State and tribal fishery managers will begin one of their largest, most intensive efforts yet to suppress invasive northern pike in Lake Roosevelt by setting as many as 500 gillnets in early May during the species’ spawn.
“We need to put a dent in them,” says WDFW’s Chuck Lee. “They’ll be easier to control if we get a handle on this earlier. The longer we wait, the more expensive it gets.”
His agency along with the Colville, Kalispel and Spokane Tribes, Chelan and Grant Counties PUD, National Park Service and the Northwest Power Planning Council are all participating in the intensive four-day, May 6-9 effort that follows on several years of netting since the fish first turned up in the reservoir in 2011.
Ten crews will set nets on Monday, Tuesday and Wednesday and pull them on Tuesday, Wednesday and Thursday.
The effort is being timed to water temperatures that spur northerns to get more active and start looking for habitat to broadcast their eggs and milt and thus become more susceptible to netting.
“We’re trying to catch mature adults before the spawn,” Lee says.
According to a notice from the Colville Tribes, nets will be set in waters 20 feet deep or less that attract staging pike and which “should also help reduce bycatch of non-target species.”
The generally cool water temps also means better survival rates for walleye and trout caught in the nets.
The latter species appears to be a favorite of the nonnative species that was flushed out of the Pend Oreille River system after being illegally introduced there, probably from Idaho’s Couer d’Alene watershed.
“We see a lot of hatchery trout in their guts, a lot of unknown trout too — wild redbands? hatchery trout?” says Lee.
Past years’ suppression efforts do appear to be paying off.
He says that where 5- and 6-year-old pike had been turning up in nets, they’re now primarily pulling in 1-, 2- and 3-year-old fish.
“If we can continue to keep on top of these females before they mature and spawn,” that will help keep the population under control, he says.
The Colvilles have also been paying anglers a bounty for pike heads.
The ultimate worry is that if northerns escape Roosevelt and get through Lake Rufus Woods below it, they’ll have a feast in the form of hatchery and wild ESA-listed salmon and steelhead smolts awaiting at the mouth of the Okanogan River — perhaps even returning adult sockeye.
Lee says that pike are slowly moving down Roosevelt. Where populations were focused around the mouths of the Kettle and Colville Rivers, fish are turning up at Hunters and outside the Spokane Arm where the impoundment swings west.
Along with the tribes whose reservations border Roosevelt, the Upper Columbia United Tribes will be on hand to observe the effort, Lee says.
“I’m kind of excited to see us get this group together to suppress pike,” he says of all the participants.