7428

• UCREFRP Catalog Number: 7428
• Author: Tyus, H. M.
• Title: Management of Native Warmwater Fishes of the Upper Colorado River.
• USFW Year: 1990.
• USFW - Doc Type: \
• Copyright Material: NO

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Management of native warmwater fishes of the upper Colorado River
Harold M. Tyus
U.S. Fish and Wildlife Service
1680 West Highway 40, Room 1210
Vernal, Utah 84078
Abstract.--Native warmwater fishes of the Colorado River have declined,
and four big-river fishes are in danger of extincti Of these, Colorado
squawfish Ptychocheilus Lucius, humpback chub Gila elegans, an onytail are
listed as federally-endangered, and razorback sucker auchen texanus, is
proposed for listing. These fishes declined in abundance before much was known
about their ecological requiremegts_. Their rarity, continuing habitat change,
and 1 ack of knowledge about leas ~t~a'~i tat needs have made t
management programs difficult to develop and implement. Recent efforts to
recover the listed fishes to a less-endangered status have resulted in some
management activities, and most of these are supported by funds obtained
through the Upper Colorado River Basin Recovery Implementation Program.
Although the future of native warmwater fishes of the Colorado River is
uncertain, this interagency program provides incentives for management of
these fishes.
INTRODUCTION
Native North American fishes are declining in species and population
abundance. During the past 100 years, 3 genera, 27 species and 13 subspecies
of fishes have become extinc ~ nd an additional 364 rare fishes are threatened
with extinction (Williams et~. 1989). Habitats of stream and riverine fishes
have been especially impacted, and there are few rivers remaining in North
America whose annual flow patterns have not been severely altered. It is
unknown whether the rate of loss of these natural faunas can be reduced,
because community-level disturbances often result from species extirpations.
The fate of native Colorado River fishes in the Southwestern United States is
of particular concern, because widespread and drastic habitat loss has
severely impacted this unique fauna.
The Colorado River basin comprises about ~o of the land mass of the
continental United States. Located in extremely grid country, its waters are a
precious commodity (Fradkin 1981; Carlson and Muth 1989). Construction of
large mainstream projects began in the early 1900s (Fradkin 1981; Carlson and
Muth 1989), and by the 1960s, much of the mainstream Colorado River had been