The Save Our Seas Foundation (SOSF) White Shark Research Team together with the Shark Spotters tracked a 3-metre great white shark for 24 hours straight. This was the first successful overnight continuous track of a white shark in False Bay.
Studying white sharks along the False Bay coast. Hours of surveying is required to spot the sharks swimming inshore.
Following reports from the Shark Spotters of shark sightings close to shore within the last two weeks in False Bay, the Save Our Seas Foundation white shark research team headed out to survey the coast for sharks and attempt to tag one of them. They found a white shark at 12h42 on Tuesday 8th December swimming along the surface between Seal Island and Strandfontein. After monitoring the shark’s behaviour for a few minutes the research boat slowly approached the shark to get a photographic identification of its dorsal fin, assign a catalogue number and determine the shark’s size and sex. After closer inspection it was determined that the shark was a 3-meter female, subsequently named Deepblue.
Collecting the dorsal ID of the 3-meter female white shark subsequently named Deepblue. Naming the sharks makes recording re-sighting information much easier in the field than remembering the complicated catalogue number.
Alison Kock, the white shark project leader with the SOSF and Shark Spotters, then tagged the animal at the base of her dorsal fin. The tag allowed the researchers to follow the shark in real time using specialized equipment mounted on the boat. “It is important to asses the shark’s behaviour while doing a track such as this in order to maintain the correct tracking distance; too far and the shark could swim out of range, too close and the boat disturbs her behaviour,” said Alison.
Alison tags Deepblue with a Vemco continuous pinger at the base of her dorsal fin. The tag emits a continuous signal which is used to track in real time.
Although the research team was prepared to track her across False Bay, Deepblue remained in the general area between Strandfontein and Seal Island. She was in no hurry to swim anywhere and her swimming speed varied between 2 – 4 km / hour. Deepblue spent a considerable amount of time at the surface and sometimes it appeared as though she was just drifting in the current and not actively swimming at all. Occasionally she swam within 200 meters from the coast before swimming as far as 4 kilometers offshore again.
Morne and Brocq (aka Maverick and Goose) take the first shift tracking Deepblue.
The team recorded interesting behaviour like this where a large yellowtail, Seriola lalandi, was seen swimming alongside the shark. PS. Look carefully between the pectoral fin and caudal fin to see the fish.
During the daylight track the team observed Deepblue approach another white shark of similar size at the surface. She slowly followed the second shark within 5 meters for a few seconds before breaking off the encounter and swimming in the opposite direction. Deepblue’s night behaviour was similar to her daytime behaviour, except that she went further offshore and also made some excursions in the direction of Gordon’s Bay and then towards Muizenberg, but always returning to Strandfontein.
“We did, however get an unforgettable surprise during the night, when bioluminescent plankton lit up both the ocean and the shark in a sparkling green glow,” said Alison.
A magical sunset in False Bay in the company of a white shark named Deepblue
No wind, calm waters, a sunset to take your breath away. This is what it's all about.
The research has previously documented the inshore behaviour of white sharks during summer. However, it is still unclear why exactly the sharks are present close to shore. Three predominant theories exist, namely 1) the sharks are predating on summer fish and smaller species of shark prevalent in the bay during summer time 2) environmental conditions such as warmer water or oxygen rich water may be what’s attracting them and 3) the inshore behaviour may be related to reproduction. Tracking the sharks in this way is a step towards determining the factors involved in inshore white shark activity.
The team would like to thank Dave Hurwitz of Simonstown Boat Company for assisting with the logistics of the track. Keep track of the team yourself when the next weather gap lets them track white sharks again at www.saveourseas.com.
Adrian and Brocq in good spirits even though we were all cold and starving during the night time track. Note to scientist - put food and coffee higher up on priority list next time around.
A spectacular sunrise in False Bay.
Additional information
The Save Our Seas Foundation White Shark Project was initiated in 2003 and is a dedicated research programme focusing on the ecology and behaviour of white sharks in False Bay, Cape Town, South Africa. It is collaboration between the Save Our Seas Shark Center, University of Cape Town, Department of Environmental Affairs and Tourism Marine and Coastal Management Branch and Shark Spotters.
