A parasite called Proliferate Kidney Disease caused the death of an estimated 4,000 whitefish in the Yellowstone River back in August. As a result, Montana Fish, Wildlife and Parks examined some of the bodies of water in the immediate vicinity. FWP public information officer Vivaca Crowser explains.

“We have confirmed that the parasite is present in the upper and lower Madison, the East Gallatin, Bighorn, Stillwater, and Boulder River near Big Timber,” said Crowser. “It had already been confirmed on the Jefferson and Shields River and we are going to continue more statewide survey work as well.”

According to Crowser, the presence of this parasite doesn’t mean we are going to see in those other waters the same thing we saw in the Yellowstone.

“Its presence can go and not cause any trouble for a long time, but then when you have other environmental factors like low flows and higher water temperatures it may prompt it to start affecting fish like we saw with the whitefish,” Crowser said. “There is still a lot of uncertainty and exactly what level of triggers do we need to see it start to have an effect on fish. I think just knowing it is there is helpful so that if you do start to see some of that you can take precautions.”

The Clark Fork and Bitterroot Rivers have not been tested as of now, but Crowser says they should be part of the FWP’s sampling plan for the upcoming year.