8166

• UCREFRP Catalog Number: 8166
• Author: McAda, C. W. and L. R. Kaeding.
• Title: Relations Between the Habitat Use of Age-0 Colorado Squawfish and Those of Other Sympatric Fishes in the Upper Colorado River Basin.
• USFW Year: 1989.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

1 determine the feasibility of flow-related habitat management as presently
envisioned.
Methods
Data were collected from the Green and Colorado rivers during the
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Service in 1979-1981 (Tyus et al. 1982; Valdez et al. 1982). The SSP utilized
a sampling design that divided the Green and Colorado rivers into relatively
homogeneous sections on the basis of river morphometry. Within each section,
two 0.5-mi reaches were randomly selected for sampling during a 24-hr period.
Sampling in suitable habitats was with seines, trammel nets and
electrofishing. Most seine samples were taken in mid to late afternoon,
electrofishing was conducted at mid day and in early evening, and trammel nets
were set in early evening and pulled by midnight. Each river section was
sampled during pre runoff, runoff and postrunoff periods. Our data analyses
were limited to the seine samples taken during the postrunoff period (July to
September) of 1979 and 1980, the season when age-0 Colorado squawfish
(generally 25-60 mm TL) are available. The postrunoff period was not sampled
in 1981.
Samples were taken within individual habitat types using 0.3- or 0.6-cm-
mesh seines. Habitat types were categorized as backwater, eddy, pool,
shoreline, run or riffle. Seining was usually done in habitats with average
depths < 1 m, about the maximum depth at which seining is efficient. Fishes
were identified, grouped into size classes, enumerated. and released alive.
The areal extent of each seining effort was quantified, and water depth and
water velocity (at 0.6 total depth) were measured at two equidistant points
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