7194

• UCREFRP Catalog Number: 7194
• Author: Nesler, T. P.
• Title: Aquatic Nongame Research - 1985-86 Squawfish-Humpback Studies.
• USFW Year: 1986.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

1

Annual Job Progress Report

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Projf=~ct. No.: Q2-.Q.1-_~)~?

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Study No.:

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Study objective:

Develop research/management criteria for the
conservation and enhancement of populations of
endangered fish species in the Upper Colorado
River Basin.

INTRODUCTION

The period covered by this report was a transition period for the
project in terms of field studies conducted and principal investigators
involved. Studies on identification of habitat requirements and limiting
f act.ol-s fOt- Col or.::\do ::,qua.~~f i sM (E.t.Y.:.~.h9J;hei l..!:l2. l.!-lc ius) and humpbac k chub
(Gil..?.:. ~Y(lh~) ~-\jere near completion. The specific object.ives crf thes-e
studies were to (1) delimit the reproductive range of Colorado squawfish
in the lower Yampa and Colorado rivers within the State, and (2) evaluate
factors limiting reproduction and recruitment of Colorado squawfish. The
results of this work have been presented in Haynes et ala (1985), and
cover studies from 1981-1985 on young-of-the year (yay) stages of these
species in the Yampa and Colorado rivers. A third objective of this
project was to develop taxonomic techniques for identifying and
discrimina.ting between early life history stages of Gila species and their
hybrids native to the Upper Colorado River Basin. This objective is being
addressed in a Ph.D. dissertation in preparation by R. Muth, Larval Fish
Laboratory, Colorado State University. Completion is expected by spring
of 1987.
Concurrent with this final report process, further larval fish
sampling was conducted in Yampa Canyon at the 80:< Elder site on the Yampa
River during July-August 1985. This work was done at the request of the
U.S. Fish and Wildlife Service in Vernal, Utah, and was conducted to
provide supplemental data for an ongoing study of the impacts of
controlled !-eleases from Flaming Gorge Reservoir on survival of
young-of-the-year Colorado squawfish in the Green River downstream from
the Yampa River confluence. Further it was anticipated that this sampling
would provide additional data on the effects of seasonal temperature/flow
regimes on larval Colorado squawfish production. Evaluation of these
effects is the primary focus of this report.
Another objective of the 1985-86 work plan was to develop a research
project consistent with the recovery plans and priorities of the Colorado
River Fishes Project Recovery Team for endangered fishes in the Upper
Basin. The Study Narrative attached to this report as Appendix B
describes the current work plans and research proposals for 1986-1991.

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