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

successful reproduction. Anderson (2005) also found increased abundance of young smallmouth
bass in the Yampa River in 2001, 2003, and 2004 when summer water temperatures were elevated
(no sampling conducted in 2002).
The literature supports the idea that cooler, higher flows and flow fluctuations may limit
growth and reproductive success by smallmouth bass (Lucas and Orth 1995, Peterson and Kwak
1999). Effects of flow and temperature regimes on smallmouth bass in Lodore Canyon and
downstream will require additional monitoring in years when higher flows and cooler water
temperatures prevail. High flows and turbidity events are known to displace young smallmouth
bass from nests (Winemiller and Taylor 1982, Lukas and Orth 1995, Peterson and Kwak 1999).
Use of flow manipulations from Flaming Gorge Dam to disadvantage smallmouth bass will
require additional information so that effects can be optimized if implemented. Minimal
information needs are onset and duration of the spawning season of smallmouth bass in relation to
water temperature and other important environmental variables, and flow levels needed to cause
the desired negative effect. Flow management activities to disadvantage selected species need to
consider potential effects on other fishes in the system.
Slightly increased abundance of brown trout between the study periods 1994 to 1996 and
2002 to 2004 was not expected because of warm summer temperatures in the latter period.
Apparently longer periods of warm water or higher temperatures are required to impact brown
trout populations in Lodore canyon.
Composition and reproductive status of the fish community of the Green River upstream of
the Yampa River, 1962-2004.-Limited sampling during pre-impoundment investigations in the
present-day reservoir basin area documented that eleven native and six introduced fishes, and one
catostomid hybrid inhabited that reach prior to 1960 (Table 10). All native fishes, including
endangered Colorado pikeminnow, bonytail, humpback chub, and razorback sucker inhabited the
reach and likely reproduced there.
During reservoir filling from 1963 to 1967, sampling yielded seven native and eight
introduced taxa in the study area. The limited reproduction noted (Vanicek and Kramer 1969,
Vanicek et al. 1970) for only a few species occurred in 1965 when reservoir discharge was
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