Pacific lamprey (Lampetra tridentata) populations throughout the Columbia River Basin (CRB) are in decline.  Due to declining lamprey abundances in the CRB, harvest has been limited, with a primary collection location for the four Treaty Tribes (Warm Springs, Yakama, Umatilla, and Nez Perce) at Willamette Falls on the Willamette River (Rkm 42.6) in Oregon City, Oregon.  Declining lamprey populations are of primary concern to the Confederated Tribes of Warm Springs Reservation of Oregon due to their high cultural and environmental value.  Despite the importance of this fishery, there is currently no estimate of adult escapement upstream of Willamette Falls.  Harvest is the only data available to represent trends in abundance.  However, harvest rates have varied due to increased catch regulations and restrictions; therefore, are very poor indicators of abundance.  Development of a method to track changes in abundance of Pacific lamprey through time and estimate adult escapement will be used to better manage harvest levels and alert biologists of low returns to protect this unique fish species and the cultural fishery.  

Project objectives in 2010 will focus on:
1) Develop a protocol for and index of adult Pacific lamprey abundance at Willamette Falls for long-term monitoring;
2) Determine the feasibility of estimating adult Pacific lamprey abundance and escapement at Willamette Falls;
3) Investigate the detection rate of a half-duplex PIT tag interrogator at the Sullivan Plant at Willamette Falls to detect PIT tagged Pacific lamprey used for the population estimate; and
4) Create a Willamette Falls Pacific Lamprey Working Group (a sub-section of the Willamette River Pacific Lamprey Working Group in development by USFWS) to coordinate research and monitoring activities and provide technical guidance.