Oceanographic influences on patterns in North Pacific salmon abundance

Abstract

We identified three dominant patterns of temporal variation (1951–2002) in the abundance of 34 stock groups of wild North American and Asian pink salmon (Oncorhynchus gorbuscha), chum salmon (Oncorhynchus keta), and sockeye salmon (Oncorhynchus nerka) that were related to patterns of oceanographic variability. We identified these patterns using three different ordination methods and found consistent patterns across these methods. Alaskan salmon dominated the most prominent pattern, which exhibited a positive abundance shift in the mid-1970s. In general, warm (cold) periods in the Gulf of Alaska and eastern Bering Sea corresponded with high (low) abundance years for these stock groups. The second abundance pattern captured differences among Asian, northern North American, and southern North American population groups and was associated with an intense, large-scale Aleutian Low. To our knowledge, this is the first analysis that identifies regional patterns of covariation in salmon abundance around the entire North Pacific Rim, and it highlights the existence of basin-wide covariations in wild salmon abundance that are associated with spatially coherent and regionally distinct patterns in North Pacific climate.