Darrah Springs Hatchery, operated by the California Department of Fish and Wildlife (CDFW), was partially released from quarantine on Oct. 9 after being in quarantine since May because of whirling disease.
Extensive DNA testing of the fish by a commercial sciences lab have determined that all the trout in the hatchery building and the lower rearing ponds are free of the disease and the hatchery is resuming normal operations for that portion of the facility.
“We were able to save thousands of fish by isolating them from the disease and will be able to grow and plant them into state waters very soon,” said Linda Radford, CDFW Regional Hatchery Supervisor. “Unfortunately part of the hatchery is still infected and we will have to destroy some fish.”
The upper part of the hatchery, located near the town of Paynes Creek, is still infected with the disease; the fish there will be destroyed, recycled and used for pet food and other purposes. The fish rearing areas still infected will be dried up and not utilized until the water supply can be either disinfected through a water treatment system or pathology testing verifies that the water supply no longer is infected.
Approximately 160,000 fish will be euthanized. The disposal of infected hatchery-raised trout is a necessary precaution to prevent the spread of disease to non-infected state waters where the fish would normally be planted.
Whirling disease is caused by Myxobolus cerebralis, a protozoan parasite that destroys cartilage in the vertebral column of trout and salmon. It can be fatal to infected trout and salmon but does not affect humans or other wildlife or fish. The whirling disease parasite is naturally present in some streams and rivers in California. Hatchery outbreaks are unusual but not unheard of (there has never been another outbreak of whirling disease in the department’s hatcheries in northern California).
Darrah Springs Hatchery supplies catchable trout for waters in Lassen, Modoc, Shasta, Siskiyou and Trinity counties and is one of 21 state-run hatcheries that provide millions of fish for California anglers.