Spatial suitability analysis for finfish aquaculture: A case study from center-east coast of Tunisia

This paper outlines a methodology for selecting offshore sites for finfish cage farming, based on Spatial Multi-Criteria Evaluation and mathematical model (Degree of compatibility, DC). This approach is effective at the screening level, even in areas with limited field data, where informed decision-making is critical, or in conflict zones where marine spatial planning becomes essential. The case study was conducted at the center-east coast of Tunisia, Monastir’s Bay, where the central government plans to develop offshore aquaculture activities. The methodology consists of two steps. First, selection criteria are identified. Twenty-two factors were used to assess cage site suitability, including physical characteristics, and socioeconomic, and environmental conditions. These criteria were spatialized and classified into six macro-criteria: domain areas, hydrodynamics, environmental conservation, pollution prevention, interaction with existing coastal uses, and logistic efficiency. All criteria were spatially analyzed using GIS tools and multi-criteria analysis. In the second step, a degree of compatibility assessment model under two scenarios was applied to establish the most suitable areas for finfish aquaculture. The findings show that the procedure enables site selection by integrating the suitability of a site for aquaculture purposes with the conservation of the local receiving ecosystem under spatial restrictions set by existing activities. Few highly suitable sites (high DC value) exist, primarily constrained by intensive coastal usage and conflicts among various users. These smaller areas of suitability should be considered within the broader context of coastal activities. This study serves as a model to support sustainable aquaculture expansion and site selection methodologies that align with ecosystem-based approaches to aquaculture.