Changing central Pacific El Niños reduce stability of North American salmon survival rates.

摘要: Pacific salmon are a dominant component of the northeast ecosystem. Their status is concern because abundance highly variable—including protected stocks, recently closed fishery, and actively managed fisheries that provide substantial ecosystem services. Variable ocean conditions, such as Decadal Oscillation (PDO), have influenced these fisheries, while diminished diversity freshwater habitats increased variability via portfolio effect. We address question how recent changes in conditions will affect populations two species. Since 1980s, El Nino Southern (ENSO) events been more frequently associated with central tropical warming (CPW) rather than canonical eastern ENSO (EPW). CPW linked to North Gyre (NPGO), whereas EPW PDO, different indicators Ocean productivity. Here we show both coho Chinook survival rates along western America indicate NPGO, explains since 1980s. The observed increase NPGO variance decades was accompanied by an coherence local species, increasing Such increases among stocks usually attributed controllable influences hatcheries habitat degradation, but unknown mechanism underlying climate effect identified here not directly subject management actions.