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Genetic evidence of killer whale predation on white sharks in Australia
  • +8
  • Isabella M. Reeves,
  • Andrew Weeks,
  • Alison Towner,
  • Rachael Impey,
  • Jessica Fish,
  • Zach Clark,
  • Paul Butcher,
  • Lauren Meyer,
  • David Donnelly,
  • Charlie Huveneers,
  • Adam Miller
Isabella M. Reeves
Flinders University
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Andrew Weeks
The University of Melbourne
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Alison Towner
Rhodes University Department of Ichthyology and Fisheries Science
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Rachael Impey
EnviroDNA
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Jessica Fish
Deakin University Faculty of Science Engineering and Built Environment
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Zach Clark
Deakin University Faculty of Science Engineering and Built Environment
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Paul Butcher
NSW Government
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Lauren Meyer
Flinders University
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David Donnelly
Killer Whales Australia
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Charlie Huveneers
Flinders University
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Adam Miller
Flinders University

Corresponding Author:[email protected]

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Abstract

Killer whales (Orcinus orca) have been documented to prey on white sharks (Carcharodon carcharias), in some cases causing localised shark displacement and triggering ecological cascades. Notably, a series of such predation events have been reported from South Africa over the last decade, with killer whales specifically targeting shark’s liver. However, observations of these interactions are rare and knowledge of their frequency across the world’s oceans remain limited. In October 2023, a 4.7 m (total length) white shark carcass washed ashore in south-eastern Australia, coinciding with reports from citizen scientists of killer whales hunting a large, unidentified prey item in the area. Visual inspection of the carcass revealed that the liver, digestive and reproductive organs were missing, and the presence of four distinctive bite wounds, one of which was characteristic of killer whale liver extraction as seen in South Africa. Genomic analyses performed on swabs taken from the bite wounds confirmed the presence of killer whale DNA in the major bite area, while the other bites were embedded with genetic material from the scavenging broadnose sevengill shark (Notorynchus cepedianus). These results provide confirmed evidence of killer whale predation on white sharks in Australia, and the likely selective consumption of the liver, suggesting predations of this nature are more globally prevalent than currently assumed.
02 Sep 2024Submitted to Ecology and Evolution
11 Sep 2024Submission Checks Completed
11 Sep 2024Assigned to Editor
16 Sep 2024Reviewer(s) Assigned