The History of Surprises Associated with Pacific Salmon Returns Signals that Critical Information is Missing from Our Understanding of their Population Dynamics
Richard J. Beamish and Ruston M. Sweeting
Abstract.—Every year biologists around the rim of the subarctic Pacific eagerly wait to compare salmon abundances to expectations. After decades of surprises, it would seem logical to conclude that critical information is missing from the calculations of expected returns. Recent studies on the dynamics of coho salmon Oncorhynchus kisutch in the Strait of Georgia showed that growth in the early marine period strongly affects marine survival. In other studies, DNA stock identification methods are now being used to identify the feeding areas of various species and stocks of Pacific salmon throughout the subarctic Pacific. Thus, it is possible to relate regional ocean and climate conditions to marine survival. Complete life cycle studies that include information from freshwater, on ocean entry timing, early marine growth and ocean conditions in the locations that salmon populations feed or spend their winter are now technically possible. There is an international spirit of cooperation that, if properly funded, would support the focus of scientists to provide the missing information needed to produce reliable forecasts of adult Pacific salmon abundances.