Large marine protected areas are increasingly being implemented across the oceans. However, the dynamic nature of pelagic environments presents unique challenges for their management. Conducting surveillance and monitoring in vast areas requires the development of innovative and cost-effective methods. In the western Mediterranean, cetacean populations are impacted by anthropogenic threats stemming from human activities such as commercial shipping, which leads to underwater noise pollution and often lethal ship strikes. Recently, gliders have been equipped with hydrophones, becoming excellent platforms for passive acoustic monitoring (PAM), a non-invasive technique that enables monitoring of ocean soundscapes across extensive pelagic areas. PAM is highly effective for detecting the presence of marine mammals as well as instances of anthropogenic noise at multiple depths and locations, regardless of weather conditions.

The primary goal of the CESCAB mission (Cetacean Soundscapes in the Cabrera Archipelago National Park) is to advance the simultaneous monitoring of marine megafauna, ship-based activities and the marine environment within a large marine protected area (MPA), the Cabrera Archipelago National Park. This MPA is of special significance in terms of marine and terrestrial biodiversity. In 2019, this MPA was extended to include the adjacent pelagic habitats due to their importance for migration, feeding and reproduction of at least eight cetacean species, all of which are included in the Spanish List of Wild Species in Special Protection Regime and/or in the Spanish Catalog of Endangered Species. CESCAB mission has two specific objectives: 1) to monitor the presence of marine mammal species; 2) to assess underwater noise resulting from maritime activities.

An ocean glider equipped with a hydrophone and oceanographic sensors was deployed on a 30-day mission to characterize the 3D soundscape and sub-surface oceanographic properties in the Cabrera Archipelago MPA in August 2024. The mission is designed to monitor the soundscape within the protected area boundaries, but also in the adjacent areas with the goal of evaluating differences in marine traffic density. The remotely collected data will also be complemented with visual sightings and acoustic detections from boat surveys carried out by Asociación TURSIOPS.