Listen

The fight to save Columbia River salmon could hinge on a major battle taking place in the basin鈥檚 biggest reservoir. It pits biologists against a fish: The invasive northern pike.

 They eat anything in their path 鈥� they鈥檝e even been spotted chomping on ducks and bats. That鈥檚 bad news for soft-bellied fish, like rainbow trout.

鈥淭hese pike here, they can really prey on a lot of fishes that these other fish in the reservoir right now can鈥檛,鈥� said Travis Rehm, a fisheries biologist with the Spokane Tribe of Indians.

Rehm is one of the anglers standing in their way as the Spokane Tribe and other fisheries managers launch a counter attack. Biologists are catching as many northern pike as they can in Lake Roosevelt, the reservoir held back by the Grand Coulee Dam.

If the fish make it past Grand Coulee and the next dam downriver 鈥� Chief Joseph Dam 鈥� it could be game over for the Columbia鈥檚 threatened and endangered salmon and steelhead populations.

These native fish populate the 545-mile section of the Columbia River below the Chief Joseph Dam 鈥� plus thousands of miles of tributary rivers and streams.

鈥淣ative species here haven鈥檛 evolved to deal with a predator that鈥檚 quite like pike,鈥� Rehm said.

To push back the northern pike鈥檚 steady progression, biologists will be on the water for much of the summer, setting and checking about 15 gillnets each day. The goal: snagging as many northern pike as possible.

Biologists are catching as many northern pike as they can in Lake Roosevelt, the reservoir held back by the Grand Coulee Dam. CREDIT: COURTNEY FLATT/NWPB

Rehm and two other biologists, Andy Miller and Joe Cronrath, check the gillnets within 24 hours after they鈥檝e set them in place.

These biologists know where to place the gillnets: near channels, in shallower areas, where the northern pike 鈥� apex predators in these waters 鈥� like to ambush prey. Tribal biologists also set gillnets for northern pike last year.

鈥淭he hotspots haven鈥檛 changed. The densities within those have, and they鈥檙e just increasing,鈥� Rehm said.

Gillnets are controversial because fish that aren鈥檛 being targeted 鈥� like smallmouth bass, walleye and northern pikeminnow 鈥� get tangled in the nets. But Rehm said they鈥檙e trying to be careful.

鈥淲e鈥檙e doing our best to minimize bycatch and be as cognizant of everything as possible,鈥� he said.

All of the non-native fish the team catch are gutted. If people will eat the fish, the biologists deftly filet it 鈥� along with the northern pike 鈥� and take it to the Spokane Tribe鈥檚 food bank.

Biologist Travis Rehm pulls in a northern pike with a gillnet. The biologists caught 21 northern pike on Lake Roosevelt in one day.

CREDIT: COURTNEY FLATT/NWPB

They keep the heads of the larger northern pike. Tiny bones in the head can tell them how old the northern pike is and where it鈥檚 been. They clip its fin to collect DNA, which can help biologists track northern pike spawning.

Recently, biologists for   to netting northern pike. The cadre saturated known hotspots with gillnets for a week. In the end, they caught 439 northern pike.

They especially want to catch female northern pike before they spawn. Each fish can have somewhere around 10,000 eggs. Fewer eggs mean fewer pike in the future.

鈥淲e stopped at least 2,160,000 eggs from being released into the water during this one week survey,鈥� said Holly McLellan, the lead biologist with the Confederated Tribes of the Colville Reservation.

In a different area of Lake Roosevelt called the Sanpoil Arm, Colville biologists netted a whopping 28-pound female northern pike. McLellan said the eggs from that fish alone weighed 4 pounds.

In this vast reservoir, the presence of these predatory outsiders means other fish could be in trouble. In California and Alaska, northern pike ate all the types of fish anglers like to catch.

鈥淭he [hatchery] rainbow trout are getting hammered,鈥� Rehm said.

Biologists have found northern pike like to eat the hatchery-raised rainbow trout in Lake Roosevelt. This particular fish had three rainbow trout in its stomach.

CREDIT: COURTNEY FLATT/NWPB

All day long, biologists find hatchery rainbow trout inside northern pike stomachs. One fish had recently eaten three rainbow trout.

Northern pike didn鈥檛 just all-of-a-sudden show up in Lake Roosevelt. They were illegally introduced into Montana as early as the 1950s 鈥� thanks to outdoorsmen who took it upon themselves to bring these game fish from the Midwest by the bucketful to stock Western waters 鈥� nowadays, conservation scientists refer to these folks as 鈥渂ucket biologists.鈥�

Since then, the northern pike have been relentlessly swimming, reproducing, and eating their way down the tributaries and lakes of Montana, Idaho, and Washington 鈥� all connected waters that are part of the Columbia Basin.

Tony Grover is the fish and wildlife director for the Northwest Power and Conservation Council, which can direct money toward the northern pike eradication. Grover said the only times these fish have been completely stopped is in isolated waters.

鈥淎ny time they鈥檝e shown up in larger, interconnected systems, it鈥檚 been impossible to eradicate them. So now that they鈥檙e in the system, they鈥檙e here to stay, almost certainly,鈥� Grover said.

Once fisheries managers recognized the threat these invaders posed to native species, they tried to stop it. The Kalispel Tribe of Indians knocked back the northern pike population in Washington鈥檚   on the Pend Oreille River.

But some fish made it past their nets and on toward the Columbia.

Northern pike entered Lake Roosevelt around 2011 and kept moving. They鈥檝e nearly covered the lake鈥檚 150-mile length and have been spotted within 17 miles of Grand Coulee Dam, where the Colville Tribe recently caught the large female northern pike.

Grover worries smaller northern pike could one day slip through the Grand Coulee Dam鈥檚 turbines. He said it could be just a few more years before that happens.

Northern pike are voracious. Because their mouths open so wide, they can eat a lot of fish other predators can鈥檛.

CREDIT: COURTNEY FLATT/NWPB

To help with the fight, managers are paying anglers $10-a-head for any northern pike they catch.

Back at the lake, Rehm said he鈥檚 鈥渃autiously optimistic鈥� they can slow the pike鈥檚 progress.

鈥淚f we can get a handle on them and be able to manageably net them, it鈥檒l be a lot easier go,鈥� Rehm said.

On this day, Rehm and the other biologists catch 21 northern pike.

鈥淲e鈥檒l give them hell, he said. 鈥淭hat鈥檚 the plan.鈥�

Copyright 2019 Northwest Public Broadcasting

Related Stories:

/

/

Copyright 2019