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<br />1 .0 INTRODUCTION
<br />
<br />The flannelmouth sucker [Catostomus latipinnis (Baird and Girard)],
<br />is a member of the distinctive fish community endemic to the Colorado
<br />River Basin (Minckley et a/. 1986). Its distribution is restricted to larger
<br />streams and rivers of the middle and upper Colorado River drainage in
<br />Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming (Woodling
<br />1985). It has been reported from the Colorado mainstem, and most of the
<br />larger tributaries including the Green, Vampa, Gunnison, Uncompahgre,
<br />Dolores, San Juan, Little Colorado and Gila Rivers.
<br />
<br />Like other members of the unique Colorado Basin assemblege, such
<br />as the Colorado Squawfish [Ptychocheilus lucius (Girard)], Razorback
<br />sucker [Xyrauchen texanus (Abbott)], bluehead sucker [Catostomus
<br />discobolus (Cope)], Humpback Chub [Gila cypha (Miller)], and Bonytail [Gila
<br />elegans (Baird and Girard)], the flannelmouth has experienced recent
<br />declines owing to construction of irrigation impoundments and
<br />introduction of exotics that prey or compete with native species. The
<br />species has disappeared from several locations since 1960. Minckley
<br />(1973) reported that the species does not appear able to maintain viable
<br />populations in impoundments. Woodling (1985) indicated that introduced
<br />white suckers [Catostomus commersoni (Lacepede)] and long nose suckers
<br />[Catostomus catostomus (Forster)], have replaced native flannelmouth and
<br />bluehead suckers in the Gunnison River, above Blue Mesa Reservoir.
<br />
<br />Nevertheless, flannelmouth are relatively abundant compared to
<br />other species. For example, Karp and Tyus (1990) reported that the
<br />flannel mouth sucker was the most abundant species captured by
<br />electrofishing and angling in the Green and Vampa Rivers in Dinosaur
<br />National Monument from 1987 to 1989, comprising 2,159 of 7,885 fish
<br />captured. During this study, 1,812 bluehead suckers, 1,238 roundtail chub,
<br />109 humpback chub, 27 colorado squawfish, 4 razorback suckers, and 2
<br />mountain whitefish were captured. Non-native fish captured included
<br />1,100 carp, 1,091 channel catfish, 227 trout, 31 black bullhead, 15
<br />northem pike, 13 white sucker, 6 small mouth bass and 1 green sunfish.
<br />This and similar studies indicate that the flannel mouth is still more
<br />widely distributed and have larger populations than many other native
<br />species in the basin, such as the razorback sucker, Colorado squawfish,
<br />humpback chub and bonytail, which are protected by the states and either
<br />already listed or are candidates for Federal listing under the Endangered
<br />Species Act [Johnson 1987, Williams et a/. 1989]. In contrast,
<br />flannelmouths are not protected by any state, but they have been
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