The Minnesota Department of Natural Resources (DNR) is releasing marked walleye fry this spring in Lake Kabetogama at Voyageurs National Park to better understand the species’ natural reproduction and recruitment cycles. The work may help researchers understand why young walleye survival rate has declined on the lake recently, after remaining steady for almost two decades.

This will be the first year of a three-year study; similar studies will be undertaken on several other Minnesota lakes.

A pre-determined number of walleye fry from Pike River Hatchery on Lake Vermilion will be marked with oxytetracyclene (OTC) prior to release. The OTC will leave a mark on bony structures within the fish. That’s how they will be differentiated from walleye produced naturally when the DNR collects the fish through sampling.

Sampling will be done throughout the summer to collect young-of-year walleye, which will be examined for marks. The ratio of marked and unmarked fish in the sample will provide a population estimate, which biologists will use to estimate wild fry production.

The DNR has an extensive sampling program on Lake Kabetogama that includes annual fall gill netting, spring and fall electrofishing, shoreline seining, and trawling. The information gained from this study, when combined with other sampling results, will provide additional insight on walleye production and survival on the lake.

Lake Kabetogama has long been one of Minnesota’s premier walleye lakes, a fishery that has been sustained through natural reproduction. However, a documented increase in juvenile walleye mortality in recent years has biologists concerned about walleye production in Kabetogama. Many different factors in the lake could be affecting walleye natural reproduction and recruitment.

Conducting this research at the earliest life stages will help biologists better understand the relationship between spawning stock and wild fry production on Lake Kabetogama. It will provide baseline information for future studies and help guide future management decisions.

The long-term goal of the DNR and Voyageurs National Park is to manage Lake Kabetogama for a healthy, native fish community sustained by natural reproduction.