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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Fish Ecology
DIFFERENT LIFE HISTORY OF BROOK TROUT POPULATIONS INVADING MID-ELEVATION AND HIGH-ELEVATION CUTTHROAT TROUT STREAMS IN COLORADO.
B.M. Kennedy, D.P. Peterson, and K.D. Fausch. Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, Colorado, 80523
Brook trout, native to eastern North America, have invaded many montane coldwater systems of western North America. These invasions are implicated in the decline of native cutthroat trout, but there is little information on the mechanisms involved. We tested whether brook trout populations invading streams at two different elevations varied in life history characteristics that influence population dynamics and potential invasion success. In the mid–elevation stream (2683 m), water temperatures were warmer and brook trout apparently grew faster (i.e., had longer lengths-at-age), became sexually mature earlier, and had shorter life spans compared to those in the high–elevation stream (3195 m). This suggests that flexibility in brook trout life history allows brook trout to maximize their chance of establishment and invasion success among elevations. We propose that in mid–elevation streams, fast growth and early maturity maximizes fitness and can lead to rapid establishment and high population growth rates. In high–elevation streams, slow growth, later maturity, and a long life span may allow brook trout to successfully establish populations in marginal habitats where recruitment is often poor. Landscape–scale models predicting brook trout invasion rates, distribution, and population growth rates should incorporate data from multiple elevations to account for differences in life history.
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