3102

• UCREFRP Catalog Number: 3102
• Author: Wick, E. J., J. A. Hawkins and C. A. Carlson.
• Title: Colorado Squawfish and Humpback Chub Population and Habitat Monitoring 1983-1984.
• USFW Year: 1985.
• USFW - Doc Type: Ft. Collins, CO.
• Copyright Material: NO

SUMMARY
This report covers the transition period 1983 and 1984,
between extensive'sampling on the Yampa, White, Colorado, and
Gunnison rivers in 1981 and 1982, and the establishment of a
scaled-down monitoring program concentrating initially on the Yampa
River in 1984. On August 22-28, 1983 sampling was conducted on the
Colorado River from Lorna to Grand Junction, river mile (RMI)
150-170. Results of 1983 collections were compared to collections
made in this same river reach in 1981. Native roundtail chub and
speckled dace dominated 1983 seine collections while red shiners
and fathead minnows dominated 1981 seine collections. Differences
in species composition were attributed to the high flow levels of
1983 in contrast to low flow levels of 1981. Effect of sampling
date in terms of cumulative temperature was also compared. Even
though the actual collection date was 10 days later in 1983, in
terms of temperature [number of days that exceeded 200 Celsius
(C)], sampling occurred 35 days later in 1981. The collection of
one young-of-year (13mm) Colorado squawfish at RMI 153.8 indicated
that spawning occurred in 1983 within or upstream of this river
segment. Several gravel pits located within the study segment were
breached by the high water causing alterations in habitat and infux
of introduced species into the riverine environment.
On the Yampa River, special site sampling was conducted
October 5-7, 1983. In 1984, a new monitoring program was initiated'
on the Yampa River. The sampling design was based on temperature
and flow relationships. Sampling was scheduled to occur during
three time periods based on minimum temperature: runoff (1200),
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