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smallmouth bass and native fish populations. For example, density of smallmouth bass ranged from 100 to 143 fish per mile at little Yampa Canyon and from 247 to 393 fish per mile at lily Park. Small mouth bass larger than 250 mm comprised 11 % of the bass at lily Park and 43% of the bass at little Yampa Canyon. lily Park also had little angling pressure, fewer recaptures of tagged fish, lower abundance of other centrarchids, and higher abundance of native species. Smallmouth bass were extremely rare at both sites 23 years ago when native fishes were a dominant part of the fish community. Bioenergetics modeling supports that invasive small mouth bass at their current levels are highly capable of consuming large quantities of native fishes and therefore present the greatest predatory threat to native fishes in the Yampa River (Johnson et al. 2008). Smallmouth bass numbers increased from near zero to 51 % of the fish community from 1984 to 2007 at little Yampa Canyon and from zero to 25% of the fish community at lily Park during the same period. Smallmouth bass are now the dominant predator in the middle Yampa River and their rise in abundance was concurrent with the decline of native fish in the Yampa River. Concurrently, catch rates of all other fishes declined 77% at little Yampa Canyon and 54% at lily Park from 1984 to 2007. In 2007, native fish comprised no more than 8% of the fish community at little Yampa Canyon and 56% of the fish community at lily Park. Although our removal efforts were associated with a decline in abundance of smallmouth bass in our study area, those removals were not sufficient to effect a native fish response (Bestgen et al 2007). Higher removal rates, both within the study area and at other study areas may be needed to adequately reduce the predatory threat of smallmouth bass in the Yampa River and to restore the native fish community. 25