The Mille Lacs Fishery Advisory Committee (MLFAC) heard a presentation by the Mille Lacs Band DNR and the Great Lakes Indian Fish and Wildlife Commission (GLIFWC) on Monday, August 27, at Appeldoorn’s Sunset Bay Resort.
Carl Klimah, fish biologist for Mille Lacs Band DNR, and Dr. Aaron Schultz, Climate Change Biologist for GLIFWC, present- ed an overview of the Band’s ogaa tagging and tracking study to the 13 committee members and 25 members of the public in attendance.
The study, Carl explained, is to test their theory that rising water temperatures in the lake cause walleye to concentrate into smaller pockets of cooler water, leading to greater predation of juvenile walleye by adults — a theory Carl calls “the squeeze.”
“Every fish species has an ideal temperature at which their health, and their growth, is optimized,” Carl explained. “Wall- eye really like cold water. By tagging and tracking these fish, we’ll be able to analyze their movement in relation to water temperature and depth to test our theory.”
So far Carl and Aaron, along with numerous volunteers from the Band and GLIFWC, have tagged and released 20 adult walleyes for the study.
They plan to tag an additional 50 adults and 35 juveniles this fall. Next spring, they will tag an additional 35 juveniles.
Carl said the reason for tagging half of the juveniles this fall and half in the spring is due to the shorter battery life of the juvenile walleye tags. “We need to make sure we get a complete year of data, and juvenile tags only last a little over 250 days.”
Steve Besser, MLFAC committee member, asked if 70 fish was enough to get real data on a lake the size of Mille Lacs.
“The sample size is really robust compared to telemetry studies undertaken on larger lakes like the Great Lakes,” Aaron responded. “With the fish we plan to tag, we’ll be able to clearly map the home range of adult and juvenile walleye in Mille Lacs Lake.”
In addition to the presentation on the telemetry study, the MLFAC members discussed coming up with a management plan for the state’s harvest of walleye — a task that Minnesota DNR Area Manager Tom Heinrich described as a “long- term process.”
“In Lake of the Woods, where there was very little controversy, it took all winter to create a plan,” he said. “We’ll take our time with this.”
MLFAC chairperson Dean Hanson asked if there was a correlation between how much biomass is tied up in larger fish, and how that might affect recruitment of young walleye. Heinrichs pointed to a Lake Ontario study that showed that walleyes, which can live up to 20 years, can take up a disproportional amount of “ecological space” and can affect the abundance of younger year classes.
Paul Koering, MLFAC member and Crow Wing County Commissioner, said Red Lake experienced a collapse in the fishery but came back due to catch-and-release measures. He asked if catch-and-release could “fix” Mille Lacs, too.
Tom Heinrich replied, “In Red Lake you had a lake that was overharvested and collapsed as a result. In Mille Lacs you have a lake with ecological conditions that have changed and is no longer able to sustain the walleye population you had in the 1980s and 1990s. That’s just not coming back, so catch-and-release as a strategy to repair the lake isn’t a fea- sible expectation.”