7381

• UCREFRP Catalog Number: 7381
• Author: Valdez, R. A. and W. J. Masslich.
• Title: Winter Habitat Study of Endangered Fish - Green River Annual Summary Report - 1986-87.
• USFW Year: 1987.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

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conducted by the FWS.

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Much of the work done by the FWS has served to provide information for the
evaluation of water development impacts on these listed fishes in the Green and
Colorado rivers, as prescribed by Section 7 of the Endangered Species Act. The
BOR has been in consultation with the FWS on the operation of Flaming.Gorge Dam
as information on the needs of the fishes is accumulated.

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Results of studies by the CRFP have indicated that the operation of
Flaming Gorge Dam may, at certain times of the year, affect the reproduction
and recruitment of the endangered or native fishes in the Green River System.
In satisfying requirements of Section 7 of the Act, the FWS and BOR have
entered into an Interagency Agreement to collect biological and physical
information on the endangered fishes that is specific to the operation of
Flaming Gorge Dam. The objective of these studies is to obtain information to
enable the FWS to reconunend operational criteria for Flaming Gorge Dam that
will insure the continued survival and promote the recovery of these species.

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Prior to this investigation, information on the flow needs of these fish
had been collected only in the spring, summer and fall. No data had been
collected on flow needs and migrational or movement patterns of the fishes
during the winter. To date, studies have demonstrated that the operation of
Flaming Gorge Dam has the potential of greatly influencing the survi val of
larval or young fish while they occupy backwaters for nursery areas during the
summer period. Similarly, the operation of the dam during the winter also has
the potential of affecting the early life stages of fish and habitat occupied
by the adults.

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There is a need for additional studies to collect information on winter
habitat needs of all life stages of the endangered fishes and determine the
extent that these fish are impacted or displaced by the operation of the dam in
the winter. This information would allow the FWS to make flow reconunendations
for the operation of Flaming Gorge Dam on a seasonal basis that would ensure
the survival and promote the recovery of the endangered fish of the Green and
Colorado River Systems.

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The purpose of this study is to characterize the winter habitat needs of
adult Colorado squawfish and razorback suckers through the use of
radiotelemetry and ~The humpback chub and bonytail chub are not included
in this study. The bonytail is extremely rare in the upper Colorado River
basin, to the extent that information on this species cannot be readily
collected. The humpback chub has been excluded because the species is non-
migratory and restricted to canyon-type habitats that are not as greatly
affected by flow changes as are other types of riverine habitats.

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