Sign that says mandatory watercraft inspection ahead

Homeland & Arrival Date: Quagga mussels are native to the Caspian Sea drainage area in Eurasia. They most likely arrived as stowaways in the ballast water of ocean going ships. They were discovered in the Great Lakes region in September 1989, when one was spotted near Port Colborne, Lake Erie. They weren't identified as a distinct species until 1991.

Quagga mussel and zebra mussel comparison © Myriah M. Richerson

How to Identify: Closely related to another invader, the zebra mussel, they look similar, both having 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 2 shells attach) side of the quagga mussel is convex which makes the quagga mussel topple over when you try to stand it up on a flat surface. The zebra mussel will remain upright when placed in this position.

Life History: Quaggas like silty or sandy lake bottoms. They can live in waters ranging from warm and shallow to deep and cold. They are also able to tolerate somewhat salty water.

A quagga mussel feeds all year, even in winter when its cousin the zebra mussel is dormant.

So far, in Wisconsin, the quagga has been found only in Lake Michigan waters - not in any inland lakes. But because they prefer silt- and sand-bottomed lakes, quagga mussels may be able to successfully invade inland lakes, including some lakes that are not good habitat for zebra mussels. Quagga mussels have also found their way out west. They were recently discovered in Arizona.

Impact: Because they are extreme water/food filters, they eat up the food source of fish and can change the food web in a lake. They also take in lots of pollutants (at levels higher than the surrounding area), which can harm wildlife that eat them.

Some researchers believe that Lake Erie's dead zone may be that way because of their non-stop feeding, ability to live in deep water (up to 130m in the Great Lakes), and the excretion of phosphorous with their waste.

The quagga mussels, like zebra mussels, also clog water intake pipes and underwater screens. This plugs up pumps at power and water treatment plants which is frustrating and costs money to fix! Also, they build up in places where we go for summer fun - on boat docks, breakwalls, buoys, boats and beaches. Ouch - keep your sandals on!

How to stop the spread: 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 be sure to remove all plants from the boat and trailer as well.

If you have a boat, ask your parents to do the following:

  • 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/or hot tap water, especially if moored for more than a day, or, dry your boat and equipment completely for at least 5 days.

Learn about native mussels of Wisconsin.