Pacific Lamprey spawn in the Tualatin River and then over the next 3 to 7 years migrate to the ocean. After spending 1 to 3 years in the ocean, they migrate back to freshwater (but not necessarily to the Tualatin River). Lampreys, as a species, are a few hundred million years old, making them older than dinosaurs.
Pacific Lamprey migration was previously blocked by the Balm Grove Dam on Gales Creek. Since the dam was removed in 2022, Pacific Lamprey are now found upriver from where the dam was removed. Pacific Lamprey are valued as a “First Food” by the Grand Ronde.
