New Zealand mud snail found at Jones Hole hatchery; Division outlines purge, cleaning and temporary stocking changes
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Summary
Staff reported eDNA and visual detections of New Zealand mud snail in Jones Hole Hatchery raceways, described immediate steps to move fish and treat infrastructure, and said some hatchery rainbow production will be reduced temporarily while cutthroat needs are prioritized.
Division staff told the Blue Ribbon council that environmental DNA and visual surveys confirmed New Zealand mud snails (Potamopyrgus antipodarum) were present in parts of Jones Hole Hatchery’s raceways and clarifier pond.
What the Division is doing now: Staff reported they have moved fish out of the affected raceways (A, B and D are cleared) and plan to purge the remaining E raceway by routing fish to waters known to be positive for the snail so they do not introduce snails to currently uninfested waters. Staff described a stepped treatment plan: pressure washing, heat treatment where feasible, physical re‑routing and burying of daylighted spring channels, and installation of copper‑lined sections of pipe where appropriate (snails will not crawl on copper). Personnel also plan to rotate raceway dry‑downs and will keep limited certified disease monitoring fish on site while most raceways are decontaminated and dried. The hatchery will remain dry for a defined treatment period beginning August 1; staff said a multi‑step cleaning timeline is already scheduled and that they have procured supplemental federal funds and re‑purposed feed savings to help cover immediate costs.
Stocking impacts: Because Jones Hole supplies significant catchable rainbow production, staff said they will reallocate some stocked volumes and prioritize Bear Lake cutthroat quotas that cannot be sourced from New Zealand mud snail‑free facilities. To avoid moving snails into uninfested waters, some rainbow planting levels will be reduced in 2026; staff said recorded quotas for Strawberry and Schofield will still be filled through alternate production or timing adjustments.
Why it matters: New Zealand mud snails reproduce clonally and can reach extremely high densities, displacing native macroinvertebrates and changing food webs. Because the hatchery draws spring and bypass water that touches multiple raceways, staff stressed the priority is to avoid transferring snails to waters that are currently free of the species. Members were told there will be an operational cost and short‑term alteration in some stocking schedules but that the Division’s plan aims to maintain priority conservation stocking and avoid spreading the invasive species to uninfested waters.
Staff said they will provide regular updates to the council and invited members to review the decontamination schedule and to assist with outreach messaging to anglers and partners if needed.
