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

The discovery of these 13 ripe Colorado squawfish at RK 26.4
prompted an intensive survey of the lower 32 km of the Yampa River.
Between 1 and 9 July, a total of 35 ripe or spent adults were captured,
of which one (No. 1313) was a local recapture and one (No. 1537B) was a
recapture from 1978 (Table 3). Counting the fish captured (36) and
those with radiotags at lease 43 adult Colorado squawfish were present
in the lower Yampa Canyon between 5 June and 9 July. In addition, three
fish observed during this period were recaptures; two had been tagged
with dangler tags on the upper Yampa River in 1978 and 1980 and one had
been tagged in the upper Green in 1981. Although the lower Yampa Canyon
was repeatedly sampled, no adults were collected after 9 July in 1980 or
1981. It is concluded this movement represented a major spawning
migration and five adults captured before 19 June, 1981 possibly were
early migrants. It is likely that the observed spawning migration is
historic since Holden and Stalnaker (1975) reported increased numbers of
ripe Colorado squawfish in the lower Yampa River in July 1968-1970.
Collections made by Seethaler (1978) also indicated increased numbers of
Colorado squawfish in the lower Yampa River in July 1974-75. The findings
of this study disagree with the hypothesis (Joseph et al. 1977) that
Colorado squawfish spawn in the same area in which they live all year.
The presence of ripe Colorado squawfish in a river section does not
necessarily reflect a spawning area, since ripe males can be stripped of
milt for an extended time period. Therefore, it is important to con-
sider the results of larval fish collections conducted by the CDOW in
August 1980, and the more intensive sampling by the CDOW and FWS in
July-August 1981. The 1980 collections produced larval Colorado squaw-
fish in the lower 16 km of the Yampa River. Although the lower 190 km
of the Yampa River was intensively sampled in 1981, larval Colorado
squawfish (9-13 mm) were collected only in the lower 20 km. This supports
the conclusion that spawning is restricted to the lower 32 km as suggested
by fish behavior radiotelemetry and the collections of ripe fish.
A physical characterization was made of the river section at RK
26.4 on 5 July 1981, in order to evaluate spawning habitat requirements
for Colorado squawfish. Sonar depth profiles were taken at locations
presented in Figure 16. Table 6 summarizes major physical paraTeters.
Noon temperature was 22°C and conductivity was 340 micromhos/cm . The
largest number of spawning Colorado squawfish was obtained by floating a
trammel net from transect 3 to transect 1 (Fig. 15). The depth profiles
and velocity components are best represented by locations la, 2a, 2b,
and 3a (Fig. 16) for this collection. The depth ranges from 0.9 to 2.1 m
and the velocity ranged from 0.0 to 0.08 m/s. Primary substrate at this
location was cobble/rubble, with a mean diameter of about 7.5 cm. When
these data are compared to information obtained for the northern squaw-
fish (Beamesderfer and Congleton 1981) it is apparent that differences
in habitat selection occurred between the two species; the northern
squawfish was found spawning at about 10°C in water depths of 4.8 m and
a velocity of 0.05 m/s.
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