Pacific lamprey exhibit at least two different life-history paths when fish enter freshwateron their summer spawning migration

The University of Idaho received a $199,860 Project Grant award from the Department of the Interior Fish and Wildlife Service under the National Fish Habitat Partnership (CFDA 15.686) program, effective June 16, 2025, through June 15, 2026. The project develops a molecular-based epigenetic analysis method to determine Pacific lamprey sex and maturation status. This research addresses a critical management need in the Columbia River Basin, where understanding whether lamprey will follow accelerated spawning pathways (spawning within one year of freshwater entry) or delayed pathways (spawning after remaining in freshwater for over one year) is essential for effective population management. The project involves conducting epigenetic analysis of known-sex lamprey specimens to identify genomic markers indicative of sex and maturation status, with the goal of developing a practical test for sexing Pacific lamprey in the field.

Washington State University was designated as a sub-awardee on this grant, receiving a separate sub-award on September 17, 2025, under the project titled "USDI Lamprey Epigenetics." The collaborative research structure leverages expertise across both institutions to advance conservation outcomes for native Pacific lamprey populations in the Pacific Northwest region.

Some fish travel to spawning habitat by thefollowing spring, mature, and spawn. Another cohort delays this process for at least ayear, remaining in freshwater, not feeding, to spawn the following year. Compared tomaturing lamprey, those that elect to delay spawning must survive in freshwater for a fullyear longer. An important advantage of knowing which life-history trajectory a lampreywill take could significantly aid ongoing management activities to increase pacificlamprey populations in the columbia river basin. The purpose of this project is toemploy a molecular-based approach, epigenetic analysis, to develop a method fordetermining pacific lamprey SEX maturation. Epigenetic analysis of known SEX lamprey, both female and male, will be conducted to explore the potential of this technique toidentify genomic markers indicative of lamprey SEX and maturation. Suitable markerswould then be used to develop a test that could be utilized to SEX pacific lamprey.