The Sublette County Journal
Volume 4, Number 38 - 5/18/00
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70,000 Rainbows to be destroyed
by Rob Shaul
The microscopic parasite that causes whirling disease has been detected in a lot of 70,000 41/2-inch rainbow trout at the Daniel fish hatchery, according to a May 12 press release from the Wyoming Game & Fish Department. The disease was also found in a group of 50,000 8- to 9-inch rainbows at the Dubois fish hatchery.
While whirling disease has been found in the Green and New Fork Rivers as they pass through Sublette County, and Forty Rod Creek, which runs adjacent to the Daniel Hatchery, this is the first time whirling disease has been found in a Wyoming hatchery.
"Since we (G&F) will not stock these infected fish they will be destroyed," said Mike Stone, G&F fisheries chief. He says additional testing is currently underway on all the other groups of fish at both hatcheries to determine how many fish will have to be removed from the stocking schedule and source of infection. "Until the remaining groups of fish have been cleared by this additional testing, no fish will be stocked from the either hatchery," stone said.
Source of Infection
"We don't know where the infection (at the Daniel Hatchery) came from," said Steve Sharon, the G&F's Fish Culture Supervisor. Mr. Sharon notes that the water source for the Daniel Hatchery comes from "closed" sources - a spring and a deep well system. Because of this, Mr. Sharon says it's unlikely the infection came from the Daniel hatchery's water source. It's more likely the infection came from a fish transfer.
The G&F is currently testing all the other lots of fish at the Daniel Hatchery. If infected fish are found in several of the other lots, it's possible the water supply has been infected. If not, it's more likely the infection came from a fish transfer.
Mr. Stone notes that both the Daniel and Dubois Hatcheries were tested for Whirling Disease last July - and both tests were negative.
Following the discovery of whirling disease in Forty Rod Creek in 1998, the G&F began a major, $800,000, upgrade to the Daniel Hatchery. A major part of that project was replacing the dirt raceways with cleaner, concrete raceways, and covering the raceways with a metal building. Concrete raceways break the life cycle of the whirling disease spore, says Daniel Hatchery Supervisor George Gunn.
Much of that work has been completed, continues Mr. Gunn. The project is on line to be completed by the end of May.
Currently, the Daniel Hatchery is under quarantine, with no fish coming in or going out. Mr. Gunn says the hatchery is currently growing several hundred thousand trout, in addition to the 70,000 rainbows infected with the disease. The G&F doesn't know when the quarantine will be lifted.
Whirling disease is caused by a microscopic parasite that attacks the cartilage in the head and spine of young fish. Fish sometimes display a whirling behavior and develop a black tail. Rainbow trout are most susceptible to the disease.
Though several Wyoming waterways have been infected with the disease, Wyoming has yet to see the large fish die-offs caused by the disease that have been experienced in Colorado and Montana.
Photo credits: Joyce Bohm
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