8231

• UCREFRP Catalog Number: 8231
• Author: Maddux, H. R.
• Title: Draft Environmental Assessment For Procedures For Stocking Of Nonnative Fish Species In The Upper Colorado River Basin.
• USFW Year: 1996.
• USFW - Doc Type: Grand Junction, CO.
• Copyright Material: NO

ENVIRONMENTAL ASSESSMENT
PROJECT TITLE: Procedures for Stocking of Nonnative Fish Species in the Upper
Colorado River Basin.
I. PURPOSE AND NEED
A. Pur ose: Endangered fishes in the Upper Colorado River Basin have been
and continue to be impacted by water depletions, operation of dams.
floodplain habitat disruption and nonnative fishes that compete with or
prey upon native fishes. Numerous recovery actions are underway to
resolve flow, migration barrier, and habitat quality problems. A
strategic plan is being developed to remove or reduce existing
populations of nonnative fish from habitat of the endangered fishes.
The highest priority measure in the Recovery Program's draft strategic
plan for control of nonnative fish is to prevent additional fish
introductions that could further exacerbate the existing interactions
between nonnative and endangered fishes.
The specific purpose of developing procedures to guide future nonnative
fish stocking actions is to reduce, minimize, and/or eliminate impacts
of nonnative fish on native fish. The goal is to continue to allow
nonnative fish stocking for recreational fishing and private
aquaculture, provided that such stocking is compatible with recovery of
the endangered Colorado River fishes. The Recovery Program requires
that "stocking of nonnative species will be confined to areas where the
absence of potential conflict with rare or endangered species can be
demonstrated."
B. Need for Action: The Colorado squawfish (see Appendix A for list of
fish scientific and common names used in this document) and humpback
chub were listed as endangered species on March 11, 1967. The bonytail
was listed as endangered on April 23, 1980. The razorback sucker was
listed as endangered on October 23, 1991. All four of these species are
protected under the Endangered Species Act of 1973, as amended, and
various State laws and statues. Critical habitat was formally
designated March 21, 1994. Critical habitat identifies the areas needed
for the recovery of listed species and the features of the habitat that
require protection. The formal designation included numerous reaches of
river and the associated 100-year floodplain.
Habitat degradation has been identified as the major cause of declining
populations of razorback sucker, Colorado squawfish, humpback chub, and
bonytail. Habitat degradation has occurred primarily as a result of
construction of dams, water depletions, and diking of the floodplain.
These changes in habitat have created an environment conducive to the
establishment and proliferation of nonnative fishes. In recent years,
dams in the upper Colorado River Basin have been reoperated to restore
more natural conditions for the endangered fishes. Fish passage
problems are being addressed (Recovery Program 1996). Flooded
bottomland habitats are once again becoming accessible to the fish