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

When all years were combined, most fishes were captured at average
water temperatures in the backwaters we sampled (G-tests, P > 0.05;
Figure 2). However, in the cooler (13.10C), upper nursery area, Colorado
squawfish was seldom taken in backwaters < 100C (G-test, 1 df, P < 0.01),
and it was most abundant (CPUE) at 14.SoC (range 6 - 26.S0C). Few young
Colorado squawfish were captured in high flow years of 1983-84 and
backwaters were exceptionally cool in those years (average 8.20C).
However, the catch of young Colorado squawfish within years indicated
that fish present in autumn used available backwaters regardless of
temperature (paired t-test, P > 0.05).
In the warmer (18.70C), lower nursery area, five of seven fish
species displayed little temperature preference. Colorado squawfish were
present in backwaters ranging from 14.2 to 34.30C, but most abundant at
19.30C (range 14.4 - 2S.60C). However, channel catfish were captured in
backwaters warmer than 17.50C (G-test, 1 df, P < 0.01), and suckers
occurred more frequently in backwaters < ISoC (G-test, 1 df, P < 0.01)
Most species, including Colorado squawfish, fathead minnow, chub,
channel catfish and sand shiner, were captured in backwaters deeper than
15 cm (G-tests, P < 0.05, Figure 3), but red shiner and suckers were
ubiquitous in backwaters of all depths (G-tests, P > 0.05). In the
deeper, upper nursery area, Colorado squawfish used slightly deeper
backwaters than did red shiner and suckers (G-tests, P < 0.05), but
backwater depths used by all fishes were similar (coefficients of overlap
> 0.8; Table 6).
Backwater size did not generally influence habitat selection of the
more common species, although Colorado squawfish occurred more frequently

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