Yellowstone River Closure: Thousands Of Fish Die From Parasite, Outbreak Could Last For Months

A human-spread parasitic disease may be the cause of Friday’s Yellowstone River closure, say Montana officials. Along a 183-mile stretch, Montana Fish, Wildlife and Parks closed the river to the public after thousands of fish turned up dead in an alarming way.

“This kill is unprecedented in magnitude. We haven’t seen something like this in Montana,” FWP spokeswoman Andrea Jones said. “It’s one of the most serious diseases to impact whitefish and trout.”

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The river is closed indefinitely from Yellowstone National Park to Highway 212 in Laurel, Montana, and includes the Boulder, Shields, and Stillwater rivers. As of now, no one can raft, fish, or swim in the area until further notice.

Friday morning, the number of dead fish counted reached 4,000, but experts are sure the real figure is much higher. The massive deaths prompted FWP officials to call for the river’s closure until a source can be confirmed. According to samples sent to the U.S. Fish and Wildlife Service’s Fish Health Center in Bozeman, the fish may have died from kidney disease.

It is believed a dangerous parasite in the water is being absorbed by the fish through their gills. The organism ultimately makes its way into the kidneys, causing them to fail. The microscopic creature is found mostly in Canada, the U.S., and parts of Europe. Authorities assure the parasite is not harmful to humans.

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River conditions can also make the disease worse on the fish. Cold-water species, like mountain whitefish and trout, are especially susceptible to infection when river flow level is low and water temperature is high. Often similar outbreaks persevere until water temperature drops as winter approaches.

While the parasite may not affect people, it is being spread by human contact. The deadly organism is finding its way into the Yellowstone River by way of boats, tubes, waders, and other interactions with humans.

By keeping people out of the area, FWP believes the parasite can be contained and prevented from contaminating nearby rivers. Officials will continually monitor the situation and re-open the area as soon as possible. However, officials are prepared to extend the river closure for months if fish are still dying.

Currently, there are no reports of dead fish inside Yellowstone National Park. As such, the park will remain open for now.

“At this time, the NPS [National Park Service] is not considering expanding the river closure inside Yellowstone National Park. Crews are actively assessing the Yellowstone River and its tributaries inside the park’s northern boundary and have not discovered any dead fish,” the agency said in a statement.

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The Yellowstone River closure is having a negative impact on local businesses that make the majority of their money on both tourists and locals who visit the area in the summer. While July sees the most visitors to the river, a short season caused by the closure “is going to be really tough on a lot of people.”

“Everybody is kind of in shock right now, and it’s hard because we don’t have any answers,” said Robin Trotter, owner of Yellowstone Raft Company in Gardiner. “We’re open for another month, so if you take a month out of your five-month season, it’s pretty impactful.”

Some companies had to turn customers away or hope they could return when the river is open once more.

“We still have a bunch of trips scheduled for the next few weeks, so we’re either going to have to cancel or take clients up to Yellowstone National Park and do what we can,” said Dan Gigone of Sweetwater Fly Shop. “We rely on this part of the year to provide the money to keep us going through the winter.”

While the Yellowstone River closure has Montana officials alarmed, this isn’t the first time they have dealt with the same disease. Over the past two decades, the parasite affected fish in two other Montana locations as well as other places in Idaho, Oregon, and Washington.

[Photo by David McNew/Getty Images]