Linkages between climate, growth, competition at sea and production of sockeye salmon populations in Bristol Bay, 1955-2000

Bristol Bay, Alaska, supports one of the largest and most valuable salmon fisheries in the world. Salmon abundance in Bristol Bay and other northern areas more than doubled after the 1976–77 marine climate shift. However, in 1997–98, a major El Niño event led to unusual oceanographic conditions and Bristol Bay sockeye salmon production was unexpectedly low. Nevertheless, the effect of climate on biological mechanisms leading to greater salmon survival and production are poorly understood. In order to test several hypotheses linking climate to salmon growth, interspecific and intraspecific competition, and salmon production, we measured annual marine and freshwater scale growth of Bristol Bay sockeye salmon, 1955 to 2000.