<figure><img src="https://images.theconversation.com/files/473862/original/file-20220713-20-peajvi.jpg?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1050&amp;h=700&amp;fit=crop" /><figcaption><span class="caption">shutterstock</span> </figcaption></figure><p>Great white sharks have long been at the top of the food chain in parts of South Africa’s oceans. In their peak winter hunting months, around 100 great white sharks a day could be observed off the coast of the Western Cape province. But in 2017, great white shark carcasses began to wash up on beaches at Gansbaai, one of the main sites where the species usually gathered. Some were <a href="https://www.tandfonline.com/doi/abs/10.2989/1814232X.2022.2066723#:%7E:text=Research%20Papers-,Fear%20at%20the%20top%3A%20killer%20whale%20predation%20drives%20white%20shark,South%20Africa's%20largest%20aggregation%20site&amp;text=Risk%2Dinduced%20fear%20effects%20exerted,on%20ecosystem%20structure%20and%20function.">missing their livers</a>. And the numbers of great white sharks in Gansbaai <a href="https://esajournals.onlinelibrary.wiley.com/doi/full/10.1002/ecs2.2531">started to drop</a>. In fact, they just vanished for up to a year at a time. What was the cause?</p> <p>The culprits appear to be a pair of male killer whales, which researchers have named Port and Starboard, that arrived in the area. They have a signature way of tearing open their prey and they favour the nutrient-rich liver. </p> <figure class="align-center zoomable"> <a href="https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img alt="Two killer whales in water" src="https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=373&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=373&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=373&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=469&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=469&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/473907/original/file-20220713-9316-cprrjv.JPG?ixlib=rb-4.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=469&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a> <figcaption> <span class="caption">Port and Starboard.</span> <span class="attribution"><span class="source">David Hurwitz</span></span> </figcaption> </figure> <p>Though killer whales are known to hunt sharks far from shore elsewhere in the world, this was the first time the carcasses had washed up on a beach and become available for scientific study.</p> <p>In today’s episode of Pasha, shark biologist and PhD candidate Alison Towner tells the unfolding story of the impact the killer whales are having on South Africa’s marine ecosystems. Great white sharks are fleeing to other parts of the coast and their absence affects other species like African penguins and Cape fur <a href="https://www.nature.com/articles/s41598-019-39356-2">seals</a>.</p> <figure class="align-center zoomable"> <a href="https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=1000&amp;fit=clip"><img alt="Great white shark dead on beach as people surround it." src="https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;fit=clip" srcset="https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=600&amp;h=288&amp;fit=crop&amp;dpr=1 600w, https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=30&amp;auto=format&amp;w=600&amp;h=288&amp;fit=crop&amp;dpr=2 1200w, https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=15&amp;auto=format&amp;w=600&amp;h=288&amp;fit=crop&amp;dpr=3 1800w, https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=45&amp;auto=format&amp;w=754&amp;h=362&amp;fit=crop&amp;dpr=1 754w, https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=30&amp;auto=format&amp;w=754&amp;h=362&amp;fit=crop&amp;dpr=2 1508w, https://images.theconversation.com/files/473861/original/file-20220713-24-zifvc4.JPG?ixlib=rb-4.1.0&amp;q=15&amp;auto=format&amp;w=754&amp;h=362&amp;fit=crop&amp;dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a> <figcaption> <span class="caption"></span> <span class="attribution"><span class="source">Tami Kaschke, Dyer Island Conservation Trust</span></span> </figcaption> </figure> <p>It’s a novel situation, with concerns for the <a href="https://www.dffe.gov.za/sites/default/files/reports/sharksconservationmanagement_nationaplanofaction_review2020october.pdf">tourism</a> and <a href="https://dict.org.za/">conservation</a> sectors – and no simple answers.</p> <hr> <p><strong>Photo</strong> “Great white shark” by Mogens Trolle, found on <a href="https://www.shutterstock.com/image-photo/great-white-shark-south-africa-132857996">Shutterstock</a>.</p> <p><strong>Music</strong> “Happy African Village” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p> <p>“African Moon” by John Bartmann, found on <a href="http://freemusicarchive.org/music/John_Bartmann/Public_Domain_Soundtrack_Music_Album_One/happy-african-village">FreeMusicArchive.org</a> licensed under <a href="https://creativecommons.org/publicdomain/zero/1.0/">CC0 1</a>.</p> <p><strong>Sounds</strong> “orcas (killer whales)” by MBARI_MARS found on <a href="https://freesound.org/people/MBARI_MARS/sounds/458854/">Freesound</a> licensed under <a href="http://creativecommons.org/licenses/by-nc/3.0/">attribution noncommercial 3.0 license</a>.</p><img src="https://counter.theconversation.com/content/186931/count.gif" alt="The Conversation" width="1" height="1" />