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Conservation Genetics

, Volume 9, Issue 3, pp 627–636 | Cite as

Population structure of bottlenose dolphins (Tursiops aduncus) impacted by bycatch along the east coast of South Africa

  • Ada Natoli
  • Victor M. Peddemors
  • A. Rus Hoelzel
Research Article

Abstract

Shark nets placed along the coast of KwaZulu-Natal to protect bathers from shark attacks result in an incidental by-catch of bottlenose dolphins (Tursiops aduncus) at twice the level suggested by the IWC as the maximum sustainable capture rate for a cetacean population. Observational data reported the presence of at least two putative populations, one a seasonal migratory population moving into the KwaZulu-Natal area following the movement of sardines, and the other a coastal, apparently resident population. Some observations indicated possible further subdivision of the coastal population. We analysed nine microsatellite loci and 599 bps of the mitochondrial control region and found small but significant differentiation within the putative coastal population (FST = 0.022) separated north and south of Ifafa. There was weaker evidence for differentiation between the southern coastal and migratory populations (FST = 0.012). Genetic diversity was low for both types of markers in all populations, and the pattern of mtDNA variation was consistent with a founder event. Considering the high capture rate, the low level of genetic diversity, and the evidence of possible population differentiation along the coast, we suggest that particular care should be taken in managing the take from shark nets especially in the north coastal area of KZN where the population showed the higher degree of differentiation.

Keywords

South Africa Bottlenose dolphin Tursiops aduncus Population genetics 

Notes

Acknowledgments

Thanks to the director & staff of the Natal Sharks Board for their support in collecting the samples (biopsies collected under permit to Natal Shark Board). We thank the University of Milano scholarship and Marion Zunz Award to Ada Natoli, the CNR (Centro Nazionale di Ricerche—Italy) grants to Ada Natoli and the University of Durham for their financial contribution.

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Ada Natoli
    • 1
  • Victor M. Peddemors
    • 2
    • 3
  • A. Rus Hoelzel
    • 1
  1. 1.Department of Biological SciencesUniversity of DurhamDurhamUK
  2. 2.University of KwaZulu-NatalDurbanSouth Africa
  3. 3.Sea Predator Research UnitSydneyAustralia

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