Northern pike kept in check in northeast Wash.

An unwanted piscatorial predator is becoming less common in northeast Washington.

Twenty years after the first northern pike was detected in Box Canyon Reservoir on the Pend Oreille River system, state and tribal suppression efforts seem to be keeping the carnivorous fish in check there and in Lake Roosevelt.

Over the past 12 years, gillnets set by the Kalispel Tribe in the Pend Oreille system have removed nearly 20,000 northern pike. Downstream, in Lake Roosevelt, suppression efforts by the Colville Tribes, the Spokane Tribe and the Washington Department of Fish and Wildlife have removed just over 20,000 since 2015.

In recent years, the pike are fewer and farther between. In Box Canyon Reservoir, for example, the Kalispel Tribe caught nearly 6,500 pike in 2013. This year, they caught fewer than 300.

“We were able to crash that population,” said Joe Maroney, director of fisheries and water resources for the Kalispel Tribe.

That’s good news for all the other fish in the Columbia and Pend Oreille rivers, and a reason for optimism as fishery managers continue trying to keep the piscavores from moving downstream, where they could pose a threat to protected steelhead and salmon. It has also allowed gillnetting crews to become more targeted in how they deploy their nets, and to use fewer of them.

Still, there is no end in sight. Because pike are notoriously fecund, eradication is all but impossible, and officials plan to continue suppression efforts for the foreseeable future. Maroney refers to the work as “mowing the grass.”

Northern pike are a prized gamefish in many places. They’re toothy critters that grow big and old — sometimes weighing more than 40 pounds and older than 20 years — and they’re known to take flies and lures aggressively, making them a fun target for anglers.

They’re also known to eat their way through a fishery, feeding on minnows, perch and any other finned creature they deem edible.

Pike are native to parts of Alaska and Canada, and parts of the Midwest. They aren’t native to the Columbia River drainage, however, and only showed up through illegal introductions in western Montana and northern Idaho.

Though they had existed in the Clark Fork River system in Montana for decades, the fish hadn’t been confirmed downstream of Albeni Falls Dam until 2004, when Kalispel Tribe fisheries crews found northern pike during routine surveys of Box Canyon Reservoir.

“We were like ‘Oh, OK. This is kind of interesting,’ ” he said.

Initial population estimates put the number of pike in the reservoir at about 400. But within a few years, the numbers exploded.

In 2010, the Kalispel Tribe estimated there were about 5,500 in the reservoir, Maroney said. The next year, that nearly doubled to 10,000.

Other species suffered. Declines became apparent in other species in the river, such as trout and mountain whitefish.

The Kalispel Tribe began its suppression program on Box Canyon Reservoir in 2012. That spring, crews set just more than 1,000 gillnets and removed about 5,800 pike.

They’ve been back at it every year since. Progress started showing in 2015, the first year the number of pike caught dropped below 1,000. Perhaps more important, crews were averaging less than one pike per net.

Meanwhile, alarm bells were going off downstream in Lake Roosevelt.

Holly McLellan, a biologist with the Confederated Tribes of the Colville Reservation, said a few pike had shown up in fisheries surveys starting in 2011, and that the fish are believed to have washed downstream from the Pend Oreille drainage. By 2015 they were seeing adults and juveniles — a sign the species had taken hold and was naturally reproducing.

Since then, the Colville Tribes, the Spokane Tribe and the Washington Department of Fish and Wildlife have all been working to suppress and monitor the lake’s pike population. Gillnetting started in 2015, and has since removed more than 14,000 fish, according to Chuck Lee, who leads the state agency’s pike work.

Another 6,000 have been removed from the reservoir through other methods, including an angler reward program run by the Colville Tribes. Anglers can turn in the head of a northern pike at certain sites around the lake for a $10-per-head reward.

Officials working on Roosevelt have seen the same trend as the Kalispel Tribe — catch rates are dropping.

The angler reward program, responsible for more than 3,600 dead pike since 2017, provides a good example.

McLellan said more than 1,000 heads were turned in during the first year. Over the past four years, the tribe has collected between 60 and 100 heads each year.

“Those trends are following our decrease in abundance,” McLellan said.

Reduced catch rates have allowed crews to become more targeted in their gillnetting and other efforts. It generally means there are fewer pike. But it doesn’t mean the fish aren’t moving, particularly in a reservoir as big and complex as Lake Roosevelt.

McLellan said crews are finding more of the fish in the middle portion of the reservoir — roughly from the mouth of the Spokane River upstream to the Gifford area.

“There’s a slow creep of the fish moving downstream,” she said.

Downstream migration is a major concern for fisheries officials, particularly if the fish were to slip below Grand Coulee or Chief Joseph dams.

McLellan’s team is monitoring Banks Lake and Lake Rufus Woods for the possibility of a pike invasion. This spring, the department finalized a northern pike rapid response plan that lines out how the agency will respond if the predators show up in more places.

Even the invasion of a couple of fish can have major consequences. Lee, the Fish and Wildlife biologist, said a single pike can lay more than 100,000 eggs, and that the spawning of just a few fish can lead to a population explosion.

That also means the few fish that evade a gillnet can still pose a problem, and that sustained effort is key to keeping numbers low.

The Kalispel Tribe knows that from experience. Maroney said the COVID-19 pandemic limited their ability to do the suppression work in 2020, and a report shows they set just 155 nets and caught 115 pike.

Then, for the next two years, pike numbers were back up. In 2021, they caught more than 600. In 2022, they caught more than 800.

Catch numbers were down again in 2023 and 2024, a sign they’ve gotten things back under control. But that taught officials that they can’t ease up.

“It was an interesting example,” Maroney said. “If you take the foot off the gas, the fish will come back.”