Fish virus detected in salmon at Kootenai Falls

For the first time in Montana, a virus that targets kokanee salmon has been detected in state waters.

The virus, infectious hematopoietic necrosis, recently was found in salmon tissue samples collected below Kootenai Falls in November by Montana Fish, Wildlife and Parks. 

The virus doesn’t affect people but it can kill the fish by attacking blood-producing tissues in their kidneys.

Fisheries Manager Mark Deleray said the virus apparently was introduced by salmon swimming upstream from Idaho’s portion of the Kootenai River. Idaho has been dealing with the virus since the 1970s, and in 2013 it was found in portions of the Kootenai River in British Columbia.

“Montana has very strict fish health policies; we’re very protective and diligent in enforcing them,” Deleray said.

Specifically, the state forbids the transport of fish between bodies of water.

“We have a problem in this area with people illegally moving fish from one water body to another,” he said. “The idea behind that is to start a population of that species in another water body.”

If the virus continues to spread, kokanee salmon hatcheries are perhaps the most at risk, with outbreaks of the virus capable of causing up to 90 percent mortality. 

The state maintains hatcheries near Eureka and Somers, but Ken Staigmiller, a fish health coordinator with the state fisheries agency, said Montana is in a good position to keep the virus from affecting those populations.

“The big difference between our hatcheries and other ones in the Pacific Northwest is we do have closed water supplies. We don’t have any cold-water hatcheries that get untreated water from the rivers and streams,” Staigmiller said. “The other thing is … our eggs come from Lake Mary Ronan, which we test annually.”

He added that the state will ramp up its testing efforts and will strengthen basic protocols to lessen the chance of accidental infection of clean populations.

“Any time you get a finding like this, it makes you re-examine everything you’re doing and make sure you’re not missing anything,” he said.

Deleray said precautions by boaters and anglers in the area also could help prevent the virus from spreading further.

“We really encourage people to make sure their boats and fishing gear are clean and dry, and that will minimize the opportunity for these types of organisms to be transferred to other bodies of water,” he said.

Other fish such as rainbow trout and bull trout can contract the disease, but Staigmiller said the mortality rates for those species are far lower with the strain of the virus that was found in the Kootenai River.

Reporter Samuel Wilson may be reached at 758-4407 or by email at swilson@dailyinterlake.com.