MINNEAPOLIS (WCCO) — When winter’s ice melts into springtime waves, the mystery of Mille Lacs will again be in the news. The lake’s depleting walleye population is still stumping anglers and scientists.
“We can certainly learn a lot more about the lake so we can determine what the solution is,” said Brad Parsons, the DNR’s central region fisheries manager.
Parsons said when the ice is gone this spring, biologists will strip 10 to 20 million eggs from the lake and grow them in a St. Paul hatchery.
“We mark them with an antibiotic solution that actually puts a little mark on the ear bone,” said Parsons. “That way we can tell what is naturally produced in the lake and what we had put in there.”
Almost immediately after they hatch, the marked fry will go back into the lake and grow into small fingerlings throughout the summer.
“It’s very important that when we put these marked stocked fry out there, they behave like the wild fry do, so we want them in there at the same stage,” said Parsons.
The idea is to compare the stocked fry with the lake’s naturally reproduced population. This could provide answers as to why young walleye are not surviving.
“With the marked ratio out there, we can determine the hatching success of natural eggs in the lake, and we can determine the number of natural fry that are out there,” said Parsons.
He also said the exercise will not bolster the lake’s walleye year class; rather, it will give insight into why a once prolific lake is failing.
Because Mille Lacs walleye are a unique strain, the DNR cannot use eggs from any other lake. They hope to have their first glimpse at the data when they recapture the fingerlings in early fall.