9314 ‎(2)‎

• UCREFRP Catalog Number: 9314
• Author: Wick, E. J. and J. A. Hawkins.
• Title: Colorado Squawfish Winter Habitat Study.
• USFW Year: 1989.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

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The Colorado squawfish (Ptychocheilus lucius) was once distributed
throughout the entire Colorado River Basin in main channels and larger
tributaries. Today it is restricted to the remaining free-flowing segments of
larger rivers above Glen canyon Dam which forms Lake Powell. These rivers
include the Green, Yampa, Gunnison, and White in Colorado and Utah, the
mainstem Colorado River below Grand Junction, Colorado and the San Juan River
of Utah and New Mexico (Holden and Wick 1982).
Rivers of the Colorado River Basin are characterized by extremes in flaw,
turbidity, and velocity. Historical flows varying from a few hundred cubic
feet per second (cfs) to almost 400,000 cfs were reported at Yuma, Arizona
(Behnke and Benson 1983). The environmental extremes of the River Basin, plus
millions of years of isolation from neighboring river basins, caused a high
degree of endemism (fish found only in the Colorado River Basin) in its fish
fauna. Only 13 species are native (occur naturally) above Lake Powell. Of
those, six are endemic (Behnke and Benson 1983). These include the Colorado
squawfish, three chubs, and the razorback and flannelmouth suckers; all are
members of the minnow and sucker families. The Colorado squawfish evolved
into the role of the_ top predatory fish species, presumably because of its
isolation from other large fish predators. In this evolutionary process, the
Colorado squawfish adapted to the wide range of environmental conditions
(flaws, temperatures, and turbidities).
The Colorado squawfi.sh also developed a unique reproductive strategy (Tyus
1986). Recent studies using radio-telemetry in the Upper Colorado River Basin
(Tyus and NlcAda 1984; Wick et al. 1983) have documented that squawfish migrate
hundreds of miles to preferred spawning areas and return to their pre-spawning
locations. Colorado squawfish numbers have declined because dams have blocked
migratory routes and cold tailwater releases have drastically altered
temperature regimes throughout much of the Colorado River Basin (Holden and
Crist 1978 and Seethaler 1978).
Habitat use by adult Colorado squawfish varies considerably depending upon
flaw, season, and habitat availability in specific rivers and river reaches
(Carlson et al. 1979; Twedt and Holden 1980; Miller et al. 1982; Wick et al.
1985). Cn the Yampa River in early spring, as water levels are just beginning
to rise, Colorado squawfish are found in main-channel runs and shoreline
habitats. Colorado squawfish are also frequently found near the flooded
mouths of tributary streams and in eddies. As run-off flows increase in May
and June, use of law velocity backwater habitat increases considerably in
areas where it is available. Otherwise, Colorado squawfish use large main-
channel eddies (Wick et al. 1983).
Natural backwaters are formed when tributary streams and gulches are
flooded at high run-off flaws. Man-made backwaters are side channels that are
modified by ranchers. Usually, the upstream end of the side channel is diked
off to protect cultivated fields or provide watering areas for livestock. In
late June, as water levels recede, squawfish move into the main stream and
begin their spawning migration downstream into the lover portion of Yampa
Canyon (Wick et al. 1983). This migration usually begins as maximum water
temperatures warm to 14-2000 (Tyus et al. 1987). Fish usually spend 3 to 4
weeks in Yampa Canyon during the spawning period. Pool and eddy habitats are
used for staging. Ran, rapid, side channel, and chute channel habitats with
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