Shark Med studies sharks and rays in Cabrera National Park

Shark Med and the Save the Med Foundation will carry out the Shark and Ray Project in the Maritime-Terrestrial National Park of the Cabrera Archipelago (PNMTAC). This project will study their diversity, abundance, seasonality, and movement patterns using non-invasive techniques over the next two years (2024-2025), aiming to better understand the current situation of various shark and ray species in Cabrera National Park.

The purpose of this project is to generate scientific information regarding the presence of pelagic and demersal elasmobranchs in the study area, including their density indices and seasonality, while also obtaining information about their trophic ecology and movement patterns. Additionally, the project seeks to understand the habitat use and migration routes of the manta ray (Mobula mobular). The goal is to shed light on the limited information available about the biology and ecology of these species and the impacts they face, and to cross-reference this information with risk maps to minimize interactions and threats to these species.

In the Balearic Sea, 32 species of sharks, 27 rays, and 1 chimera have been recorded, but more than half of these species are threatened. According to the IUCN Red List on the conservation status of Mediterranean sharks and rays, in 2019, 53% of these species were already estimated to be endangered, making the Mediterranean the region with the highest percentage of threatened elasmobranchs. The main cause of this decline is overfishing. Most species are part of the bycatch in various fisheries, most of which are multispecies. Additionally, there is growing concern about the increase in targeted fishing for pelagic sharks. Although some pelagic species are strictly protected under Spanish law (e.g., the great white shark Carcharodon carcharias, hammerhead sharks Sphyrna spp., and manta rays M. mobular), they are still captured in unknown quantities, leading to high mortality even if sometimes released.

Several species present in the Balearic Sea are highly migratory, such as the manta ray and the blue shark (Prionace glauca), which are evaluated by the IUCN (2016) as endangered and critically endangered in the Mediterranean, respectively. Defining their migration routes and population connectivity is essential for the conservation of these species, as their protection in one area is ineffective if they migrate to others where they are heavily fished. Therefore, once the results of this project are obtained, the information will be disseminated internationally to promote the implementation of management measures to ensure the conservation of these species. The methodology used in this study is based on three pillars: generating remote underwater video images with baited BRUVs (Baited Remote Underwater Video), extracting environmental DNA by filtering water samples, and tagging manta rays with satellite tags.

Gabriel Morey, an elasmobranch biologist, assures that "the results of this project will fill the knowledge gap we have about the ecology of sharks and rays. Doing it in Cabrera has the added value of contributing to the park's management, especially now that it covers a large area of open waters where we know very little about what happens." Dr. Eric Clua adds, "Currently, Shark Med is using a state-of-the-art underwater robot designed by the French company Marepolis. This device optimizes the collection of water samples for environmental DNA analysis. It is a non-invasive technique that will allow us to know which elasmobranchs still inhabit the waters of the Balearic Sea, even if their presence is minimal, such as the iconic great white shark (Carcharodon carcharias)."