6011

• UCREFRP Catalog Number: 6011
• Author: Miller, W. H., et al.
• Title: Colorado River Fisheries Investigations
• USFW Year: 1981.
• USFW - Doc Type: Preliminary Draft Report.
• Copyright Material: NO

_ to mid-August this radio-tagged fish exhibited moderate
From mid Apra expected spawning
movement up to 7 miles. Close monitoring bracketed the season but no
behavioral patterns were observed that would indicate that
this fish had participated in spawning activities. _ ?.
.---?"-
The Walter Walker Wildlife Area on the Colorado River provides
th. Consistent captures of
static-water environment of 4-6 ft dep
est that this area provides a very attractive
razorback suckers sug8 it presents a highly
environment for the razorback sucker though
atypical environment for the Colorado River.
-- - ,"
Temperature Tolerances and Preferances
Chemical and
of the
rated in some
The razorback sucker has not been incorporated
priority.
laboratory testing programs because it was given a lower About 800 subadult razorback suckers were available from eggs
at Willow Beach NFH in 1974. About 700 of the smaller fish,
produced of their temperature
150-350 mm, were shipped to Utah State for study
swimming ability at various temperatures. The results of
preference and
are resented in Appendix I. In addition, field collections
these studies p the Upper
our group in
and radio-tracking of a razorback adult by
Colorado Basin and others in the Lower Colorado River Basin differences and.
show how these fish respond to temperature and chemical differ
may
changes as they occur in the wild. .
subadults preferred a temperature of
In temperature tests at USU,
about 230C when acclimated to 20 or 260C. Acclimated to 8 or 140C, few
fish could operate the temperature selection apparatus. Those that did
selected temperatures higher than 23°C•
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