Evaluating the Status and Trends of Smallmouth Bass Populations in Michigan Streams and Rivers

The science-based management of Michigan’s 58,000 km of stream resources is a daunting but important task.  In 2002 the Michigan Department of Natural Resources implemented a status and trends survey program consisting of fixed index sites and a stratified random sampling approach to better understand the spatial and temporal characteristics of Smallmouth Bass populations.  Using data collected from 206 stream surveys conducted between 2002 and 2014, we characterized the statewide patterns in Smallmouth Bass abundance, developed fish-habitat models to explain patterns, and evaluated whether fish-habitat relationships changed over time.  Our results indicate that Smallmouth Bass density is highest in Michigan’s large and very large, warm streams, and lowest in small and medium-sized streams.  There was no difference among characteristics predictive of Smallmouth Bass density across the first and second six-year sampling periods.  Our analysis of current status provides a benchmark for evaluating future change in Smallmouth Bass populations. In addition, our fish-habitat models can inform local management by identifying limiting habitat factors and generating stream-specific expectations for Smallmouth bass abundance.