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Invasive Mud Snails Detected In Western Montana For First Time

Tiny New Zealand mud snails surround a dime for scale.
Montana Fish, Wildlife and Parks
New Zealand mud snails were discovered for the first time west of the Continental Divide in Montana last month.

The first discovery of an invasive snail west of the Continental Divide in Montana is pushing wildlife officials to quarantine a fish hatchery south of Hamilton.

A colony of New Zealand mud snails was found at the private commercial fish hatchery last month.

Montana Fish, Wildlife and Parks Spokesperson Greg Lemon says they likely hitchhiked to the Bitterroot in shipments from a fish hatchery in South Dakota this and last spring.

"The first thing we did was quarantine the hatchery so they weren’t taking fish out anywhere else. We’re now working with them on an eradication plan and contacting the pond owners where they’ve delivered fish in the past two years," Lemon says.

Lemon says the Bitterroot hatchery stocks about 100 private ponds in western Montana and drains into an irrigation canal. FWP has surveyed sections of the nearby Bitterroot River and Skalkaho Creek and has not found mud snails there.

Invasive New Zealand mud snails are present in the Madison, Missouri and Yellowstone Rivers. They outcompete native mussels, snails and aquatic insects and can impact food chains of native trout. They’ve also impacted freshwater supplies: In Australia they’ve emerged from home water taps.

This year, FWP inspected more than 104,000 boats for aquatic invasive species and intercepted 14 contaminated with zebra and quagga mussels. While the agency found new populations curlyleaf pondweed and Asian clams, no mussels were found in the 180 waterbodies sampled.