9685

• UCREFRP Catalog Number: 9685
• Author: Tyus, H. M. and C. A. Karp.
• Title: Habitat Use and Streamflow Needs of Rare and Endangered Fishes
• USFW Year: 1989.
• USFW - Doc Type: Flaming Gorge Studies - 2nd Preliminary Draft.
• Copyright Material: NO

PART I: FLAMING GORGE STUDIES
Introduction
The Bureau of Reclamation (BR) and the Fish and 4lildlife Service (FWS)
have been in consultation on various 8R projects in the Colorado River basin
under provisions of the Endangered Species Act of 1973, as amended. The
operation of Flaming Gorge Dam has long been of concern because early
investigators stated that construction and operation of the Dam adversely
impacted native fishes in the Green River (e.g., Vanicek et ai. 1970; Holden
and Stalnaker 1975). More recent investigations have demonstrated that timing
and magnitude of water releases were critical to the maintenance and recovery
of some endangered fishes (Tyus et al. 1987).
Information on habitat use and streamf]ow needs of the endangered fishes
and on potential effects of widespread introductions of non-native fishes, is
essential for FWS to prepare a Biological Opinion under Section 7 of the
Endangered Species Act. Lack of such information resulted in the establishment
of the Colorado River Fishes Project by FWS 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
Ptychocheilus Lucius, and humpback chub Gila cypha in the Green River. Data
.were also collected on the razorback sucker Xyrauchen texanus, a candidate
species for federal protection under the Act, and protected by all states
where extant populations exist.
This report summarizes findings of several initiatives designed by FWS
and BR to evaluate habitat use and flow needs of endangered fishes in the
Green River basin. Part I describes the environmental setting, and presents
findings of each initiative. Part II summarizes and consolidates available
information on each species, and Part Iii summarizes flow needs for use in the
preparation of a biological opinion on the operation of Flaming Gorge Dam.
Detailed scopes of work pertaining to the individual investigations were
presented in modifications to the Interagency Agreement between BR and FWS
(FWS 14-16-006-86-953R) dated 9 June 1986. Most studies were conducted by
FWS, 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 (including evaluation of spring, summer, and
fall requirements of Colorado squawfish) and new research initiatives
(including 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, effects of low summer/fall flows on young Colorado
squawfish).-This report consolidates all studies and presents flow
recommendations derived from them in partial fulfillment of the Interagency
Agreement.
Environmental Setting
Legal agreements in 1928 (Carlson and Carlson 1982) separated the
Colorado River into upper and lower basins near Lee Ferry, Arizona. More
recently, the upper basin was sub-divided into three hydrologic sub-basins:
Green, Upper Main-Stem, and San Juan-Color~do (Iornes et al. 965). The Green
River sub-basin comprises about 116,000 km of the 284,000 km occupied by the
upper Colorado River basin (see Appendix for conversion to English system).
3