State officials are reminding people enjoying the outdoors this fall to clean their gear — and their pets — between excursions.
A biologist found several hundred New Zealand mud snails in the mud of Blue Slough between Cosmopolis and Montesano. The tiny snails are an invasive species that can cause problems for fish.
“New Zealand mud snails are a cause for concern whenever you find them. This is potentially very early in their infestation. There’s a possibility they were recently introduced and they’re not going to survive in that area, there’s a lot of unknowns,” said Allen Pleus, aquatic invasive species coordinator for the state Department of Fish & Wildlife.
“We know that New Zealand mud snails are tolerant of saline conditions, they’re in Capitol Lake, and the literature shows they can also survive in brackish waters. As far as what they can actually do in that region, we don’t know,” Pleus said.
The snails have only been seen in the United States since the 1980s. With invasive spartina grass, it took more than 100 years to begin to see the impacts of its explosive growth. It’s hard to know the long-term impacts of the snails’ success, Pleus said, but for now we know “they’re not good.”
Even one snail could lead to trouble: A single female can clone herself, and within three years the population can reach 12 million, according to Fish & Wildlife. The snails can take over as the dominant invertibrate, consuming up to half the available resources in a stream.
Pleus said in some streams in Montana, the snails crowded out native species fish like trout and salmon like to eat.
“In those situations, they did find correlations to lower body weight in the fish, and longer-term concerns about the success of those fish in those streams. What happens is these snails feed at the basic food level of algaes and detritus, and they out-compete our native species,” he explained. The fish “don’t have as much to feed on and if they try to feed on the mud snails — first, they are very low in nutritional value, and they can pass through (the fish) unharmed.”
Once the snails infest an area, they are very difficult to remove. Capitol Lake has been infested since 2009 despite numerous efforts to remove them. Pleus said a survey is needed to determine whether the snails have infested a wider area in the Chehalis River Basin, but in the meantime, the best thing people enjoying the area can do is help prevent any further spread.
“Our first message is prevention. People need to do the ‘clean, drain, dry.’ Any equipment that they use in the water, that could be kayaks, that could be boats. Dogs aren’t equipment, but dogs are often taken into those situations. … They get muddy, the mud contains the mud snails, they go to another location, the mud snails drop off and that’s how they spread,” Pleus said.
The snails have essentially a door in their shells allowing them to seal up, potentially surviving for weeks out of water, so cleaning is essential.
Fish & Wildlife recommends cleaning waders, shoes, life vests, boat hulls and other gear with a stiff-bristled brush before leaving a water body. If cleaning isn’t possible there, put the items in a plastic bag to clean them at home.
Freezing gear for 4-8 hours at 26 degrees Fahrenheit or below, or soaking for at least five minutes in hot water at least 120 degrees are both recommended options, depending on the material. For more information on the snails and how to clean outdoor equipment, visit http://1.usa.gov/18sBX1c.