Fish assemblages along the coasts of Tunisia: a baseline study to assess the effectiveness of future Marine Protected Areas

The present study investigated coastal fish assemblages, using Underwater Visual Census (UVC) transects, that can be used as a baseline, at 3 locations in Tunisia (southern Mediterranean basin) where 3 MPAs will be established, before the implementation of protection measures. At each location, we used a sampling design where fish censuses were performed in two types of zone: zones that will be inside MPAs, and zones that will remain outside. On the whole, 49 taxa belonging to 19 families were censused. Our findings provided evidence of overfishing throughout the sampled areas, especially in terms of dominance of small- and medium-sized individuals of commercially relevant species. Our analyses, moreover, did not show any significant difference between fish assemblages (considering both density and biomass of whole assemblages, the different trophic categories and size distribution of commercial species) between future protected and unprotected zones. Overall, results suggest that: 1) current fish assemblages at the three studied locations are likely to be seriously impacted by fishing activities, and 2) these data could be used as a reliable baseline to assess the effectiveness of protection measures within the MPAs that will be established in the future. Our study is the first in Tunisia, and along the North African coasts, that has assessed distribution patterns of coastal fish assemblages by means of UVC, using a formal spatially replicated sampling design for resource management.