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DISTRIBUTION AND EXTENT OF NON-NATIVE FISH IN WESTERN STREAMS AND RIVERS
Citation:
Whittier, T R. DISTRIBUTION AND EXTENT OF NON-NATIVE FISH IN WESTERN STREAMS AND RIVERS. Presented at American Fisheries Society meeting, Baltimore, MD, August 19-23, 2002.
Description:
Introduced species can produce a variety of impacts on native assemblages and ecosystems. Reliable knowledge about the extent of non-native species should be a useful tool for effective management of fisheries and aquatic ecosystems. It is well known that many non-native fish species have been introduced into the rivers and streams of the western USA, but currently there are no statistically-based estimates of the occurrence density (as a proportion of stream length) of non-natives, nor the strength of non-native invasions in the region (as the proportion stream length with multiple non-natives). I present results from the first year of the Environmental Monitoring and Assessment Program (EMAP) Western Pilot Study (a statistically-designed survey), to further document the distributions and extent of non-native fish species in 12 western states. Forty non-native fish species were collected at nearly half of the 204 sampled sites. As many as six non-native species were collected at some river sites. Common carp, brook trout and brown trout were the most commonly collected non-native species. Carp were only common in the plains ecoregions and uncommon elsewhere, and the two trout were found throughout the mountains regions of the west.