7216

• UCREFRP Catalog Number: 7216
• 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: 1988.
• Copyright Material: NO

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 morphology. Within each section,
two 0.8-km reaches were randomly selected for sampling during a 24-hr period.
Sampling was with seines, trammel nets and electrofishing in suitable
habitats. Each river section was sampled during pre runoff, runoff and
post runoff periods. Our data analyses were limited to the seine samples taken
during postrunoff period, the season when age-0 Colorado squawfish are
available. In addition, analyses were limited to 1980 data. Data were
combined among sections within rivers.
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; deep-water habitats could not effectively be
sampled. 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 along a transect that passed through the center of the area
sampled. Dominant substrate size was estimated visually and given a numeric
code according to a modified Wentworth Scale--silt (1), sand (2), gravel (3),
rubble (4), boulder (5), bedrock (6) (Bovee and Cochnauer 1977).
Multiple discriminant analysis (Green 1979; Klecka 1984) was used to
compare habitats used by age-0 Colorado squawfish with those used by each of
six sympatric species (red shiner Notropis lutrensis, sand shiner N.
stramineus, channel catfish Ictalurus punctatus, speckled dace Rhinichthys