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<br /> <br />sampling detected the presence of introduced green sunfish and one additional hybrid <br />combination, taxa not collected in the 1978-1980 period. <br />Overall, numerical abundance of native species declined from 92 % to 65 % of the fish <br />community between the two sampling periods. Only a single native taxon, mountain whitefish, <br />increased in relative abundance, while speckled dace abundance declined sharply and mountain <br />sucker disappeared. The five remaining native taxa were similar in abundance between the two <br />periods. Seven introduced taxa increased in abundance, three taxa, including two Coldwater <br />salmonids, declined in abundance, and four were unchanged. Largest increases were by cool- <br />water tolerant fishes such as brown trout Salmo trutta, redside shiner Richardsonius balteatus, <br />and white sucker. Abundance of hybrid suckers also increased. <br />At the lower Lodore Canyon site at Alcove Brook, collections in 1978-1980 revealed the <br />presence of eight native fishes, 13 introduced ones, and one hybrid sucker combination. <br />Sampling in 1994-1996 detected seven native fishes, 13 introduced ones, and five hybrid sucker <br />combinations. Six native taxa, speckled dace, Colorado pikeminnow, roundtail chub, <br />flannehnouth and bluehead suckers, and mottled sculpin were common to the two periods, as was <br />hybrid flannelmouth X razorback sucker. Razorback and mountain suckers were detected at this <br />site in early collections, but not later, and mountain whitefish and flannelmouth X bluehead <br />sucker hybrids were detected in later collections but not earlier ones. Seven introduced taxa and <br />hybrid flannehnouth X razorback sucker were common to each period. Early collections <br />documented the presence of creek chub, Utah chub, and black bullhead Amieurus melas, which <br />were not collected in the later period. Collections made in 1994-1996 detected the presence of <br />introduced northern pike, green sunfish, and smallmouth bass which may have recently colonized <br />from the Yampa River, and four additional catostomid hybrid combinations. <br />Overall, abundance of native species in lower Lodore Canyon declined from 32 % to 21 <br />of the fish community between the two sampling periods. Two native taxa, mountain <br />whitefish and Colorado pikeminnow, increased in abundance, while speckled dace, roundtail <br />chub, razorback sucker, mountain sucker, and mottled sculpin declined in abundance. Only two <br />16 <br />