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Commercial catches of Pacific salmon (Oncorhynchus spp.) in Bristol Bay and the Alaska Peninsula began in the late 1800s and, by the early 1900s, these were the largest salmon fisheries in the world.
Initially, restrictions on fishing gear and location were used to limit fishing efficiency; then in 1924 Congress passed the White Act, which required that 50% of the returning salmon be allowed to spawn.
There was no biological basis for this figure and it bore no relationship to principles of population dynamics. nerka) salmon catches declined from approximately 22 to 16 million fish per year, followed by a second significant decline to approximately 10 million per year in the mid-1940s. Thompson, Director of the School of Fisheries at the University of Washington, to investigate factors influencing the dramatic decline in salmon abundance in southwestern Alaska.
We have documented differences in egg size that correspond to the sizes of the spawning substrates (Wetzel, Quinn et al. There are also differences in size, age structure, and morphology (especially the sexually dimorphic dorsal hump of male sockeye salmon) that correspond to stream size (Bishop 1990, Wetzel 1993) and vulnerability to bear predation (Hanson 1992, Quinn in prep.).
In addition to these forms of natural selection, we have also examined the selective effects of the gillnet fishery on size and shape of adult sockeye salmon (Hamon 1995).
During the last decade we have continued many of the same themes initiated by earlier researchers but have taken advantage of the long periods of record now available.
We have investigated interrelationships between abundance and growth of planktivorous fishes (especially sticklebacks and juvenile sockeye salmon) and the seasonal and interannual trends in phytoplankton and zooplankton (e.g., Work 1992, Reischauer 1996). Variation in life history characteristics and morphology of sockeye salmon (Oncorhynchus nerka) in the Kvichak River system, Bristol Bay, Alaska. The sites are located on the edge of Beringia (the great Pleistocene refuge from glaciation) and contain animals and plants found nowhere else in North America. Initial research at the Wood River Lakes and throughout Bristol Bay was aimed at determining the carrying capacity of spawning and rearing environments (Burgner et al. To achieve this goal, basic techniques were devised for estimating spawning densities of salmon, determining the age of fish by scale or otolith patterns, conducting stream surveys, estimating the abundance of emigrating juvenile salmon (smolts), and quantitative sampling of salmon catches. The research objectives of this program were to determine physical and biological factors influencing sockeye salmon production. These objectives were developed at a time when the fundamental biology of salmon was poorly known and there were no long-term studies integrating salmon and their ecosystems in a holistic manner. Studies on freshwater ecology included seasonal and interannual variations in juvenile fish abundance and distribution (Rogers 1973, Newcome 1976); effects of lake enrichment on the phytoplankton, zooplankton, and limnetic fishes in small, oligotrophic Little Togiak Lake (Rogers 1979, Hardy 1979); density-dependent growth of juvenile (Burgner 1987) and maturing sockeye salmon (Rogers 1980); functional response and size-biased predation by Arctic char, Salvelinus alpinus, on juvenile sockeye salmon (Ruggerone and Rogers 1984); and parasites of juvenile sockeye salmon (Burke 1978).