7202

• UCREFRP Catalog Number: 7202
• Author: Osmundson, D. B. and L. R. Kaeding.
• Title: Studies of Colorado Squawfish and Razorback Sucker Use of the '15-Mile Reach' of the Upper Colorado River as Part of Conservation Measures for the Green Mountain and Ruedi Reservoir Water Sales
• USFW Year: 1989.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

t
day range reported by Hamman (1981) for fertilized eggs of hatchery-reared
squawfish incubated at 20-24 C.
RESULTS
Adult Relative Abundance
The Colorado River Fishery Project (CRFP), U.S. Fish and Wildlife Service,
has conducted studies on the rare fishes of the upper Colorado River since
1979. From 1979 to 1985, studies encompassed the length of river from the
upper end of Lake Powell, Utah, to Rifle, Colorado, including the 15-mile
reach. As part of the standardized surveys of the Colorado River upstream
from Lake Powell conducted between 1979 and 1981, the river was divided
into 11 reaches, each from 13 to 50 miles long (Valdez et al. 1982). Each
reach was extensively sampled annually during pre-runoff, runoff and post-
runoff periods. Results showed captures of adult Colorado squawfish (>
450 mm TL) were fairly evenly distributed among the seven reaches that
occur between the Colorado River confluence with the Green River and
Palisade, Colorado. The mean number of adults captured per reach was 3.1
(SD - 1.3) and the mean number of fish caught per mile per reach was 0.12
(SD = 0.04). Three adult Colorado squawfish, or 0.10 per mile, were
captured from the Grand Valley area, the reach between the towns of Pali-
sade and Loma, Colorado. Thus relative abundance of Colorado squawfish in
the Grand Valley was about average that of the seven Colorado River reach-
es where adult squawfish were captured (Table 1). Length of the Grand
Valley reach is about 16% of the total length of these seven reaches.
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