Spatial Multi-Criteria Decision Analysis for Aquaculture Site Selection in Greece using GIS

By Guus Maessen

Abstract
This study evaluates spatial suitability for marine aquaculture in Greece for Gilthead seabream and European seabass. A Multi-Criteria Decision Analysis (MCDA) approach was applied using Geographic Information Systems (GIS) and Remote Sensing (RS) data. A constraint mask was introduced to exclude areas considered unfeasible for aquaculture. Suitability Scores were assessed through a Analytical Hierarchy Process (AHP) and Weighted Linear Combination (WLC). Water quality, socio-economic and biophysical factors were used to map suitability under three different scenarios: Blue Growth, Environmental Growth and Economical Growth. A sensitivity analysis was performed to evaluate the model’s performance. Last, a spatial comparison with established fish farms carried out. Biophysical factors were the most restrictive, while water quality factors were the least restrictive. Higher Suitability Scores were found in the Environmental Growth model, prioritizing water quality factors. This aligned with the established fish farms, which had significantly higher Suitability Scores. The mask showed a mismatch with the existing fish farms, excluding approximately one-third of them. The model’s performance was overall stable and robust. This study demonstrated how a holistic GIS-based MCDA approach can contribute to a more sustainable form of Marine Spatial Planning.