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

and year scales for 2002 to 2004 data. Capture rates of common species in trammel net samples
were calculated as fish per net h, where a net h is one 22.9 m-long trammel net set for one h. We
also compared day-time (nets set between 0800 and 1700 h) and night-time (nets set after 1700 h
or before 0800 h the following day) capture rates of chubs. Species composition and abundance
in drift samples were compared across years. Influence of disturbance events was determined by
examining drift rates associated with storm-induced turbidity or flow events. Species accounts
for rare or endangered native fishes and selected non-native fishes present details that were not
previously described.
Historical changes in fish communities were also assessed using data for the regulated
reach of the Green River upstream of the Yampa River. We compared composition and
reproductive status of each species for time periods corresponding to just prior to Flaming Gorge
Dam closure (historical), just after reservoir filling and commencement of normal operations in
1967, after installation of a temperature control device via penstock modifications in 1978, after
discharge re-regulation in 1992 (1994 to 1996 sampling), and for the 2002 to 2004 period (this
study). Data gathered from historical sources (Bosley 1960, Gaufin et al. 1960, Banks 1964,
Smith 1966, Vanicek et al. 1970, Holden and Crist 1981, Bestgen and Crist 2000) were used to
assess reproductive status in the reach based on presence of young fish or by assumptions about
the probability of reproduction given water temperature regimes in the reach and presence of
adults. Reproductive status of fishes from 1967 to 1978 was inferred from data gathered in 1964
and 1966 by Vanicek et al. (1970) and data collected in 1978 (Holden and Crist 1981) prior to
temperature modifications. Data describing the reproductive status of fishes in 1965 was not
used because flows from Flaming Gorge Dam were low and warm during reservoir-filling and
were not typical of conditions from 1967 to 1978 (Vanicek et al. 1970).
Historical changes in species composition and relative abundance of fishes specific to
Lodore Canyon were assessed by comparing data collected in three periods: 1978 to 1980
(Holden and Crist 1981), 1994 to 1996 (Bestgen and Crist 2000), and 2002 to 2004 (this study).
Holden and Crist (1981) sampled fishes at fixed sites (not continuous as in the latter two periods)
including a 1.9-km-long upper Lodore Canyon site near Wade and Curtis Campground (RK
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