Whale Shark for Lunch

Glenn Moore's blog | Created 1 decade ago

Museums are wonderful places, with collections that are full of history and from time to time real gems and interesting stories pop up among the artefacts and specimens.  Among the Western Australian Museum’s large fish collection, we have a few shelves of dry material – mostly skulls, bones and teeth.  We recently had a research visitor to the museum working with our Department of Palaeontology: Dr. Michael Newbrey from the Royal Tyrrell Museum of Palaeontology in Alberta, Canada - he studies fossil fish (palaeoichthyology) and is especially interested in the centra of sharks.  A centrum is the main central body of a vertebra (centra is plural).  Of course, examining the bones of living species helps to understand fossil bones, and Dr Newbrey asked to look through our dry collection.

As we searched through the boxes, we came to a pair of large shark centra.  On the label, the bones had been identified as belonging to a Basking Shark Cetorhinus maximus, but Dr Newbrey immediately recognised them as centra from the largest fish in the world, the Whale Shark Rhincodon typus.  However, what intrigued us the most was that the label also stated that the collection locality was Albany, on the south coast of Western Australia.

Whale Sharks are typically restricted to tropical waters, but Dr Newbrey was adamant that these bones from Albany belonged to this species.  He thought they appeared incomplete or damaged, as if they had been exposed to acid.  We decided to investigate further and looked up the original records.

Our records showed that the Whale Shark centra had been donated to the Western Australian Museum by the Fisheries Department.  To our surprise, we discovered that the centra had been found inside the stomach of a 4.5m male White Shark Carcharodon carcharias!  That is why the centra looked as though they had been exposed to acid – it was stomach acid.  The White Shark had been caught at the Cheynes Beach Whaling Station (near Albany) in the 1960s.  Not surprisingly, it was common for White Sharks to come to the station (which operated from 1952 to 1978) to feed on the dead whales that were tied up awaiting processing.  The oil from whale blubber was so valuable that the sharks were often hunted to prevent them eating the whale flesh.  Fisheries Officer Colin Ostle was based at the station from 1967-1974 and it was his job to measure and take samples from the whales, but he also inspected the sharks and took samples from their guts.  We assume that it was Colin who donated the centra to the Museum.

What we don’t know is how the White Shark came to feed on a Whale Shark.  Whale Sharks are generally tropical, although we do know they appear on the south coast during years of very warm sea temperatures (there was one recorded in Albany in 2012). White Sharks are most common in the southern parts of Australia, however they do occur throughout tropical regions too.  Did the White Shark feed on the Whale Shark in the north and swim down to Albany where it was caught?  Or, did the Whale Shark get to the south coast and then perish in the cold water before being devoured by the White Shark?  Was the Whale Shark dead or alive when the White Shark found it?  Unfortunately, we’ll never know the answers to these intriging questions.