Population-Scale Monitoring in a Minimally Disturbed Coastal Watershed

Multi-species and habitat responses to environmental disturbances and to restoration are rarely evaluated at population or watershed scales. Salmon River, a 200 km² watershed on the central Oregon coast, provides a unique opportunity to accomplish this for a complement of anadromous species and habitats. Salmon studies and estuary restoration began in the watershed in 1975, shortly after the U.S. Congress designated the estuary as part of the Cascade Head Scenic Research Area.  The CHSRA supports long-term studies, experimentation, and ecosystem research in forest, coastal prairie, and aquatic environments. Fish research and monitoring has assessed long-term population trends, population structure, life history characteristics, and responses to wetland restoration of Chinook and coho salmon and cutthroat trout. The watershed is a tractable size to quantify juvenile, smolt, and adult salmon populations; and estuary restoration treatments have been large enough to produce a measurable population response. Minimally disturbed systems like Salmon River also are invaluable for understanding natural processes and developing management and restoration strategies for more heavily modified basins. Long duration monitoring of minimally disturbed reference populations will become increasingly important to understand population viability under changing freshwater, marine, and climatic conditions.