A shrinking globe brings snails from New Zealand to the American River, but fortunately, they won’t have much of a negative impact on the salmon, though other aquatic species will suffer.
Snails pose threat via Lake Natoma trout hatchery
Tiny invasive species can travel inside fish, infest more waterways and destroy food source.
By Matt Weiser - mweiser@sacbee.com
Published 12:00 am PST Tuesday, November 27, 2007
A tiny but tough and very hungry foreign snail has invaded the American River, prompting concern that waters throughout the state could become infested if it gains a foothold in the river's trout hatchery.
The New Zealand mudsnail has been confirmed in two locations on the river this month, both below Lake Natoma. On other rivers, the snail has been known to carpet the river bottom at more than 500,000 per square meter, and it could devour food available to native fish in the river.
But officials are equally concerned about preventing the snail from being transported by human activity above Nimbus Dam and into Lake Natoma, the water supply for the state's American River Trout Hatchery.
The tiny snail – less than 5 millimeters long – can survive in the stomachs of fish for up to three days and be excreted alive into new waters. So the millions of trout transplanted from the hatchery each year to lakes throughout the state could spread the snail far and wide…
In the American River, it was found Nov. 12 about a half-mile below Sunrise Bridge by Ken Davis, an independent aquatic biologist based in Sacramento; then on Nov. 14 at San Juan Rapids by Mike Healey, a fisheries biologist at the Department of Fish and Game.
"They are reproducing," said Davis. "Everything is there for them to prosper."
Navicky said the effect on the river's primary native fish – salmon and steelhead – might not be severe. That's because these fish are migratory, spend most of their time in other places, and don't feed much when they return to spawn.
