GARDINER – An angler caught a smallmouth bass on Feb. 19 while fishing on the Gardner River at its confluence with the Yellowstone River, just outside of Yellowstone National Park.

Smallmouth bass are not native to this area, and an established population could pose threats to native fish in the upper Yellowstone River and others.

How the bass arrived at this location is unknown. It is illegal for people to move live fish from one waterbody to another without prior authorization from Montana Fish, Wildlife & Parks.

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.

FWP fisheries staff have not found smallmouth bass during yearly sampling efforts in the upper Yellowstone River.

One of FWP’s primary management goals in this area is to protect native Yellowstone cutthroat trout, which spawn in the tributaries and upper reaches of the Yellowstone River. An established population of invasive smallmouth bass could occupy the same areas, preying on and displacing trout and other native fish.

Anglers are the primary means of managing smallmouth bass where needed. FWP staff are preparing a proposed emergency rule for the Fish and Wildlife Commission to consider, which could require anglers to kill and report any smallmouth bass caught in the upper Yellowstone River.

Until any proposed rules can be implemented, anglers are asked to voluntarily kill, remove and document any smallmouth bass caught in the Yellowstone River and its tributaries between the Springdale Fishing Access Site east of Livingston upstream to the Yellowstone National Park boundary and provide them to FWP for testing.