Pacific lamprey are parasitic during the marine phase (i.e., the consume a host's blood), therefore standard methods of identifying prey (visual examination of gut contents) are ineffective; blood looks like blood, regardless of the source.  Genetic techniques such as metabarcoding gut contents are needed to determine which hosts were parasitized.  Knowing which fishes lamprey use as hosts and how it varies in time and space are essential to understand basic lamprey marine ecology. It is also needed to inform concerns about host availability (and bycatch in fisheries), contaminants, and the effects of climate change on host abundances. The goals of this project are to use genetic methods to 1) determine prey of pacific lamprey and 2) the origin of lamprey, using both ocean- and river-caught lamprey.  Measurable objectives are identification and quantification of species present in lamprey guts, as well as the origins of the lamprey themselves. Specifically, we will perform species identification of fish remnants in the gut contents of 50 individual Pacific Lamprey from each of 4 sites (West Coast commercial Pacific
hake and Groundfish fisheries, Willamette Falls, and Bonneville Dam) based on mitochondrial barcodes.  Gut contents will be sampled in both for foregut and hindgut of each specimen.  A total of 400 gut samples will be analyzed (i.e., 50 individual Pacific Lamprey x 4 sites x 2 regions of the gut = 400 samples).  Percent species composition for each site will be calculated across all 50 individuals to estimate relative abundance of each prey species.  Deliverables include genetic data on host composition and lamprey origins, and a final report.  Results will be disseminated as talks at lamprey-focused conferences (e.g., Lamprey Info exchange) and general seminars (e.g., USFWS seminar series, internal presentations within respective agencies). A final report and peer reviewed publication will also provide the information and recommendations.