Fluvial and adfluvial brook trout (Salvelinus fontinalis ) movement patterns within Sevenmile Creek and Mosquito River, Pictured Rocks National Lakeshore, Michigan

Pictured Rocks National Lakeshore (PIRO) is home to several partially migrating populations of brook trout (Salvelinus fontinalis). The presence of fluvial and adfluvial movement patterns led to a large scale study of their movement behavior and morphological characteristics. The study involved measuring and implanting brook trout with passive integrated transponder (PIT) tags beginning in 2004 within Sevenmile Creek and Mosquito River. The project used radio frequency identification (RFID) antennas at the mouth of each river to detect PIT tagged brook trout moving in and out of the streams. Electroshocking within the rivers was used to track within stream movements of brook trout. A subset of fluvial individuals in both systems was found to move the entire sampled length of each stream. A combined 53% of all fluvial brook trout were found more than 150 m from their original capture location (OCL). Brook trout density was significantly correlated to fluvial movement within Mosquito River, suggesting that density could be a stimulus for fluvial movements. Also within Sevenmile Creek 62%, of individuals were correctly assigned as fluvial or adfluvial using their OCL. Overall the lack of distinguishing characteristics between fluvial and adfluvial brook trout suggests that these life history tactics are varying degrees on a movement continuum within brook trout populations.