How do changes in the shoreline habitat affect fish populations? How does recreational fishing affect inland fish populations? How does stocking influence angler success? Finding answers to questions like these is a big part of why the Michigan Department of Natural Resources does fisheries surveys – in fact, the DNR conducted 220 inland fisheries surveys last year alone.
In 2020, staff from eight DNR fisheries management units completed 125 surveys of inland lakes and 95 stream surveys, even in the face of the COVID pandemic. Anyone fishing those waters might have seen crews collecting key data on one of Michigan’s world-class fisheries. So, just what do crews look for?
According to Jim Dexter, DNR Fisheries Division chief, surveys fall into three categories:
Evaluating management actions.
Understanding status and trends.
Finding answers to new questions or concerns.
“Our management units stepped up this year and were able to safely conduct inland fisheries surveys to evaluate if management actions, like fish stocking or habitat improvement projects, had the desired effect,” Dexter said. “Surveys help us understand whether or not our management actions resulted in better recreational fishing in certain areas or improved a lake’s overall health.”
Other annual surveys help managers track the status and trends of fish communities and important aquatic habitat on different lakes, providing a picture of these lakes geographically and over time.
Dexter said streams throughout the state are handled a little differently, through two types of status and trends surveys: fixed sites and random sites.
“At fixed sites, we annually estimate fish population abundance – usually trout in coldwater streams and smallmouth bass in warmer waters – on a three-year rotation, while random site surveys are intended to give a species snapshot and show relative abundance,” he said. “We collect in-stream habitat data at all our status and trends sites.”
Fisheries managers use that third category, discretionary surveys, to answer questions or address current concerns, perhaps something raised by a local biologist, an angling group or a lake association. Such surveys might be conducted to assess habitat suitability for a threatened or endangered fish species.
No matter the type of survey, DNR fisheries managers use the resulting information to strategize their actions, detect early indicators of invasive species, recognize developing threats to fish and habitat health, and much more. If you’d like to learn about the DNR’s lake and stream surveys, especially in your part of the state, contact the fisheries management unit in your area.
Throughout April and early May, the DNR also will offer virtual “Conversations & Coffee” meetings around the state, providing an informal opportunity to connect with local fisheries biologists and managers about the work they do.