9549

• UCREFRP Catalog Number: 9549
• Author: Bestgen, K. R., K. A. Zelasko, R. I. Compton and T. Chart.
• Title: Response of the Green River Fish Community to Changes in Flow Temperature Regimes from Flaming Gorge Dam since 1996 based on sampling conducted from 2002 to 2004.
• USFW Year: 2006.
• USFW - Doc Type: 115,
• Copyright Material: NO

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sampling mortality. More intensive capture-recapture sampling to document population
abundance of chub species would be useful on a less than annual basis. All chubs should be PIT
tagged to better understand abundance, survival, and movement of those species.
Small-bodied fishes.-We recommend two seine sampling passes, one in each of summer
and autumn. Native fish abundance and species richness was usually high in summer, so
sampling then is needed to document annual reproductive success. Autumn sampling for
monitoring is also advantageous because non-native fish abundance and species richness is high
and fish are larger and easier to identify.
Drift net sampling is one means to detect reproduction by adult Colorado pikeminnow in
the Green River upstream of the Yampa River. This sampling is relatively easily accomplished
when associated drift net sampling occurs in the lower Yampa River and may be a viable
substitute for electrofishing sampling conducted in summer to detect whether ripe Colorado
pikeminnow are using Lodore Canyon.
Sampling of any kind is not recommended in spring. Fish activity may be reduced when
water temperatures are cold, and higher flows may limit sampling efficiency. Higher flows in
spring due to elevated runoff from the Yampa River especially limits effectiveness of sampling in
Whirlpool Canyon and downstream. This is because eddies that are sampled with trammel nets
and backwaters that are sampled by seines are mostly washed out at higher flows.
CONCLUSIONS
? The impacts of construction and operation of Flaming Gorge Dam on physical habitat in
the highly regulated reach of the Green River from the dam downstream to the Yampa
River and in Whirlpool Canyon downstream of the Yampa River were partially
remediated by thermal modifications implemented in 1978, discharge re-regulation in
1992, and 2002 to 2004 drought-period changes to baseflow levels and patterns.
? Thermal enhancement of the regulated reach via penstock modification in 1978 had a
large restorative effect because reproduction by most native fishes in the Green River
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