Idaho's Pacific Lamprey

During their time embedded in the stream, they filter feed, similar to how mussels filter the water and feed on the particles within it. You can think of these little guys as part of the cleanup crews in our rivers. During this time, they are only a few inches long and lack eyes. Like salmon and steelhead, when they reach a certain size, they decide it is time to go to the ocean. Then they develop eyes and begin to form teeth. The total length of a Pacific Lamprey at this stage in development is typically 6 inches or longer. During this transformation, they completely change how they eat. Once they have reached the ocean, they begin a parasitic lifestyle. They attach themselves onto fish with their newly formed teeth and suck blood from their host. They typically stay in the ocean for 1 - 3 years before they head back to where their life started to spawn. When Pacific Lamprey return from the ocean, they range in size from a foot to a little over 2 feet in length. Like salmon, Pacific Lampreys do not eat while returning to their spawning ground. Pacific Lampreys have been seen to shrink 20% during their time in the rivers before spawning! Once they have completed spawning, they die just like salmon. Very little is truly known about Pacific Lamprey due to their elusive lifestyle. However, this doesn't mean that they don't play a vital role environmentally and culturally.