A 7500-year paleolimnological record of environmental change and salmon abundance in the Oregon Coast Range

Pacific salmon (Oncohrynchus) abundance has declined significantly over the last century. The lack of a long-term context of salmon abundance hinders restoration efforts. A ca. 6000-year record of coho salmon abundance in the Oregon Coast Range was developed using paleolimnological techniques (δ15N and complimentary proxies) at Woahink Lake and compared to a control lake (Triangle Lake) that is inaccessible to salmon. Proxies of salmon abundance declined over the record, consistent with a reduction in coastal upwelling and marine forage caused by increasing Pacific sea-surface temperatures. The record suggests that salmon abundance was anomalously high at the time of early Euro-American settlement. The resolution of this study is limited by low sedimentation rates and additional factors influencing δ 15N concentrations. Visual stratigraphy, magnetic susceptibility, loss-on-ignition, organic carbon and nitrogen, bulk density, biogenic silica, δ 15N, δ13C, and pollen were used to reconstruct vegetation, earthquake disturbances, and the dune-barrage origin of the lake