Biologists highlight threats to Pacific lamprey

NORTH CENTRAL WASHINGTON — For decades, Pacific lamprey have struggled to overcome a reputation as terrifying, blood-sucking parasites, fueled by their vampire aesthetic, parasitic nature, and villainous pop-culture portrayals, such as Animal Planet’s “Blood Lake: Attack of the Killer Lampreys.”

“We challenge you to think differently about that, because these are amazing fish deserving of our curiosity and respect and our help, and we should treat them as such,” said Fish Biologist Anne Grote of the U.S. Fish and Wildlife Service (USFWS), during a Science on Tap presentation on March 3.

Pacific lamprey are not so much villains as they are victims of misconceptions, public neglect and ecological threats. However, the ancient species plays a key role in river ecosystems and holds deep cultural importance for Indigenous communities.

According to USFWS, Pacific lamprey are one of the most widely distributed anadromous species in the Pacific Rim, with findings in Japan, Canada, Mexico, and states like Alaska, Washington, Oregon, Idaho and California. They are one of about 40 known lamprey species that exist today. However, there is still a lot unknown about the ancient species, with new discoveries constantly updating the research, said Grote.

“Unlike salmon, lamprey have not really been studied to death yet. It's a really exciting species to work with, because we are very much still in the era of doing fundamental science about lampreys,” said Grote

Lamprey start as larvae in the early stages of their life, drifting into areas of low velocity and fine substrates where they burrow, grow and live as filter feeders. Larval lampreys act similarly to earthworms, said Grote. As they burrow, they help decompact and oxygenate the sediment. By filter feeding, they improve water quality and cycle nutrients.

“We still don't really know exactly how long the larval stage lasts,” added Leavenworth Fisheries Complex Park Ranger Sophia Troeh, stating that the research originally understood it to last at least several years. However, ongoing studies suggest it could exceed 10 years.

Like salmon, Pacific lamprey have an anadromous life cycle. They eventually develop eyes and teeth, transforming into juveniles over a several month period. Then, they migrate to the ocean, where they live their adult lives as parasites, feeding on a wide variety of marine and anadromous fish. According to WDFW, adult Pacific lamprey return from the ocean after one to three years. As soon as they leave, they stop eating completely.

After their return to freshwater, Troeh said the species can wait up to three years before they actually spawn. Once ready to spawn, the lamprey builds a nest using their mouth to clear rocks, and can lay up to 200,000 eggs.

“If you see a lamprey nest in the stream, you'll know it, because unlike a salmon nest that has like an excavated pit and a pillow, lampreys make a ring of the rocks around their nest,” said Grote.

Pacific lamprey die after spawning, with their bodies distributing a wealth of ocean nutrients into the freshwater system. However, they are also an important food source while alive.

“Lamprey do not have bones, and they are very oily, which in wildlife terms, translates to super delicious. And basically everything wants to eat them,” said Grote. “We kind of lovingly refer to them as floating sticks of butter.”

Like salmon, lamprey have also been a culturally important food since time immemorial for tribal communities throughout the Pacific Northwest, and are considered both medicinal and nutritious.

The Pacific lamprey’s biology and life cycle is a recipe for longevity. Lamprey are one of the oldest living lineages in the world, according to WDFW. With fossil records dating back about 450 million years ago, the ancient species predates dinosaurs and trees. Lamprey have survived at least four mass extinction events.

Yet, Pacific lamprey populations have been in severe decline, especially in the Columbia River Basin. According to the Columbia River Inter-Tribal Fish Commission, counts of 400,000 adults were recorded at Bonneville Dam 60 years ago, compared with fewer than 20,000 in recent years.

In the Wenatchee River Basin specifically, adult Pacific lamprey face numerous barriers to getting upstream, while juvenile lamprey are vulnerable to getting pulled into irrigation diversions moving downstream. The species is also impacted by increasing river temperatures, habitat loss, and pollution.

“If you are lamprey wanting to spawn in the Wenatchee River, you need to cross seven main stem hydroelectric dams on the Columbia and then potentially two more here in the Wenatchee River itself,” said Grote, noting the Dryden and Tumwater dams.

While awareness and support has gained momentum for salmon, Pacific lamprey have been chronically overlooked. Many dams have implemented fish passages to help salmon, but the flow velocity and designs aren’t conducive to lamprey. Lamprey are not strong swimmers, and instead of jumping like salmon, they use the suction of their mouths to climb. 

“We love to build things with 90 degree corners,” said Grote. “You can't maintain suction with your little disc around a 90 degree corner.”

In the early 2000s, advocates attempted to get protections and funding for Pacific lamprey by adding it to the Endangered Species Act (ESA) list, but the petition was denied in part due to limited data on the species’ status.

This decision and the cultural importance of Pacific lampreys sparked a collaborative effort to restore the species between Tribes, federal, state and local agencies: Pacific Lamprey Conservation Initiative (PLCI). Additionally, conservation and rehabilitation efforts have been spearheaded by Native American Tribes.

For instance, the Yakama Nation, in partnership with the USFWS, has relocated spawning lamprey above dams into the upper Wenatchee River over the past decade. Grote said Pacific lamprey were historically found up to the mouth of Lake Wenatchee, but the species was not detected above Tumwater Dam as of 2015. After years of these distribution efforts, she said, larval lamprey are now being found in Nason Creek and the Chiwawa River.

While some progress has been made, PLCI’s 2022 assessment listed most of the Upper Columbia River basin as critically imperiled, with the species considered possibly extirpated, or locally extinct, in some subbasins.

“Our Pacific Lamprey are in trouble,” said Grote.

Taylor Caldwell: 509-433-7276 or taylor@ward.media