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

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method would have to incorporate recent data that demonstrate extensive
movements of the young fish from backwaters to other habitats in response
to differences in water temperatures, and perhaps other variables as well.
Such movements confound the results of simple seining studies, some of
which have suggested higher concentrations of young fish in the Spring
than in the previous Autumn.
FWS studies in 1980-1981 (Tyus 1991) demonstrated that young Colorado
squawfish could be marked and recaptured weeks later. We would evaluate
the use of other marking methods for fish recognition, and select a non-
lethal mark that could be retained for a least 6 months. The
effectiveness of this mark and its effects on the fish would be evaluated
by using hatchery reared fish.
Existing data and information on: the effects of environmental variables
on habitat selection in young Colorado squawfish, differences in
behavioral patterns, differences in relative abundance of various size
classes of young squawfish, and mark/recapture data would be used to
design a new plan of study that would be proposed to further evaluate data
gaps for 1992. The basis for this issue paper would be an evaluation of
standing crops of various size classes, and annual growth increments of
fish that have been previously aged.
This work can best be accomplished in the Green River because of the long-
term extensive database, and large standing crops of the fish.
VI. Task Description (FY-1992):
Task 1: Evaluate binary coded wire tags and half tags as non-lethal
marks for Colorado squawfish 40-70 mm TL by conducting a
laboratory mark retention/recognition study on hatchery fish.
Task 2: Conduct a pilot field study to determine the feasibility of
estimation overwinter survival by making riverwide population
estimates of age-0 fish in Autumn and age-1 fish in spring
prior to spring runoff.
a.) Estimate backwater population size of age-0 or age-1
fish by randomly selecting backwaters and make a
population estimate for those backwaters and measure
backwater area.
b.) Use videography techniques to determine total backwater
area -available
c.) For each estimate, determine fraction of young Colorado
squawfish using backwaters by sampling shoreline,
eddies, and other types of river habitat as well as
backwater habitat.
Task 3: Design a long term study to relate overwinter survival and
winter flows
VII. Study Schedule (start/end by task):
1. Evaluate non-lethal mark
2. Pilot field study
a. Autumn estimate:
b. Spring estimate:
3. Study design:
4. Final report:
1 Aug 91 - 15 Apr. 92
30 Oct. 91
15 Apr. 92
1 Oct. 92
15 Mar. 93
VIII. FY-92 Work
- Description of work:
- Deliverables:
Evaluate non-lethal
study, study design.
annual report
C10
mark, pilot field