Identification of thirteen pelagic shark species of the Indian ocean occurring around Sri Lanka; using morphological characters of their fins

Sharks are of great commercial importance in the marine fisheries sector in Sri Lanka. They are taken in large quantities for human consumption, especially to obtain shark fins, which is an export oriented product and to a lesser extent for the extraction of liver oil. Past research has reported 60 species of sharks. Among the shark landings in Sri Lanka Silky shark (Carchahinus falciformis) is the dominant species followed by Blue sharks (Prionace glauca) Oceanic whitetip shark (Carcharhinus longimanus) and Scalloped hammerhead (Sphyrna lewini) respectively. Contribution of other sharks including Shortfin mako (Isurus oxyrinchus), Smooth hammerhead shark (Sphyrna zygaena), Longfin mako (Isurus paucus) Great hammerhead shark(Sphyrna mokarran) and Blacktip reef shark (Carcharhinus melanopterus) sharks to the total shark landings is relatively very small. Under the Shark Fisheries Management regulations in 2015; prohibition of catching Common thresher shark (Alopias vulpinus), Big-eye thresher shark (Alopias superciliosus), Pelagic thresher shark (Alopias pelagicus), Oceanic whitetip shark (Carcharhinus longimanus) and Whale shark (Rhincodon typus) in high seas were declared.
Fins from these species crossing international boundaries are required to be accompanied by an export permit issued by the national CITES authority. One of the most important issues in identify by species by using shark fins. Accordingly, it is important to investigate the morphological characteristics of shark fins in establishing a key to discriminate species. In this study, shark fins from 9 species landed mainly in large pelagic fishery and 5 species prohibited catching in high seas were used for examination.
To assist in identification of fins, we have designed an easy-to-use identification key based on morphological characteristics of the fin such as fin colour, distinct markings, fin shape to be used by fisheries field officers, custom officers, wildlife inspectors, and fishers to provisionally identify detached, dried, unprocessed dorsal, pectoral and caudal fins from pelagic sharks that are commonly occurring around Sri Lanka,
Results of our examination revealed that the species were identifiable by the morphological characteristics of any fin among the first dorsal, pectoral and caudal fins.