Migration, Size, and Age Structure of Brook Trout (Salvelinus fontinalis) from Two Lake Superior Tributaries

Brook trout (Salvelinus fontinalis) from Lake Superior and its tributaries exhibit a variety of life histories and different growth characteristics; however, life history-specific effects on population dynamics are not well understood. The goal of this study was to characterize the movement patterns of brook trout in two streams with access to Lake Superior and compare age and growth metrics between fish that moved into Lake Superior (coasters) and resident brook trout that remained within the streams (residents). There were no significant differences in length, condition factor, or relative weight between coasters and residents from a given stream. Less than 5% of PIT tagged fish were detected emigrating from the study streams, although there was a peak in migration during the fall. The length distribution of fish differed among years for both streams. The data demonstrate that migratory brook trout are likely present, though rare, in the study streams and multiple life histories are present in sympatry. The lack of differences in growth metrics among the different life history groups has implications for the management and restoration of migratory brook trout populations and demonstrates that identification of migratory brook trout within Lake Superior tributaries may not be straightforward.