Stock-Specific Distributions of Asian and North American Salmon in the Open Ocean, Interannual Changes, and Oceanographic Conditions

Knowledge of migration routes, migration timing, and resident areas for populations of Pacific salmon in the open ocean is vital to understanding their status and role in North Pacific marine ecosystems. In this paper we review information from the literature, as well as some previously unpublished data, on stock-specific distribution and migration patterns of salmon in the open ocean, interannual variation in these patterns, and associated ocean conditions, and we consider what this information can tell us about ocean conditions on small- to mid-size scales. We conclude that climate-driven changes in open-ocean feeding areas and along the migratory routes of Asian and North American salmon can result in predictable interannual changes in stock-specific distribution, migration patterns, and other biological characteristics. Global climate change is currently causing more frequent and un- predictable environmental changes in the open ocean habitats through which salmon migrate. Data on changes in the distribution and migration of indicator stocks of adult salmon returning from the open ocean might provide an "advance warning" of interannual changes in North Pacific marine ecosystems.