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Wednesday, February 28, 2024
Feb. 28, 2024

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Northern Pike remains top invasive species in Columbia River system

Predator fish known to eat salmon and steelhead smolts

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Northern Pike, such as this one taken during a gill net operation, have been welcomed by some anglers for their game fish qualities. However, pike are voracious predators, and could decimate out-migrating salmon smolts if they make it to the anadromous zones of the Columbia River.
Northern Pike, such as this one taken during a gill net operation, have been welcomed by some anglers for their game fish qualities. However, pike are voracious predators, and could decimate out-migrating salmon smolts if they make it to the anadromous zones of the Columbia River. (WDFW photo) Photo Gallery

Northern Pike, a non-native predator with a voracious appetite, has been found in several systems that feed the Columbia River, and while many anglers welcome them as a hard-fighting game fish, they are giving state biologists headaches.

That is because if those pike make it into the anadromous sections of the Columbia, they could do incredible damage to the already struggling salmon and steelhead runs therein.

And, they are not too far from doing just that.

According to Jesse Schultz, the Prevention Lead for the Washington Department of Fish and Wildlife’s Aquatic Invasive Species Unit, the Northern Pike is the greatest current threat to native fish in the Columbia River.

They have already shown up in several systems in the upper Columbia basin. Two areas in particular worry Schultz, the Pend Oreille drainage, and Franklin D. Roosevelt Lake, the impoundment behind Grand Coulee Dam on the upper Columbia.

“Northern Pike is one of the most dangerous invasive species we have in Washington,” Schultz said. “In the Columbia River we cannot let the pike get into the anadromous part of the river.”

The Columbia is already home to a host of non-native predator fish, including bass and walleye, but the pike is a much more aggressive predator, and would find the out-migrating salmon and steelhead smolts a tempting target.

While many invasive species hitch rides in ballast water or shipments of goods and food, some are purposely planted by people illegally. This crime is often referred to as Bucket Biology, and is the suspected mode of introduction for the Northern Pike.

In Lake Roosevelt the species has been limited to the upper half of the reservoir so far, but the state has been actively engaged in a population suppression strategy with the Colville and Spokane tribes. That strategy has included gill-netting as well as fostering competitions to catch and remove as many pike as possible.

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“We are never going to rid the pike from the whole system,” said Schultz, “but we are suppressing it as much as we can.”

When asked if it would be possible for the pike to move down out of the reservoir, he replied that it was.

“It is a strong possibility. Banks Lake is immediately below Grand Coulee, and we have used environmental DNA in Banks.”

Northern Pike were detected.

“It’s tricky because we do pick up Northern Pike in Banks Lake, but it could just be the DNA from Roosevelt,” Schultz said.

Schultz explains that fish continuously sluff off DNA into the water they inhabit, and new technology makes it possible to detect this DNA in water. The advantage is you do not have to actually handle a species to know it is present.

He reports that the department has already developed a plan of action should the pike move into the anadromous zone. If the pike do show, they have a plan in hand and are ready to move quickly.

Other invasive species are not predatory, but could do even more damage than pike. These include Quagga and Zebra mussels, two species of the same family that are filter feeders. They have infested the Great Lakes and many other rivers and lakes across the eastern United States and the Midwest with devastating consequences.

The species have no natural predators, and quickly replace most biomass in the waters they infest. They attach themselves to any solid structure, and have clogged hydro systems, flood control structures, and every bit of infrastructure they colonize.

“For us that is one of our biggest tasks and projects; keeping them out of Washington,” Schultz said. “As of yet there has never been a verified or confirmed zebra or quagga mussel in Washington waters.”

He is concerned about the effects such a species would have on the hydropower dams on the Columbia River, not to mention the Snake, and all the small impoundments in the tributaries.

It’s not just hydropower facilities that would be impacted. Schultz points to the system of irrigation and other agricultural facilities that would be infected.

“It would be catastrophic,” he said. “They are going to clog everything, not just the hydro. It doesn’t matter what the use is, all of our infrastructure will be clogging.”

That’s not all. These filter feeders would remove most of the phytoplankton, which are what young salmon feed on. Less food means fewer and smaller juveniles. The water clears out, and that lets sunshine in even deeper, leading to massive blooms of water vegetation.

How do we stop these invaders?

The WDFW offers plenty of useful resources on their aquatic invasive species webpage.

There is information on the invasive threats facing Washington waters, how to report possible sightings of invasive species, among other things.

The department also sets up mandatory check stations regionally, and depending on the season, they may be operating as many as five stations at one time.

“One of our biggest check stations is on I-90 right at the border with Idaho at Spokane. It is mandatory for all boaters to stop and get checked.”

He reports that the department tries hard to complete the exams and get people back on the road quickly.

He also points to the strategy of clean, drain, and dry.

“That’s actually a law,” Schultz said. “Transporting any kind of water craft, be it a boat or jet ski or anything. The law says it has to be cleaned and drained, and cleaned means no organic material. No mud, no vegetation, no organic material of any kind.”

“Drain” refers to lake water that is typically kept in the live wells, and the bilge area. That’s simply pulling the plug.

“If boaters did that many threats could be eliminated. The only way the Quagga mussels can get to Washington is by humans.”

People can also call the hotline and schedule an inspection and cleaning appointment.

“We decontaminate with hot water that kills mussels but does not harm the boat. And, it’s free.”

Boots are another way species can move from water to water. Schultz said freezing your footwear for at least 24 hours will kill most hitch hikers. Do this whenever you are moving between different bodies of water.

Call WDFW’s Aquatic Invasive Species hotline with any questions at 1-888-WDFW-AIS or email ais@dfw.wa.gov.

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