Trends in the status of Pacific salmon populations in Washington, Oregon, California, and Idaho

Over the past 3 years, the National Marine Fisheries Service, Northwest Fisheries Science Center has conducted coastwide status reviews of Pacific salmon (Oncorhynchus spp.), in Washington, Oregon, California, and Idaho. Patterns of stock health have emerged that relate to life history, and freshwater and marine distribution. For most species, the health of natural populations declines from north to south. The health of natural populations also declines from west to east as the length of freshwater migration increases. Across species and life history strategies, declines in natural populations generally increase with the length of freshwater residence. Populations of pink salmon (Oncorhynchus gorbuscha ), and chum salmon (O. keta) are doing relatively well, while populations of chinook (O. tshawytscha), coho (O. kisutch), and sockeye (O. nerka) have experienced greater declines. Trends in abundance of natural populations of steelhead (O. mykiss), and chinook and coho salmon are obscured to some degree by extensive hatchery programs. These patterns implicate the availability and quality of freshwater habitat as a primary factor in observed declines in abundance.