7282

• UCREFRP Catalog Number: 7282
• Author: U.S. Fish and Wildlife Service, R. I. P.
• Title: Final Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin.
• USFW Year: 1987.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

' d. The bonytail chub will be reintroduced immediately into the upper basin to
improve the status of the species and to provide adequate numbers to study
habitat needs. The following stipulations are included:
1. Suitable sites in the upper basin will be located;
2. Reintroduced individuals should be disease-free;
3. Stocking should occur in areas which will reduce the possibility of
hybridization with the humpback and roundtail chub;
4. Reintroduced species will be marked and monitored to assist in
collecting habitat and life history data; and
5. Hatchery stocks will be augmented with new genetic material before
future reintroductions are attempted.
e. Consideration will be given to supplementing existing populations of the
razorback sucker, humpback chub, and squawfish where studies conclude that
it would help promote self-sustaining populations. The following
stipulations apply:
1. Reintroductions should be undertaken using hatchery-reared fish or
fish reared in grow-out pond situations;
2. Research pertaining to reintroductions of hatchery-reared fishes will
' not be conducted in confirmed spawning areas; and
3. Extreme caution will be used to protect the genetic integrity of wild
populations when introducing hatchery-reared fishes into the various
' subbasins.
4.4 NONNATIVE SPECIES AND SPORTFISHING
' Since the late 1800's, over 40 species of fishes have been stocked into upper
basin rivers and tributaries. Many of these species have been successful
because of the changes in the river system that favor these nonnative fishes.
' Nonnative fish species are successfully reproducing and are in many cases,
out-reproducing native fish due largely to better adaptation to present
environmental conditions. Presently, nonnative (exotic) species comprise over
65 percent of the fish species found in the upper basin. Over 30 different
' nonnative species have become established in the present range of the four
rare fish. Federal and State agencies continue to participate in the raising
and stocking of some salmonid species, though trout are not considered to be a
direct competitor. The States also stock a few other nonnative fish in the
upper Colorado River (Appendix 6.5.1).
There are 14 fishes native to the upper basin, including 6 endemic to the
Colorado River system. Three of the endemic species are federally listed as
endangered, and one is a candidate species (Appendix 6.5.2). These four
species are the focus of this program.
Though difficult to fully assess, competition with, and predation from,
nonnative species has played a role in the decline of these rare fishes,
particularly for the squawfish and razorback sucker. The rigorous nature of
the humpback chub habitat appears to allow them a competitive advantage over
nonnative species. The situation with the bonytail remains unclear.

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