New Zealand mud snails discovered at FWP hatchery
By Moosetrack Megan

Posted: March 31, 2022

HELENA – New Zealand mud snails were discovered earlier this month at Montana Fish, Wildlife & Park’s Bluewater State Fish Hatchery south of Laurel. To eliminate the threat of further spread, nearly all of the rainbow trout and largemouth bass at the facility will be destroyed.

New Zealand mud snails are an aquatic invasive species found in a variety of waterbodies across Montana. The snails have the ability to expand in population size and in distribution very rapidly, potentially changing the ecology of waterbodies where they are located. Once established in waterbodies, they are hard, if not impossible to eradicate.

Mud snails were discovered at FWP’s Bluewater Hatchery in 2020. The hatchery was quarantined then and decontaminated. The source of the new infestation is unknown, though FWP staff believe cracks in older concrete tanks might have allowed mud snails from the previous infestation to survive decontamination.

“We are conducting a full decontamination and our oldest concrete settling basins, where this infestation was discovered, will no longer be used,” said Eileen Ryce, FWP fisheries division administrator.

The largemouth bass that will be destroyed are brood stock and large enough to eat. FWP staff will hand out the dead bass to youth under 12 or anyone with a fishing license on Friday, April 2, from 9:30 a.m. to noon, and Saturday, 9 a.m. to noon. There is a limit of 5 bass per individual. That hatchery is located at 700 Bluewater Creek Road, Bridger, MT. People who pick up fish need to make sure to dispose of the entrails and carcasses in the household garbage, not in a waterway or down the drain into a wastewater system.

Some rainbow trout at the facility will be stocked as planned. These fish are in an interior part of the hatchery that is not connected with the area where the mud snails were found. No mud snails were found in the interior part of the hatchery.

The loss of investment in the hatchery stock, the value of the fish and the cost of decontamination is estimated at $225,000. The effect on FWP’s stocking program will be mitigated as much as possible by stock from other hatcheries.