7816

• UCREFRP Catalog Number: 7816
• Author: Tyus, H. M.
• Title: Movement and Habitat Use of Young Colorado Squawfish in the Green River, Utah
• USFW Year: 1991
• USFW - Doc Type: Journal of Freshwater Ecology
• Copyright Material: YES

Two sites were selected in 1981 to better evaluate movements of the
young fish. One Labyrinth Canyon site was sampled 1-3 April 1981, and
another site at Ouray was sampled 6-7 October and 4-6 November 1981.
Shoreline runs, eddies, and backwaters were sampled at 2100-0200 h,
0600-0700 h, 1100-1500 h, 1700-1800 h, and water temperatures of
backwaters and the main river channel were recorded at sample times. Ihe
relationship between catch of fish per area seined (number of fish m- )
during the four time periods and average water temperatures of the
backwaters during those intervals were evaluated by correlation
analyses.
Colorado squawfish spawn in July and early August (Haynes et al.
1984, Tyus and Karp 1989) and age-O fish were considered too small and
difficult to mark until October. Thus, habitat use and movements of age-
o fish were evaluated in October and November, and those of age-l fish
were evaluated the following April. Sampling was changed each year from
1979 to 1981 as more was learned about fish behavior. In 1979, use of
backwater habitats was evaluated in October and November. However, some
seine-hauls were possible only after breaking and removing a thin ice
cover, and this backwater disturbance and infrequent temperature
recordings limited the use of those data. In 1980, more specific habitat
use information was obtained in April from a backwater, nearby eddies,
and shoreline runs (Figure 2). In 1981, fish habitat use and movements
were further evaluated with respect to season (April, October and
November), time of day, and water temperature.

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Figure 2. Habitat types sampled in the Green River in 1979 and 1980
(upper), and 1981 (lower). Arrows show direction of water flow. Band b
= backwaters, E = eddies, $= shoreline runs.

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