Spiny Waterfleas in Mille Lacs

Spiny waterfleas have been discovered in Lake Mille Lacs. The Minnesota Department of Natural Resources Aitkin Area Fisheries staff discovered the invasive species last week. It is the first such discovery outside of Lake Superior and the U.S.-Canadian border waters.

Spiny waterfleas impact on lake ecosystems are largely unknown. Waterfleas compete with small fish for food called zooplankton. While larger fish eat them, tiny fish may not be able to consume this invader. In certain types of lakes, they can change the species and numbers of zooplankton, which may harm those lake ecosystems.

The spiny waterfleas in Lake Mille Lacs were first observed collecting on fishing lines in the water. The find was later confirmed from water samples collected by the DNR.

Anglers are often the first to discover spiny waterfleas because they become tangled to fishing gear. The waterfleas can be a nuisance to anglers, collecting in gobs on fishing lines.