Unchecked, they breed like water rabbits, devour native fish by the thousands and accumulate so many pollutants in their bodies that they’re harmful to eat.
Tribal and government experts agree that the northern pike must be stopped. The Kalispel Tribe, on the frontline of the war against this introduced, invasive species, has developed an innovative and effective program to do just that.
“Northern pike shouldn’t be thought of as a game fish anywhere in the [Columbia] basin,” said Deane Osterman, executive director of natural resources for the Kalispel Tribe. “They should be persona-non-grata and should be killed on sight.”
These may sound like strong words for an environmental steward to utter. But the threat is real, and it’s what he and his colleagues have been doing since March 19, when efforts began to greatly reduce the pike population by scooping the fish up in nets in the southern portion of Box Canyon on the Pend Oreille River. The work, which recently concluded, had pulled in 5,593 pike as of June 2.
About 16,000 other fish, the vast majority of them yellow perch or tench, were also picked up, but approximately 90 percent of those were returned to the water unharmed—and the 10 percent that died, roughly 1,600 fish, “is a whole lot less than the removed pike would have eaten,” said Jason Connor, the tribe’s fisheries project manager.
“We’ve seen pike with up to 35 prey items in their stomachs in a single meal,” he said. “Even if every single fish we’ve caught was killed, that’s still a fraction of what would have been eaten by the 5,500 pike we’ve removed.”
The Kalispel began monitoring the pike population as far back as 2005 and conducted a spring index netting survey starting in 2010 to profile annual changes in the fish’s population. What they found, according to the Kalispel’s website, was “exponential growth” of the pike, whose numbers grew from 400 adults to 5,500 adults between 2006 and 2010. Northern pike were also discovered in Boundary Reservoir and the un-dammed parts of the Columbia River in Canada, as well as Lake Roosevelt and two lakes in Spokane County, the site said. They now extend from the upper Columbia River near Castlegar, British Columbia, downstream to Lake Roosevelt, where they are still low in number. Only the Grand Coulee and Chief Joseph dams separate them from anadromous runs of salmon and steelhead.
To Kalispel are going all-out to keep this threat at bay.
“We’re fishing twenty nets a day. They’re all 150 feet long with thirty-foot panels,” Connor said. The mesh ranges in size to catch various-sized fish, but the smaller sizes were not used so as to avoid inadvertently capturing small yellow perch.
Over the next two years the Kalispel plan to keep the same level of intensity each and keep pike 87 percent below 2010 levels, according to Connor. The spring netting survey in 2010 yielded an average of 12.5 pike per net, he said. In the beginning of 2011 it was 13.2.
“After our initial five weeks of suppression this year we were at 2.9 pike per net night,” Connor said. “Our goal of 87 percent reduction would be 1.7 northern pike per net night. We got pretty close to our goal within weeks.”
But any drop in vigilance could allow the population to skyrocket again. The State of Washington agrees with the tribe and has changed pike’s classification from game fish to prohibitive species.
“Pike are not welcome,” Connor said. To enlist the public’s help in catching and killing these invasive beasts, the Kalispel Tribe is holding two fishing derbies this summer, one from June 29–July 1 and the second from August 3–5. PikePalooza 2012 not only holds the promise of ridding the river of a pest but also offers cash and prizes.
If it were simply a matter of catching and eating the pike, that would be one thing. But as it turns out, it’s dangerous to consume pike regularly. Tissue samples measured for levels of mercury, PCBs and dioxins show that pike bioaccumulate chemicals, meaning the substances collect in their bodies as they grow, without being excreted. Washington now advises women and children to eat no fish longer than 24 inches, and no more than two meals per month of the smaller fish.
“Now we have several tons of fish flesh to deal with when we remove it from the reservoir,” said Connor. “It would be completely irresponsible to distribute those to any needy group.”
The Kalispel Reservation is very small but fronts the river. Fish have historically been extremely important to the tribe. Before the advent of hydroelectric dams and invasive species like pike, tribal members put up huge amounts of salmon to carry them throughout the year. Dams have prevented anadromous fish such as salmon and steelhead from reaching this area, and pike have dramatically reduced trout and mountain whitefish, two native species that were formerly important.
Funding for the project has come from a variety of sources: the tribe, utility companies (Bonneville Power, Seattle City Light, Avista) and the Bureau of Indian Affairs.
“We are highly impacted by hydropower,” Osterman said. “The Kalispel Tribe is arguably the most highly impacted ethnic group in North America by hydropower. In a 150-mile stretch of river there are eight major hydroelectric dams.”
The biologists admit frustration in removing an opportunity for tribal members to take fish while being unable to immediately replace it with something else.
“The benefits are yet to be realized. They are out there a decade,” Osterman said. But without this step the future could be much worse, especially if pike were to reach salmon and steelhead waters.