WHIRLING DISEASE AT MILES CITY HATCHERY

MONTANA FISH, WILDLIFE & PARKS
FOR IMMEDIATE RELEASE - NOVEMBER 10, 2005
Contact Tom Palmer, (406) 444-3051, or visit FWP's website at
fwp.mt.gov

ANNUAL TEST DETECTS WHIRLING DISEASE AT MILES CITY HATCHERY

      Montana Fish, Wildlife & Parks officials placed the state's Miles City
Hatchery under quarantine this week after whirling disease was detected
in a sample of young rainbow trout collected for annual fish-health tests.
      "Our primary aim with annual tests is to maintain the high standard of
health at each of Montana's 10 fish hatcheries," said Gary Bertellotti, chief
of FWP's hatchery bureau in Helena. "We collected a total of 60 trout for
health testing and detected an extremely low level of whirling disease
infection in one sample."
      This is the first time whirling disease has been detected in a state
hatchery. Whirling disease is a potentially fatal ailment of trout and
salmon caused by a microscopic parasite with a complex two-host
lifecycle. The parasite consumes the cartilage of young fish, which cause
the fish to swim erratically. It was first found in Montana in 1994.
      The Miles City Hatchery is the state's warm-water fish hatchery where
50 million walleye fry and two million walleye fingerlings are raised
annually for stocking in Montana lakes and reservoirs. The hatchery also
raises large and small mouth bass, northern pike, tiger muskie, channel
catfish, sauger, and pallid sturgeon. None of those warm-water fish are
susceptible to the whirling disease parasite.
      Bertellotti said the Miles City Hatchery raises small trout at the facility
as a food source for bass brood stock and as a detection species for
certain virus, bacteria, and parasites that cause fish diseases. The 60 fish
collected for the test where separated into 12 batches with each batch
containing five fish. Whirling disease was detected in only one of the
samples.
      Under the quarantine, which is designed to substantially reduce the
risk of spreading disease, fish cannot be transported from the facility.
      "Plans are now being developed to ensure that Miles City Hatchery is
safe and that no infected fish or whirling disease organisms will leave the
hatchery and FWP will be able to produce warm water fish for stocking
next spring." Bertellotti said. "We've collected more trout for testing from
the Miles City Hatchery and are retesting the samples we originally tested.
Our policy is to sample more fish to confirm the original test results
before we take additional action."
      Because the water source for the hatchery is primarily the Yellowstone
River, Bertellotti said officials suspect that the fish were exposed to the
whirling disease parasite in the hatchery's rearing tanks supplied by
Yellowstone River water. "It's too early to draw any conclusions about the
Yellowstone River, but we have to assume that the parasite came in either
with the water or perhaps from birds that utilize the hatchery ponds after
eating infected fish elsewhere in the state."
       Bertellotti cautioned that the tests results are preliminary and that
additional tests are underway. He said several fish were placed in special
cages this week to determine the presence of whirling disease in the
Yellowstone River near the hatchery intake, the hatchery intake settling
pond, the hatchery building, and in the effluent pond.
      Fish from these cages will be collected after 10 days, brought to
FWP's whirling disease experimental lab in Bozeman and examined.
Additional experiment stations will be placed in the Yellowstone drainage
in the spring. These stations will monitor whirling disease infection levels
at different locations in the Yellowstone River system.
      Bertellotti said the quarantine will be lifted when additional tests
show the parasite is eliminated from the Miles City Hatchery, but a partial
lifting of the quarantine may be possible if follow-up tests now underway
show other fish are not infected. Bertellotti stressed, however, that no
infected fish would be stocked into Montana waters.
      Under an agreement with the U.S. Fish and Wildlife Service, FWP
obtain ownership of the Miles City Hatchery in 1983. Since then more
than $10 million dollars has been spent to renovate and expand the
hatchery to meet growing needs for warm water fish throughout Montana.
                                              -fwp-