WSP04079

• File Number: 8240.200.40.J
• Description: Yampa
• State: CO
• Basin: Yampa/White
• Water Division: 6
• Date: 7/1/1989
• Title: Habitat Use and Streamflow Needs of Rare and Endangered Fishes, Yampa River, Colorado
• Water Supply Pro - Doc Type: Publication

Wick et al. 1985). During winter, adult Colorado
squawfish use backwaters (ephemeral along-shore
embayments), runs, and eddies, but are most common,
and presumably feed, in shallow, ice-covered shoreline
areas where large schools of minnows have been
observed (Wick and Hawkins 1989). Local
nonmigratory movements of adult Colorado squawfish
in nonbreeding seasons may be indicative of
home-range behavior (Tyus et al. 1987; Tyus 1989; Wick
and Hawkins 1989).
In spring and early summer in the Yampa River, adult
Colorado squawfish were most often located in
backwater habitats or flooded bottomlands.
Radio-tracking data indicated high use of shoreline
backwater habitat in 1981 (a low-flow year; 66%, N = 6
individual fish) and high use of flooded bottomlands
during 1983 (a high-flow year; 40%, N = 10). None of
the 10 fish located during 1983 were in backwater
habitat. Wick et al. (1983) noted that in 1982 (an
average-flow year), adult Colorado squawfish used
flooded shoreline areas in spring but moved to
backwater habitats as the river level dropped. High use
of flooded shorelines was also noted for adult Colorado
squawfish in the Green River during the 2 high-flow
years, 1983 and 1984 (Tyus et al. 1987).
Adult Colorado squawfish occupied a variety of
habitats in mid-to-Iate summer, but were most common
in eddies, pools, runs, and shoreline backwaters, over
sand and silt substrates (Fig. 5). Visual observations in
shallow water indicated that adults use sheltered
microhabitats behind boulders, flooded vegetation, or
other cover. During summer, radio-tagged fish were
most often located in deeper shoreline habitats, where

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HABITAT TYPE

Flg.S. Habitat use by radio-tagged Coloradosquawfish in the
Yampa River, June-August, 1981-85, 1987, 1988. ED =
eddy; PO = pool; RI/RU = riffle/run < 1.67 m depth: BA
= backwater; RU = run> 1.67 m depth; SH = shoreline;
MT = mouth of tributary; MB = mouth of backwater: FB
= flooded bottom; RA = rapid.

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ADJUSTED DATE

Fig. 6. Movement patterns of radio-tagged Colorado
squawfish migrating to Yampa River spawning grounds,
1981-85, 1987, and 1988. Spawning reach is delineated by
(===J; 0 = midpoint of calcnlated optimum spawning
period for each year. Adjusted date scale in 28-day
increments.

movements suggested heavy use of eddy-run interface
(Tyus et al. 1987).

Spawning

Two major Colorado squawfish spawning migrations
have beea identified by Service biologists in the Green
River basin by tracking radio-tagged fish. One migration
was discovered in the Yampa River and upper Green
River in 1981 (Tyus and McAda 1984), confirmed in
1982 (Wick et al. 1983), and again from 1983 to 1988
(Tyus et al. 1987). Movement patterns of fish migrating
to the Yampa River spawning reach are presented for
1981-88 (Fig. 6). In May and early June, Colorado
squawfish began downstream migrations in the Yampa
and White rivers and upstream migrations in the Green
River to spawn in riffle and pool habitat of the lower
51.2 km of the Yampa Canyon (Fig. 4). The only other
confirmed Colorado squawfish spawniag site in the
Green River basin is in Gray Canyon (RK 224-256) of
the Green River (Tyus et al. 1987; U.S. Fish and Wildlife
Service, unpublished data).