For The First Time, New Evidence Shows Sharks Are Not Always Top Of The Food Chain

In a world-first, New Zealand leopard seals have been discovered feeding on sharks. While leopard seals are known as apex predators who feed on a variety of prey such as penguins and other seals, sharks have now been discovered to be an important menu item.

By sorting through the scat (poop) of over 100 leopard seal,“Our findings show this is the first record of leopard seals, anywhere in the world, feeding on sharks,”said Dr Krista van der Linde of LeopardSeals.org and the World Wide Fund for Nature-New Zealand (WWF-New Zealand) and the study’s senior author. She added, “When we founded LeopardSeals.org, I knew we were going to find some interesting things, but this is the next-level of incredible.”

Dr Lara Shepherd from Te Papa Museum and a co-author of the study said,“We looked at the remains left in the scat and combined the morphological examination with DNA sequencing, just like a real-world CSI show in order to identify the shark remains.”

Rick Bout, a citizen scientist who joined LeopardSeals.org to help with data collection, noted, “This is now the largest collection of leopard seal poop in the world and that shows the power of collaboration between scientists and folks, like myself, who care about the environment. From working with this team I’ve also had the chance to be one of the co-authors of this remarkable study.”

This study produced further surprises when researchers found two other unique cartilaginous (non-bony) fish, both close relatives of sharks, were part of the seals diet. Van der Linde added, “We were blown away to find that sharks were on the menu, but then we also found Elephant fish and Ghost sharks were also being hunted by the leopard seals. These fish have large spines to help protect them from predators and sure enough there were wounds on the leopard seals, sometimes even big spines embedded in their faces, one leopard seal had at least 14 such wounds.”

Dr Ingrid Visser, co-founder of LeopardSeals.org and study co-author said, “I’ve been researching one of New Zealand’s top predators, the Orca, for 30 years and I’ve seen them eat sharks on a regular basis. To know there is another marine mammal also munching on sharks, well, that has implications for the whole food web and our understanding of how it all is interlinked.”

Dr van der Linde concluded, “The relatively high number of shark remains also indicates that sharks could be an important part of the seals diet around New Zealand.”

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A copy of the study can also be downloaded here:

https://www.frontiersin.org/articles/10.3389/fmars.2021.795358/full

For further information on leopard seals in New Zealand, follow Leopard Seals NZ on Facebook or Instagram or visit www.leopardseals.org.

FOOTNOTE: Consider yourself a truly dedicated citizen scientist? Then the team at LeopardSeals.org wants your help! If you see a leopard seal, anywhere in New Zealand, call 0800 LEOPARD (0800 536 7273). If you spot a poo (scat), even better. Co-author and LeopardSeals.org researcher Rick Bout says, “Scat samples are invaluable to us and we want your help to continue to build our poo library! Be sure to follow Department of Conservation guidelines by keeping at least 20 m away from leopard seals at all times, if you can collect a scat sample for us, we would be very grateful!”

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