Winter habitat preferences of cetaceans in the Northwestern mediterranean sea

Abstract Information on winter distribution and habitat preferences of cetaceans in the Northwestern Mediterranean Sea (NWMS) is still limited. Using observational data collected from 2008 to 2020 using platforms of opportunity during winter (November–March), this work investigates species presence and habitat use across the NWMS at different spatial scales. In total, 51,030 km on-effort and 852 sightings were analysed. All the eight regular cetacean species were identified. Fin whales, sperm whales, striped dolphins and bottlenose dolphins showed a preference for the routes in Liguro-Provencal basin and the Tyrrhenian Sea. Habitat models confirmed that the distribution of cetacean species at basin-scale is shaped primarily by bathymetric features, and dynamic variables such as sea surface temperature, eddy kinetic energy and sea surface chlorophyll concentration have a role in determining species-specific habitat preferences. At subregional scale, the differences highlighted in the habitat use suggested that some areas, like the Liguro-Provencal basin are mainly used to perform feeding activities, while others more probably work as warm resting areas and/or travelling corridors. Results highlight the importance of NWMS as a key area for cetaceans during winter, therefore habitat preferences throughout the year should be considered to properly manage the overlap between marine resources and human activities.