Status of Brook Trout in the Windigo Area at Isle Royale National Park

Lake Superior once supported over 120 lake dwelling “coaster” brook trout (Salvelinus fontinalis) populations.  Today, about 10 percent of those populations persist.  Isle Royale National Park, Michigan, is home to three of those populations.  Researchers suggests that the abundance and distribution of stream brook trout is important for the persistence of nearby coaster populations.  To understand the relationship between coasters in Washington Harbor and stream dwelling brook trout in Washington Creek we established stream and lake shore survey stations and installed a PIT tag detection station to track movement of fish in and out of Washington Creek.  We found that the abundance of brook trout is low compared to non-native rainbow trout (Oncorhynchus mykiss) and coho salmon (Oncorhynchus kisutch).  The movement of brook trout in and out of the stream is influenced primarily by season and stream discharge.  Despite watershed and harvest protection aforded by national park status, the influence of non-native salmonines and climate change threaten long-term persistence of brook trout in the Windigo area.