Theoretical Study on Spatially Explicit Fisheries Management

      Global fish production continues to outpace world population growth, and about 30 percent of fish stocks were estimated as fished at biologically unsustainable levels in 2011. In response to the history of failures of sustainable fisheries managements, spatially explicit fisheries management has been recognized as a crucial approach to sustainable fisheries management and conservation of marine ecosystem in the last decade. Introducing marine protected areas (MPAs), locations where at least some extractive activities are prohibited is a central tool for a spatially explicit approach to fisheries management. Recently, MPAs have attracted much attention as a tool for sustainable fisheries management, recovering depleted species, and conservation for valuable species. However, there still exist many unknowns concerning spatial fisheries management. As a result, a number of MPAs have been established ad hoc manners and without scientific knowledge, causing poor management outcomes. To develop general insights into spatial explicit approach to fisheries management, this thesis is developed with aims at modeling the spatially explicit dynamics of harvested population as well as fisheries, and exploring their expected outcomes in terms of both ecological and socioeconomic perspectives. In this talk, I will give two different topics. First talk is focused on the effect of establishing MPAs, which shows that introducing MPAs could cause unintended outcomes such as decreasing the population number of a prey species. Second, I will discuss the appropriate spatial unit scale of a spatial fisheries management, which will be a basis for the effort and MPAs allocations in spatial management. Our result shows that fishery profit result in a diminishing return as managers apply a finer management unit scale.