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Zebra Mussels Discovered in Lake Ashtabula


The North Dakota Game and Fish Department has confirmed the presence of invasive zebra mussels in Lake Ashtabula.

Last week, an angler discovered a suspected zebra mussel and turned it into Game and Fish aquatic nuisance species coordinator Jessica Howell. Howell confirmed it as an adult zebra mussel, and subsequent inspections of Lake Ashtabula, an impoundment on the Sheyenne River in Barnes and Griggs counties in east central North Dakota, also found well-established populations of zebra mussels of various ages throughout the lake.

At 5,200 acres, Lake Ashtabula is operated by the U.S. Army Corps of Engineers, and it offers a variety of outdoor activities such as boating, swimming, fishing, camping and skiing. Howell said it’s unknown how these small, sharp-shelled mussels were introduced into Lake Ashtabula, and there is no known method to completely rid a lake of zebra mussels.    

“This situation shows how important it is for boaters, anglers, swimmers and skiers to be aware of aquatic nuisance species and to take precautions to prevent their spread,” Howell said. “Everyone who uses this lake now plays a key role in stemming the spread of these mussels to uninfested waters.”

Because of this new finding, the Game and Fish Department has classified Lake Ashtabula, and the Sheyenne River downstream all the way to the Red River, as Class I ANS infested water. Emergency rules will go into effect immediately to prohibit the movement of water away from the lake and river, including water for transferring bait. Notices will be posted at lake access sites and popular shore-fishing spots along the river.

The Red River is the state’s only other Class I ANS water. Adult zebra mussels were discovered in the Red in 2015.

Prevention is the best way to avoid spreading ANS, Howell said, as they often travel by “hitchhiking” with unsuspecting lake-goers. “Always clean, drain and dry boats and other equipment before using another lake,” Howell said. “Also, don’t transfer lake water or live fish to another body of water. This can help stop the spread of not only zebra mussels, but most aquatic nuisance species that may be present.”  

Zebra mussels attach to solid objects, so lake-goers should be careful when handling mussel-encrusted objects and when grabbing an underwater object when they can’t see what their hands may be grasping. Visitors should protect their feet when wading, or walking on shoreline rocks.

Zebra mussels are just one of the nonnative aquatic species that threaten North Dakota waters and native wildlife, Howell said. North Dakota regulations designed to prevent the spread of ANS include:

  •           Remove aquatic vegetation before leaving the water access and do not import into North Dakota.
  •           Drain all water before leaving the water access.
  •           Remove drain plugs and devices that hold back water, and leave open and out during transport.
  •           Do not import bait. For Class I ANS Infested waters, bait cannot be transported in water away from the river or lake. In all other areas, bait must be transported in a container that holds 5 gallons or less. Fish cleaning stations are available around Lake Ashtabula to dispose of unused bait. Remember that it is illegal to dump unused bait on shore or into the lake. If no fish cleaning station is available, place in a dry container and dispose of the bait at home.

In addition to North Dakota regulations, the Game and Fish Department strongly recommends that all equipment is cleaned, drained and dried every time it is used.

  •           Clean – remove plants, animals, and excessive mud prior to leaving a water access
  •           Drain – drain all water prior to leaving a water access
  •           Dry – allow equipment to dry completely before using again or disinfect

For more information about aquatic nuisance species in North Dakota, options for disinfection, or to report a possible ANS, visit

About Zebra Mussels

Zebra mussels are dime-sized mollusks with striped, sharp-edged, two-part shells. They can produce large populations in a short time and do not require a host fish to reproduce. A large female zebra mussel can produce 1 million eggs, and fertilized eggs develop into microscopic veligers that are invisible to the naked eye. Veligers drift in the water for at least two weeks before they settle out as young mussels, which quickly grow to adult size and reproduce within a few months.

After settling, zebra mussels develop byssal threads that attach their shells to submerged hard surfaces such as rocks, piers and flooded timber. They also attach to pipes, water intake structures, boat hulls, propellers and submerged parts of outboard motors. As populations increase, they can clog intake pipes and prevent water treatment and electrical generating plants from drawing water. Removing large numbers of zebra mussels to ensure adequate water flow can be labor-intensive and costly.

Zebra mussels are native to the Black and Caspian seas of western Asia and eastern Europe, and were spread around the world in the ballast water of cargo ships. They were first discovered in the United States in Lake St. Clair and the Detroit River in 1988, and quickly spread throughout the Great Lakes and other rivers including the Mississippi, Illinois, Ohio, Tennessee, Arkansas and Hudson. Moving water in boats and bait buckets has been identified as a likely vector, as has importing used boat lifts and docks.