6012

• UCREFRP Catalog Number: 6012
• Author: Miller, W. H., D. L. Archer, H. M. Tyus and K. C. Harper.
• Title: Colorado River Fishery Project
• USFW Year: 1982.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

Collections of larvae in the lower Yampa River have corroborated
the hypothesis that a number of squawfish congregated in the vicinity of
RM 16.5 to spawn. Collections of large numbers of larvae below Split
Mountain Gorge and Gray Canyon indicate that these too are spawning
areas (figure 3). The downstream drift of larvae has only recently been `-
recognized and is not fully explored, however, there appears to be a
very significant survival mechanism in operation. Larval squawfish
drifted downstream away from the swifter, more harsh environments that
provide suitable spawning habitat into the more moderate river reaches
with a greater prevalence of the needed backwaters and other quiet water
niches. '
In the Colorado, the picture is not nearly as clear for YOY dis-
stribution (Figure 2). Collections of a few larvae below Loma (RM 154)
and the presence of what appears to be good spawning habitat suggests
that spawning occured between Loma and Blacly~ocks Canyon. However, few ~
_ YOY were captured for considerable distances downstream. The collection
of most YOY squawfish in the Colorado River has been between Potash (RM
47) and the head of Cataract Canyon (RM 3). This may have reflected
poor survival from the upstream spawning activity or drift may be much
more extensive than anticipated due to the absence of good nursery
habitat for a considerable distance downstream. The Green River empties
into this section also and could conceivably be the source of many of
these small fish. Also possible is the presence of potential spawning
areas in the Professor Canyon area (RM) from which these YOY could have `~"
emigrated.
Migration and Movement
Tagging and radio tracking programs documented movement and spawning
migrations of Colorado squawfish. In the main Colorado River, 144 wild
adult Colorado squawfish were tagged between July 1979 and July 1981.
Of this number seven were recaptured. No extensive movement was documentec
for these squawfish with a maximum distance between tagging recapture
site of about 20 mi. In February 1980, approximately 1,500 hatchery
reared adult Colorado squawfish gage group V~'~were released near Moab on
the Colorado River. One of the-thirteen recaptured hatchery fish moved
approximately 46 mi in a year, with others moving lesser distances.
In the Green River, fish were tagged between July 1979 and July
1981. Of these, ten were recaptured. Extensive movement was noted with
one fish moving over 200 mi in slightly over a year and another moving
over 100 mi. These two recaptures also exhibited movement from the
Green River into the Yampa River.
Six adult Colorado squawfish were implanted with radio transmitters
in the Green River in April and May of 1980. Four of these fish were
tracked for over four months. Two of them moved extensively up to 284
mi and 223 mi, while three remained rather stationary. Eight adult
Colorado squawfish were radio-tagged in the Green River during April and
May of 1981. One fish moved about 217 mi in about four months and the
others showed lesser movement. Other associated radio tagging studies
in the Yampa and White Rivers also document various movement patterns.
JZ