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

fishes at a 1.9-km-long upper Lodore Canyon site near upper Wade and Curtis Campground
(river kilometer (RK) 581), and a 1.6-km-long lower Lodore Canyon site near Alcove Brook (RK
561). To make valid comparisons with their fish composition data, we used a subset of our
samples collected in a 4.8 RK reach encompassing their fixed stations. Recognizing that there
are potential biases, we combined seine and electrofishing data for these comparisons to be
consistent with Holden and Crist (1981). We then assessed changes in species composition
between the two periods by comparing the number and relative abundance of native and
introduced species captured in each period. We acknowledge that differences in habitat,
collecting gear, and sampling effort may affect assessments of faunal differences between the
two periods. Therefore, our qualitative assessments of temporal change were conservative.
Longitudinal changes in the fish community, 1994-1996.-Longitudinal species abundance
patterns correlated with downstream temperature shifts may facilitate understanding of how
Flaming Gorge Dam influences the fish community. Analyses of longitudinal shifts in
community composition were conducted both for small-bodied fishes captured primarily by
seining and for large-bodied fishes captured primarily by electrofishing. Seine samples of small-
bodied fishes were collected from six mostly contiguous Green River reaches: a Browns Park
reach, four 8-RK reaches within Lodore Canyon, and an Island and Rainbow parks reach.
Lodore Canyon fish samples were divided among the four relatively short reaches to facilitate
detection of downstream shifts in community composition and structure. The upper terminus of
the first and most upstream Lodore Canyon reach extended from RK 586.9 downstream to RK
579. The second reach extended from RK 578.9 downstream to RK 571, the third reach from
RK 570.9 to RK 563, and the fourth from RK 562.9 to RK 555, the confluence of the Green and
Yampa rivers. Samples were also collected in a seventh reach, the lower 2 km of the Yampa
River. Yampa River collections were used to compare and contrast the fish community of a
warm, unregulated river to the fish community present in a regulated river that is affected by cold
water releases and altered discharge patterns.
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