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

accurate assessment of annual reproduction and recruitment of
young.
Sampling of adult Colorado squawfish immediately before and
during spawning and of larval Colorado squawf ish in backwaters
should be minimized to reduce disturbance and sampling
mortality.
Collection of life-history, abundance (using marked or tagged
fish), and fishery-type data on all fishes (including non-
natives) is important.
Elements of the SDCR
Element 1 - Reproduction. This element addresses hypotheses 2, 3,
4, 8, 9, and 10. Objectives of the related study ("Annual
assessment of Colorado squawfish reproduction and larval abundance
in the lower Yampa River, Colorado, and the lower Green River,
Utah") are to use collections of drifting larvae to document
Colorado squawfish spawning, determine peaks in relative abundance
of drifting Colorado squawfish larvae, and determine the relative
abundance of Colorado squawfish larvae transported into nursery
habitats.
Data gathered from the Reproduction element of SDCR will provide
information necessary to determine;
-relationships between relative reproductive success and
annual flow regimes,
-a relative measure of larval Colorado squawfish input into
downstream nursery habitats (e.g., Jensen-ouray area and
Mineral Bottom area),
-timing of spawning of selected species and thus timing of
spring flow releases from Flaming Gorge for enhancement of
spawning by desired species in the Green River, and
-Impact of any potentially catastrophic events in the drainage
such as the 1990 oil spill on the Yampa River, or other
incidents on reproductive success of native and non-native
species.
Element 2 - Age-0 Survival to Fall (Age-0 Recruitment). This
element addresses hypotheses 3,6,7,8,9 and includes, at this time,
two ongoing studies (1) "Availability and quality of nursery
habitat" and (2) "An evaluation of Colorado squawfish recruitment".
Aspects of the study to evaluate Colorado squawfish recruitment
also relate to Element 3.
Data gathered from these studies will provide information on
several topics including;
- relationships between annual relative abundance of age-0 Colorado
squawfish and relative reproductive success,
-effects of regulated summer/fall flows on survival and growth of
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