7047

• UCREFRP Catalog Number: 7047
• Author: Tyus, H. M. and C. A. Karp.
• Title: Habitat Use and Streamflow Needs of Rare and Endangered Fishes in the Green River, Utah
• USFW Year: 1991.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

availability of usable rare fish habitat in the downstream Green River (Tyus
and Karp 1989).
FLAMING GORGE STUDIES
Background
The Bureau of Reclamation (BR) and the Fish and Wildlife Service (FWS)
have been in consultation on various BR projects in the Colorado River basin
under provisions of the Endangered Species Act of 1973, as amended. The
construction and operation of one of these projects, Flaming Gorge Dam, has
long been of concern because of its potential adverse impacts on native fishes
in the Green River (e.g., Vanicek et al. 1970; Holden and Stalnaker 1975).
Recent investigations have demonstrated that the timing and magnitude of water
releases from the dam can inundate nursery habitats that are critical. to the
maintenance and recovery of Colorado squawfish in the Green River basin (Tyus
and Haines 1991), and have impacts on other fishes as well (reviewed by Tyus
and Karp 1989).
Habitat use and streamflow needs of endangered fishes, and potential
effects of widespread introduced fishes on the Green River system constitute
basic background information considered essential by FWS for the preparation
of a Biological .Opinion for Flaming Gorge Dam under Section 7 of the
Endangered Species-Act. Lack of such information resulted in the establishment
of the Colorado River Fishes Project in the late 1970's. The objectives of
this project, funded principally by BR and staffed by FWS biologists, included
collection of life history information on the Colorado squawfish and humpback
chub in the Green River. Data were also collected on the razorback sucker, a
species proposed for federal listing and protection under the Act (U.S.
Department of the Interior 1990). The razorback sucker is protected by all
states where known populations exist.
This report summarizes findings of several endangered fish studies
designed by FWS and BR, and provides recommendations for management and
recovery of these fishes in the Green River basin. Detailed scopes of work for
individual studies were presented in modifications to the Interagency
Agreement between BR and FWS (#FWS 14-16-006-86-953R) dated 9 June 1986. FWS
employees acted as principal investigators for most studies; however, two
studies were performed by BR with assistance from FWS, and two studies were
conducted by private contractors. These studies included continuation of
ongoing projects (i.e., evaluation of spring, summer, and fall requirements of
Colorado squawfish) and new research initiatives (i.e., evaluation of spring
and early summer habitat use of razorback sucker and humpback chub, potential
effects of introduced fishes on Colorado squawfish and humpback chub, winter
flow needs of Colorado squawfish and razorback sucker, and effects of low
summer/fall flows on young Colorado squawfish). This report consolidates all
studies, contrasts these findings with those of others, and presents flow
recommendations and temperature regimes needed for recovery of these fishes in
partial fulfillment of the Interagency Agreement.
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