9315

• UCREFRP Catalog Number: 9315
• Author: Harvey, M. D. and R. A. Mussetter.
• Title: Evaluation of the Required Frequency of Bar Forming Events and 2-Dimensional Hydrodynamic Modeling at Colorado Squawfish Spawning Sites in the Lower Yampa Canyon, Colorado.
• USFW Year: 1996.
• USFW - Doc Type: Fort Collins.
• Copyright Material: NO

III.
IV.
Study Goals, Objectives, and End Product
Goal -- Data from this study will be used as part of an annual assessment
of reproduction and recruitment of Colorado =uawfish (and other fishes)
so that various hypotheses regarding the affe__s of modified operation of
Flaming Gorge Dam can be evaluated. Information will facilitate
assessment of relationships between relative reproductive success and
annual flow regimes (specifically flow releases from Flaming Gorge Dam)
and provide a relative measure of input of fish larvae into downstream
nursery habitats.
objectives --
1.) To document timing and duration of spawning by Colorado squawfish
(and other fishes) as measured by capture of drifting larvae.
2.) To determine peaks in abundance of transported Colorado squawfish
larvae during the spawning season.
3.) To determine the relative abundance of Colorado squawfish larvae
transported from spawning areas in the lower Yampa River (Yampa
Canyon) and the lower Green River (Grey and Desolation canyons) into
downstream nursery habitats (Jensen-Ouray and Mineral Bottom areas,
respectively).
Some Assumptions --
1.) Results of previous studies on young Colorado squawfish in the Green
River system provide accurate baseline information on movements and
distribution.
2.) Efforts of this study and of other FGFRI studies (e.g., SDCR Tasks
2 and 3) will be sufficient to provide accurate, more-detailed
information on distribution and relative abundance of young Colorado
squawfish.
3.) Most larvae are produced in two spawning areas (i.e., lower Yampa
Canyon and Grey and Desolation canyons) and most are transported
into the two nursery areas (i.e., Jensen-Ouray and Mineral Bottom,
respectively).
In order to more rigorously assess these assumptions, use of marked larvae
and additional drift-net stations (e.g., upstream of the Grey-Desolation
spawning area and downstream of the Mineral Bottom nursery area) and seine
sampling (throughout the Green River and covering a greater temporal
period; other than what is proposed under SDCR Elements 2 and 3) would be
necessary. However, we believe that previous studies have provided
accurate baseline information, approval to use marked larvae in the Green
River system is probably not forthcoming, and logistics and costs
associated with additional sampling would be prohibitive. Information
from hypotheses-testing study 5 (hypotheses-testing Task 5; especially the
ageing and growth work) will facilitate assessment of these assumptions.
End Product -- A summary report will be submitted at the end of each
fiscal wear. At the end of the 5-year effort, information will be
integrated with results of other Flaming Gorge investigations.
Study_iraa:
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