The development of synoptic tools is required to derive the potential habitat of fin whales Balaenoptera physalus on a large-scale basis in the Mediterranean Sea, as the species has a largely unknown distribution and is at high risk of ship strike. We propose a foraging habitat model for fin whales in the western Mediterranean Sea relying on species ecology for the choice of predictors. The selected environmental variables are direct predictors and resource predictors available at daily and basin scales. Feeding habitat was determined mainly from the simultaneous occurrence of large oceanic fronts of satellite-derived sea-surface chlorophyll content (chl a) and temperature (SST). A specific range of surface chl a content (0.11 to 0.39 mg m−3) and a minimum water depth (92 m) were also identified to be important regional criteria. Daily maps were calibrated and evaluated against independent sets of fin whale sightings (presence data only). Specific chl a fronts represented the main predictor of feeding environment; therefore, derived habitat is a potential, rather than effective, habitat, but is functionally linked to a proxy of its resource (chl a production of fronts). The model performs well, with 80% of the presence data <9.7 km from the predicted potential habitat. The computed monthly, seasonal and annual maps of potential feeding habitat from 2000 to 2010 correlate, for the most part, with current knowledge on fin whale ecology. Overall, fin whale potential habitat occurs frequently during summer in dynamic areas of the general circulation, and is substantially more spread over the basin in winter. However, the results also displayed high year-to-year variations (40 to 50%), which are essential to consider when assessing migration patterns and recommending protection and conservation measures.JRC.G.4-Maritime affair

Spatially explicit risk assessment is an essential component of Marine Spatial Planning (MSP), which provides a comprehensive framework for managing multiple uses of the marine environment, minimizing environmental impacts and conflicts among users. In this study, we assessed the risk of the exposure to high intensity vessel traffic areas for the three most abundant cetacean species (Stenella coeruleoalba, Tursiops truncatus and Balaenoptera physalus) in the southern area of the Pelagos Sanctuary, which is the only pelagic Marine Protected Area (MPA) for marine mammals in the Mediterranean Sea. In particular, we modeled the occurrence of the three cetacean species as a function of habitat variables in June by using hierarchical Bayesian spatial-temporal models. Similarly, we modelled the marine traffic intensity in order to find high risk areas and estimated the potential conflict due to the overlap with the cetacean home ranges. Results identified two main hot-spots of high intensity marine traffic in the area, which partially overlap with the area of presence of the studied species. Our findings emphasize the need for nationally relevant and transboundary planning and management measures for these marine species.