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

abundant in the 2002 to 2004 period than before (Fig. 31). Relatively larger fish were present in
reaches LD 1 to LD3, and small fish predominated in samples in LD4 and downstream. Large
white suckers were uncommon in Whirlpool Canyon.
Hybrid suckers were present in most reaches of the study area and comprised 3.9% of all
fishes captured in the 1994 to 1996 sampling period and were 7% of all suckers captured by
electrofishing in Lodore Canyon. Hybrids, particularly those involving white sucker as a
putative parent, were most abundant upstream and represented 9.0, 8.8, and 8.6% of all suckers
captured in Lodore reaches 1 through 3, respectively. Numerical abundance of hybrids declined
in LD4 to 4.2% of all catostomids captured.
In 2002 to 2004 sampling, hybrid suckers comprised 4.3% of all fishes captured and were
8.5% of all suckers captured by electrofishing in Lodore Canyon. Hybrid suckers comprised
2.4% of all fishes captured in Whirlpool Canyon samples and were 4.2% of all suckers captured
there by electrofishing in the 2002 to 2004 period. Flannelmouth x white sucker was the most
abundant hybrid captured, followed by flannelmouth x bluehead sucker and bluehead x white
sucker. Hybrids, particularly those involving white sucker as a putative parent, were most
abundant upstream and represented 13.2 and 9.0% of all suckers captured in Lodore Canyon in
LD1 and LD2, respectively. Hybrid sucker abundance declined in lower Lodore reaches LD3
and LD4 to 5.3 and 6.4%, respectively, of all catostomids captured, but overall, relative
abundance of hybrid suckers increased in 2002 to 2004 in all reaches of Lodore Canyon. In each
of the 1994 to 1996 and 2002 to 2004 periods, relative abundance of hybrids declined
downstream consistent with a downstream decline in white sucker abundance.
Channel catfish showed increased distribution and abundance in Lodore Canyon in the
recent sampling period compared to 1994 to 1996 (Fig. 32). In 1994 to 1996, channel catfish
was nearly absent from reaches LD 1 and LD2 and was found in low abundance in LD3 and LD4.
Relative abundance and CPUE data showed that channel catfish was more abundant in upper
Lodore Canyon in 2002 to 2004 and more than doubled their abundance in LD4. Catch rates
increased from 1.3 fish/h in 1994 to 1996 to 6.1 fish/h in the 2002 to 2004 period, a significant
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