9393

• UCREFRP Catalog Number: 9393
• Author: Crist, L. and R. Williams.
• Title: Five Year Flaming Gorge Research Program FY 1995.
• USFW Year: 1994.
• USFW - Doc Type: 32-41, Fg-I,
• Copyright Material: NO

CORE-RESEARCH STUDIES
Study #32. Annual assessment of Colorado squawfish reproduction and larval
abundance in the lower Yampa River, Colorado, and the lower Green River,
Utah.
Study Goals
This study is intended to document annual reproduction and recruitment to
Age-0 of Colorado squawfish in the Green and Yampa rivers and examine the
relationships among flow and reproduction and larval production.
Relationship to Research Program
Annual assessment of Colorado squawfish reproduction and larval abundance
is necessary to identify and assess factors influencing recruitment of Age-0
fish. The analysis of how flow and the reproduction and early recruitment of
Colorado squawfish are linked is supported by the results of the Early Biology
Studies (conducted 1991-1993). Information derived from this-study is also
important to the interpretation of results of other studies, especially the
Nursery Habitat Study (study #33).
Description of Work
This study is being conducted jointly by the LFL and UDWR under the lead of
the LFL. The study is ongoing but was expanded in FY 1994 by the addition
of another drift station. Study objectives include documentation of timing and
duration of spawning by Colorado squawfish as measured by capture of
drifting larvae, determination of peaks in abundance of drifting larvae, and
determination of the relative abundance of larvae transported from two
spawning locations and into downstream nursery areas. Reproduction will be
assessed using drift-net sampling at three sites: 1) Yampa River immediately
upstream of the Green-Yampa River confluence, 2) Green River downstream
of Split Mountain Canyon and upstream of Jensen, Utah (sites 1 and 2 cover
Colorado squawfish produced in the Yampa River), and 3) Green River below
the Colorado squawfish spawning area in Desolation/Gray canyons. Site 2 is
anew drift station implemented in FY 1994 to better quantify input of larval
fish to the Green River nursery areas.
Study #33. Assessment of Colorado squawfish nursery habitat in the Green
River.
Study Goals
The overall goals of this study are to determine the relative importance of
various types of backwater habitats to Colorado squawfish and the influence
of spring test flows on the formation and maintenance of those habitats.
Relationship to Research Program
Data from this study will be used to refine spring, summer and fall flow
recommendations. This study will provide a basis for determining the
Flaming Gorge Research Program 23