RICHLAND, Wash. – Pacific lamprey are a toothy, eel-like fish. They serve as an important food source for Northwest tribes. Their populations have dramatically declined throughout the Columbia River system.
But researchers are working on a new way protect their habitat, with a little bit of a shock.
Tribal elders will tell you parts of the Columbia River used to be black with Pacific lamprey. That was up until the 1950s. Images of lamprey-covered rocks at Celilo Falls evoke Medusa’s head.
“So many fish at the dams that they were clogging up traps and pipes,” said Brian McIlraith, the lamprey project leader at the Columbia River Inter-Tribal Fish Commission.
McIlraith said lamprey populations have sharply declined since the mid-20th century. The fatty eel-like fish are an important part of Columbia River tribes’ diets. But salmon and steelhead restoration has overshadowed their decline.
“Probably the historic low was in 2010,” he said.
An estimated 23,000 lamprey were in the Columbia that year. The tribes and state and federal partners are working to slow the lamprey population decline.
McIlraith says biologists don’t know much about Pacific lamprey from their life cycle to where they live.
“We don’t even know what makes good habitat good habitat. We kind of know what it looks like, but we don’t know why fish cluster in certain locations, whether it’s the sediment, or the flow, or dissolved oxygen. We figure the more we learn about that, it’ll help us help them in the long run,” McIlraith said.
One thing they do know: juvenile lamprey like to bury themselves in the sandy silt. Typically they spend about seven years at river bottoms, feeding on algae and other phytoplankton.
Most often researchers have found lamprey habitat by wading into shallow tributaries.
“The methods that we have right now, it takes a lot of people and a lot of time to really sample all areas,” he said.
But researchers at Pacific Northwest National Laboratory in Richland, Wash., have developed a way to find juvenile lamprey habitat in the Columbia and Snake River systems. Other sampling techniques don’t work as well in the fast-moving rivers.
Bob Mueller is a research scientist. He stands in the middle of the lab’s new aquatic research center and points to a device that looks like a small, metal sled.
“This is deployed from a boat. It’s a weighted platform. It’s got a video camera on it. And it’s got wires that come down on each side of it. And this is an electroshocking system,” Mueller said.
The wires drag on the river bottom. They deliver a small shock to the lamprey. It’s sort of the equivalent of shocking someone with your finger. To show how the device works, Mueller narrates a video of an experiment on the river from this summer.
“We’re kind of drifting fairly slow here. But as we’re applying the shock the lamprey that are in that vicinity will come up, become visible. You see one right there,” Mueller said.
The device works best in clear water. Researchers tested the equipment in the lab. They found that 60 percent of lamprey left the river bottom when they were shocked. Mueller says that gives researchers a baseline to estimate how many lamprey they find.
The video allows researchers to figure out the lamprey’s size. They can then estimate ages.
Mueller says knowing more about where lamprey live can help prevent dredging and watershed projects that disturb habitat.
“If those areas are known and characterized, you can set those aside as protected zones. You don’t want to disrupt those in any way, if you can help it,” Mueller said.
Lab researchers will test the electroshocking device in a river this winter.