7177

• UCREFRP Catalog Number: 7177
• Author: Miller, W. H., H. M. Tyus and C. W. McAda.
• Title: Movement, Migration and Habitat Preference of Radiotelemetered Colorado Squawfish; Green, White and Yampa Rivers, Colorado and Utah.
• USFW Year: 1983.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

Colorado squawfish appear to be very selective in their choice of
spawning habitat in the wild. Based on an inspection of the only known
spawning site in the lower 32 km of the Yampa River, the site must
contain cobble/rubble substrate and deep pool/riffle habitat. Also,
suitable temperature and flow conditions must be met. More importantly,
Colorado squawfish appear to have a homing instinct (probably acquired
in early life) and may travel 160 km or more either upstream or downstream
to reach their historic spawning grounds. The homing mechanism involved
in this spawning migration is unknown.
3 It is stressed that habitat preference data for spawning sites
represents only one location and is preliminary. Further efforts are
underway (Miller et al. 1983a,b) to further define spawning conditions
and preferences of Colorado squawfish and should result in a much better
understanding of the needs of these fish.
Distribution and Abundance vs Migration
Other workers have postulated spawning migration in Colorado
squawfish and there are many reports of spring spawning migrations by
early settlers who called the Colorado squawfish "salmon" (Sigler and
Miller 1963). Joseph et al. (1977) reviewed information concerning
movement and spawning and concluded that large individuals possibly
migrate long distances. Even so, the possible impact of movement and
long distance migration has not been considered in previous studies and
may lead to erroneous conclusions about distribution, abundance, survivor-
ship and other life history factors. In order to assess the impact of
Colorado squawfish movement and migration, the results of the CRFP
studies in the Green, White and Yampa rivers and the results of other
studies were compared with radiotelemetry data.
As suggested by Northcote (1967) migratory movement greatly affects
capture and often confounds determinations of recruitment and produc-
tion. The behavior of Colorado squawfish No. 165 in the Green River in
1980, illustrates how extensive movement could bias apparent habitat
preference data obtained by the use of passive gear (set nets), since
this fish would have a greater susceptibility for capture while moving
between preferred habitats. This is especially true for migrating fish.
In addition, Colorado squawfish collections in the Green River in 1979-
81 produced a typical survivorship histogram (Miller et al. 1982c).
However, a comparison of this histogram with a similar one from the
White River (Miller et al. 1982a) indicates that Colorado squawfish were
moving between the Green and the White rivers. It is likely that this
movement would not have been discovered if the Green River study had
been done in a vacuum or if radiotelemetry was not employed.
Previous studies of the
squawfish did not incorporate
patterns. As a result, the s
misinterpreted. The capture
should not be interpreted to
supporting evidence.
abundance and distribution of Colorado
a consideration of potential movement
tatus of Colorado squawfish was frequently
of ripe males (in probable migration)
indicate a spawning area without other
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