7037

• UCREFRP Catalog Number: 7037
• Author: Wyoming Game and Fish Department
• Title: Fishery Research Report
• USFW Year: 1978.
• USFW - Doc Type: Flaming Gorge Reservoir.
• Copyright Material: NO

Fish captured were recorded by species, measured to the nearest
millimeter and weighed to the nearest 10 grams. All trout were
measured and weighed; numbers of rough fish processed varied and was
dependent upon their abundance in each net.
RESULTS
Rainbow trout were the most frequent fish netted to 1965 (Tables
1, 2, 3). After that time production began to favor non-game fishes,
most notably flannel-mouth sucker, Utah chub, and since 1972, white
sucker. Utah chubs comprised nearly 50 percent of the total catch
from about 1967. White suckers seem to be increasing in abundance
with each year.
Fish population trends were relatively the same in all areas with
differences reflected in rates of decline (slopes of regression lines)
for each of the most common fish species (Figures 2, 3, 4). The rate
of decline in rainbow populations is virtually the same in each area
(-0.15 canyon and inflow, -0.16 open area). Utah chubs have been
increasing in abundance most rapidly in the open and inflow areas
while white suckers have increased most rapidly in the canyon.
There have been other species taken in the nets (cutthroat trout,
whitefish, roundtail chub, carp, mountain suckers) but they have been
taken only incidentally compared to rainbow trout. Utah chub,
flannelmouth and white sucker rates of return (indicated by net
catch) have been similar since early (1963 - 1965) in the project
(Tables 1, 2, 3).
DISCUSSION
Holcik and Pivnicka (1972) discussing changes in the ichthyomass in
a European reservoir (Klicava) related that the production of the im-
poundment over 14 years gradually changed to favor small forage
fishes. With these changes the fish population dropped below carrying
capacity of the reservoir. We have observed changes (indicated by
netting) in fish populations in Flaming Gorge through 14 years, but
cannot relate them to carrying capacity because it remains unknown.
Gillnet data for the reservoir show declining trout populations in all
areas and increasing numbers of Utah chubs (relatively small fish) and
white suckers. The rise of both species has been nearly meteoric.
Catch rates in nets doubled or tripled in a single year's time (Tables
2, 3 ).
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