Numbers of Pacific lamprey adults now returning past Bonneville and other federal projects are orders of magnitude lower than the numbers recorded during the last regular counting season (1969). The decrease in Columbia River Basin lamprey populations above Bonneville Dam is due in part to the loss of juveniles killed or injured from contact with submerged screening devices, predation by exotic and native fishes, and from delays in reaching the estuary. Upstream migrating adults are delayed or killed at hydroelectric dams as a result of velocity barriers, picket spacing problems, fallback through turbines, and entrapment under diffuser grates.
Appropriate research and follow-up actions to identify and implement passage conditions and related mitigation measures for adult and juvenile lamprey are necessary to ensure lamprey restoration.
- Document adult Pacific lamprey passage behavior and the conditions that impede optimal passage. Include and account for Pacific lamprey in ongoing and proposed passage research.
- Implement research specific to Pacific lamprey that prioritizes data collection on adult and juvenile passage behavior of this species.
- Resume daily counting of adult lamprey passing through fish ladders at mainstem dams.
- Conduct research to determine downstream passage survival of Pacific lamprey.
- Based upon research results, develop and implement recommendations to improve upstream and downstream passage survival.
- Develop and implement artificial propagation and/or transplantation programs where suitable habitat exists and where fewer lamprey are present than the rearing habitat can support.
- Increase the scale of successful artificial propagation and transplantation techniques to supplement natural lamprey production.
Research results will identify opportunities and guide recommendations for improving passage for adult and juvenile Pacific lamprey, without compromising passage for salmonid species. Improved conditions will increase passage survival, help to stabilize recent population declines, and aid efforts to re-establish populations in their historic habitat.
Tribes: Conduct juvenile and adults passage studies under contract with the U.S. Army Corps of Engineers.
Tribes: Conduct studies of natural production levels and limits and artificial production techniques as part of the NPPC Fish and Wildlife Program.
*Habitat for Pacific lamprey is not addressed directly in recommended actions. Although no specific research has been done on the spawning and early life history needs of Pacific lamprey, research done elsewhere that documents lamprey spawning and early life history habits suggests the general needs of this species. This information, combined with historical information strongly suggests that recovery measures to improve the quality, quantity, and stability of salmonid spawning and rearing habitat will also improve habitat for Pacific lamprey.