Fully protected areas (no extractive activities allowed) are a spatially explicit conservation management tool commonly used to ensure populations persistence. This is achieved when an adequate fraction of a species’ population spends most of its time within the boundaries of the protected area. In this sense, species’ home ranges represent a tractable metric to provide guidance and evaluation of fully protected areas.
This study compiled and analysed peer-reviewed literature specific to the home ranges of finfishes and invertebrates of ecological and/or commercial importance in the Mediterranean Sea, relating this information to the size of 184 Mediterranean fully protected areas.
The results of the study show that one fourth of Mediterranean fully protected areas are large enough to provide protection to local populations of 11 ecologically and commercially important species. Following their results, the authors suggest a spatial area of 3.6 km2 as the minimal threshold in fully protected areas, revisable when new home range data are available, thus ensuring benefits to as many species as possible.
The authors state that even though the analyses suggest that many of the small existing marine protected areas are individually providing benefits to the local populations of the studies species, the overall benefits (i.e. at meta-population and species level) could be small because the total coverage of marine protected is cumulatively small. Bearing this in mind, and linking the spatial requirements of fully protected areas to recent studies on connectivity among protected areas, the authors extrapolate minimal requirements needed to implement beneficial marine protection: Taking the entire Mediterranean coastline as a practical example and conservatively allowing for 50 km between marine protected areas, at least 1.7% of the coastal area between 0 and 50 m depth should be protected from any form of fishing through a network of fully protected areas. This would be in line with the recent call to fully protect 2% of the Mediterranean Sea issued in the Tangier Declaration.
Di Franco et al. (2018) Linking home ranges to protected area size: The case study of the Mediterranean Sea. Biological Conservation 221:175-181