Zebra Mussels Have Invaded Maryland Waters

BALTIMORE (WJZ) -- Their numbers are growing and they are here to stay.

Alex DeMetrick reports after years of watching and worrying, a destructive pest has made its way into Maryland waters.

For a big threat, they fit in a small jar---but then, that's about as large as zebra mussels grow. It's their ability to reproduce that's huge.

"Females can produce tens of thousands to hundreds of thousands of larva a year and they breed for a long period of time," said DNR biologist Matt Ashton.

And in the Midwest, they've been doing it for decades.

Originally brought to the US in the ballast water of ships, zebra mussels are an invasive species, literally smothering and out-eating native mussels. It's a pest whose exploding numbers stick to everything, clogging intake pipes at power plants and water treatment facilities.

Five years ago above Conowingo Dam, two zebra mussels were found. This year, in a handful of underwater collection spots where the Susquehanna empties into the bay.

"We found just over 500 of them," Ashton said.

But near Havre de Grace, others have been finding far more.

"We're hearing from watermen that fish on the flats they're finding hundreds to thousands of their gear that sits for weeks at a time," said Ashton.

Now that they're establishing themselves in Maryland, there's no getting rid of zebra mussels.

"They really are here to stay and it's important that they stay in one place and not travel to other water bodies," Ashton said.

Saltier water further south in the bay will protect most of the Chesapeake but wherever there is fresh water, there is the threat zebra mussels could spread and because people most often provide the free ride, warning signs are going up.

Zebra mussels are natural hitchhikers. Their microscopic larva can be carried by boats, bait and even boots.

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