ESR 14:13-22 (2011)  -  doi:10.3354/esr00337

Global phylogeography of the dusky shark Carcharhinus obscurus: implications for fisheries management and monitoring the shark fin trade

Martin T. Benavides1, Rebekah L. Horn2, Kevin A. Feldheim3, Mahmood S. Shivji2, Shelley C. Clarke4, Sabine Wintner5, Lisa Natanson6, Matias Braccini7, Jessica J. Boomer8, Simon J. B. Gulak9, Demian D. Chapman1,* 

1Institute for Ocean Conservation Science & School of Marine and Atmospheric Science, Stony Brook University, Stony Brook, New York 11794, USA
2Guy Harvey Research Institute and Save Our Seas Shark Center, Nova Southeastern University Oceanographic Center, Dania Beach, Florida 33004, USA
3Field Museum, Pritzker Laboratory for Molecular Systematics and Evolution, 1400 South Lake Shore Drive, Chicago, Illinois 60605, USA
4Oceanic Fisheries Programme, Secretariat of the Pacific Community, BPD5 CEDEX, Noumea 98848, New Caledonia
5KwaZulu-Natal Sharks Board, Private Bag 2, Umhlanga Rocks 4320 and Biomedical Resource Unit, University of KwaZulu-Natal, Durban 4000, South Africa
6NOAA Fisheries Service, 28 Tarzwell Dr., Narragansett, Rhode Island 02882, USA
7Fisheries Centre, The University of British Columbia, Vancouver, British Columbia V6T1Z4, Canada
8Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
9NOAA Fisheries Service, Southeast Fisheries Science Center, 3500 Delwood Beach Road, Panama City, Florida 32408, USA
*‑Corresponding author.Email:

ABSTRACT: Genetic stock structure information is needed to delineate management units and monitor trade in sharks, many of which are heavily exploited and declining. The dusky shark Carcharhinus obscurus is a large apex predator that is sought after for its fins and is considered highly susceptible to overexploitation. The International Union for the Conservation of Nature (IUCN) classifies this species as ‘Vulnerable’ globally and ‘Endangered’ in the northwest Atlantic. We make the first assessment of global stock structure of C. obscurus by analyzing part of the mitochondrial control region (mtCR) in 255 individuals sampled from 8 geographically dispersed locations. We found 25 mtCR haplotypes and rejected a null hypothesis of panmixia (analysis of molecular variance, ΦST = 0.55, p < 0.000001), detecting significant differentiation between 3 management units: US Atlantic (USATL), South Africa (SAF), and Australia (AUS). We also found preliminary evidence of population structure between the USATL and southwest Atlantic (Brazil). There were no shared haplotypes between the western Atlantic and Indo-Pacific. These analyses suggest that replenishment of the collapsed USATL management unit via immigration of females from elsewhere is unlikely. Mixed stock analysis (MSA) simulations show that reconstruction of the relative contributions of USATL, SAF, and AUS management units to the Asian fin trade is possible using these mtCR sequences. We suggest avenues for obtaining samples to conduct MSA of the shark fin trade, which could enhance management of dusky sharks and other species that are exploited for their fins.

KEY WORDS: Mitochondrial DNA · Phylogeography · Conservation · Mixed stock analysis

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Cite this article as: Benavides MT, Horn RL, Feldheim KA, Shivji MS and others (2011) Global phylogeography of the dusky shark Carcharhinus obscurus: implications for fisheries management and monitoring the shark fin trade. Endang Species Res 14:13-22

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