5 October, 2018 5 October, 2018

Behind The Scenes – 4.9m Great White Necropsy

In 2017, before taking on the position of online editor here at Zag, my office was the ocean and sharks were my business. 2018 has seen me trade diving and tagging equipment for keyboards and smartphones, and salt-sprayed hair for aircon and dry eyes. Last year I was employed as the field coordinator and skipper for the South African Shark Conservancy (SASC), my daily routine included chopping up kak loads of sardines, launching a boat without sinking my boss’s car (no exaggeration that almost happened), navigating the capes waters and dodging jaws as I measured and tagged every shark we caught. Operating across the bay from the world renowned ‘Shark Alley’ in Gansbaai, great whites were never too far away from the action.

I got to witness some truly crazy shit on the water. From countless superpods of dolphin and southern right whales breaching straight out of the water 20m’s from my little 5 man boat, soaking everyone on board in the process. So as you can imagine I have a couple of stories to swap down at my local. Among the barflies and fisherman,  the most well-received involved two of the most iconic ocean heavyweights, the Orcinus orca (killer whale) & Carcharodon carcharias (great white). 

Following the predation of a 1.5 ton nearly 5m female white shark by an orca, I received a phone call from my boss at the time, Meaghen McCord, saying that if I wasn’t on the water already I should get my ass over to Gansbaai to assist in the necropsy. At this point, as a full-on shark frother, I was tripping out! This would be one of many white shark corpses to wash up along the Southern Cape Coast in 2017, ranging in size from 2.7metres to 4.9 metres. The two females and three males all had one thing in common: holes puncturing the muscle wall between the pectoral fins. Turns out Free Willy was more gangsta than we thought.   

Although the opening scene from Jaws II immediately springs to mind, in which an orca washes up with huge bite marks on it, the reality has turned out to be the exact opposite.

The bite marks inflicted, missing liver, together with confirmed sightings indicate that orcas were responsible for this precisely-targeted predation. The liver had been sucked out by these cetacean Hannibal Lecter esque predators, leaving the rest of the body intact. Due to the absence of a swim bladder sharks use their nutrient-rich liver, which can weigh up to 1/3 of their total body weight, to control their buoyancy. The squalene rich organ making for one helluva snack for the two orca, affectionately dubbed Port and Starboard due to their collapsed dorsal fins. In fact, it accounts for an energy source higher than whale blubber.

The attacks might have been new in South Africa, but certainly aren’t out of the ordinary where orca are concerned, those homies can eat pretty much anything—they’re like the velociraptors of the oceans. Shit man, I’m so stoked we’re off their menu on account of us being junk food and all. The diet of orcas is often geographic or population specific. These aquatic pandas predating in South African waters have been documented targeting smaller shark species for their livers.

Cow sharks, blues, and makos caught on longlines have had their livers removed by orcas, alongside the brains of billfish. Cow shark carcasses, void of livers, have also washed ashore along the same stretch of coast, and again, these events followed nearby orca sightings. But how did they take down a 4.9m beast?

When it comes to intellect in the animal kingdom, orca- members of the dolphin family- are damn smart, like Stephan Hawkin smart. They knew how to exploit an evolutionary trait, common to all sharks. A phenomenon known as tonic immobility. This is a natural state of paralysis, brought about when sharks are positioned ventral side up.

For certain species of shark like the great white, which is unable to pump water across its gills unless it keeps swimming, the consequence of being maintained within this ‘tonic’ state for too long is a case of “that’s all she wrote folks”. Effectively, killer whales have figured out how to drown their prey. Yeah, sharks can drown.

Researchers regularly use this natural adaptation to their advantage when surgically implanting acoustic tags. The rapid induction and recovery of the animals optimises the surgical procedure, especially so as field work often takes place in complex fieldwork conditions. 

From this almost religious experience, I took away 5 important lessons:

1 – Don’t stand downwind, a decomposing 4.8m beast stinks, especially when the stomach is removed and ‘groomed’ for parasites. If not your existence will be measured between leftover dry heaves. 

2 – White shark females are hard to charm, this one estimated to be around 30 odd years old was still a virgin judging by the unraptured hymen. Yeah, science can be pretty intrusive.

3 – Size doesn’t matter to an orca, big or small they coming for you all. 

4 – A 4.8m shark is BIG. Like if it was a table you would be able to re-enact the last supper, comfortably. 

5 – Sharkskin will dull any blade, even wolverines adamantium slashers will need to hit the wet stone after making white shark nigiri.   

**Further credit must be extended the way of Marine Dynammics and the South African Sharck Conservancy for allowing me to be present and involved on the day.** 





Leave a reply

Your email address will not be published. Required fields are marked *