Seasonal and Ontogenetic Movements of Brook Trout within the Lake Superior Tributaries of Pictured Rocks National Lakeshore, Michigan

Using data collected in a long term brook trout monitoring study within the Pictured Rocks National Lakeshore, Michigan, we identified individual brook trout migrating from their natal streams into Lake Superior from 2004-2011 using PIT telemetry.  Since migration into Lake Superior is not found throughout the entire population, individual fish may be acting in response to environmental factors resulting in partial migration.  We tracked movements at the individual level allowing for the determination of characteristics normally lost at the population level.  Such characteristics include both short and long term movements as well as individual growth patterns in response to the adoption of alternate life history tactics.  The objective of this study was to evaluate seasonal and ontogenetic inter- and intra-stream movements among individual brook trout at an individual level.  Throughout this study approximately 1000 individuals (>100mm) were implanted with PIT tags per field season.  Of the individuals tagged, approximately 10-12% were detected moving between Lake Superior and their natal stream.  Movements were evaluated with respect to growth patterns, size at age, and population density.  A significant difference in individual movements was found among the three streams sampled.