DNRE Fisheries Surveys Help Biologists Understand the Resource

Have you ever wondered what the Michigan Department of Natural Resources and Environment (DNRE) Fisheries Division was doing when you saw one of its boats lifting nets from an inland lake?

Or what its wader-clad sampling crew was doing in the river as you drove past on a nearby bridge?

Or how, with more than 10,000 inland lakes and 36,000-plus miles of rivers and streams statewide, the Fisheries Division can fulfill its mission to protect and enhance fish environments, habitat, populations, and other forms of aquatic life, and to promote optimum use of these resources for benefit of the people of Michigan?

It's not surprising that fulfilling the DNRE's mission is a challenging task given the sheer number and different types of lakes and streams in the state. Michigan's inland lakes range from small, shallow ponds that support panfish to large, deep lakes that support diverse fish communities including yellow perch, walleye, and lake trout. The state's wide variety of streams includes small, cold, headwater creeks that support brook trout, large rivers with diverse communities of warm-water fishes, and everything in between. These natural resources provide a number of different benefits to people, from incredible recreational opportunities such as fishing to a source for water and energy.

However, the long-term quality of these natural resources and the benefits that they provide is threatened by an ever-growing list of disturbances including pollution, landscape development, invasive species, over-fishing, and climate change. The effective management needed to protect inland lakes and streams from such threats -- and to conserve them for future generations -- depends upon information assessing their current condition and how they are changing over time. Collecting that information is where the boat lifting nets or sampling crew in the river comes into play: There's a good chance you saw data being collected for Fisheries Division's Status and Trends Program (STP).

As part of a broader resource inventory plan, Fisheries Division began the STP nearly 10 years ago to collect the data needed by fisheries biologists, policy-makers, and the public to address inland fisheries management needs. The STP surveys fish communities and habitats in lakes and streams that are representative of the broad range of waters found in Michigan. Each survey is carried out using same the methods to guarantee that data collected from different water bodies can be compared statewide. About 40% of Fisheries Division's total survey effort is directed towards STP sampling. The remaining 60% is dedicated to management evaluations, such as determining how well stocked fish survive in a lake or if a habitat improvement project increased the number of fish in a stream.

The STP has three specific goals. The first goal of the STP is to collect the information needed to maintain an inventory of inland habitat and fish community characteristics across the state. Fulfilling this goal leads to some of Fisheries Division's most visible activities (such as netting fish or collecting habitat information) during the open-water months. The second and third goals of the STP happen behind the scenes. Fisheries biologists work extensively with the statewide data set to develop "reference points" for local, regional, and statewide management needs and to assess the status of, and detect changes to, aquatic communities across Michigan.

"Reference points allow fisheries managers to put the results of one survey into the context of other surveys completed across the state," said Todd Wills, DNRE fisheries biologist responsible for analysis of stream data collected through the STP. "By collecting information using the same methods, a manager can determine whether the abundance of any fish species in a given water body, from forage fish such as shiners to important game fish such as smallmouth bass, are at, above, or below the expected value determined from similar water bodies in Michigan. The same can be said of other measurements such as physical habitat, water chemistry, and temperature."

Added fisheries biologist and STP inland lake specialist Kevin Wehrly: "This allows Fisheries Division to efficiently and effectively manage fisheries across the state. Fish and habitat data collected during a survey in the western Upper Peninsula assist in the interpretation of results from surveys in the southeast Lower Peninsula by creating a realistic benchmark for making statewide comparisons.

"By using the suite of detailed information available for Michigan's lakes and streams, a manager can determine not only how well one fishery compares to another, but also reasons why abundance is lower or higher than expected," Wehrly continued. "The availability of statewide reference points for all game and non-game fish species, as well as habitat conditions, paint a much more complete picture of the resource than what we've had in the past. This puts fisheries officials and our partner organizations in a better position to take management action if necessary."

Besides documenting the current status of inland lake and stream fisheries to meet today's management needs, the STP also establishes baseline conditions against which future monitoring results can be compared. Comparisons such as these will enable fisheries managers to determine trends, or how inland fishery resources change through time in response to natural and human-induced disturbances. This proactive, long-term monitoring approach will help maker sure that Michigan's lakes and streams continue to be wisely managed well into the future.