What's causing the Lake Mille Lacs walleye to disappear?
Researchers from the Mille Lacs Band of Ojibwe and the Great Lakes Indian Fish & Wildlife Commission have launched a new study to try to find out. The scientists want to test their hypothesis that the lake 's warmer lake temperatures and increased water clarity due to invasive species are crowding walleye into smaller areas of the lake, resulting in bigger walleye eating smaller ones.
Concern over the health of the lake's walleye population has led state officials to impose stricter angling limits on the popular destination lake. Walleye fishing is catch-and-release only for the third consecutive season this year.
1The Mille Lacs Band of Ojibwe received a nearly $200,000 grant from the U.S. Fish and Wildlife Service to use acoustic telemetry technology to study the walleye population on the popular central Minnesota lake. They launched from Shah-bush-kung Bay public access in Vineland, Minn., on July 13, 2018.Paul Middlestaedt for MPR News2A small transmitter inserted into the walleye will send data to receivers that were placed throughout the lake in a grid pattern.Paul Middlestaedt for MPR News3Sixty-one acoustic receivers attached to a concrete anchor were placed in a grid pattern throughout Lake Mille Lacs to collect data from walleye inserted with a special transmitter. They were placed in various habitats in the lake in depths ranging from 10 to 40 feet deep.Paul Middlestaedt for MPR News4Aaron Shultz, climate change fisheries biologist with the Great Lakes Indian Fish & Wildlife Commission, holds a thin green strand with a phone number that will let anglers know that the walleye has been implanted with a special transmitter tag.Paul Middlestaedt for MPR News5Shultz inserts a small transmitter tag into the fish's abdominal cavity.Paul Middlestaedt for MPR News6Intern Brandon Johnson holds a sedated walleye while Schultz performs the surgical procedure to insert a small transmitter tag. The fish is sedated using a machine that sends an electrical pulse to its muscles.Paul Middlestaedt for MPR News7The surgical procedure to insert the transmitter tag in the sedated fish takes only a few minutes.Paul Middlestaedt for MPR News8This is the first time the acoustic telemetry technology has been used on a large inland Minnesota lake, although it's been used extensively on the Great Lakes.Paul Middlestaedt for MPR News9After the walleye are tagged and have recovered, they are released back into the lake. The tags emit a pinging sound, which is picked up when they are within range of receivers in the lake. Researchers expect to hear from each fish at least once every hour.Paul Middlestaedt for MPR News10Along with the fish's location, researchers can track the depth and temperature of the water where they spend time throughout the year.Paul Middlestaedt for MPR News
