Population genetic structure of the oceanic whitetip shark, Carcharhinus longimanus, along the Indian coast

Abstract

Sharks are undergoing population declines worldwide and it is imperative to devise conservation and management strategies to prevent their extinction. Oceanic whitetip sharks are large pelagic sharks distributed circumglobally and recent IUCN assessments classified them as “critically endangered.” Considering their vulnerability, we investigated the intraspecific diversity and genetic stock structure of oceanic whitetip shark, Carcharhinus longimanus, along the Indian coast using mitochondrial control region sequences so that viable management guidelines can be formulated in the Indian Ocean region. Population genetic analyses revealed a lack of significant genetic differentiation along the Indian coast indicating substantial gene flow and connectivity among populations. Comparisons of data of the present study with that of Atlantic Ocean regions indicated significant connectivity and gene flow between Indian and East Atlantic regions and a lack of connectivity between Indian and West Atlantic Ocean regions. Oceanic whitetip sharks have substantial capacity for oceanic migration resulting in the mixing of gene pools. Despite these capabilities, overfishing is one of the major drivers of population decline worldwide, resulting in severe fragmentation of populations. Based on the results of the present study, this species can be managed as a single stock along the Indian coast. Further co-management measures along with countries bordering East Atlantic coast can also be devised. Management should consider a complete or seasonal ban of the fishery in addition to restrictions in gear types.