This dissertation explores how natural ecosystem can be integrated with economic system through two case studies of multiple species interactions, or predator-prey relations. By the inclusion of biological, ecological and economic aspects, the integrated approaches aim at more clearly understanding of how regional ecosystem and economy interact with each other, given threats of resource extinction and environmental shock. I also explain strategies and policy regimes that can be considered to achieve efficient and sustainable ecosystem management in those circumstances. The first case study focuses on a predator-prey relation in the Pacific Ocean between the United States and Canada, where endangered/threatened predators feed primarily on co...