6028

• UCREFRP Catalog Number: 6028
• Author: Wick, E. J., D. L. Stoneburner and J. A. Hawkins.
• Title: Observations on the Ecology of Colorado Squawfish ‎(
• USFW Year: 1983.
• Copyright Material: NO

INTRODUCTION
The Yampa River originates on the western slope of the Rocky
Mountains near Yampa, Colorado. It is the largest tributary to the •
Green River. The Yampa flows first in a northerly and then in a
westerly direction to its confluence with the Green River in Dinosaur
National Monument (Fig. 1). The Yampa River can be characterized as a
system of extreme hydrologic events. Dramatic seasonal fluctuations in
flow create equally dramatic changes in temperature, turbidity,
conductivity, and quantity of allochthonous material. These seasonal
variations in flow and water quality also exhibit long-term pulses
caused by annual variations in precipitation and accumulation of snow in
mountainous regions of the river watershed. Amid these hydrologic
extremes the endemic Colorado squawfish evolved a unique migratory
reproductive strategy.
Historically, migration of Colorado squawfish (Ptychocheilus
lucius) was considered a predictable summer event in many of the rivers
of western Colorado (Sigler and Miller, 1963; Joseph et al., 1977;
Behnke and Benson, 1980). However, neither origin nor destination of
the migrants was documented. It was assumed that the migration was
related to spawning.
Recent studies, conducted by the U.S. Fish and Wildlife Service
(USFWS), Colorado Division of Wildlife (CDOW), and Utah Division of
Wildlife Resources in the Upper Colorado River basin (Wick et al., 1981;
e
Haynes and Muth, 1982; Miller et al., 1982a,b, 1983b; Tyus et al.,
1982a,b; Radant et al., 1983) produced new data regarding the movements
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