Yellowstone River Parasite Same One That Killed Whitefish In Upper Snake River

Aug 25, 2016

Credit Amy Meredith / Flickr Creative Commons

In an unprecedented move, Montana officials last week closed a 200-mile stretch of one of the most popular fisheries in the West. The Yellowstone River has been contaminated with a parasite that’s killed thousands of whitefish, the same parasite that continues to impact some Idaho rivers. 

The parasite first invaded the Upper Snake River in 2012. And Idaho Fish and Game officials tell the Bozeman Daily Chronicle that it's still there. The newspaper reports that unlike in Montana, Idaho didn’t have the authority to close down the waterway when the parasite killed fish.

Four years later, officials are still seeing fish mortality in the Upper Snake once the river gets hot and low late in the season. It’s still not clear how the parasite got into the river in the first place -- or how many fish it’s killed over the years -- but officials speculate that the organism could have attached to people and spread on the river.

Montana officials hope to stop the spread of the parasite by shutting down the Yellowstone. There’s no timeline for how long the waterway could remain closed.

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