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Drain pipe blamed for mudsnail infestation in Bluewater Fish Hatchery

Drain pipe blamed for mudsnail infestation in Bluewater Fish Hatchery

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Bluewater Fish Hatchery

A drain pipe submerged in an adjacent creek may have allowed New Zealand mudsnails to migrate up from the stream and infest the Bluewater Fish Hatchery this summer.

The operating procedures for the hatchery call for the pipe to be elevated above the creek, but over the years the pipe has become submerged. 

That's according to the results of an investigation launched by Montana Fish, Wildlife & Parks’ following detection of the invasive species on Aug. 18.

The hatchery, the third largest production facility in the state, is located east of Bridger alongside a spring. Fish were stocked from the hatchery this spring in regional lakes and ponds, but "There's no reason to believe they went out with those fish," said Bob Gibson, FWP's information officer in Billings.

Since discovery of the snails, the hatchery staff has killed and disposed of 20,000 pounds of trout being reared at the facility, a loss estimated at about $85,000. FWP staff are also working on a containment and mitigation strategy. Uncertain is whether infected fish were stocked at lakes or reservoirs, and what led to the infestation.

"There's no reason to believe mudsnails got out of the hatchery," Gibson said. "(Aquatic Invasive Species) crews are making a list of all places fish went to in the last couple of years. As you can imagine, that's going to be a pretty big list. The plan is now to go in and aggressively sample all of those places."

This is the first time New Zealand mudnsails have been found at an FWP hatchery. The plan is to make up the losses from Bluewater with surplus fish from other FWP hatcheries.

New Zealand mudsnails are an aquatic invasive species. They were first discovered in Montana in 1995 in the Madison River above Hebgen Lake. Since then, the snails have been detected in locations across the state. New Zealand mudsnails can be eaten by fish and other animals, like birds, but unlike native snails they are undigestible and can be spread by fish and wildlife into other waterbodies.

In a confined facility, like a fish hatchery, mudsnails can be quickly eradicated and the facility decontaminated. 

All hatcheries in Montana are inspected annually for AIS and fish pathogens. The mudsnails at Bluewater Fish Hatchery were detected during the hatchery’s annual inspection.

To help prevent the spread of AIS, people working and recreating in and around Montana waterways must practice clean, drain, dry. For more information on AIS, please go online to


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