Aquatic Invasives

Aquatic invasive species, also called "exotic species", are non-native plants and animals that threaten native species and aquatic ecosystems. They can destroy fish and wildlife habitat, spoil boating and swimming areas, and reduce recreational values.

Because these species are not native, there is not a predator or control species here to keep their numbers in check. Unlike native species, most have little to no food value, nor do they provide habitat. They take over and replace native species that provide food and habitat for fish and wildlife.

See FOG's Be A Friend-Stop the Spread brochure and learn how you can prevent the spread of aquatic invasive species into and out of the Gile Flowage.

Aquatic invasive species that threaten the Gile Flowage include:

Spiny Water Flea- A native of Asia, this tiny crustacean was brought to Lake Superior in the ballast water of transoceanic ships. It was discovered in the Gile Flowage in 2003. This aquatic invader probably hitch-hiked its way into the Flowage on fishing equipment or in bait bucket water used on Lake Superior and dumped into the Flowage. Spiny water fleas eat the microscopic freshwater plankton needed by baby game fish. Because they are so spiny, most fish will not eat them, so their populations can boom. For more information you can read: Spiny Water Flea Highlights or the Spiny Water Flea Presentation both prepared by the Wisconsin Department of natural resources. Here is a great video produced by the University of Wisconsin-Extension, University of Wisconsin Madison, and the University of Wisconsin Sea grant: “Stop the Spiny Water Flea Invasion”

Eurasian Water Milfoil- This aquatic invader resembles a beneficial native water milfoil, except that it forms extensive mats of vegetation that can take over a lake. Eurasian Water Milfoil, spreads like aquatic quackgrass. A little piece on a boat prop, recreational equipment, or in water dumped from a live well, can spread to choke a lake with weeds. Eurasian Water Milfoil is found in many northern Wisconsin lakes, including nearby Weber Lake less than 6 miles away, but has not yet been discovered in the Gile Flowage. Please removal all weeds from boat props and equipment away from the boat landing and stop the spread of this nasty invasive!

Purple Loosestrife- This showy purple wetland plant looks harmless, but it can quickly overtake shoreland areas. Producing over 2 million seeds per plant per year, it also spreads by an extensive root system. It chokes out native wetland plants that provide food and habitat for fish and wildlife. Purple Loosestrife is found throughout northern Wisconsin, but has not yet significantly invaded wetlands near the Flowage.

Chinese Apple or "Mystery" Snail- This large aquarium type snail is found both in the Gile Flowage and Lake Gogebic, 30 miles away. It was probably transported between these water bodies via bait bucket or live well water. The impact of this exotic snail on native mollusks is unknown.

If you suspect or discover any aquatic invasives in the Gile Flowage, immediately report this to our citizen lakes monitor volunteer Cathy Butcher at and the Wisconsin DNR.

Be a Friend of the Flowage... Stop the Spread of Aquatic Invasives