Integrating Modeling and GIS to Examine Habitat Use Relationships in Wild and Stocked Brook Trout

Brook trout (Salvelinus fontinalis) are stocked regularly as an important ecological and recreational species in streams of the Upper Midwest, yet their use of habitat in comparison with wild brook trout is poorly understood.  Studies targeting niche selection are significant as concerns for viability increase and the role of stocking in rehabilitation programs is evaluated. Seasonal habitat use by wild and stocked (Tobin Harbor strain) brook trout was assessed in two Lake Superior tributaries within Pictured Rocks National Lakeshore, MI.  A 2.7 km reach of Mosquito River and 2.1 km reach of Sevenmile Creek, divided into 150 m reaches, were surveyed by electrofishing in dual spring, summer, and fall seasons for brook trout and exotic Pacific salmonids (Oncorhynchus spp.).  Habitat variables of depth, flow, discharge, temperature, pH, cover, substrate, and woody debris associated with each reach and electrofishing event were quantified.  Reaches were mapped by Trimble Receiver and GPS Pathfinder.  Seasonal catch per unit effort (abundance of fish/m²) and habitat layers were created and evaluated by reach in ArcGIS 10, indicating stocked brook trout were dominant over wild in several reaches, perhaps driven by cover and stream depth.  Linear regression modeling will further determine habitat and distribution relationships.