[MARMAM] New paper on genetic differentiation in short-beaked common dolphins from southern Australia

Kerstin Bilgmann kbilgman at gse.mq.edu.au
Sun Jan 11 14:53:21 PST 2009

The following paper has been published in Animal Conservation.
A pdf file is available at
or by emailing me at kbilgman at gse.mq.edu.au

Common dolphins subject to fisheries impacts in Southern Australia are
genetically differentiated: implications for conservation.
K. Bilgmann, L. M. Möller, R. G. Harcourt, R. Gales, L. B. Beheregaray

Interactions between short-beaked common dolphins Delphinus delphis and
the fishing industry of South Australia (SA) have lead to serious
concerns over the long-term viability of the local dolphin population.
Common dolphins are gregarious animals with high vagility and are
expected to display limited genetic differentiation over large spatial
scales. Here, we investigate population genetic structure of southern
Australian common dolphins using mitochondrial DNA control region
sequences and seven microsatellite markers. We found unexpected levels
of genetic differentiation for short-beaked common dolphins over a
distance of ~1500 km. Although no genetic structure was observed in
common dolphins along the coast of SA, we detected marked
differentiation between dolphins from SA and south-eastern Tasmania,
suggesting a minimum of two genetic populations in southern Australia.
We hypothesize that the ephemeral distribution of small pelagic fish
enhances movement and dispersal between dolphin groups at a local level.
However, clear differences in water temperature, habitat features and
fish abundance between SA and Tasmania may contribute to the
contemporary isolation observed between dolphin populations. Our
findings have important consequences for developing conservation
management strategies, because SA has the largest purse-seine fishery by
weight in Australia, and substantial numbers of fatal common dolphin
interactions have occurred. In 2004/2005 alone, an estimated 1728 common
dolphins were encircled and 377 died over a 7-month period. If these
impacts lead to a reduction in population size, it is unlikely that
dolphins from the adjacent south-eastern Tasmanian population will
replace the lost individuals. Recommendations for assessing the impacts
of the fishery are presented. The information herein may also have
implications for fisheries–marine mammal interactions in coastal and
neritic habitats in other areas of the world. Moreover, we demonstrate
that a species commonly thought to be wide ranging can show an
unexpected degree of genetic differentiation.

Dr Kerstin Bilgmann

Scientific Officer
Sea Water Facility Manager
Biological Sciences
Marine Mammal Research Group
Graduate School of the Environment

Macquarie University, Sydney
NSW 2109, Australia
Email: kbilgman at gse.mq.edu.au
Ph: + 61 2 9850 7982
Fax: + 61 2 9850 7972

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