7281 ‎(2)‎

• UCREFRP Catalog Number: 7281
• Author: U.S. Fish and Wildlife Service.
• Title: Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin, Environmental Assessment, November 1987.
• USFW Year: 1987.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

' CHAPTER IV ENVIRONMENTAL CONSEQUENCES
Habitat Development and Maintenance
Colorado Squawfish.--Manmade backwaters could possibly increase survival and
growth of these fish during early years of life, especially if accompanying
' problems of nonnative fish predation on or competition with young-of-the-year
and juvenile Colorado squawfish can be controlled. Natural backwaters in the
Upper Basin are small areas at the mouths of small intermittent tributaries,
side channels, and embayments at the edges of the main channels. The
' permanence of a backwater is dependent upon streamflow conditions, and their
dynamic nature may make them difficult to construct and maintain.
' Instream habitat improvement structures such as jetties might be used to
provide habitats for Colorado squawfish, but the benefits of these structures
have not yet been proven. Favorable habitat conditions created by structures
' could be outweighed by negative impacts, including proliferation of introduced
fishes that prey on or compete with rare fishes in these habitats.
Development of spawning habitats could increase or enhance spawning sites used
by rare fishes, or provide areas suitable for reintroducing eggs or larvae of
' hatchery origin. Studies will be conducted to determine the relative value of
habitat development and improvement actions for rare fishes.
An experimental fish passage facility will be evaluated to determine if fish
' passage facilities are a viable recovery technique. If so, fish passage
facilities can be used to allow rare fish to reoccupy formerly inhabited
' reaches now blocked by dams. These facilities will most likely benefit the
Colorado squawfish and razorback sucker because these species can exhibit
extensive movement. Although adult Colorado squawfish use the upper reaches
of the major tributaries and mainstream rivers, there are no known spawning
' areas above existing dams. Therefore, the importance to the recovery effort
of extending the range through additional fish passages is unknown at this
time.
' Humpback Chub, BonYtail Chub, and Razorback Sucker.--Habitat development
actions have been directed primarily toward the Colorado squawfish. However,
ponds were developed in 1987 for rearing young razorback suckers at Ouray
' National Wildlife Refuge, Utah.
Stocking of Rare Fish Species
' Hatcheries provide refugia and can prevent extinction for the rare fishes.
Artificial propagation and stocking will also be used to produce fishes for
research to learn how rare fish populations can be made self-sustaining.
' Stocking may also be used to augment existing populations or to reestablish
the species in unoccupied habitat where suitable conditions exist. Efforts
will be made to preserve genetic diversity of broodstocks for propagation and
stocking efforts.
Colorado squawfish.--Research will be conducted to determine if stocking could
be used to augment Colorado squawfish populations in the Colorado River.
Though stocking cannot substitute for the need to provide.adequate habitat, it
may enhance the distribution and overall recovery prospects for the Colorado
squawfish in the Upper Basin. Hatchery-reared Colorado squawfish are

IV-B-2