Invasive Zebra Mussels Continue Trek Inland in Pa. Waterways

Boaters and anglers are being asked to take steps to prevent the further spread of zebra mussels after the Pennsylvania Department of Environmental Protection discovered the nuisance species in Conneaut Lake.

Regional DEP staff found three zebra mussels during June 10 sampling, two in the lake and one in the Conneaut Outlet immediately below the lake.

"The small number suggests that the current population of zebra mussels is relatively small and may not yet be self-sustaining," DEP Northwest Regional Director Kelly Burch said. "We need the public's help to keep the mussels from gaining a foothold in Conneaut Lake and to keep them from spreading to other area waterways."

Introduced to the Great Lakes through ballast water from a freighter from Europe, zebra mussels have caused environmental havoc and millions of dollars in property damage as they've been transported to other waterways.

Adult zebra mussels are small, clam-like animals about the size of a fingernail, but they can grow to be two inches long. They have a zebra-striped pattern on the shell.

State and local biologists have monitored Pennsylvania waters since zebra mussels were discovered in Erie's Presque Isle Bay in the late 1980s. DEP biologist James Grazio has studied zebra mussels since they first emerged in the region.

"Zebra mussels disrupt the food chain by devouring the microscopic aquatic plants that support the existence of native mussels and fish," Grazio said. "They are a hazard to swimmers because of their sharp shells and can damage boat motors by clogging water intakes."

Adult zebra mussels can attach themselves to the hull of a boat or any hard underwater surface. A boat moving from one body of water to another may also carry zebra mussel larvae, or veligers, which cannot be seen by the naked eye but feel like grit or sand on a hard surface. Veligers can survive and be transported in standing water found in the live wells, bilges, trailer frames or other exposed gear.

Adult zebra mussels can survive 10 to 14 days in a moist environment such as a damp boat or gear, or even a wet cloth or rag. If the mussels are in completely dry surroundings, they will die within five days. 

Methods to kill the mussels and veligers include spraying the boat and trailer with high-pressure water, drying the boat and equipment for at least five days before launching elsewhere, or rinsing the boat and any equipment that normally gets wet using a concentration of one-half cup salt to one gallon of hot water. Salt will kill the mussels, but a thorough rinse with fresh water is needed to prevent it from damaging gear.

Adult zebra mussels can be found in other western Pennsylvania waters, including the Ohio River and lower portions of the Allegheny and Monongahela rivers. Other occurrences of zebra mussels have been reported from northwestern Pennsylvania lakes, such as Edinboro and Sandy lakes, as well as upper French Creek in Crawford County and Conewango Creek in Warren County.

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