7363

• UCREFRP Catalog Number: 7363
• Author: Haines, G. B. and H. M. Tyus.
• Title: Influence of Environmental Factors on Distribution and Abundance of Age-0 Colorado Squawfish in the Green River, Utah.
• USFW Year: 1989.
• USFW - Doc Type: Vernal, Utah.
• Copyright Material: NO

species. Indices of abundance were estimated as catch per m2 seined
(CPUE) for each backwater. Relationships between streamflow,
temperature, and species abundance were evaluated by calculating
correlation coefficients of loge (annual CPUE + 1) and maximum
instantaneous discharge, mean August discharge, and backwater
temperature. Discharge data were obtained from U.S. Geological Survey
gaging station records at Green River and Jensen, Utah.
Habitat use was determined by counting presence/absence of fish for
seven to ten categories of backwater temperature, maximum depth and size.
Temperature categories were: <10.0, 10.0-12.5, 12.5-15.0, 15.0.17.5,
17.5-20.0, 20.0-22.5, 22.5-25.0, 25.0-27.5, 27.5-30.0, and> 30.00C.
Maximum depth categories were: < 15.2, 15.2-30.5, 30.5-45.7, 45.7-61.0,
61.0-76.2, 76.2-91.4, and> 91.4 cm. Size categories were < 250, 250-
500, 500-750, 750-1000, 1,000-1,250, 1,250-1,500, and> 1500 m2. G-tests
of goodness-of-fit were used to evaluate habitat use and availability,
and G-tests of independence were used to compare habitat use between
species pairs (Sokal and Rohlf 1981). A habitat overlap index (Schoener
1970) was used to examine the extent of habitat-use overlap between pairs
of species (0 indicated no overlap; 1 indicated complete overlap).

RESULTS

Distribution. abundance and soecies associations. Drift-net samples
contained 1,706 fishes of which native species were most abundant:
Colorado squawfish (38%), suckers (33%), and speckled dace Rhinichthvs
osculus (14%, Table 1). Introduced fishes (predominately channel catfish
Ictalurus punctatus, 3%) composed less than 4% of the drift.

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