Quagga Mussel


The quagga mussel is a close relative of the zebra mussel. Quagga mussels are similar in size to zebra mussels; shells of quagga mussels are rounder and without ridges. They have dark concentric rings on the shell and are pale in color near the hinge. A single female mussel can produce more than 1 million eggs per year.

How It Spreads

Quagga mussels are primarily spread by boaters. Their eggs hatch into a larval form, called veligers, which are free-floating, unlike any of the native mollusks found in the Great Lakes. This larvae can be unintentionally transported in the live wells or bilge water of recreational boats, and they easily attach to boat hulls and trailers. Quagga mussels also cling to vegetation or any other object taken from water where they are present.

Impacts to Rivers

Quagga mussels tolerate a wider range of extremes in temperature, water depth and substrates than the zebra mussel. Quagga mussels are extraordinary water filterers, able to remove large amounts of phytoplankton and suspended particulates from lakes and streams. This ability decreases food sources for native species altering the delicate balance of the aquatic food web.

Quagga mussels clog water structures such as pipes and screens, which reduces pumping capabilities for water treatment and power plants—creating huge problems for industries and communities burdened with removal and clean-up costs. Recreation and industry may also be negatively impacted by quagga mussels when docks,buoys, boats, beaches, and breakwalls are heavily colonized by the species


River Alliance of Wisconsin Factsheet (Lower Wisconsin River Basin AIS Strategic Plan)

United States Geological Survey Factsheet

Distribution (United States Geological Survey)