Montana Fish, Wildlife & Parks announced today that it placed its trout hatchery in Lewistown under a fish-health quarantine.
The quarantine at the state's Big Springs Trout Hatchery was imposed last week when a bacteria that causes bacterial kidney disease, or BKD, in trout was found in some rainbow trout and Arctic grayling at the facility. The fish were hatched from eggs gathered from wild fish in southwestern Montana.
Under the quarantine, which is designed to substantially reduce the risk of spreading the disease, fish cannot be transported from the facility.
"We have already collected more tissue samples for testing from Big Springs Trout Hatchery," said Jim Peterson, FWP's fish health coordinator. "Our policy is to sample more fish to confirm the original test results before we take additional action."
BKD is a stress-related bacterial pathogen that affects the kidneys of fish. The bacteria that causes the disease occurs naturally in Montana and in many other trout waters throughout the United States, but can be especially problematic in hatcheries. The bacteria was detected by U.S. Fish and Wildlife Service pathologists at the Fish Health Center in Bozeman during a routine annual health inspection of Big Spring Trout Hatchery fish.
The infected rainbow trout were hatched from wild rainbow trout eggs collected and fertilized last spring from Red Rocks River upstream of Clark Canyon Reservoir. The infected grayling were similarly gathered from two southwestern Montana lakes. Rainbow trout eggs from the Red Rocks River site were also hatched at the state's Giant Springs Hatchery in Great Falls and grayling eggs from the southwestern Montana lakes were also hatched at the state's Bluewater Trout Hatchery near Bridger. Those fish are currently being tested for the bacteria that causes BKD.
BKD can be transmitted through infected fish and infected fish eggs. It is resistant to traditional egg-disinfectant techniques. While the bacteria was detected in about eight percent of the 60 rainbow trout and 60 grayling tested, none of the infected fish manifested clinical signs of the disease, which includes swollen kidneys and an enlarged abdomen. None of the fish at the hatchery appear sick and none have died, officials said.
At the egg-gathering sites, adult fish from which eggs are collected are routinely tested for various fish pathogens, including BKD, to reduce the risk of bringing a disease from the wild into a hatchery. In addition, the eggs are held in isolation until fish health results are reported. In this case, no disease was detected in the adult fish from which eggs were collected.
Chris Hunter, chief of FWP's Fisheries Division in Helena, said Big Spring Trout Hatchery fish are now being thoroughly tested for BKD. He said the quarantine will be lifted when additional tests show the bacteria has been eliminated from the Big Springs Trout Hatchery, but a partial lifting of the quarantine may be possible if follow-up tests now underway show other fish are not infected. Hunter stressed, however, that no infected fish will be stocked into Montana waters. The rainbow trout from Big Springs Trout Hatchery were to be stocked in Canyon Ferry and Holter lakes near Helena, and the grayling were to be used for restoration stocking in Montana. The Arctic grayling is a candidate species for federal protection under the Endangered Species Act. Big Springs Trout Hatchery annually stocks about 1.25 million rainbow trout, 40,000 grayling and a total of 600,000 cutthroat trout, brown trout and kokanee salmon.
Should any of the hatchery's fish become unavailable for stocking, officials said they will reevaluate the year's fish stocking plans to best meet the needs of Montana anglers.In past years, two commercial fish hatcheries were quarantined due to BKD. Both hatcheries destroyed the infected fish and are back in operation. In 1996, FWP quarantined the federal Bozeman Fish Technology Center hatchery after grayling there were found with the bacteria that causes BKD. In the 1970s and early 1980s, FWP battled BKD in Yellowstone cutthroat trout brood stock at its Yellowstone River Trout Hatchery in Big Timber.