Fisheries Resources
Pacific Region

Pacific Lamprey (Entosphenus tridentatus)

Life History

Shortly after hatching in freshwater streams, lamprey larvae or ammocoetes drift downstream into areas of low velocity and fine substrates where they burrow, and live as filter feeders for up to 7 years. Metamorphosis to macropthalmia (juvenile phase) occurs gradually over several months from July to November before their migration to the ocean in the winter and early spring. During this transformation they develop eyes and teeth. As adults in the ocean, Pacific Lamprey are parasitic and feed on the body fluids and blood of marine fishes. After spending 1 to 3 years in the marine environment, Pacific Lamprey stop feeding and migrate back to freshwater between February and June. They overwinter in fresh water until they spawn the following year between March and July. After spawning, lamprey die within days.

On Our Website You Can:

Learn about the Pacific Lamprey Conservation Initiative

Join the Pacific Lamprey Geocaching Adventure: Travel bugs have been launched in the Pacific Northwest in four different locations. Go to our Pacific Lamprey geocaching page for more information on their locations.


Education & Outreach
A girl photographs a lamprey at the Wenatchee River Salmon Festival. Credit: Dave Herasimtschuk

For Kids

Last updated: February 19, 2015

Pacific Region Fisheries Resources
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