8026

• UCREFRP Catalog Number: 8026
• Author: Berry, C., R. Bulkley, D. Osmundson and V. Rosen.
• Title: Survival of Stocked Colorado Squawfish with Reference to Largemouth Bass Predation.
• USFW Year: 1985.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

lot will be stocked in the fall of 1983 and the second and third lots
in the spring and fall of 1984. Exact dates of stocking will depend on
when the hatcheries involved can have the fish ready, and in the case
of the spring plant, after the flood subsides and the ponds again
become isolated from the river.
The fish will be graded into three size groups at the hatchery.
The mid-size group will not be used, thus leaving two distinct non-
overlapping size-classes. Every fish will be tagged with a coded wire
microtag (CWT), which will indicate the size-group and season of stock-
ing. The number of fish in each size-group will be automatically count-
ed as the fish are tagged. Due to hatchery constraints, squawfish used
for the fall 1983 plant will be raised at Dexter National Fish Hatchery;
those for the spring and fall 1984 plant will be raised at Willow Beach
NFH.
5. Bass Stomach Content Analysis
Largemouth bass diets will be monitored before and after squawfish
stocking. Bass will be collected at night using electrofishing gear and
the lengths of each and the presence or absence of food in the stomach
recorded. Those bass with food in their stomachs will have their stomach
contents removed with a glass tube of the appropriate diameter in the
manner outlined by Forney (1974). Contents will be preserved in bottles
of Yo formalin labeled with the date, pond, and length of bass. This
rtutine will be performed a minimum of once prior to stocking, the
night after stocking, and once weekly for three weeks subsequent to
stocking. Stomach contents will be later analysed in the lab, and number,
volume, and length of identified items recorded.
6. Survival of Squawfish
The number of squawfish stocked in each pond will be compared to the
estimated number remaining 2-6 months later. Survival of fish stocked
in the fall will be estimated the following spring before the river
floods. Survival of those stocked in the spring will be estimated the
fall of the same year just prior to the second fall stocking. The size
of these fish preclude the use of fin-clips or floy tags and thus a
removal-based population estimator will be employed. A minimum of four
sampling events will be made at each pond and effort per visit held
constant. Squawfish will be collected with a 137 x 2.4 m bagged seine
of 6 mm nylon mesh. Data will be run through program CAPTURE and Model
Mbh used as the removal-based estimator (Otis et al. 1978).
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