8058

• UCREFRP Catalog Number: 8058
• Author: Wydoski, R. S.
• Title: Annual Propagation Operation Plan 1996.
• USFW Year: 1996.
• USFW - Doc Type: Denver.
• Copyright Material: NO

genetic data to indicate that the two stocks are separate. Some
exchange between the two locations has been documented. Three
adult humpback chubs of 43 tagged in Westwater Canyon moved
upstream to Black Rocks Canyon (Valdez et al. 1982). About 1,200
humpback chubs were PIT-tagged by the Utah Division of Wildlife
Resources through 1994 and most recaptures of these fish were close
to the point of release (T. Chart, 1994, Personal Communication).
Several of the fish tagged by Utah in Westwater Canyon were
recaptured by the Colorado Division of Wildlife in Black Rocks
Canyon (B. Elmblad, 1995, Personal Communication).
Long-Term Research. Razorback suckers and Colorado squawfish are
being reared at the Ouray Endangered Fish Facility to determine if
these fish species imprint to spawning areas from olfaction cues
(Scholz et al. 1993) based on the strong fidelity to spawning areas
by Colorado squawfish (Tyus 1990) and razorback suckers (Tyus and
Karp 1990).
It is anticipated that the male razorback suckers will attain a
total length of 350-400 mm (about 14-16 inches) and some will
mature in the spring of 1996. Some females are expected to mature
(at 18 inches TL) in the spring of 1997 when additional results
will be available to make a preliminary evaluation as to whether or
not razorback suckers imprint through olfaction cues.
Improved growth of the chemoreception study fish is expected in
1996 when they will be reared at much lower densities in the new
ponds at the Ouray Endangered Fish Facility. A higher proportion
of the research fish should reach sexual maturity in the spring of
1997 because of the expected improved growth.
The growth of Colorado squawfish has increased substantially in the
new ponds at the Ouray Endangered Fish Facility. Lower loading
rates and higher zooplankton production have contributed to the
increase in growth. Some of these fish are expected to mature in
1997 based on the increased growth rate in the new ponds.
IX
References
Chart, T. 1994. Personal communication. Utah Division of Wildlife
Resource, Moab, Utah.
Elmblad, B. 1995. Personal communication. Colorado Division of
Wildlife, Grand Junction.
Hamman, R.L. 1981. Hybridization of three species of chub in a
hatchery. Progressive Fish-Culturist 43: 140-141.
Lentsch, L.D. Y. Converse, P.D. Thompson, and T.A. Crowl. 1995.
Bonytail reintroduction plan for the Upper Colorado River Basin. Final
draft report. Utah Division of Wildlife Resources, Salt Lake City.
30 pp.
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