Hamilton fish hatchery remains under quarantine awaiting a final check to ensure that it’s free of invasive New Zealand mud snails.
Montana Fish, Wildlife and Parks discovered the snails at the Bitterroot Fish Hatchery in August and curtailed its operations immediately.
Since then, FWP officials have checked about 40 of the estimated 100 private ponds that received fish from the hatchery. So far, they have not found any new infestations.
“To date, we haven’t seen anything,” said FWP Aquatic Invasive Species Bureau Chief Thomas Woolf. “Mud snails can be transferred in the gut of a fish. They can survive being ingested. … A lot of the ponds aren’t great habitat for the mud snails.”
Smaller than a grain of rice, New Zealand mud snails have high reproduction rates that can create conditions where other native macroinvertebrates can’t compete.
They were first discovered in the United States in 1987 in Idaho’s Snake River. In Montana, the snails first appeared in the Madison River above Hebgen Reservoir in 1995. Since then, they have been found in the Missouri, Yellowstone and Bighorn rivers.
Last summer’s discovery at the Bitterroot hatchery was the first time New Zealand mud snails had been found in western Montana.
The Bitterroot Fish Hatchery has been owned and operated by Dan and Becky Brandborg since 1996.
The hatchery celebrated its 100th anniversary last year. It was built by Marcus Daly II, the son of the founder of Hamilton. Initially, the hatchery had the capacity to raise 7 million large trout and sockeye salmon and 11 million minnows. Some of those early fish were loaded into milk cans and used to stock high mountain streams and lakes in the Bitterroot.
The Daly family sold the hatchery to the state, which ran it for 40 years before it was privatized in the late 1960s.
Dan Brandborg said this was the first time the family has turned off the underground spring used to fill the hatchery since they’ve owned it.
“We’ve worked with FWP to sterilize the fish house, and dewatered the mud bottom ponds,” Brandborg said. “That’s our main tool to get rid of the snails, is to dry everything out and let it freeze. We’re doing everything we can to ensure the snails are gone. FWP has been great to work with. Our No.1 priority is protecting the resource in this valley.”
The Brandborgs are now looking for a different source for the trout they import into the state and distribute to pond owners.
The snails found at the Hamilton hatchery most likely came from a South Dakota hatchery that had supplied the Bitterroot facility. Mud snails were found at the South Dakota hatchery this summer.
Finding a new hatchery has been a challenge.
“Montana is really strict on whose fish health reports they will accept,” Brandborg said. “It’s our impression that they are the strictest in the Northwest. … We’re getting a new hatchery approved. We haven’t sealed the deal yet but I think we are in good shape.”
With many other private hatcheries now closed, Brandborg said theirs is now the largest provider of trout to private owners in the state.
“A lot of older owners have retired and shut their places down,” he said.
The Bitterroot hatchery has the advantage of its water coming from an underground spring that arrives on-site through a quarter-mile-long pipeline.
“There is no surface water involved,” he said. “It’s totally sealed. That’s one of the reasons that other hatcheries have gone out of business. Their water sources aren’t bio-safe and protected.”
Woolf said the Bitterroot hatchery will be inspected again before the Brandborgs are allowed to restock it.
“He’s are doing everything right,” Woolf said. “What happened to him was really no fault of his own. He is seeking out a source of fish that are disease-free and free of invasive species. There is a limited number of hatchery facilities that are cleared for importing into Montana.
“From the state’s perspective, we want to do everything we can to protect the resource,” he said. “We want to make sure that there are no additional problems.”