Great white shark in False Bay

Shark tale follow-up

After his shark sighting at Long Beach last week, Tony emailed local guru Georgina Jones of SURG – more on SURG (Southern Underwater Research Group), and Georgina’s work in particular, will follow in another post (probably a book review). Tony wanted to find out whether his observation that there was no visible marine life, no fish and no movement at Long Beach on the day he saw the shark had anything to do with the presence of the creature, or whether it was uncorrelated. Georgina passed Tony’s email on to Alison Kock at Save Our Seas, a veteran white shark researcher based in Cape Town.

Alison’s reply – which is filled with fascinating nuggets of information about shark monitoring in Cape Town and great whites in general – is reproduced below:

Thank-you very much for forwarding this encounter. I keep a database of all white shark-human encounters in Cape waters and with your permission would like to add this encounter and your name, Tony and contact numbers to this database. Interestingly another sighting in the same area was recorded on the 23 August, and there were two white shark sightings at Fish Hoek on the 25 Aug, and one on the 24 and one on the 20th (sharkspotters.org.za has sightings recorded at shark spotter beaches).

Tony, regards your observation one would certainly expect that larger fish and seals would be absent from an area temporarily where a white shark is patrolling. However, it’s also conceivable that smaller marine animals could perceive the shark as a threat. A huge misconception is that white sharks only eat these larger animals, but various smaller fish and invertebrates (bivalves, cuttlefish, squids, octopus, pilchards etc) have also been recorded in white shark stomach contents, particularly smaller sharks (Geremy Cliff data). Thus, these animals may also respond to an immediate presence of a white shark if perceived as a threat. However, I wouldn’t expect this behaviour to persist for long periods of time.

We have deployed small animal-borne cameras on white sharks over the years and have been able to get a sharks POV of what happens on a reef when the shark swims over it. Some smaller fish which you wouldn’t think to be on the menu do react by swimming out of harms way. However, the behaviour is usually instantaneous with ‘normal’ behaviour by the fish resuming almost as soon as the shark’s head has moved past. When we observe white sharks around the research boat, we record similar behaviour, the chumming often attracts large groups of various species of ‘bait fish’, these fish almost always respond to the approaching shark by moving out the way temporarily.

Thanks Alison!

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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