8134

• UCREFRP Catalog Number: 8134
• Author: Valdez, R. A.
• Title: Significance of the Palisade to Grand Junction Reach of the Colorado River to the Endangered Fishes ERI ‎(C035-06)‎.
• USFW Year: 1985.
• USFW - Doc Type: \
• Copyright Material: NO

3-5

Colorado squawfi sh composed 0-1% of the total fi shes caught duri ng two
sample periods within the 10-mile reach (Figure 3-2). No squawfish were
captured above RM 180.0.

FWS personnel feel that, although adult squawfish are captured in the
lower Gunnison River, it is unlikely that the larval fish seen in the
Colorado River in 1982 originated in the Gunnison (Lynn Kaeding, U.S. FWS,
personal communication with Richard Valdez, ERl, June 25, 1985).
Radiotelemetry and seining efforts in the the lower Gunnison River have been
similar to those on the Colorado River, and no evidence of adult spawning
aggregations or larval fish has been found in the Gunnison.

3.2.2 Razorback Sucker

A total of 136 razorback suckers have been reported from the IS-mile
reach between 1974 and 1984 (Table 3-1). All but two of these fish were
captured in flooded gravel pits. Like the Colorado squawfish, this
statistic does not necessarily indicate a preference for this habitat, but
it does reflect on their increased susceptibility to capture under these
conditions.

No radiotel emetry studies have been conducted on the razorback sucker
in the Colorado River, and so, no information is available for the species
that is comparable with movement data of the squawfish. However, the
regular occurrence of the species within the reach is significant. Of 52
razorbac ks captured in the 289 mil es of the Upper Colorado Ri ver from 1979
to 1981, 15 were caught within this IS-mile reach (Valdez et ale 1982).

At least two investigators (George Kidd, Northwest Fisheries Research,
personal communication with Richard Valdez, U.S. FWS, Grand Junction,
Colorado, June 1979; Valdez et al. 1982) have caught large numbers of adult
razorback suckers in Clifton Ponds and the Palisade Labor Camp (both
abandoned gravel pits). Kidd found several females readily expelling
eggs in June 1977, and Valdez et al. reported several ripe and tubercled
males and females in spawning condition and coloration in early June 1981.
These observations suggest that the razorback has attempted to spawn within
the subject reach.

Studies of the species in the lower Colorado River Basin (Ulmer 1981;
Lowdermilk 1981) would suggest that the razorbacks are probably spawning in
the quiet backwaters and gravel pits in lieu of the main river channel,
which is at flood stage during spawning time. However, no evidence of
successful reproduction (fertile eggs, larvae, YOY, juveniles) has ever been
found in this reach of the Colorado River. This lack of reproductive
success can only be speculated as being caused by excessive siltation,
predation by other fishes, or perhaps problems with water quantity or
qua 1 i ty (Wi c k et a 1. 1982).

3.3 Proposed Studies

Studies of the subject reach are to be admini stered by the U. S. Fish
and Wildlife Service, Region 6, Denver Colorado. Field studies are to be
coordinated by the Grand Junction Field Station of the Colorado River Fishes
Monitoring Project (CRFMP). The supervising office for this project,