The sharks and rays of Palau: biological diversity, status, and social and cultural dimensions

Abstract

Anthropogenic pressures have been increasing on shark and ray populations globally, and their conservation and management can be compromised by lack of information on their diversity and status of species. This study presents a desktop review of the sharks and rays of the Republic of Palau, drawing on citizen science, fisheries data and other scientific literature to document their diversity, economic and cultural values, and pressures affecting their populations. This account of Palau’s sharks and rays includes a preliminary assessment of risks based-on existing risk assessments, and their biological productivity. Records were found documenting 56 sharks and rays in Palau: 31 species are considered here as ‘confirmed and verified’, 10 species as ‘requires verification’, and 11 species listed as ‘plausible’. An additional two species are listed as ‘unlikely’, and two species is ‘unknown’ due to the taxonomy being unclear. The biological productivity analysis showed that the basking shark (Cetorhinus maximus) had the lowest productivity of Palau’s sharks and rays, while the blue shark (Prionace glauca) showed the highest productivity of species examined. Historically, fishing mortality presented the most significant threat to Palau’s sharks and rays, but recent conservation initiatives have the potential to significantly reduce this threat as large areas are closed to fishing following the full implementation of the Palau National Marine Sanctuary in 2020. Palau’s sharks have a wide range of social and cultural values and are important to tourism. This study presents a new synthesis and overview of available information including citizen science, but also highlights the need for further local taxonomic work and research.