I’ve been told that there’s been an “explosion” of invasive trapdoor snails in our lake. What are they? Where did they come from?—Lola Archibald, via email
Trapdoor snails (a.k.a. Chinese mystery snails) are aquatic snails native to eastern Russia and Southeast Asia. According to Fisheries and Oceans Canada, they invaded North America through “the aquarium trade”: they were released as unwanted pets.
“It seems like a weird pathway of introduction,” admits Rebecca D’Orazio with the Invasive Species Centre. “But sometimes people just lose interest in pets.” Or maybe they weren’t all that interested in them in the first place. They’re snails.
These invaders never got the same headlines as, say, zebra mussels, but they’ve been around for a while. They were first reported in the Niagara River in 1931 and have since spread to various other Canadian lakes and rivers. And they can be as destructive as any other aquatic invasive. The snails eat food necessary for native species to survive; they transfer diseases and parasites to fish and other aquatic creatures; they clog intake pipes; and, when they experience large “die-offs”—so long, suckers!—they can accumulate on beaches, says D’Orazio. “That’s not what anybody wants.”
Video Quiz: Test your invasive species knowledge
The snails reproduce rapidly, can live up to five years and grow to seven centimetres, and can survive out of water. Possibly most disturbing: there’s evidence that they can transmit disease to humans, says D’Orazio. Gah!
You can help curb the spread of invasive snails the same way you’d stop the spread of any aquatic invader: make sure your boat is spic and span before you move it from your lake to another water body. (Follow the Clean, Drain, Dry! method: see invasivespeciescentre.ca/know-before-you-go.) “Our focus is always on prevention,” says D’Orazio. “Once something is established, it can be almost impossible to eradicate.”
Got a question to Cottage Q&A? Send it to answers@cottagelife.com.
This article was originally published in the September/October 2023 issue of Cottage Life.
Related Story This lake association successfully eradicated invasive Eurasian watermilfoil. Here’s how they did it
Related Story Nova Scotia Christmas tree growers are working to stop the spread of a plant-damaging pathogen
Related Story Meet 7 of cottage country’s tiniest creatures