Effects of Varying Local Winter Stream Patterns on the Condition of Coldwater Fishes

Changing environmental conditions such as climate change may affect streams differentially within a small area based on varying geomorphological characteristics.  These effects may be exacerbated in periods when fishes are seasonally stressed such as winter in the north. “Winter” is comprised of a diverse combination of factors that form a functional winter duration and pattern for the stream; this winter characterization may be dramatically different than another nearby stream that may otherwise appear similar and may also be managed similarly. Our project examines the relationships between functional winter length/pattern and the condition of the fish community present within each study reach. Functional winter length and pattern within each of 13 small coldwater streams in Michigan’s central Upper Peninsula was assessed using temperature, ice cover, velocity, ice breakup intervals, and other in-stream conditions.  These systems are dominated by salmonid fishes, but also include a variety of other stream fishes including Cottus spp. Fish condition and relative weight of species present was assessed using fall and spring electrofishing.  Our data suggest that changes in condition of fish present within study reaches is related to the functional winter length and that local winter conditions may be relevant to successful management in northern systems.