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Potamopyrgus antipodarum
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THE CRIMES:Competes for space and food resources. Changes the food web. Mud snails reproduce quickly to form very dense colonies that cover rocks, sand, mud, gravel and hard debris crowding out native macro invertebrates (e.g. snails, mayflies, stoneflies, midges, caddis flies). As grazers they eat the same food as native species. Unlike the native species they don't make good "fish food". Mud snails are not very nutritious and even pass straight through fish without being digested. With less nutritious food available the numbers of recreational fish, trout and salmon decline. DESCRIPTION:Mud snails are tiny grey to brown aquatic snails and range in size from a grain of sand to just bigger than a BB. about 5mm or 1/8th inch. The shells have 5-8 whorls and a trap door called an operculum which can close tight. The Interrogation
Where are you from?
We come from New Zealand, where we live in all kinds of freshwater habitats.
How did you get here?
Getting around is easy for us since we are almost invisible to our human vectors. We hide out in mud,
sand, plant fragments, gravel and your gear, nets, muddy boots and laces, boat wells, ballast water, trailers and even
hitchhike on other animals. Undetected we have hitched rides to Australia, Europe, Great Britain and North American. In
1980's we were discovered at Yellowstone National Park in the Snake River and have since spread to many waters across
western USA. In 2005 we arrived at the Deschutes River in Oregon. We have even hitched a ride to the Great Lakes.
What’s your problem?
Our presence is cause for concern. My kind can survive in a wide range of water temperatures and
salinities so we spread quickly in new environments. Almost any freshwater habitat is good for us from silted river
bottoms to clear mountain streams to estuaries. Our operculum shuts tight so we can live out of water for several days.
Reproduction is easy for us it only takes one female to produce from 20 to 120 clones about the size of black pepper or
sand grains. Our colonies can rapidly reach from 100,000 to 750,000 mud snails per square meter. We are not fussy eaters
and graze on bottom dwelling periphyton (diatoms, algae, bacteria) and detritus. In our new environments there are no
native parasites such as trematodes (parasitic worms) or predators to slow us down as there are in New Zealand.
We have been implicated in the decline of fish such as trout, so fishermen aren't happy to see us. With a decline in recreational fish the tourism industry could suffer which makes even more people unhappy. We are also thought to be a potential bio fouler if facilities draw from waters where we live. How can we control you?
WOW! Once we are established it will be really difficult to get rid of us. There are some things
you can do that will help control our spread. You should "Inspect", "Rinse" and "Scrub" all outdoor recreational gear,
such as boots, nets, boats, and trailers away from the shore. We can be killed by completely drying gear for 48hours,
or soaking gear in hot water (at least 120 degrees). Cleaning gear with a 50% solution of Formula 409 and water for 5
minutes or freezing your gear for three hours should also kill us. You can also help slow us down by sharing our ID
Watch Card with others. Lastly if you spot us or any other invasive species REPORT US. 1-877-STOP-ANS (1-877-768-7267).
In Oregon call toll free 1-866-INVADER
Reward:
The honor of protecting our water resources— A healthier environment and more opportunities to enjoy our
natural areas.
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