CS17 Invasive Species
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
McGrathCC, University of Colorado, Boulder, USA, claire.mcgrath@colorado.edu
Lewis, W, M, University of Colorado, Boulder, USA, lewis@spot.colorado.edu
 
POPULATION DYNAMICS AND TROPHIC INTERACTIONS OF NATIVE GREENBACK CUTTHROAT TROUT AND NON-NATIVE BROOK TROUT IN MONTANE STREAMS IN COLORADO
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Non-native brook trout displace native greenback cutthroat trout in high-elevation streams in Colorado. However, the ecological mechanisms by which this displacement occurs are unknown. We use field studies to describe the population dynamics and feeding ecology of the two species, in order to investigate potential mechanisms by which brook trout may displace greenback cutthroat trout, and to describe the trophic roles of the native and non-native trouts. Population data show that invasion by brook trout decreases recruitment and/or survival of young-of-year greenback cutthroat trout. Similarly, body condition, stomach content, and stable isotope analyses suggest that interspecific competition for food among adult trout is not the major mechanism for displacement of greenback cutthroat trout. Continuing research is focusing on competition for food among young-of-year trout and predation upon greenback fry as possible mechanisms for displacement of greenback cutthroat trout by brook trout.