Office of External Affairs
Mountain-Prairie Region


U.S. Fish and Wildlife Service
Mountain-Prairie Region
134 Union Boulevard
Lakewood, Colorado 80228

August 14, 2009

Contacts:  Leith Edgar  303-236-4588


                Kurt Schilling  605-665-3352








Working closely with South Dakota Game, Fish and Parks, U.S. Fish and Wildlife Service biologists confirmed the presence of Asian clams above the Gavins Point National Fish Hatchery at Lewis and Clark Lake, near Tabor, S.D.  Gavins Point staff immediately initiated efforts to determine whether this aquatic nuisance species had contaminated the hatchery.  No live Asian clams have been documented to date, though dead adults have been found in a few outdoor rearing ponds.


This variety of Asian clam (Corbicula fluminea) was previously discovered in the Missouri River system below Gavins Point NFH. The concern is that the Asian clam could be introduced into the hatchery, where the endangered pallid sturgeon, paddlefish, and other fishes are reared.  Although the introduction of Asian clams do not directly threaten the health of pallid sturgeon or other fishes, the possible presence of the clam in the hatchery could result in its spread during the stocking of these fish.  Preventing the spread of all aquatic invasive species is a priority for the Service. Asian clams can be problematic because they are prolific, consume large quantities of food, and are capable of rapid growth. Its spread can displace native species, reduce biodiversity and alter food chains.


Asian clams are native to Southeast Asia. Since first discovered in 1930 in California the species has spread to 39 states including South Dakota. The species can have an economic impact by clogging water intake pipes; damaging boat engines; and impacting drinking water, aquaculture and irrigation facilities. Additional information on the Asian clam can be found at


“As members of the Service, we consider invasive species as a serious threat to the health of aquatic resources. Our staff at the hatchery works tirelessly to protect the nation’s pallid sturgeon,” said Kurt Schilling, Project Leader Gavins Point NFH. “We believe the safeguards we have in place are protecting  the Missouri River and one of its most precious fish – the pallid sturgeon, but we do recognize the need to conduct a thorough analysis of our operations.  We are currently working with U.S. Geological Survey scientists to determine if the chemical treatment procedures we use for stocking will prevent the spread of the Asian clam.”


Gavins Point has a robust system of controls in place to protect its facility from invasive species. The controls were first put in place to guard against the possible introduction of zebra or quagga mussels (Dreissena spp.). To protect the hatchery’s pallid sturgeon production, all lake water used for rearing the pallid sturgeon is filtered through a rotary drum filter and disinfected by ultraviolet light to prevent introduction of disease and aquatic invasive species to the hatchery.


Additional caution is used by personnel of Gavins Point NFH when stocking waterways with juvenile fish by following protocols similar to those used in several other Midwest states.  First, only well water is used to transport fish off station.  Well water is not at risk for the introduction of the Asian clam.  Second, the well water and the fish intended for stocking are treated with a potassium chloride solution followed by a low level formalin treatment before being released.  These treatments do not harm the fish but will kill many organisms that may attach to the fish.  Hatchery staff is trying to determine if this protocol is adequate to kill Asian clams.


The pallid sturgeon is an ancient species that has existed since the days of the dinosaurs. The Service listed the species as endangered in 1990 and established a Pallid Sturgeon Recovery Plan in cooperation with states, tribes, conservation organizations and private entities. Eight federal and state hatcheries - including Gavins Point NFH - raise pallid sturgeon for stocking into the Missouri River system to help recover this highly endangered fish. Additional information on the pallid sturgeon can be found at .


The mission of the U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people. We are both a leader and trusted partner in fish and wildlife conservation, known for our scientific excellence, stewardship of lands and natural resources, dedicated professionals and commitment to public service. For more information on our work and the people who make it happen, visit



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