7384

• UCREFRP Catalog Number: 7384
• Author: Tyus, H. M.
• Title: Colorado Squawfish.
• USFW Year: n.d.
• USFW - Doc Type: Vernal, Utah.
• Copyright Material: NO

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sites was confirmed by collections of small larvae immediately downstream, but
not upstream of Gray and Yampa Canyons, from 1980 to present (Haynes et al
1984, Tyus et al 1987). It is possible that other spawning sites exist,
including a site in Labyrinth and Stillwater canyons in the lower Green River
(Tyus et al. 1987). If so, they are not as large as the other two areas. 1~
Colorado squawfish spawning sites have been discovered in the Upper Main Stem
Colorado River, or elsewhere, despite years of study.
Homing behavior (Tyus 1985) has been noted in Colorado squawfish by long
distance movement patterns and recaptures of the same fish on spawning grounds
for a number of years (Tyus et al 1987, Wick et al 1983). A fidelity to these
spawning areas has also been demonstrated by repeated recaptures of the same
individuals on the same spawning grounds, and no fish has used more than one
spawning area (ie. no interchange of Yampa and Gray canyon spawners) (Tyus et
al 1987, Wick et al 1983). Additional unpublished FWS data also shows that
some fish pass through one spawning ground in route to another. Because Lack
of suitable spawning substrate is not judged a limiting factor, and migrating
fish pass through many km of apparantly suitable spawning areas, an olf actory
homing mechanism was proposed (Tyus 1985) to account for this behavior.
Turbid conditions in the Green River basin precludes direct observations of
spawning behavior of the fish in its natural riverine habitat. However,
radiotelemetry observations of spawning behavior in the wild were provided by
Archer and Tyus (1964), and Hamman (1981) noted the behavior of spawning fish '
in a hatchery. Fish behavior is similiar to that described for a congener, the
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