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Lamprey on the rise

by: PAMPLIN MEDIA GROUP: JONATHAN HOUSE - A lamprey ladder at Bonneville Dam snakes its way over the powerhouse. The new design enables more lamprey to continue upstream to spawn. The Bonneville Dam on the Columbia River is known for its impressive spillways and fish ladders, but tucked among the massive infrastructure

project are two long metal tubes that might just be the answer to saving one of the Columbia River’s unique and threatened species: the Pacific lamprey.

Lamprey are vampiric, eel-like fish that have called the Columbia River home for millennia. Many Native American tribes eat lamprey — a jawless fish sometimes called lamprey eels — and use the toothy fish for ceremonial and medicinal purposes, but over the past decades lamprey numbers have dropped dramatically.

More than 300,000 passed through the dam yearly in the 1960s, but only 6,000 lamprey made it through the dam in 2010, according to the U.S. Army Corps of Engineers.

“In the past, lamprey weren’t a consideration,” says 

by: PAMPLIN MEDIA GROUP: JONATHAN HOUSE - A lamprey gets measured during its passage through the Bonneville Dam.Diane Fredlund, Army Corps spokeswoman. “Nobody thought about them. Back in the 1930s (when Bonneville was built) nobody really knew much about them and whether or not that was going to be a problem. As they’ve been getting more attention, we started to look at what they truly needed.”

Why the numbers have plummeted remains a mystery. Lamprey numbers have dropped across the West Coast. In Oregon, the fish were once harvested at sites across the Columbia River Basin, but today are only found at Willamette Falls in Oregon City.

Ben Hausmann, an Army Corps fisheries biologist at Bonneville Dam, says it’s obvious that dams have played a role in the decline.

“I think it’s a combination of things,” he says. “I think most of it is those numbers are finally catching up to us. We didn’t have good passages through the dams for lamprey.”

Like salmon, lamprey spend their lives in the ocean and return to rivers to spawn. But the lamprey have trouble navigating traditional fish ladders.

by: PAMPLIN MEDIA GROUP: JONATHAN HOUSE - Lamprey dont do well with traditional fish ladders, but specially designed tubes seem to be helping the threatened species surmount and pass through the Bonneville Dam.“Our ladders aren’t set up to pass lamprey,” Hausmann says. “Historically, all we cared about were salmon. These guys have a sucker mouth, so they don’t do well with 90-degree angles at all, and the ladder is almost exclusively 90 degrees.”

Water in traditional fish ladders also moves too quickly for most lamprey, he says.

“I don’t want to put human traits on them, but they just don’t try the same way that salmon do. Salmon will bang their heads against something until they get through it. Lamprey will try maybe a handful of times, and then you’ll never see them again.”

But last year, engineers at Bonneville Dam installed a new lamprey-friendly ladder that is yielding encouraging results at increasing the lamprey population.

A pipe to success

The small ductlike system of pipes runs from the river over the dam and to the other side. A thin trickle of water is pumped through to attract the fish and spur them on their way.

“It’s underwhelming compared to the big fish ladders,” Hausmann says. “But that’s all it takes.”

The new fish ladder installed last year, which resembles a small pipeline, works in tandem with the salmon fish ladder already in place. The entrance to the lamprey ladder is underneath the salmon ladder on the by: PAMPLIN MEDIA GROUP: JONATHAN HOUSE - The sharp angles and fast-moving water at traditional fish ladders such as this one at Bonneville Dam work for salmon but not for lamprey. Washington side of the river, where the majority of fish congregate.

Lamprey find the entrance near the bottom of the river, where the water moves slower. The fish are guided to the enclosed cylindrical ladder, where they climb up steep ramps over the dam and back to the river on the other side.

The long fish tunnel rises sharply in places, but Hausmann says the lamprey have no problem scaling the enclosed structure.

Lamprey climb waterfalls to reach spawning grounds, and use their suction-cup mouths to latch onto the rocks and spring themselves forward.

“It’s pretty much straight up in parts, but they just climb. They latch with their mouths and then scurry and latch again.”

The first year the ladder was installed, only a handful of fish passed through to the other side of the dam, Hausmann says.

“They take a little bit of seasoning,” he says. “They have a really sensitive olfactory sense. If it smells weird or if you stick your hand in there, the passage (rate) will stop. It wasn’t until that metal seasoned, and got some of that river smell and other lamprey smell that they started coming. Otherwise they just won’t go.”

Numbers aren’t yet available for how many fish have passed through the fish ladders this year. But anecdotally, Hausmann says he’s seeing many more lamprey make their way through the dam.

“The first year it didn’t do very well, but with some structural modifications it’s doing great. It’s really passing fish,” he says.

That’s based on tagged fish that are released downsteam. Tagged fish help researchers see how well the fish ladders are working.

“It’s a little extra work for the fish, but that’s the way to do it. We get all the info on how they approach and how long it takes,” Hausmann says.

Bonneville has installed two lamprey ladders — its first ladder was installed in 2009 — and plans are in the works to install a third near the Oregon shoreline.

by: PAMPLIN MEDIA GROUP: JONATHAN HOUSE - A fish at Bonneville Dam is scanned for a tag by members of the Columbia River Inter-Tribal Fish Committee.“Lamprey high season runs from the end of June and into July,” Fredlund says. “So we should see numbers start jumping up in the coming months.”

Tribal effort

The early success of the revamped Bonneville fish ladders is “great news,” says Kelly Dirksen, fish and wildlife program manager for the Confederated Tribes of the Grand Ronde. “That success means it can be done,” he says.

Now similar efforts must occur at other dams in the Willamette and Columbia basins, Dirksen says. “We really believe to restore and recover lamprey is going to require effort by everybody.”

The Grand Ronde tribes, working with the Army Corps, are in the second year of a seven-year project to transport lamprey from the Willamette Falls area to Fall Creek Reservoir in Lane County. “Fish are in a system where they haven’t been for 50 years,” Dirksen says.

Unlike salmon, lamprey don’t have the same need to return to where they were spawned, he says. “They’re looking for the scent of other lamprey.”