AIS / Fisheries
September AIS: Mystery Snails
Best Detected by walking your shoreline because when snails die, their shells wash up on shore.
- Prefer shallow highly productive lakes and slow-moving streams with soft mud, silt, or sand substrate
- Productive systems provide minimum calcium requirements for shell growth
- Feed non-selectively on organic and inorganic bottom material, diatoms, and algae
- Prefer pH of 6.3-8.5, dissolved oxygen 7-11 ppm, and depths up to 3m
- Usually buried in sediment but can seal ‘trap door’ tight and float at the surface
- In the fall, migrate to deeper water to overwinter
- Most growth occurs in spring and summer when the water is warmer
- More likely to occur near boat landings, and in water bodies near population centers or with a high shoreline housing density
How Did They Get Here?
- First sold live in Chinese food markets in the 1890’s, then intentionally released to create a locally-harvestable supply
- Also released from aquariums and water gardens
- Now transported via bait buckets and livewells
- Will attach to macrophytes that can tangle on boat trailers or inadvertently occur in sediment on anchors
- Ability to close operculum makes them resistant to desiccation on a boat or trailer
- Bear live young which can be ‘stored’ inside the adult for long periods of time
Why Are They A Problem?
- Both species potential vectors for the transmission of parasites and diseases
- In Korea, Chinese Mystery snails host human intestinal trematode parasites
- Clog screens of water intake pipes
- Restructure established food webs through competition with native species for food and space, which negatively impacts native gastropods
- Banded Mystery snails significantly reduce survival of largemouth bass eggs in guarded nests
What Can Be Done?
- Squish ‘em!
- Physical removal: baiting and hand netting
- More snail eating turtles!
Chinese Mystery Snail
Banded Mystery Snail
Note: DNR permits are required for chemical treatments, mechanical treatments, some manual treatments, biological control, bottom screening, and buoy/barrier placement.