COMMON NAMES: Pacific lamprey, Three tooth lamprey, Tridentate lamprey, Ksuyas, Asum

SCIENTIFIC NAME: Lampetra tridentata synonym: Entosphenus tridentatus


Pacific lamprey have a large mouth which is like a suction cup with three large sharp teeth. The larvae hatch in streams and live out the juvenile stage of their life cycle as sedentary filter feeders, often burrowing into river banks at sites of pools and eddies. This stage typically lasts four to six years. The larvae then undergo metamorphosis and the adult which emerges migrates toward the Pacific during which time they are predated by other fish and birds. Once they reach the ocean they enter the parasitic phase of the life cycle which is thought to last up to 3.5 years, feeding on the blood of other fish including salmon, hake, and pollock, and also whales such as the humpback and sperm whale.  The adult then returns to freshwater to spawn, with females producing as many as 200,000+ eggs.


Pacific lampreys inhabit the Pacific coast from the Aleutian Islands to Baja California, Mexico, and inland to the upper reaches of rivers which run into the Pacific.


Lampreys are known as 'living fossils' because they are largely unchanged from their pre-historic ancestors. Pacific lampreys have cultural significance for Native Americans; in the Sahaptin language they are called ksuyas or asum, and are consumed as a religious as well as a subsistence food by the peoples of the mid-Columbia River Plateau. They also have medicinal use; the oil of a drying lamprey is applied topically to infected skin in conjunction with a purifying sweat bath. It has also been used traditionally to cure ear aches and as a hair conditioner. Pacific lamprey are usually fished from the rapids at night when they are most active, using a dip net, pole and hook, or bare hands. Unfortunately large-scale damming of the Columbia river has created lakes instead of rapids, disturbing traditional fishing sites and practices. Pacific Lamprey were also used as a food by early fur-trappers in the Pacific Northwest, and later as a feed for salmon and livestock by fish culturists and farmers in Oregon. Lamprey larvae also play an important ecological role in nutrient cycling in streams, and both larvae and adults are an important and rich food source for other species.


Close, D. A., Fitzpatrick, M. S., & Li, H. W. (2002). The ecological and cultural importance of a species at risk of extinction, Pacific lamprey. Fisheries, 27(7), 19-25.

Eisner, T. (2003). Living fossils: on lampreys, Baronia, and the search for medicinals.  BioScience, 53(3), 265-269.


Jennie has an academic background in Biology and Ethnobotany and is currently studying for a PhD in Geography. She has interests in ethnobiology, biocultural conservation, traditional knowledge, and sustainable food systems.