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

566 m3/s, but sometimes declined to < 2 m3/s in late summer (U. S. Geological Survey et seq.;
Maybell Gauge, 09251000).
METHODS
Collections of small-bodied (< 150 mm TL, most were 25 to 75-mm TL) and large-
bodied (150- mm TL or greater) fishes were made from 2002 to 2004 to describe current
distribution and abundance patterns of fishes in the Green River from Swinging Bridge in
Browns Park to the downstream end of Island-Rainbow Park. Water temperature and discharge
data were used to understand the relationship of physical factors to longitudinal distribution and
abundance patterns of fishes in the regulated portion of the Green River. Discharge and
temperature regimes associated with specific dam operations were compared to changes in fish
distribution and abundance patterns.
Collection of small-bodied fish.-Low-velocity channel margins in Browns Park, Lodore
and Whirlpool canyons, and Island-Rainbow Park were sampled with seines (1.3 and 4.6 in
length, 1.6 and 4.7-mm mesh). Seine sampling was conducted in spring, summer, and autumn in
each year from 2002 to 2004. Habitat types sampled were mostly backwaters, but channel
margin eddies, low velocity runs and pools, and a few riffles were also sampled. More effort
was expended in larger habitat areas and less in smaller ones so that the proportion of the habitat
sampled was approximately equal across different-sized areas. Riffles were occasionally "kick-
seined", whereby substrate was vigorously disturbed and dislodged fish were captured in a
stationary downstream seine. Some vouchers were preserved in 10% formalin and identified at
the Larval Fish Laboratory, Colorado State University. We scrutinized all young chubs captured
and preserved in 2002 to 2004 by counting dorsal and anal fin rays, and characterizing shape
characteristics of the snout and mouth (mouth terminal in roundtail chub Gila robusta, slightly
subterminal in humpback chub), body depth, fin lengths, and the line of the angle of the anal fin
base relative to the upper lobe of the caudal fin, which assisted with identifications (Muth 1990,
Douglas et al. 1989).
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