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These wriggly leech-like creatures not parasitic

Pacific lampreys are passing over Willamette Falls this month, and are entering streams near you.

Photo Credit: SUBMITTED PHOTO - Carson McVay, a resident of Oregon City and a biologist with the Warm Springs Tribe, is participating in a study to measure the abundance of Pacific Lamprey passing Willamette Falls.Lampreys are like nothing else you’ll ever see. Lampreys are a unique class of ancient animals that pre-date the dinosaurs. They lack bones, paired limbs and jaws. The young ones are blind and burrow in the mud where they filter feed on algae. Some lampreys are anadromous, migrating between freshwater streams and the ocean. Some of them are ecto-parasites that cling to the skin of their hosts by their jawless sucker mouths and suck blood. They are very slimy and wiggly. When people get to know them, most will agree that lampreys are rather macabre.

Every June and July, Pacific Lampreys return from the ocean to their spawning grounds in Oregon. Back in the 1800s, historians described the annual spectacle at Willamette Falls when abundant lampreys filled the chutes until “...at a short distance the rocks appeared to be covered with a profuse growth of kelp.” Today, Pacific Lampreys have become rare or extinct throughout most of their historic range. While abundance has severely declined in the Willamette River, it remains one of the most important lamprey spawning grounds on the West Coast.

Lampreys have long been harvested by people as a traditional food and as a source of natural medicines, including essential oils, vitamins and anticoagulants. Native Americans along the Oregon Coast and in the Columbia Basin added lampreys to their diets because the species were a rich source of nutrients that were not readily available in other local foods. Today the only harvest of Pacific Lampreys occurs at Willamette Falls, under a permit from Oregon Department of Fish and Wildlife, because the species is too rare in other rivers. Tribal people from the Oregon coast to the Snake River gather at Willamette Falls in June and July to collect lampreys, alongside a handful of nontribal fishers who also enjoy a lamprey dinner. Lampreys are also important in the diet of other native species, such as sturgeon, marine mammals, fish and birds. Like salmon, adult lampreys die after they spawn, contributing rich nutrients to rivers and streams. The decline of the historically abundant lampreys has likely contributed to ecological imbalances and disruptions in natural predator-prey systems and nutrition cycles. A stream that cannot support lampreys is impoverished for other species, including for humans.

Pacific Lampreys are one of four species of lampreys in the Willamette Valley. The River Lamprey is also anadromous and parasitic and lives in the main channel of the Willamette below the falls. The other two species are small, resident brook lampreys that live in tributaries and filter feed on algae throughout their lives. The Western Brook Lamprey occurs throughout the Willamette Basin, while the endemic Pacific Brook Lamprey is apparently unique to the lower Clackamas River. All the species are now rare, protected species in Oregon.

Development in the Willamette Valley, and elsewhere, has been hard on lampreys. Passage barriers, caused by road culverts, water diversions and dams block migration routes that lampreys need to move through their habitats. Toxins from industry, urbanization and agriculture have poisoned their water and the mud they burrow in. Lampreys are sucked up by dredges, diverted into fields, and stranded when wetlands are drained. Loss of stream-side vegetation causes summer-time water temperatures to heat up to lethal levels. The gentle backwaters that lampreys call home are lost when meandering side channels and streams are channelized, drained and buried in box culverts. After living on earth for 500 million years, lampreys are finding life with humans to be a struggle.

In recognition of the Willamette Basin’s value to lampreys, and of lamprey’s value to our ecosystems, the Greater Oregon City Watershed Council recently adopted lampreys as their mascot. This summer, take a moment to take care of the streams in your neighborhoods because lampreys live in a stream near you. (And don’t worry! Willamette River lampreys are not parasitic when they are in fresh water!)

Kathryn Kostow is biologist at ODFW and a member of the Greater Oregon City Watershed Council.



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  • 25 Oct 2014

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