Patterns of larval Pacific Lamprey occupancy and abundance suggest that certain natal areas are more productive than other areas.  What is less clear is whether these productive natal areas act as sources for returning adults.  Identifying natal areas that contribute to adult Pacific Lamprey production (and identifying characteristics of those areas) will help guide conservation efforts such as passage and restoration in the Pacific Northwest. Isotopic signatures in statoliths have the potential to define natal origins of Pacific lamprey.  As statoliths develop in an individual, they store elements from surrounding water; thus, elemental and isotopic composition of the core and early layers relate to the chemical composition of water at the individual’s natal region. The chemical composition of river water is a function of underlying geology and land use. To identify natal origin from microchemistry in statoliths, chemical signatures must be stable and different among natal areas. OSU will analyze statoliths to assess natal origins in pacific lamprey.