7375

• UCREFRP Catalog Number: 7375
• Author: Wengert, M. W.
• Title: Flaming Gorge Reservoir Fisheries Management Investigations Six Year Completion Report ‎(1977-1983)‎.
• USFW Year: 1985.
• USFW - Doc Type: \
• Copyright Material: NO

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trout throughout the project period have been unacceptable. Returns by weight
have ranged from 72.4 percent in 1978 to 39.7 percent in 1980. Catch rates for
trout have not exceed 0.5 fish per hour since 1974. Since that time, catch
rates have declined steadily and only during 1981 did catch rates show any
increase over the previous years.
If all strains fail to meet the guidelines of the evaluation, it may be that
kokanee salmon will dominate the small trout harvest category. Kokanee are
very efficient plankton feeders and may be able to out compete or at least co-
exist with the Utah chub and white sucker for available plankton. The harvest
of kokanee has been increasingly dramatically since 1978, when only 27 kokanee
were harvested.
During 1981, the kokanee harvest was 2,148 fish. Average lengths and
weights of kokanee have been considerably larger (Table 26) than for rainbow
trout. A dramatic increase in the population of kokanee could cause a decline
in the average length and weight of kokanee. This may be a benefit to the
fishery as a whole, because kokanee would then be available as a forage fish for
more than the first two years of their life cycle in Flaming Gorge.
Flaming Gorge Reservoir has developed into a very important trophy fishery
for brown and lake trout. Brown trout were the second most abundant fish in the
harvest until 1979 when they were exceeded by lake trout (Figure 7).
Brown trout were first introduced into Flaming Gorge in 1966 (Table 2) to
make use of a rapidly expanding Utah chub population. The browns grew
exceedingly well and a world renowned brown trout fishery developed. Brown
trout larger than 20 pounds were not uncommon, in fact, the North American
brown trout record weighing 33 pounds 10 ounces and measuring 40 inches was
caught in 1977. Coincidentally, 1977 was also the year the trophy brown trout
fishery peaked (Figure 7). Since 1979, average lengths and weights have
steadily decreased. An attempt to revive the brown trout fishery was started in
1980, when the first of 3 years of increased brown trout plants was made. The
harvest of brown trout increased in 1982 to the levels seen during 1979 (Figure
7), although average length and weight were quite low (Table 26). Returns to
the creel have also been low (Table 20). However, returns to the creel by
weight have been more encouraging (Table 21), with a 52 percent by weight return
during 1982. Evaluation of the returns of fall planted advanced fingerlings (5
inches) versus spring planted catchable-size (8 inches) browns should be
completed by 1988, the year of the next intensive creel survey. A final deci-
sion can then be made as to which planting procedure produces the best results.
The basis for continuing brown trout stocking will be the ability to produce a
return rate of at least 1.5 pounds to the fisherman's creel for each pound of
brown trout planted. During the interim period, every other year plants of
catchable brown trout will be made, based upon the preliminary results from the
1982 creel survey.
The brown trout planted during 1980, 1981, and 1983 will be faced with dif-
ferent environmental, plankton and forage factors than did the first plants of
brown trout in the reservoir. Brown trout grew well in the late 1960's and
early 1970's because abundant plankton produced rapid growth to a size which
allowed foraging on a rapidly expanding Utah chub population. There were no
other large populations of predators in the lake, so the brown trout assumed the
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