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

similar turbidity event occurred, and only 5 fish were captured (three flannelmouth sucker, one
white sucker, and one smallmouth bass). A similar situation occurred in 1994: most fish
captured that year (N = 223, 72.6%) were taken on 7 July when water turbidity increased
dramatically from thunderstorm runoff.
Large captures of fish, including smallmouth bass, in drift net samples in the Green River
upstream of the Yampa River in 2003 and 2004 associated with turbidity events suggested
susceptibility to displacement. The literature also suggested negative effects of flow increases
on early life stages of smallmouth bass (Lukas and Orth 1995, Peterson and Kwak 1999,
references therein); Winemiller and Taylor (1982) documented negative effects of turbidity and
high flows on disruption of smallmouth bass spawning, nest destruction, and displacement of
young. Increased flows levels via dam releases or turbidity events may be potential controlling
mechanisms for early life stages of smallmouth bass in this portion of the river.
Species accounts
Colorado pikeminnow.-Large juvenile or adult (399 mm TL or larger) Colorado
pikeminnow were captured throughout the study area in all years in the period 2002 to 2004 and
in all reaches except Browns Park. A total of 41 Colorado pikeminnow captures were made; an
additional 10 fish were observed but not netted. One individual was recaptured twice during this
study and three individuals were recaptured once each. Thus, we captured a total of 37
individuals. We captured one Colorado pikeminnow by angling, 35 by electrofishing, one with a
seine, and four in trammel nets. Colorado pikeminnow averaged 573 mm TL (399 - 765 mm TL;
Fig. 15). Thirteen captures were made in 2002, 19 in 2003, and 9 in 2004. Nineteen of the
Colorado pikeminnow were found in the Green River upstream of the Yampa River and 22 were
found downstream. Mean length (589 mm TL) and weight (1,774 g) of Colorado pikeminnow in
the Green River captured upstream of the Yampa River were greater than mean length (553 mm
TL) and weight (1,463 g) for Colorado pikeminnow downstream of the Yampa River; t-tests
demonstrated marginally significant differences in length (p = 0.13) and weight (p = 0.07).
Captures and observations were made throughout Lodore and Whirlpool canyons; four captures
were from reach LD1, three from LD2, four from LD3, eight from LD4, six and 14 were from
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