Structure and Genetic Variability of the Oceanic Whitetip Shark, Carcharhinus longimanus, Determined Using Mitochondrial DNA.

Sâmia M Camargo,Miguel N Santos,Lucy Howey-Jordan,Fausto Foresti,Demian Chapman,Claudio Oliveira,Fabio H V Hazin,Edward J Brooks,Fernando F Mendonça,Daniel Fernando,Rui Coelho,Natalia J Mendes

doi:10.1371/journal.pone.0155623

Abstract

Information regarding population structure and genetic connectivity is an important contribution when establishing conservation strategies to manage threatened species. The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, large-bodied, pelagic shark listed by the IUCN (International Union for Conservation of Nature) Red List as "vulnerable" throughout its range and “critically endangered” in the western north Atlantic. In 2014, the species was protected globally under Appendix II of CITES (Convention on International Trade in Endangered Species), limiting and regulating trade. This study used partial sequences of mitochondrial DNA (mtDNA) control region to determine the population genetic structure of oceanic whitetip sharks across the Atlantic and Indian Oceans. 724 base pairs were obtained from 215 individuals that identifed nine polymorphic sites and defined 12 distinct haplotypes. Total nucleotide diversity (π) was 0.0013 and haplotype diversity (h) was 0.5953. The Analysis of Molecular Variance (AMOVA) evidenced moderate levels of population structure (ɸST = 0.1039) with restricted gene flow between the western and eastern Atlantic Ocean, and a strong relationship between the latter region and the Indian Ocean. Even though the oceanic whitetip is a highly migratory animal the results presented here show that their genetic variability is slightly below average of other pelagic sharks. Additionally, this study recommends that at least two populations in the Atlantic Ocean should be considered distinct (eastern and western Atlantic) and conservation efforts should be focused in areas with the greatest genetic diversity by environmental managers.

Highlights

The effects of unsustainable fishing on populations of sharks and rays has been well-documented globally [1], and studies have shown that over the last several decades many large migratory species commonly caught in large scale pelagic marine fisheries are rapidly declining [2, 3]
The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, large-bodied, pelagic shark listed by the IUCN (International Union for Conservation of Nature) Red List as "vulnerable" throughout its range and “critically endangered” in the western north Atlantic
The results show low levels of genetic diversity for the oceanic whitetip shark in the Atlantic and in the Indian Ocean, the latter has been evaluated with a small number of individuals and in a relatively small area

Summary

Introduction

The effects of unsustainable fishing on populations of sharks and rays (elasmobranchs) has been well-documented globally [1], and studies have shown that over the last several decades many large migratory species commonly caught in large scale pelagic marine fisheries are rapidly declining [2, 3]. Recent population assessments and anecdotal reports suggest that the oceanic whitetip shark is only occasionally recorded in the Atlantic. A recent study by Coelho et al [12] covering a wide area of the Atlantic in both hemispheres indicated that the oceanic whitetip shark bycatch in pelagic longline fisheries is less than 1% of the total elasmobranch catches. Philopatric behavior, defined as the tendency of individuals to return or stay in their home areas, natal (birth) sites or adopted locales[13], was recently described in this species, highlighting the need for designated protective areas for oceanic whitetip sharks

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