Photo-USGS

Where are they from?

They are native to the Caspian Sea region of Asia and was first discovered in the Great Lakes in 1986. They most likely piggybacked off of trade ships during this time.

Why are they so harmful?

In the larval stage, they are free swimming in the water column and can spread to new areas through ballast water or currents. The adults can attach to boats, pipes, native mussels and clams, docks, etc., they can also live without water for up to 5 days making it easy to transfer to new areas from boats. It is thought that these mussels can also facilitate algae blooms in the Great Lakes that leads to “beach muck.” Zebra mussels can attach themselves to pipes and can reduce water pressure and even block industrial and water treatment pipes completely for an annual cost of $140 million for the United States and Canada.

How can I identify these mussels?

They are fingernail sized tan mussels with brown stripes. Their shells are in the shape of a D with a flat bottom that makes it easier to attack to rocks and boat hulls.

Where can I learn more?

Invasive Mussel Collab.-- https://invasivemusselcollaborative.net/about/mussel-facts/

Sea Grant Pennsylvania-- https://seagrant.psu.edu/sites/default/files/Zebra%20Mussel%20fact%20sheet%20PA%20Sea%20Grant%20March%202021.pdf