9556

• UCREFRP Catalog Number: 9556
• Author: Bestgen, K. R., K. A. Zelasko and C. T. Wilcox.
• Title: Non-native fish removal in the Green River, Lodore and Whirlpool canyons, 2002-2006, and fish community response to altered flow and temperature regimes, and non-native fish expansion.
• USFW Year: 2007.
• USFW - Doc Type: 115,
• Copyright Material: NO

were captured by all sampling gears. Native fish abundance increased to 26.4% and non-native
fishes were 72.8%; the remaining 0.8% were hybrids.
All told, 238,316 non-native fishes were captured during this study (2002-2006), and
most of those were removed. We removed 1,176 potentially problematic large-bodied fishes
captured by electrofishing in 2005 (another 411 brown trout or other salmonids were released),
and another 1,124 in 2006 (another 410 brown trout or other salmonids were released). Totals
for both years included 299 smallmouth bass, 24 northern pike, and 894 channel catfish.
Relative abundance ofnon-native fishes in Browns Park and Lodore Canyon in 2002 to
2004 increased since 1994 to 1996 sampling, but declined in 2005-2006. Increases in 2002-2004
were throughout the study area and were particularly evident for small-bodied cyprinids, channel
catfish, and smallmouth bass in the upper portions of Lodore Canyon. Declines in 2005-2006
were mostly for small-bodied species such as red shiner and fathead minnow. smallmouth bass
abundance increased in the 2005 to 2006 period, mostly because of increased abundance of
small-bodied (< 100 mm total length [TL]) individuals. Northern pike abundance remained
similar between the two periods, although northern pike recently expanded upstream where
reproduction was detected in Browns Park. White sucker and channel catfish abundance also
increased. smallmouth bass reproduction, which was not observed in Lodore Canyon prior to
this study, increased through the 2002 to 2004 period, and expanded to Browns Park in 2006.
Salmonid abundance temporarily declined in 2002, but increased in 2003 to 2006, and were
similar in abundance to that observed in 1994 to 1996. Abundance of predaceous fishes in the
Green River study area has increased.
Trammel net sampling in Whirlpool Canyon detected a small population of humpback
chub. The relatively large population of roundtail chub present in 2003 may be declining based
on sampling conducted in 2006. Hatchery-stocked bonytail were also captured.
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