DOW making progress in ridding hatcheries of WD

DOW making progress in ridding hatcheries of WD

Nov. 18, 2000

BY THE COLORADO DIVISION OF WILDLIFE

DENVER — The Colorado Division of Wildlife continues to make progress in eliminating whirling disease from state fish hatcheries. The state’s fish pathologist have recently announced that the Finger Rock hatchery in Yampa is whirling disease free.

Finger Rock is the seventh of eight hatcheries to test negative for the whirling disease (WD) parasite as a result of a concentrated effort to modernize the DOW’s fish hatcheries. Planning for modernization of the cold-water hatcheries began three and a half years ago, but construction on the Finger Rock facility started two years ago.

"This is just another step in the right direction," said Eric Hughes, Division chief of hatcheries.

Finger Rock is expected to produce an additional 200,000 WD-negative, 10-inch catchable size rainbow trout for stocking in 2001. Whirling disease is a parasitic infection of trout and salmon that exhibits a complex life cycle including two hosts – the fish and a small worm found in aquatic environments. Fish heavily infested can become deformed or exhibit the erratic tail-chasing behavior from which the disease gets its name. Eventually, heavily infected young fish may die. WD does not infect humans.

"For 100 years the Division of Wildlife built hatcheries on open surface water supplies -- rivers and streams. These open water supplies made our fish hatcheries more vulnerable to disease," Hughes said. "WD is one of several diseases that have come into the state over the past few decades. When our hatcheries became infected with the parasite, we decided to take an aggressive and pro-active approach to solve the problem."

In the case of Finger Rock, the stream water was turned off and ground water springs were secured to provide a "clean" water source. In addition, the earthen ponds were taken out of production and all fish are now reared on concrete where the worms can not complete the life cycle. After the groundwater was secured, the unit was disinfected and new fish eggs were brought in to start over. After 14 months of testing, the facility was certified negative for the whirling disease parasite.

Most of the hatchery modernization construction projects involve protecting groundwater sources from surface water contamination, which has been the source of triactinomyxons, the form of whirling disease organisms that infects fish.

The $13-million renovation and modernization of the state’s hatcheries include Mt. Ouray, Salida isolation, Buena Vista, Durango, the Bellvue production facility, the Research Hatchery, Finger Rock, Mt. Shavano, Roaring Judy, Rifle and Pitkin. Of these hatcheries, construction has been completed on all but Roaring Judy, Rifle and Pitkin. Durango was officially declared WD-free last spring. Those incomplete hatcheries still test positive for the whirling disease parasite and Mt. Shavano is the only completed hatchery still testing positive for the WD parasite.

"We are definitely making the right steps in protecting our state’s natural resources,’ Hughes said. "While there is no guarantee that all hatcheries will test negative for whirling disease year in and year out, by securing these water supplies we are now better equipped to battle contamination of all types and keep producing WD-free fish."