Quantifying the benefits of spatial fisheries management – An ecological-economic optimization approach

Improving fisheries management is a key challenge in addressing the United Nations Sustainable Development Goal 2 (Zero Hunger) and support Goals 1 (No Poverty) and 14 (Life Below Water). However, sustaining the ocean’s living resources has important dimensions beyond food security, such as cultural values, which might be of equal importance in some settings. Fisheries management faces special challenges when there is a mismatch between biological units and management units, e.g., when ecological spatial structures are not reflected in how catch limits are set. This might result in overexploitation and even the loss of sub-stocks. We use a spatially structured ecological-economic model parameterized for a pelagic schooling fish to examine how the benefits of implementing spatially differentiated fisheries management depend on biological parameters. We focus on a subset of socio-ecological variables, i.e., fisheries yield, present value of economic surplus, and loss of spawning sites (which might be linked to loss of cultural values) to demonstrate that, in theory, ideally differentiated spatial management can be implemented without exact information about recruitment behavior. For imperfectly differentiated spatial management, however, knowledge about recruitment behavior becomes key to avoiding economic losses and to sustaining stock structure, especially when there is large spatial heterogeneity in biological parameters. Knowledge about variability in site-specific productivity determines the expectation of achievable sustainable harvest levels. Further research on such ecological issues is therefore warranted, both for ecological as well as economic reasons.