Elasmobranchs of the western Arabian Gulf: Diversity, status, and implications for conservation

In spite of the ecological services provided by elasmobranchs, their diversity and populations are significantly declining even before appropriate assessments are conducted. This paper presents information on elasmobranch diversity in the Saudi waters of the Arabian Gulf based on fishery-independent and dependent surveys. A total of 369 individual sharks and batoids were collected from 119 out of 228 trawl stations surveyed between 2013 and 2016. Gymnura poecilura and Carcharhinus dussumieri were the most dominant batoid and shark species, respectively. The catch per unit area indicated the waters around Jana Island as a hotspot of elasmobranchs. A total of 135 surveys at the landing sites and fish markets from 2016 to 2020 showed that 88% of elasmobranchs (out of 4,055 individuals recorded) were caught by gill nets. Sharks were the most abundant (> 80 %) with three dominant species: Carcharhinus sorrah, C. humani, and C. limbatus. In total, 47 species of elasmobranchs (24 sharks and 23 batoids) belonging to 16 families and 5 orders were recorded from a possible 58 total species predicted by species richness extrapolators (Chao 1). High values of Margalef richness (> 2) and Shannon–Wiener index (3–4) suggested rich diversity of elasmobranchs in the study area with homogeneous distribution over the years and seasons as shown by cluster and similarity profile analysis. Of the 47 species recorded, six species were Critically Endangered regionally, six Endangered, and seven species Vulnerable according to the IUCN Red List of Threatened Species, necessitating proper management and conservation measures.