8182

• UCREFRP Catalog Number: 8182
• Author: Bestgen, K. R. and L. W. Crist.
• Title: Response of the Green River Fish Community to Construction and Re-regulation of Flaming Gorge Dam. 1962-1996\
• USFW Year: 2000.
• Copyright Material: NO

taxa, bluehead and flannehnouth suckers, were similar in abundance between the two periods.
Ten introduced taxa increased in abundance, rainbow trout declined in abundance; and ten others
remained similar in abundance between the two periods. Largest increases were by fathead
minnow Pimephales promelas, sand shiner, white sucker, and hybrid suckers. The number of
fish in collections made at each of the upper and lower Lodore Canyon sites in earlier (1978-
1980) and later (1994-1996) periods was remarkably similar. This gave us confidence that the
conclusions drawn regarding changes in community composition were not due to differences in
sample size.
Longitudinal changes in the fish community, seine samples.-The fish community of the
Green River, as measured by seine sampling in low-velocity channel margin habitats, suggested
that upstream reaches supported few species that were mostly cold- or cool-water tolerant. In
comparison, downstream reaches supported a community with higher species richness that was
composed mostly ofcool- or warm-water tolerant species (Fig. 5, Table 3). In the upstream
Browns Park reach, a total of five native and six introduced species and three hybrid sucker
combinations was detected. In descending order of abundance, fathead minnow, bluehead
sucker, flannelmouth sucker, and redside shiner made up 96 % of the fish community. Native
species represented 33 % of the fish community. Coolwater mountain whitefish and brown trout
were also captured as was a single juvenile sand shiner.
The fish assemblage of Lodore Canyon differed from that found upstream and also varied
along the longitudinal gradient of Lodore reaches 1 through 4. In reach 1 of Lodore Canyon
(LD 1), four native and five introduced species and three hybrid combinations were detected by
seine sampling. Flannehnouth sucker, bluehead sucker, white sucker, redside shiner and fathead
minnow were the most common species collected, representing 94 % of the total assemblage
structure and native fishes were 70.9 % of those captured. In reach 2 (LD2), five native and five
introduced species were detected by seine sampling. Speckled dace, flannelmouth sucker,
bluehead sucker, white sucker, and redside shiner were the most common species collected;
representing 98 % of the total fish community and native species represented 94 % of all fish
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