper Colorado River between Debeque,