Zebra Mussels Found at Lake Taneycomo, Bull Shoals

The second discovery of invasive Eurasian mussels in the Show-Me State underlines the need for vigilance among boaters, anglers.

BRANSON-Missouri’s second established population of zebra mussels has been documented at Lake Taneycomo, according to the Missouri Department of Conservation.

Private Land Regional Services Supervisor Brian Canaday said the mussels were discovered by employees of the Empire District Electric Company. The fingernail- to quarter-sized mussels were attached to a submerged log.

The same day, the Arkansas Game and Fish Commission reported the discovery of two immature zebra mussels near Lead Hill Marina on Bull Shoals Lake, downstream from Lake Taneycomo.

Scattered specimens of the zebra mussel have been observed at other locations in the Missouri in recent years. Last year’s discovery of a colony on a boat dock at Lake of the Ozarks was the first established population, however.

Zebra mussels are black-and-white striped mollusks similar to clams. Native to Europe and Asia, they were transported to the North America in the bilge or ballast water of ocean-going ships. They were first discovered in Lake St. Clair near Detroit in 1988.

Larval zebra mussels, called veligers, can survive in water left in bait buckets, boat live wells and bilge systems or the cooling systems of marine motors. They attach to hard surfaces including rock, wood, concrete, plastic, crayfish and other mussels and stay there until they die. Adult zebra mussels can live for several days out of water.

Zebra mussels get free rides to previously uninfested areas when the boats, motors or trailers to which they are attached move to other locations. Canaday said this probably is how they got into Missouri waters.

“We cannot determine exactly how or when they were introduced into Lake Taneycomo. However, tens of thousands of people visit there every year, so it is likely that zebra mussels were unintentionally transported by boats, motors, trailers, aquatic plants or other items that had previously been in infested waters.”

A single adult female zebra mussel can produce a million young each year. They can coat the surface of any item upon which they attach themselves. In some locations zebra mussels have reached densities of more than 750,000 per cubic meter - in some areas in the Mississippi River, zebra mussel shells are up to 6 feet thick on the bottom. At these high densities they can clog power plant, industrial and public drinking water intakes and encrust boat hulls, causing millions of dollars in damage. Zebra mussels directly threaten native mussel populations by suffocating them and preventing them from getting nutrients.

Conservation Department biologists watch for zebra mussels as part of their daily routine. Canaday said citizen awareness is a critical part of zebra mussel detection, however.

“There are many more boaters and anglers than Conservation Department workers. In several cases citizens or business owners have reported infested boats,” he said. “That allowed us to make sure the boats were cleaned properly before being launched.”

Missouri Stream Teams also are helping monitor lakes and streams for zebra mussels. If you would like to join the effort, call (800)781-1989 or visit the Stream Team web-site at www.mostreamteam.org.

Canaday said research on zebra mussel eradication techniques is underway. Some mollusk-specific chemicals can help control zebra mussel populations. Treating entire lakes is not feasible, however, partly because the same chemicals kill native mussels and snails. The Conservation Department can provide information to those who would like to use these chemicals.

Zebra mussels can attach to the hulls and drive units of boats left in the water. They increase water drag on the hull, reducing efficiency, and they can clog motors’ water intakes, resulting in engine damage. To prevent this, keep drive units out of water when not i n use. If possible, pump hot water through your engine's intake on a regular basis to prevent mussel growth inside the engine's cooling system.

Juvenile mussels are quite soft and are scoured off of boat hulls when cruising. Boat hulls should be inspected for infestation after extended periods without use.

If you ever move your boat, lift or dock to another body of water, follow the steps outlined below. INSPECT boats and trailers thoroughly, and remove any trash, mussels or aquatic weeds before leaving any water body. Mussels and other items removed from the boat should be properly disposed of in a trash container. DRAIN water from the motor, live-well, bilge and transom wells, and any other water from the boat and equipment before leaving any water body DUMP leftover bait in a trash container on land, away from the water.

RINSE boats, trailers and equipment (including live-wells, bilge, and cooling systems) thoroughly with hard spray or HOT (104 degrees) water, like that found at a do-it-yourself carwash. DRY boats, motors, trailers and equipment thoroughly in the hot sun (for approximately 5 days) before using them again.

For more information about zebra mussels, call (573) 751-4115 or visit www.protectyourwaters.net.  To report a potential zebra mussel sighting, contact the nearest Missouri Conservation Department office or go to: www.mdc.mo.gov/nathis/exotic/. 

-Jim Low-