FWP to instruct anglers to kill invasive smallmouth bass

After an invasive smallmouth bass was caught in the Gardner River just outside Yellowstone National Park on Feb. 19, Montana Fish, Wildlife and Parks is asking anglers to voluntarily kill the fish. FWP also will propose a rule next month that would require them to be killed and reported.

The catch worried wildlife officials as the fish is not native to the area, and an established population could harm other local fish like cutthroat trout, but so far no evidence of further invasion has been found.

According to Fish, Wildlife and Parks, February’s catch is the fifth time that a smallmouth bass has been found in Montana in the last seven years. Two smallmouth bass were caught at the Highway 89 bridge downstream of Livingston in 2014 and one near Emigrant in 2018. And a smallmouth has also been found in the Shields River, a tributary to the Yellowstone east of Livingston, this summer that FWP said appears to have come from the illegal introduction of the fish to the Cottonwood Reservoir.

While the numbers and abundance of the fish vary from place to place, their known breeding population extends from Laurel to the Big Sky Timber area, according to FWP.

“Smallmouth bass are an invasive predatory species that will threaten our wild and native trout populations if they become established in the upper Yellowstone River,” said Yellowstone National Park Lead Fisheries Biologist Todd Koel in a press release. “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.”

Since the catch, park officials and United States Geological Survey officials have been sampling and monitoring the Gardner and Yellowstone Rivers to gauge the possible extent of the invasion, but so far no evidence of further invasion from smallmouth bass has been found, according to the park.

“Biologists will continue to watch the situation closely and look to anglers to kill and report any smallmouth bass caught in Yellowstone National Park when the fishing season opens Memorial Day weekend,” park officials said in an email.

When fishing season opens up in the park on Memorial Day weekend, anyone who catches a smallmouth bass in Yellowstone National Park will be required to report and kill the fish, according to the release.

And at FWP, staff are preparing an emergency rule to go before the Fish and Wildlife Commission in April that would require anglers to kill and report any smallmouth bass caught in the upper Yellowstone River. Until then, 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, according to the press release from the agency.

“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,” the agency said in its press release.

In the U.S., there are more than 250 invasive aquatic species from other continents and more than 450 non-native aquatic species that have moved outside their natural range, according to the National Park Service. And in Yellowstone’s waters, the smallmouth bass is one of at least eight aquatic invasive species that exist. The additional species include four other fish, two mollusks and one parasite that causes whirling disease in cutthroat trout and other species.