8221

• UCREFRP Catalog Number: 8221
• Author: Van Steeter, M. M.
• Title: Historic and Current Processes Affecting Channel Change and Endangered fish Habitats of the Colorado River Near Grand Junction, Colorado.
• USFW Year: 1996.
• USFW - Doc Type: Doctor of Philosophy.
• Copyright Material: NO

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(Xyrauchen texanus), humpback chub (Gila cypha), and bony tail chub (Gila

elegans).

The following is a review of literature on endangered fishes,

including a discussion of causes of their decline, and proposed solutions
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for their recovery. The focus is on the Colorado squaw fish, which utilizes
the upper Colorado River near Grand Junction, Colorado.

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THECOLORADOSQUAWHSH
Colorado squaw fish occupy turbid rivers and their populations are
small. This makes it difficult for fish biologists to understand all the
details of the life history of these fish, but the following.is a review of what
is known.
The Colorado squaw fish is a "big river" fish which completes its life
history in the mainstem and associated flooded areas of the Colorado
River and its large tributaries. They once ranged throughout the Colorado
River basin, but are now limited to a few select reaches in the upper basin
(above Lees Ferry, AZ), primarily in the Colorado, Green, and Yampa
Rivers (Minckley, 1982; Tyus, 1992). Evolution over at least 2 million
years has allowed these fish to adapt to the highly turbid and variable
flows of the rivers in the basin, but they have become rare under the
present conditions (Tyus, 1986). The fish have survived a myriad of
conditions as the climate changed throughout this period, but now it
appears that anthropogenic impacts are pushing them towards extinction.
The Colorado squawfish is a large piscivore which historically gre~
to 1.8 meters (6 ft) in length and 40 kilograms (90 lbs) in weight (Behnke
and Benson, 1983). It is the most common of the endangered fishes of the
upper Colorado River basin (Stanford and Ward, 1986). Adults have been