Orcas targeting great whites
Great white sharks, attracted by an offshore seal colony, have brought success to the adjacent fishing village of Gansbaai along the southern African coast.
A flourishing shark cage-diving industry has sprung up, bringing jobs and money, and so benefiting the entire community.
Tourists come from far and near to experience the thrill of a real-life brush with the legendary Jaws.
In the fictional story and film Jaws, the ‘presence’ of a great white shark threatened a town; in real life in Orca the ‘absence’ of the sharks has the same effect.
Then one day, the sharks disappear. Slowly at first, but with gathering momentum, the word spreads: cage diving off Gansbaai can no longer promise the thrill of an encounter.
The crowds thin, and the once bustling community waits as their livelihoods tail off. Entrepreneurs and scientists alike are baffled. But it’s not long before shark carcasses start washing up on the beaches.
These, together with some coincidental sightings of another apex predator in the vicinity, are the first leads to the possible causes and culprits. Against the clamour and thrill of the cage-diving season in full swing,
Richard Peirce visits the unfolding drama and explores what’s behind these strange events.
Orca - The Day the Great White Sharks Disappeared by Richard Peirce
The Sevengill mystery
Finding shark carcasses on the seabed in a protected area sends out alarm signals. It is time for those who monitor our ocean and its inhabitants to step in and investigate.
In 2014, in False Bay at a popular dive site called Castle Rock Reserve near the naval port of Simon’s Town, divers started coming across the bodies of broadnose sevengill sharks (cow sharks) lying on the seabed. They were in various stages of decomposition and appeared to have been attacked and killed. The question was, by what, and why?
Marine biologist Dr Alison Kock came to hear of the reports and examined photos and videos of the carcasses, but she was unable to learn much from the available evidence, particularly as most of the carcasses were already decomposing.
One photo, however, showed such a neat, clean wound in the shark’s belly that Alison thought it had possibly been done by a fisherman with a knife. The Castle Rock Reserve is a protected area (situated to the south of Simon’s Town), so any possibility that sharks were being killed there by humans had to be investigated.
In April 2016 Alison and her team were called in to examine another carcass. These remains were fresh and they were able to discern tooth marks on both pectoral fins, and the liver was missing. Over the next few weeks several more sevengill shark carcasses were found and examined, and Kock concluded they were being preyed on by orcas.
She was later quoted as saying: “It looks as if at least two orcas had to have worked together. We saw the bite marks on the pectoral fins and then the shark was torn open to the pectoral girdle.
Based on that examination, it seems the orcas are biting on the pectorals, ripping the shark apart and then taking its liver out.”
Some months earlier, Alison had been diving at Castle Rock when she had encountered two distinctive killer whales.
They were distinctive because both of them had collapsed dorsal fins: the fin of one of them flopped to the left, and that of the other to the right. It was this sighting and the necropsies (animal autopsies) she later performed that fed Kock’s suspicion about orcas being the mystery killers.
Simon’s Town-based naturalist and marine wildlife tour skipper Dave Hurwitz first saw orcas in False Bay in 2009, when he spotted them in the town harbour, right beside his boat. Further sightings followed and, in 2015 near Seal Island in False Bay, Hurwitz saw the two orcas with their collapsed fins. “I named them ‘Port’ and ‘Starboard’. The fin of one of them flops over to the left, and the fin of the other to the right. I named them so that it would be easy to re-identify them,” said Hurwitz.
These names stuck and it wouldn’t be long before even just the mention of ‘Port and Starboard’ would be like a kick in the stomach for people in the Western Cape making their livings from shark ecotourism.
While the experts and the practitioners of cage diving remained oblivious, young Alice Farraday, on holiday in South Africa from Edinburgh, had seen orcas pass close in to Gearing’s Point in Hermanus, which lies further east along the coast. In her excitement she had disturbed a dassie (rock hyrax) that her mother was hand feeding, and then had not stopped talking about her sighting all day. She sensed that her parents didn’t really believe that she had seen two huge black-and-white “fish” swimming past, close to where the family was standing.
She didn’t know that orcas aren’t fish, but she did know what she had seen, and her parents’ apparent disbelief merely strengthened her determination to convince them. She returned to the subject repeatedly over the next couple of days, until the family happened to walk past a Hermanus book shop; Alice stopped in her tracks and pointed at the shop window, “There, see, I told you!” The little girl was pointing at a picture of a pod of orcas on the front cover of a nature book. She smiled smugly, as if to say, “You didn’t believe me, but I knew I was right”. Alice had just correctly identified the two killer whales!
At this very moment the two animals were approaching Dyer Island from the west. Although adept at hunting co-operatively, and although they had a varied diet and often fed opportunistically, today they were on a specific mission: hunting great whites.
Their goal was to extract the large shark liver, which can account for up to 24% of the shark’s body weight.
There were no squeaks or other noises between Port and Starboard as they patrolled their hunting ground - the element of surprise would be crucial.
As the late afternoon sun seemed to accelerate towards the horizon, the pair sensed the presence of a great white, using echolocation to pinpoint its precise location. The great white seemed unaware of their approach, and the attack that followed was fast, brutal and deadly. The waters around Dyer Island became the scene of a mighty clash between two giant apex predators. It would not be the last such clash.
Orca, The Day the Great White Sharks Disappeared is published by Struik Nature, Penguin Random House South Africa. It retails for R190.
He has authored several books on conservation topics, including Giant Steps (about elephants in captivity), Cuddle Me, Kill Me (about the captive lion breeding and canned hunting industry), The Poacher’s Moon (about rhino poaching) and Nicole (about a shark’s marathon journey) - all published by Struik Nature.
“The attacks by orcas on great white sharks, and their disappearance and reappearance in Western Cape waters during the last few years has caused much speculation, sensational newspaper headlines, job losses, happiness and misery. My latest book Orca tells the story of the sharks, the killer whales, and the people.”