MAISRC to Study AIS Impact on Walleye Food Web

A diverse group of researchers from across the state recently launched a new project aimed at quantifying the impacts that invasive zebra mussels and spiny waterflea are having on food webs and growth rates of fish in Minnesota’s nine largest walleye lakes.

The project, led by Dr. Gretchen Hansen, a research scientist at the Minnesota DNR, will use stable isotopes to examine what walleye are eating, where in the lake they’re finding food, and at what trophic level they’re eating. Researchers will also evaluate the growth rates of young fish to establish the impact invasive species may be having.

“We know that invasives like zebra mussels and spiny waterflea reduce native zooplankton and have an impact on the food webs in these lakes,” said Hansen. “What we don’t know is whether walleye and other game fish are able to adjust to find new food sources, or what makes one walleye population more adaptable and successful than another.”

Over the course of this and next summer, researchers will gather samples of zooplankton, invertebrates, and fish from Cass, Red, Kabetogama, Rainy, Vermilion, Lake of the Woods, Leech, Winnibigoshish, and Mille Lacs, which are at varying stages and combinations of invasion from spiny waterflea and/or zebra mussels. Red Lake is currently not infested with either species.

In addition to evaluating the food web impacts on adult walleye, researchers will examine growth rates of juvenile fish to better understand how they are impacted by, and respond to, these invasions.

“Quantifying how these AIS are disrupting the walleye food web will allow managers to set realistic goals and implement policies that could improve the fisheries in the future,” added Hansen. “It’s critical that we understand these relationships between species so we can better manage lakes.”

For more information about this project, visit the MAISRC website.

[Note from the Vermilion AIS team: We are pleased that Lake Vermilion is included in this study. Our volunteers have offered to assist MAISRC researchers when the field team is here in 2018. Vermilion does not have zebra mussels. Spiny waterfleas were found here in 2015.]

[Adapted from August 2017 MAISRC newsletter article “New project launched to determine impacts of AIS on walleye.” Photo credit Gretchen Hansen, MnDNR.]