Latest shark sightings
Muizenberg 10 December
St James 8 December
Muizenberg 8 December
Noordhoek 8 December
St James 7 December
Muizenberg 7 December
Muizenberg 5 December
St James 28 November
Muizenberg x 2 28 November
Muizenberg 25 November
Media contact
Alison Kock
White Shark Project Leader
Save Our Seas Foundation and Shark Spotters
Email: alison@saveourseas.com
Website: www.saveourseas.com & www.sharkspotters.org.za
Comments (6)
Well done to you, Morne and crew. Next time I’ll pack you some biltong and Klippies for the journey. See you guys soon, cheers, Glenn
Comment by Glenn — 15 December 2009 @ 22:57
Hi There
I have a theory which I feel is quite reasonable to consider regarding the recent shark attack in Fish Hoek. I am not a shark expert and base my theory on information gathered from various research programs on TV, magazines, etc. I will also state for the record that I am a scuba diver (qualified & diving since 1994) and have a soft spot for great whites. My theory does not rule out that the shark in question was not a great white – anything is possible, but rather that based on behavioural patterns it seems unlikely to be a great white. And it’s common human behaviour to shout ‘Great White’ when anything happens in Cape waters. Also keep in mind that your average man on the street is unlikely to differentiate between shark species. Enough said, here is my theory:
Great Whites:
•Seldom attack still standing prey
•There are hordes of great whites just behind the surf at Muizenberg on a daily basis – enjoying the oxygenated enriched waters
•Seldom goes after human targets and devours it completely (usually takes an investigative bit and discovers its not ‘kosher’ dinner).
•Needs to protrude its jaw to enable biting (pull back it’s nose) so usually attacks from below.
Zambezi:
•Often attacks still standing prey (Natal harbour where numerous fisher man have been attacked while standing in shallows catching fish in deeper channels)
•As above – often attacks in shallow water
•As above – is know to attack humans (my opinion is that crocodiles & Zambezis are of the same nature – attack and eat anything, moving or still standing, i.r.o. of environment & conditions)
•When eating – devours every morsel
•Doesn’t need to attack from below
If it was a great white as many think, how did it manoeuvre in such shallow waters, attacking a still target? Surely it would first need to knock its prey over, then come back for a bit and back again. That doesn’t seem to be the case according to eyewitness reports.
A Zambezi is not a very large shark but bulky and to the average person would appear to be huge. It comes across very aggressive and devours it’s prey quickly.
Reason behind my thinking – when I first heard about the incident, I thought it strange and unusual for great white behaviour. Then I suddenly started thinking about my recent dives in False Bay area (since start of this year). The water has been unusually warm – almost each dive has been 19 – 20 degrees C, even at 10m. Though the Zambezi is mostly located up the north east coast – it likes warm waters so comes as far south as Port Shepstone. There’s nothing stopping it from wandering further south other than water temperature. I haven’t had time to investigate water temperatures over the last few weeks up the east coast, but if False Bay is anything to go by, it could very well have wandered down a little further south than usual.
Once again I reiterate that I’m not saying it’s impossible to have been a great white – just possible that we have a visitor down for warmer climates?
Comment by Zelda — 15 January 2010 @ 14:57
Have there been any studies done on the number of sharks seen and or encountered in Fish Hoek Bay especially during yellow tail migration and trekking hauls?
Does the tourist season in December/Jan and the yellowtail migration fall in the same period and is this why there may be an increase in shark spotting?
One last suggestion. Could pamphlets be given out at the gate with your parking ticket educating people about sharks and explaining the different flag meanings. Alternatively what about a HUGE notice showing the flags explained simply for children and foreign tourists to undertand.
I think heightened awareness is key as too many people only learn after a shark attack such as this weeks tragic incident. Knowledge dispels fears and ignorance.
Thank you for doing a great job and please let me know the answers to the above.
Nancy
Comment by Nancy soller — 15 January 2010 @ 17:17
Dear Zelda,
Thanks for taking the time to write to us with a very interesting theory. However, we have confirmed without a shadow of doubt that the shark responsible for the attack at Fish Hoek was a great white.
Regards
Alison
Comment by Alison — 16 January 2010 @ 10:42
Dear Nancy,
We believe one of the main reasons white sharks are present closer to shore during our summer is because of the abundance of prey such as fish (yellowtail, cob, steenbras etc), other sharks (smooth hounds, soupfins, etc) and rays. There is a lot of bait fish (harders) close to shore at the moment due to warm and stable water conditions. Dolphins have been sighted regularly in the area over the last few days feeding on fish in the bay too. It’s likely the sharks were after the same thing.
I think extra signage which is more visible should be implemented and I believe the City have identified this need. We will also attempt to have brochures and pamphlets more accessible.
Thank-you very much for your email,
Regards
Alison
Comment by Alison — 16 January 2010 @ 10:48
In addition to being unusually warm, the sea has also been unusually rough and murky this season. You can easily get an objective measure of how this season compares to previous years, and how one week compares to another in this regard, by collecting data from the half a dozen or so SCUBA diving operators in Cape Peninsula. They always take groups SCUBA diving every weekend if the conditions are suitable. They should have records of which weekends they’ve had to cancel dives and which weekends they’ve been able to launch their boats. These records could be in the form of boat log books, divers log books, tax records for payments, Air compressor records, etc, etc and should go back several years.
Quite often the sea can be rough with minimal visibility, yet on land it can be a clear calm hot and sunny day. I’d bet that cancelled boat dives correlates to inshore shark activity better than just about any available climate data.
Comment by Rob — 18 January 2010 @ 19:48