Due to the recent increase in greenhouse gases in atmosphere, world climate is rapidly changing and in turn, the earth ecosystem responds upon the climate changes. Comparing the ecosystem in the past, the present shapes of ecosystem is the result of the serious modification. Fishery resources in marine ecosystem, which usually occupy the upper trophic level, are also inevitable from such changes, because they always react to the natural environmental conditions. The northwestern Pacific is the most productive ocean in the world producing about 30% of world catch. From time to time, however, it has been notified that abundance, distribution and species composition of major fish species were altered by climate events. Furthermore, primary productivity of the ocean is not stable under the changing environments, so that carrying capacity of the ocean varies from one climate regime to another. Major climate events such as global warming, atmospheric circulation pattern, climate regime shift in the North Pacific, and El Nino event in the Pacific tropical waters were introduced in relation to fisheries aspects. The current status and future projection of fishery production was investigated, especially in the North Pacific including Korean waters. This new paradigm, ecosystem response to environmental variability, has become the main theme in marine ecology and fishery science, and the GLOBEC-type researches might provide a solution far cause-effect mechanism as well as prediction capability. Ecosystem management principles for multi-species should be adopted for better understanding and management of ecosystem.