The indefinite closure of Montana's Yellowstone River due to a major fish kill is raising worries about lasting impacts to the region's lucrative outdoors industry.

A 183-mile stretch of the river has been closed since Aug. 19, after tens of thousands of mountain whitefish died downstream from Yellowstone National Park.

Gov. Steve Bullock on Monday declared an "invasive species emergency" because of a parasite blamed for the fish kill. The move allows the state to spend money on grants for impacted businesses and related programs.

Fly fishing guide Chase Chapman of Livingston says he's losing tens of thousands of dollars because of cancelled trips. He says the impacts will be severe if the river remains closed long, but he's not interested in retraining for another occupation.