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

cooler upper Lodore site. Consistent changes in species composition at both sites suggested a
continued shift from a cold water fish community to one dominated by cool- or warm-water taxa.
Distribution or abundance of some fishes has not changed substantially since 1980. Red
shiners, which were collected by Holden and Crist (1981) at the upstream Wade and Curtis site at
RK 580.7 (N = 3 individuals) and were common at their downstream Alcove Brook site (RK
561), were detected in our samples upstream to only RK 564.7. Sand shiners, which were
detected by Holden and Crist (1981) as far upstream as Alcove Brook, were detected as far
upstream as RK 588.7 in our samples. However, with the exception of the single individual from
Browns Park, most of our sand shiners in the Green River upstream of the Yampa River were
taken just upstream of the confluence. Lack of backwater and other low-velocity habitat in the
middle reaches of Lodore Canyon may restrict upstream dispersal of those species. The
restricted upstream distribution of these fishes may also be a response to increasingly cold
upstream water temperatures in the upper portions of Lodore Canyon, which may limit
reproduction. Those warm water species typically spawn in summer in the unregulated Yampa
River when temperatures exceed about 20 to 22°C for extended periods (pers. obs. KRB). Those
conditions likely existed only occasionally in the lower portion of Lodore Canyon.
Longitudinal changes in the fish community, seine samples.-Water temperature, and to a
lesser degree, habitat availability, appeared to control the longitudinal distribution and abundance
of fishes in low velocity habitats in the regulated reach during the period 1994-1996. In
upstream Browns Park, the fish community was relatively species poor. The most abundant
species were tolerant of relatively cold or cool-water, and native fishes were only moderately
abundant. Backwaters were relatively common in the sandy-bottomed Browns Park reach of the
Green River; two obligate backwater species, fathead minnow and redside shiner, were abundant.
Fish distribution and abundance shifted rather dramatically within the relatively short
Lodore Canyon reach. Coolwater species such as white sucker and salmonids were relatively
abundant upstream but were increasingly rare downstream, which was probably a response to
increasing downstream temperatures. Non-native cyprinids including fathead minnow and
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