2017-11-02 / Front Page

Army Corps releases triploid grass carp into lake to reduce spreading of hydrilla

The U.S. Army Corps of Engi­neers began stocking sterile triploid grass carp to reduce the abundance of hydrilla in the J. Strom Thur­mond Lake (Clark’s Hill Lake) on October 25 and will continue to do so through November 15.

The fish form a part of manage­ment strategies identified in the April 2016 Avian Vacuolar My­elinopathy (AVM) Plan for the J. Strom Thurmond Project.

The sterile carp should reduce the abundance of hydrilla by 50 percent, according to research by the Corps of Engineers. Incremental stockings will occur over the next three years. A licensed contractor will release an estimated 17,725 grass carp during the initial operation. The Corps will add additional fish in April 2018 and April 2019. The releases should lead to 15 grass carp per acre of hydrilla. In the autumn of 2019, a lake-wide survey will provide an estimate of hydrilla coverage to allow the Corps to adjust stocking rates.

Hydrilla is an invasive, noxious aquatic weed found throughout much of the United States. Hydrilla affects shoreline uses in shallow areas especially during the late summer and autumn, however, the vast majority of the lake remains navigable. Hydrilla goes dormant during the winter and re-sprouts from the root system during late spring and summer.

Research shows AVM transmit­ted through hydrilla kills a variety of water fowl that eat hydrilla and raptors that feed on the waterfowl. The weed carries a blue-green toxin called cyanobacterium. Cyanobac­teria attach to aquatic vegetation during late autumn and winter (November-February). Species known to be affected include bald eagle, American coot, great horned owl, killdeer, Canada goose, mal­lard, ring-necked duck, scaup, and bufflehead.

Hydrilla spreads easily, according to Kenneth Boyd, a wildlife biolo­gist assigned to Thurmond Lake.

“Boaters should ensure boat trail­ers, boats, and live wells are free of aquatic plants before leaving the launching area,” Boyd said. “While hydrilla may have some benefits to fish and waterfowl populations as it becomes established in some lakes, it is costly to manage and has negative impacts on lake users as plant growth clogs waterways especially along the shoreline and around docks.”

Anglers who use Thurmond Lake should become familiar with grass carp and how to identify the species. Removal of grass carp from the lake is prohibited by federal regulations and South Carolina state law.

In accordance with the Savannah District Aquatic Plant Management Plan, adjoining property owners may treat hydrilla around their docks pro­vided they obtain a no-cost permit from the Thurmond Project Office. A state-licensed pesticide applicator licensed for aquatic herbicides must apply the herbicide.

Additional information on AVM and aquatic plant management at Thurmond Lake can be ob­tained at http://www.sas.usace.army.mil/About/Divisions-and Offices/Operations-Division/J- Strom-Thurmond-Dam-and-Lake/ Natural-Resources/ or by contacting the Thurmond Project Office at 800- 533-3478 or 864-333-1159.

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