Pacific Lamprey

Entosphenus tridentatus

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Although most people wouldn’t consider the Pacific Lamprey to be a particularly attractive animal, it is a venerable and important species. Ancestors of the modern species have been found in the fossil record extending back 350 million years. (That’s over 300 million years longer than Oregon’s famous salmon species!) Although shaped like snakes, lampreys are a primitive fish. Their long rope-like body ends in a round mouth lined with small teeth. The lamprey survives by biting onto another fish and slowly draining out its blood. When the victim animal dies, the lamprey detaches and moves on. They are usually dark blue to brown in color and can grow up to 30 inches (76 cm) in length. The lamprey was an important food source to Native Americans living in Oregon. Today, it is not a popular game fish, due mostly to its unsavory appearance, status as a parasite and diminishing numbers.

Range and Habitat

The lamprey is anadromous, meaning it migrates from fresh to salt water and back again. After reaching maturity in Oregon’s rivers, the lamprey will live for the next year in the Pacific Ocean. At the end of the year, it will return to the river system where it was born to continue to reproductive cycle. Once the fish spawns, it dies. In this respect, it is similar to salmon, smelt, bass and sturgeon.

Conservation Status

The Pacific Lamprey is rapidly disappearing in the Pacific Northwest, an alarming occurrence to biologist who warn the fish is integral to the wild food chain of local rivers and the ocean. Like salmon, the lamprey return to fresh water to spawn. However, human-built impediments like dams prevent the fish from reaching its historic breeding grounds and are causing its rapid decline. Sometimes known as “earthworms of the river,” lampreys are an important food source for animals ranging from salmon to sea lions.

Photo credit: Oregon Department of Fish and Wildlife.