FWP to anglers: catch, kill and report smallmouth bass in Bitterroot River

This story is adapted from the MT Lowdown, a weekly newsletter digest containing original reporting and analysis published every Friday.

Montana Fish, Wildlife and Parks has enacted an emergency regulation for the lower stretches of the Bitterroot River after officials last week announced the “first confirmed smallmouth bass in the Bitterroot.” The department is asking anglers who catch the species to keep it, kill it, and report the catch.

Fisheries biologists are trying to keep smallmouth out of the Bitterroot to prevent the non-native fish from preying on and displacing native species.

“Smallmouth bass are a predatory and adaptable species and could have a long-term impact to this cold-water fishery,” the department said in a July 26 release. Though department personnel found no additional smallmouth bass when they surveyed the Bitterroot after the initial report, they’ve concluded that the river is suitable habitat for smallmouth to establish and sustain a population. 

The closest populations are in drainages dozens of river miles away, namely the Clark Fork below Saint Regis, which is 80 miles downstream, and the Clearwater River system, about 70 miles upstream. The smallmouth that was reported in the Bitterroot was found 3.5 miles upstream of the river’s confluence with the Clark Fork near Missoula.

In February of last year, an angler caught a smallmouth bass in another unexpected cold-water fishery, the Gardner River, which flows into the Upper Yellowstone River. 

After that incident, FWP noted that it’s illegal to move live fish from one water body to another without prior authorization from FWP.

In a recent memo to the Fish and Wildlife Commission, the department wrote that there have been reports of smallmouth at isolated private fish ponds near Hamilton, but FWP is unsure if the fish an angler caught on July 5 escaped from a private pond, emigrated from existing river populations or was introduced to the Bitterroot illegally. FWP is hoping to gain more insight into the origin of any smallmouth bass in the river system by analyzing the fish tissue and otoliths, or ear bones, of any captured fish.

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The introduction of smallmouth, which are native to the midwest, has proven problematic for fisheries in other parts of the country, including other parts of the Columbia River Basin, where researchers have implicated their introduction in the decline of Pacific salmon, for example, and warn that climate change is expected to expand suitable habitat for the species.

Former member of the Fish and Wildlife Commission and current director of Trout Unlimited’s Montana Water program Pat Byorth said there’s a “fairly broad overlap” between smallmouth habitat and trout habitat. Trout populations tend not to come out on the winning end when water temperatures rise and smallmouth gain a foothold, he said.

“The fear is that if these low water conditions, like we’re seeing in the Bitterroot and the lower Clark Fork this year, persist, we’re just going to open the door for warm-water fish in cold-water fisheries that can replace the trout,” Byorth said. “The trout are already under stress with warm, low water, and if you throw in another factor, that’s reason for concern.”

The Fish and Wildlife Commission is expected to vote on a proposal to codify FWP’s catch, kill and report guidance in its Bitterroot River fishing regulations on Aug. 17, effectively making FWP’s emergency regulation permanent.