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

In both periods, the three most abundant native fish species captured by electrofishing
were flannelmouth sucker, bluehead sucker, and mountain whitefish. All other native taxa were
relatively rare in electrofishing samples. In 2005-2006, roundtail chub declined notably in
electrofishing samples as did bonytail, and no humpback chub were collected by electrofishing.
The percent of native fishes increased during 2005-2006 due mostly to increased abundance of
flannelmouth sucker and mountain whitefish.
Seining yielded eight native and 17non-native species, and four hybrids in 2002-2004
(Table 7). Red shiner, sand shiner, fathead minnow, and redside shiner, in descending order of
abundance, were the most abundant non-native taxa collected in 2002-2004. Red shiner, sand
shiner, white sucker, redside shiner, and fathead minnow were the most abundant non-native
taxa collected in 2005-2006. Although relatively uncommon, smallmouth bass increased in
abundance in seine samples from 0.2% in 2002-2004 to 2.0% 2005-2006, an order of magnitude
change in relative abundance. Flannelmouth sucker, bluehead sucker, mountain whitefish, and
speckled dace, in descending order of abundance, were the most common native fishes collected
in the Green River in 2002-2004. In 2005-2006, bluehead sucker, flannelmouth sucker, speckled
dace, roundtail chub, and mottled sculpin, in descending order of abundance, were the most
common native fishes.
Non-native fishes were 92.4% of all fishes captured in seine samples in 2002-2004, but
declined to 76.5% in 2005-2006, due mostly to increased abundance of native bluehead and
flannelmouth sucker and roundtail chub. High non-native fish abundance in each period in seine
samples reflected the dominance of small-bodied red shiner, sand shiner, and fathead minnow in
the low-velocity habitats where most samples were collected. Those taxa dominated the fish
community in low-velocity habitats in other areas of the Colorado River Basin (Haines and Tyus
1990; Propst and Gido 2004) such as in backwaters of the middle and lower Green River, where
Haines and Tyus (1990) found that those species comprised about 90% or more of the fish
community. However, higher native fish abundance in seine samples collected in low-velocity
nearshore areas was documented in portions of the Yampa River in Little Yampa Canyon as
recently as 1999., when native fishes including roundtail chub, speckled dace, and flannelmouth
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