Diversity, distribution, and natural history of the marine snakes of Sri Lanka

Abstract

Marine snakes comprise 90% of all marine reptiles, yet they are the least known of all marine reptiles. Among the marine snakes, very little is known about the marine snakes of the Indian Ocean (IO) compared to the marine snake fauna of the Indo-West Pacific (IWP). Hence, there is a dearth of information about the diversity, systematics, distribution, abundance, natural history, and conservation of IO marine snakes. Therefore, to gain insights to the IO marine snake fauna, we conducted a systematic survey on the marine snakes in the island of Sri Lanka, a central tropical location in the IO. Eight sites around the islandwere sampled for fisheries by-catch from 2010 to the end of 2012. The study documented 14 species (Acrochordidae 1, Homalopsidae 2, Elapidae (Hydrophiinae) 11) of marine snakes from Sri Lankan waters. Our by-catch data indicates that Acrochordus granulatus, Hydrophis curtus, Hydrophis cyanocinctus, Hydrophis schistosus, Hydrophis spiralis, and Hydrophis viperinus are highly abundant (n>20). Further, data demonstrates that the most widely distributed species in Sri Lankan waters are H. spiralis and H. curtus. However, high volumes of marine snakes in fisheries by-catch indicate that fishing-related mortality is a major threat to marine snakes of Sri Lanka. Given the distinct evolutionary history of these snakes in the IO and the unique conservation value, the IO marine snake fauna (inclusive of Sri Lankan marine snakes) should be considered a separate conservation management unit.