Montana wildlife officials are warning anglers of the presence of non-native, predatory smallmouth bass that threaten trout in the upper Yellowstone River north of Yellowstone National Park.
An angler caught a small bass Feb. 19 in the Gardner River at the confluence with the Yellowstone River, Montana Fish, Wildlife and Parks reported Wednesday.
Biologists warned the fish could threaten and displace trout and other native species in the upper Yellowstone River and other waterways.
Anglers who catch a smallmouth bass in Yellowstone National Park after the season starts Memorial Day will be required to kill and report them to park officials, said Todd Koel, the park's lead fisheries biologist.
Montana FWP is drafting a proposed emergency rule for the Fish and Wildlife Commisison to consider to require anglers to kill and report all smallmouth bass caught on the upper Yellowstone River. Until that rule is approved, the agency is recommending these actions for all smallmouth bass caught from the park's borders to the Springdale Fishing Access Site east of Livingston.
Over the next few weeks, park biologists will monitor the Gardner and Yellowstone rivers to determine the extent of the invasion, Koel said.
"Our goal is to protect native fish populations and natural ecosystems. We will do everything in our power to prevent the establishment of smallmouth bass in the park and prevent them from preying on and displacing trout and other native fish,” he said in a news release.
Anglers have previously reported finding smallmouth bass in two locations on the upper Yellowstone River in the past seven years: Two smallmouth bass were caught at the Highway 89 bridge downstream of Livingston, and one near Emigrant. One smallmouth bass has also been found in the Shields River, a tributary to the Yellowstone east of Livingston.
