Integrated Coastal Management for the Improvement of Sustainable Marine Finfish Offshore Cages Based on GIS Multi-criteria Evaluation Models

Aquaculture stands as the fastest-growing sector in global food production. This industry provides numerous benefits to coastal communities (job creation, nutritious food, etc.). However, there is a scarcity of detailed information and guidance on strategic multi-objective zoning for sustainable expansion of this sector. Commonly, the expansion of marine offshore cages causes many conflicts among the same marine area users, especially the fisheries sector. Quantifying and mitigating conflicts using jointly optimized aquaculture and biodiversity objectives are prerequisite for sustainable development of this activity. Indeed, identifying suitable sites as allocated zones for aquaculture (AZA) is a critical step in any development aquaculture strategy to ensure a long-term production sustainability. We create and evaluate alternative planning scenarios for the Monastir’s Bay area, one of Tunisia’s most important aquaculture production areas. Using multi-criteria analysis, we generate a fine-scale aquaculture suitability distribution areas, and we prioritized protected areas and biodiversity for a balanced ecosystem. Geographic information systems (GIS) were used to identify the most sustainable with a suitability rating from 1 (least suitable) to 6 (most suitable). To establish a uniform scoring system, the raw data was scored based on the requirements of the surrounding ecosystem and the offshore cages system. This analysis allows to assess the impact of different criteria weights on the spatial pattern of the suitable sites. Through this study, we emphasized that an integrated multi-objective zoning approach considering the cohabitation in the same costal area of the aquaculture and other users leads to efficient planning than traditional mono specific-sector implementation. Finally, the fine-scale suitability model demonstrated superior efficiency and sustainability compared to the basic distance function. This highlights the crucial role of conducting a comprehensive ecosystem suitability analysis prior to economic investments for all intended area users. Our study provides a decision support tools to the policy makers for sustainable, effective, and efficient marine area management.