Appearance
Pacific Lamprey (Entosphenus tridentatus) are ancient, jawless fish that have existed for over 400 million years, predating the dinosaurs. They have an eel-like body, smooth and slimy skin without scales, and a distinctive toothed, funnel-like sucking mouth. Their color can range from brown to dark green on the back with a lighter underside. Adults typically range from 12 to 20 inches in length, but some species can grow even larger.
Ecology
Lamprey are anadromous, meaning they migrate from freshwater to the ocean and back to spawn. Their complex life cycle has several stages. After hatching, lamprey larvae, or ammocoetes, burrow into soft sediment in freshwater streams and rivers. They remain in this larval stage for three to seven years, feeding on algae and detritus through filter feeding. After several years as larvae, lamprey undergo a metamorphosis where they develop eyes and a toothed mouth. As juveniles, lamprey migrate to the ocean where they become parasitic, attaching to fish and feeding on their blood and bodily fluids. This ocean phase lasts one to three years. After their time in the ocean, adult lamprey return to freshwater to spawn. During their return from the ocean, Pacific Lamprey cease feeding and rely on stored energy reserves for migration and spawning. Unlike Pacific salmon, they do not always die immediately after spawning, but most will die shortly thereafter.
In the Upper Columbia River Basin, Pacific Lamprey inhabit freshwater rivers and streams. They prefer clean, gravelly substrates for spawning and soft, silty areas for their larval stage. Healthy riparian areas are crucial for providing the necessary habitat conditions for all stages of their life cycle.
Predation threatens lamprey during all life stages. Birds, fish, and mammals prey on larval and juvenile lamprey. In the ocean, larger predatory fish and marine mammals can be significant threats.
Lamprey also play a critical role in the ecosystem. As filter-feeding larvae, they help maintain water quality by consuming organic matter. As a food source, they support a diverse array of predators, contributing to the overall health of aquatic ecosystems. Additionally, adult lamprey provide nutrients to freshwater habitats after spawning and dying, enriching the ecosystem for other species.
Threats
Pacific Lamprey populations in the Columbia River have been declining since the mid-twentieth century due to activities such as logging, mining, agriculture, and urban development, which have degraded spawning and rearing habitats by increasing sedimentation and pollution and altering water flows. Dams and other barriers prevent lamprey from reaching their spawning grounds by obstructing migratory routes. Changes in water temperature and flow regimes due to climate change can impact lamprey habitat and their ability to complete their life cycle. Pollution from agricultural runoff, industrial discharges, and urban wastewater negatively affects lamprey at all life stages.
Conservation
Tribes in the Columbia River Basin have deep cultural ties to Pacific Lamprey and have harvested them as a food source for millennia. Native American Tribes were among the first entities to spearhead lamprey conservation efforts. You can learn more Pacific Lamprey and Tribal-led conservation efforts by visiting the Columbia River Inter-Tribal Fish Commission’s website. You can also learn more by visiting the Pacific Lamprey Conservation Initiative website.
Conservation efforts for lamprey in the Upper Columbia focus on habitat restoration, improving fish passage, and raising awareness about their ecological and cultural importance. Habitat restoration projects aim to enhance water quality, restore natural flow regimes, and improve spawning and rearing habitats. Fish passage improvements, such as retrofitting dams with lamprey-friendly passage systems, help facilitate their migration. Collaborative efforts among Tribes, government, non-profits, and community members are crucial for the success of these initiatives.
