Invasive clams have been found in the Salmon Arm of Shuswap Lake.
The Columbia Shuswap Invasive Species Society (CSISS) announced Sept. 16 that dead Asian clam shells (Corbicula fluminea) found on the beaches of Shuswap Lake in 2019 prompted a survey of the shore area once water levels dropped.
Live populations of Asian clams were subsequently found at Sunnybrae and Canoe beaches, and surveys are still underway.
“At Sunnybrae we were finding around 20 clams per square metre of lake bed,” said Sue Davies, aquatic coordinator for the society.
CSISS stated in a news release that the Asian clam is not to be confused with invasive zebra and quagga mussels, which have not been detected in B.C. waters. Ongoing prevention and monitoring for the mussels continues in the province, along with border inspection stations for watercraft entering B.C.
Asian clams, however, can reach densities of up to 10,000 to 20,000 per square metre of lake bed. They are filter feeders that can reduce biodiversity and food available for fish. Dense populations may have the potential to clog filters on hydro systems and water pipes, imposing costly maintenance. They are also known to harbour parasites that are harmful to humans if the clams are consumed raw.
The clams are kept as aquarium species, used as bait and eaten by people. Any one of those uses may have resulted in dead shells or live animals being discarded into Shuswap Lake.
While this is the first confirmed presence of live Asian clams in the Shuswap, it is not the first confirmation of them in B.C. They are known to exist in lakes in the Fraser Valley and on Vancouver Island, as well as in 38 U.S. states and three of the Great Lakes – Erie, Michigan and Superior.
Read more: Volunteer to monitor for invasive mussels and clams in the Okanagan
Read more: Mussel risk reminder issued in Shuswap after invasive species intercepted at inspection sites
To avoid spreading aquatic invasive species, including Asian clams, the society urges the public to clean, drain and dry all gear and watercraft following every use.
“The larvae of this species are microscopic,” said Davies. “They could hitchhike in the smallest amount of water in your watercraft and survive to populate another lake. Please make doubly sure that you clean, drain and dry all gear and watercraft every time you leave a lake or river – even if you’re going to re-launch somewhere else in Shuswap Lake. This is an important measure for all watercraft – kayaks and canoes, paddleboards and inflatables. Prevention is key.”
There are native mussels such as the Oregon floater mussel and the Winged floater mussel that can be confused with the Asian clam. The Asian clam shell is triangular shaped and usually less than 2.5 centimeters but up to 6.5 cm in length, and yellow-green to light brown with elevated growth rings.
Once established, eradication of Asian clams from a complex, connected waterbody is very unlikely and management methods are limited, stated CSISS. Impacts to the system are difficult to predict and depend on several factors. The best thing you can do is prevent further spread to other lakes or rivers.
The public is asked to report any suspected invasive species via the Provincial “Report Invasives BC” smartphone app (available for download from www.gov.bc.ca/invasive-species) and any suspected invasive zebra or quagga mussels to the Report All Poachers and Polluters hotline 1-877-952-7277.
For more information, see this fact sheet on Asian clams.
Travellers bringing watercraft to B.C. are encouraged to visit the provincial website.
To learn more about invasive species in the Columbia Shuswap region visit: http://www.columbiashuswapinvasives.org.
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