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Quagga Mussel

(Dreissena bugensis)

Photo of quagga mussel

Quagga mussels were found in Lake Erie in 1989, then spread to and throughout Lake Michigan. Now well established in the lower Great Lakes, quaggas can be found throughout the system and surrounding riverways. Quagga mussels seem to follow a similar trend to zebra mussels in the first years after the initial introduction. Since quaggas can live in a range of substrates, water conditions and at great depths with the ability to reproduce rapidly, they have the potential to have similar impacts to zebra mussels.

 Overview map of prohibited classification in WI
Prohibited (red) counties

Classification in Wisconsin: Prohibited

Ecological Threat

Quagga mussels are extreme water/food filters. They eat up the food source of fish and can drastically change an aquatic ecosystem. They also take in many pollutants (at levels higher than the surrounding area), which can harm wildlife that eats the mussel. Some researchers believe that Lake Erie's dead zone may be caused by their non-stop feeding, their ability to live in deep water (up to 130 meters in the Great Lakes), and the excretion of phosphorous with their waste. Like zebra mussels, the quagga mussels also clog water intake pipes and underwater screens. This plugs up pumps at power and water treatment plants, costing the government and businesses millions yearly to fix. In addition, quagga mussels build up in places that may hinder summer fun - piers, break walls, buoys, boats and beaches.

Quagga mussels, like zebra mussels, have black stripes on tan bodies. Unlike the zebra mussel, the quagga mussel shell has a rounded angle. The quagga is no bigger than an adult's thumbnail. It is light tan to almost white, with narrow stripes or blotchy lines. The shell is fan-shaped with pointed edges at either side. The ventral (bottom side where the two shells attach) side of the quagga mussel is convex, making it topple over when you try to stand it up on a flat surface. The zebra mussel will remain upright when placed in this position.

See the reported locations of quagga mussels in Wisconsin.

Do you know of other populations? Please send us a report.


Mechanical: Quagga mussels and zebra mussels spread in the same ways. The microscopic larvae can be carried in live wells or bilge water on boats and in bait buckets. They are sneaky and attach themselves to boat hulls and trailers. Quagga mussels stick to vegetation, so remove all plants from the boat and trailer.

Chemical: Chemical applications include chlorine, bromine, potassium permanganate solutions and even oxygen deprivation. Further research on effective industrial control measures that minimize negative impacts on ecosystem health is needed.

Prevention steps
  • Inspect and remove aquatic plants, animals and mud from the boat and equipment before leaving the boat launch.
  • Drain water from your boat and equipment before leaving the boat launch.
  • Throw away unwanted bait in the trash.
  • Spray or rinse your boat and equipment with high pressure and hot tap water, especially if moored for over a day, or dry your boat and equipment entirely for at least five days.
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