In work funded by the National Science Foundation, the Bristol Bay salmon processors and the University of Washington, the scientists looked at the shifting fortunes of the salmon in the three Bristol Bay fishing districts, each with its distinct network of rivers and lakes. Through the 1950s, '60s and mid '70s, when conditions tended to be cooler and drier because of the influence of the Pacific Decadal Oscillation, the Naknek and Kvichak network far exceeded the other two districts. The dominant contribution was from Lake Iliamna, the United State's largest lake behind the Great Lakes.
In 1977-78 the Pacific Decadal Oscillation switched to a different phase leading to warmer and wetter conditions with higher water levels and flows among the results. The productivity of the three fishing districts began shifting in response, Hilborn says.
Today Lake Iliamna contributes so few fish that it requires special protective management. The Egegik network, which feeds another of the fishing districts studied and which earlier accounted for a mere 5 percent of the catch, expanded greatly until the '90s when the third fishing district, the Nushagak, increased. In some recent years, the Nushagak has been the most important fishery in Bristol Bay. "In the 1950s, managers could have chosen to overlook the Egegik or Nushagak systems, and at the time the cost would have appeared to be low," the authors write.
The Bristol Bay sockeye stock is an amalgamation of several hundred discreet populations, or components. It's all those local adaptations that stabilize the system, Quinn says. The advantage goes to deeper-bodied males when fighting for places to spawn and attracting females, until one considers what happens
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Contact: Sandra Hines
shines@u.washington.edu
206-543-2580
University of Washington
9-May-2003