Spring Adult and Fall Juvenile Walleye Population Surveys


Cooperating with the 1854 Treaty Authority, the Fond du Lac Resource Management Division and the Minnesota Department of Natural Resources offices, the Superior National Forest’s Fisheries Program assists with the walleye (Sander vitreus) assessments in the 1854 Ceded Territory of Minnesota. The first objective of the walleye assessments is to obtain adult walleye population estimates during the spring spawning period using mark-recapture data and identify critical spawning sites where catches are the highest. The second objective targets the juvenile walleye and young-of-the-year individuals in the fall to evaluate recruitment and year-class strength. By conducting annual monitoring, fishery managers can better predict the future fishery of a lake as young fish grow into older, larger fish and more desirable to anglers.


The spring assessment takes place once the ice cover melts from the lakes and the day length increases. The warming water temperatures trigger the walleye the impulse to spawn, or breed. The walleye are electrofished from a boat at night when they congregate in shallow, rocky areas of lakes to spawn. The fish are temporarily stunned, scooped up with a dipnet and placed in an onboard tank to recover. Once the sampling station is completed, shocking operations cease and the crew begins to collect the sex, the length of the fish, and spines to determine age and growth rates for the fish. The walleyes are then released. The surveys are also important to identify critical walleye spawning habitat in area lakes. As the water temperatures begin to drop below 70 degrees the annual fall electrofishing begins. Small 3 to 6 inch, young of the year (YOY) walleyes are captured in the shallows, measured, and samples of the scales are taken for aging and growth analysis. The fish are then released. Slightly larger, age – l walleyes are sampled at the same time and their catch rates are compared from year to year. This helps determine which index (YOY or age-1) is most useful in predicting how strong of a spawning stock will be available 4-5 years in the future when those fish have reached sexual maturity. The fall assessments are useful in documenting recruitment success or failure. Should the surveys show a continued lack of recruitment, local fisheries managers may choose to reevaluate their lake management plan.


The Superior National Forest’s Fisheries Program along with other program staff assisted the 1854 Treaty Authority and Fond Du Lac Resource Management Division with electroshocking 27 lakes during their spring and fall walleye population surveys. The annual surveys will help in managing and monitoring the walleye populations and to develop long-term databases to relate trends in spawning and recruitment.


Jason Butcher (218) 626-4307




1854 Authority , Fond Du Lac Band of Lake Superior Chippewa , Minnesota Department of Natural Resources


Walleye data collection on Superior Nat. For.
Figure 1: Walleye data collection on Superior National Forest