A comprehensive fish survey is an important part of maintaining healthy fisheries in any lake. In the spring of 2023, Clean Lakes Alliance Watershed Engagement Manager Caitlin McAleavey joined a Wisconsin Department of Natural Resources (DNR) fisheries crew on Lake Kegonsa to learn more about what goes into assessing our lakes’ fish populations. The following is her account of the trip.
Fish survey team
On a sunny spring day, DNR Fisheries Biologist Dan Oele and fish technicians Mitch Trow and Josh Jonet set out on Lake Kegonsa’s latest fish survey. The boat was packed with measuring tools, scales, a large holding tank for fish, electronic tablets, collection envelopes, lifejackets, and waterproof gloves.
Five-year rotation
All five of the Greater Madison lakes are on a five-year rotation for official surveys, meaning each year one of our Yahara lakes gets a comprehensive study. Fish assessments are typically conducted in the spring, preferably soon after ice-off. These thorough examinations determine population trends, ecosystem health, potential regulation adjustments, and how our fish are faring against threats such as invasive species or impaired water quality.
Fyke nets assist DNR
Survey preparation begins with DNR staff setting out long fyke nets in shallow areas of the lake a day or two before sampling that act as holding pens for captured fish. Fyke nets are particularly useful in the spring as they draw in walleye, northern pike, and muskellunge coming closer to shore in search of suitable spawning grounds. DNR staff then visit each net set out the previous day to count, measure, weigh, and sex (if possible) each fish before it is released. DNR staff measured walleye, largemouth and smallmouth bass, bluegill, perch, northern pike, crappies, and more during the morning outing. These springtime surveys are followed up with electrofishing studies in the fall to assess spawning success and other lifecycle dynamics.
When asked about trends he’s seen in the lakes over the last decade and beyond, Oele stated, “We’re very fortunate to have fisheries that have been stable and continue producing high-quality fish for anglers.”
Fish stocking
Stocking plays a key role in maintaining these healthy populations due to prominent angler pressure on our local lakes. Oele shared that not only does the survey identify stocking needs for each lake, but also evaluates stocking success due to genetic testing done in partnership with University of Wisconsin-Stevens Point. Nonintrusive fin clips collected from certain species can determine whether that specimen or its parents were released from a hatchery or were naturally produced. This information aids DNR and other fishery managers in deciphering what makes stocking successful in some lakes and not others. Genetic testing and tracking are done for walleye and muskellunge within our lakes because of their desirability among anglers, high trophic status, and often inability of muskellunge to naturally reproduce in our heavily fished waters.
Assessments on each lake can take a few weeks to complete, especially in unpredictable spring weather. Then comes the hard work of putting it all together to formulate the reports that can be found online about a year after sampling occurs. To learn more about Yahara lakes fish assessments, visit dnr.wisconsin.gov/topic/Fishing/reports.
Thank you to DNR staff for allowing Clean Lakes Alliance to participate in the 2023 Lake Kegonsa fish survey, and to Robert Bertera for his aerial photography.
