Marching onward — Zebra mussels found in Lewisville Lake

aamusselszAnother lake in Texas now has a problem.

Less than a year following the discovery that zebra mussels had established a population in Lake Ray Roberts, the destructive invasive species has been confirmed in Lewisville Lake by the United States Geological Survey.

This is the third lake in Texas, and the second within the Trinity River basin, where zebra mussels have been discovered.

Christopher Churchill, a biologist with the USGS who has been monitoring for zebra mussels in North Texas rivers and reservoirs, discovered the live juvenile on a settlement sampler near the dam.

Churchill indicated that this latest infestation is likely the result of contaminated boats being transported to Lewisville Lake, but it could be the result of downstream transport of zebra mussels from Lake Ray Roberts via Elm Fork of the Trinity River. Also, this latest infestation appears to be relatively new as no additional specimens have been documented.

The USGS, Texas Parks and Wildlife Department, University of Texas-Arlington and others continue to closely monitor for the spread of zebra mussels in Texas.

Zebra mussels can have economic and recreational impacts in Texas reservoirs. They can clog public-water intake pipes, harm boats and motors left in infested waters by covering boat hulls and clogging water-cooling systems, annoy boat-dock owners by completely covering anything left under water and can make water recreation hazardous because of their razor-sharp edges.

With Lewisville Lake being such a popular boating destination there is a heightened risk of zebra mussels being transported to non-infested lakes by boaters. However, the spread can be slowed by making sure boats that operate in zebra mussel-infested waters are not used in any other body of water until they have been cleaned, drained and dried. In addition, TPWD adopted rules regarding the transfer of zebra mussel larvae in water from lakes Texoma, Lavon, Ray Roberts and Lewisville. To comply with these rules, boaters and anglers need to drain all water from their boats (including live wells) before leaving those lakes.

From the environmental perspective, zebra mussels are filter feeders, which mean they compete with baitfish such as shad for available forage. Any impact on baitfish in turn can affect their predators — game fish such as bass, striped bass and catfish. Zebra mussels are also very harmful to native mussel populations because they will colonize on their shells and essentially suffocate them.

TPWD Executive Director Carter Smith emphasized that the discovery underscores the importance of boaters helping to prevent the spread of zebra mussels, which can be unknowingly spread when boats and trailers are moved from lake to lake.

“With this somber news, I hope Texas boaters will always remember to “Clean, Drain, Dry” their boats, trailers and gear because all it takes is one instance of not properly cleaning to introduce this highly invasive and unwelcome species to a water body in Texas; and once they are established there is no known way to get rid of them,” Smith said.

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