Pacific Lamprey – Ancient Fish of the Columbia
Since European colonization of the Pacific Northwest began in the latter half of the 19th century, populations of salmon and steelhead have declined dramatically. A widespread effort to restore these fish populations, and the habitat on which they depend, is underway in the Columbia River Basin.
The Pacific lamprey, another important fish species which has declined dramatically since colonization, has received little attention. To address this gap, the Methow Salmon Recovery Foundation has begun an outreach and education effort to provide information that will assist in the protection and recovery of Pacific lamprey in the Columbia River Basin. We are also monitoring lamprey populations in the Methow watershed.
To help educate the public and restoration groups about the benefits of lamprey, MSRF published the Pacific Lamprey Habitat Restoration Guide in the spring of 2015. This guide summarizes lamprey life history and habitat needs and outlines best management practices and restoration techniques that benefit lamprey.
Lamprey are eel-like animals and members of a small group of jawless fish. As a species, lamprey are more than 400 million years old, making them among the most ancient of vertebrate species on Earth. Although they are classified as fish, they lack bones, paired fins, and scales. Adult lamprey are parasitic, feeding on the blood and other fluids of other fish through their distinctive toothed oral disk.
US Fish and Wildife Service Photo
Like salmon, Pacific lamprey are anadromous, meaning that they begin their lives in freshwater, migrate to the ocean, and return to freshwater as adults to spawn. Historical accounts from the Columbia River describe Pacific lamprey returning to spawn in such great numbers as to pile three layers deep in some areas. While unable to leap rapids and other obstructions during their migrations, lamprey can climb waterfalls by using their mouths as suction cups to hold onto the rocks and using quick bursts of their bodies to move themselves up.
After several years of filter-feeding, ammocoetes transform from larvae into sub-adults called macropthalmia. These young adults develop adult mouths and migrate downstream to the ocean. Their poor swimming ability and high nutrient content make them an attractive prey for predators such as birds and other fish. Predators' preference for lamprey may reduce their predation on migrating salmon.
As they enter the Pacific Ocean, the macropthalmia transform into adults and begin the parasitic phase of their lives. Their parasitism is rarely fatal or even severely harmful to their hosts. Seals, sea lions, killer whales, and numerous other fish species prey on adult Pacific lamprey in the ocean. Adult lamprey return from the sea to spawn in inland rivers. As with salmon, the adults die after spawning, releasing nutrients from the ocean into the local ecosystem.
Though early data are fairly sparse, some estimates of historical abundance can be inferred from commercial harvest records. Hundreds of thousands of lamprey were harvested annually at Willamette Falls in the late 1800s and 27 tons of adults were harvested near the mouth of the Columbia River in 1913.
Lamprey climbing Willamette Falls
Unfortunately, lamprey numbers have declined dramatically over the last century. By 1994, numbers at almost all survey locations had dropped dramatically. Recent monitoring in many locations within the Columbia River Basin has found local lamprey populations either depressed or absent from their traditional habitat. MSRF's inventory of lamprey distribution in the Methow watershed in 2008 found them present in the Chewuch River and Methow River downstream of Winthrop. They were absent from their historic habitat in the Methow River upstream of Winthrop and in the Twisp River. Annual monitoring continues at a number of sites and has shown an overall declining trend in abundance from 2008-2014.
Like salmon, lamprey are vulnerable to habitat degradation from agriculture, urban development, and other human activities. Fish passage structures at hydroelectric dams work for salmon, but because lamprey are poor swimmers and cannot jump, dams still greatly impede their migration.
The disappearance of lamprey from the Columbia River system also threatens the cultural heritage of Native American tribes, who historically relied on lamprey for subsistence, ceremonial, and medicinal purposes. Members of the River Inter-Tribal Fish Commission, including Nez Perce, Umatilla, Warm Springs, and Yakima tribes have sponsored studies and reports on the status of the species along with plans to restore Columbia River Basin populations. Tribal efforts have also encouraged Federal and State resource managers to develop management plans and guidelines aimed at reducing harm and increasing funding for habitat restoration targeting Pacific lamprey.
MSRF is interested in restoring habitat for the Pacific lamprey as part of our commitment to improving stream habitat in the Methow watershed. Modifications to existing or future salmon restoration projects could include features specifically designed to provide habitat for these ancient fish.
For more information about lamprey, please contact John Crandall at (509) 341-4341.