Thinking about shark bites (and attending a meeting)

I currently work in investments, and the investment team at the company I work for pays a lot of attention to what are known as cognitive (or behavioural) biases. Many of these biases make humans poor investors; the team I work with try actively to identify these biases when we encounter them in our own thinking about investments, and to counter them. Cognitive biases are patterns of poor judgment, hard-wired in our brains, that were once useful to us – perhaps when our ancestors were running around on the African grasslands – as they enabled quick decision making with limited information. Today, however, countless generations later and faced with survival in a concrete rather than a literal jungle, we are saddled with these brain short circuits that can in fact impair our performance in certain aspects of life, particularly in circumstances where emotions and knee-jerk reactions threaten to overwhelm logic.

Tony and I attended a meeting on on Monday 24 October 2011, held at the Fish Hoek Civic Centre. It was organised by Mark Wiley, the Western Cape Parliamentary Chair of the Committee for Culture and Sport, and was open to business owners who operate in the South Peninsula area. The focus of the meeting was to determine:

  • How the increased presence of shark sightings and the incident had affected business, sport and recreational activity in the Far South area – either positively or negatively
  • How the shark phenomenon was having an impact on the community as a whole from a perception point of view
  • If there was a need for an impact assessment
  • To advise or ask the authorities, City or otherwise, to investigate options to minimise risk to the public and for them to explore options in this regard

(I quote from the minutes – let me know if you want a copy and I will email them to you.)

Attendees included several local business owners, including Dawid Mocke of the Varsity College Surf Ski School and The Paddling Centre, Andrew Brouckaert of Fish Hoek Surf Lifesaving, some local guest house owners, Paul Botha of the Kahuna Surf Academy and a few other local surfers, Kim Kruyshaar from the Scenic South website, and a small group of ocean and/or nature lovers some of whom also have business interests in the area (we count ourselves in this group) such as Steve Benjamin of Animal Ocean, freediver Hanli Prinsloo, Jean Tresfon, Morne Hardenberg of Shark Explorers, Jenny Trethowan of Baboon Matters, and of course Sarah Titley of Shark Spotters.

During the course of the meeting I observed several of the cognitive biases I mentioned above, and realised that it’s very hard to have a conversation about an emotive topic such as shark bites on humans, without a whole host of these biases cropping up. The challenge when it comes to an issue like the shark bite one, is to remain rational and to listen to the statistics – not to the fearful, reptilian part of our brains. We need to form judgments and decisions based on evidence, and not our gut. In choosing what to have for lunch, you can listen to your gut – but not here.

What follows is a selection of statements heard (and sentiments expressed) at the meeting, and the behavioural bias inherent in each. The behavioural bias definitions are from the cognitive biases wikipedia page.

There never used to be any sharks in False Bay

“My family has lived on the mountain in Fish Hoek for sixty years and until recently no one ever saw a shark.”

Anchoring – the common human tendency to rely too heavily, or “anchor,” on one trait or piece of information when making decisions or forming thoughts.

Just because you’ve never heard of Oprah Winfrey doesn’t mean she doesn’t exist.

Just because your family never saw a shark, it doesn’t mean they weren’t there. Did they watch the sea all day, every day? Does your grandmother even know what a shark looks like when seen from an elevated point, when the sun is shining?

Your family wasn’t looking specifically for sharks, and didn’t know what to look for. The Shark Spotters undergo extensive training to distinguish between dolphins, kelp, shadows, and sharks. A lot of the time it’s not as straightforward as looking down the hill and – eureka – seeing a shark!

Sharks have only recently come to live in False Bay (and probably for sinister reasons, like to eat old people swimming at Fish Hoek)

Recency effect – the tendency to weigh recent events more than earlier events

Massive population growth and increased leisure time has given many more people access to beaches and recreational activities in the ocean. Just because they’ve only recently been drawn to our attention, it doesn’t mean sharks haven’t always been here. Sharks have been living in False Bay for longer than we have been in the area, but it’s only recently that we’ve been looking out for them – and more people in the water means more human-shark interactions.

Furthermore, as Anton Louw pointed out, evidence suggests that False Bay has been getting colder – and hence cleaner, enabling sharks to be seen more easily from above. One factor pointing in this direction is the fact that kelp, which likes cold water, never used to be found north of Miller’s Point but now proliferates off Jaggers Walk in Fish Hoek, and colder water implies cleaner water.

If there were fewer sharks in the recent past, it’s possibly because:

  • White sharks were fished aggressively until fairly recently (they became a protected species in the mid-1990’s in South Africa)
  • At one point there were only 35 seals left on seal island after aggressive culling – that means no food to support a population of white sharks, which would send them elsewhere for food in winter.

There are more sharks now that there have ever been before, and they are coming closer inshore

“I and all the surfers I know see sharks in the surf zone almost every day when we go surfing.”

Attentional Bias – implicit cognitive bias defined as the tendency of emotionally dominant stimuli in one’s environment to preferentially draw and hold attention.

Your buddy is more likely to share with you that he saw a shark while he was surfing than, say, a child’s kite or a peaked cap that got blown into the sea – although they are both equally likely. Sighting a shark carries far more emotional charge than almost anything else. It’s emotionally dominant, to say the least.

Chumming activities are teaching sharks to associate humans with food and drawing them inshore

Availability cascade – a self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or “repeat something long enough and it will become true”).

There’s no evidence for this, even though it’s a popular belief among surfers. Do some reading please. Or buy this book (and read it).

The shark population is exploding

“Just look at how many sharks have been sighted at Fish Hoek beach this spring! The population is out of control!”

Confirmation bias – the tendency to search for or interpret information in a way that confirms one’s preconceptions.

The population of an apex predator cannot explode – it simply cannot happen. Such predators are typically are slow growing, slow reproducing creatures that produce few young, with high energy requirements. The population of everything else lower in the food web – EVERYTHING – would have to explode first, before the shark population could “explode”. And then it probably wouldn’t be a population explosion – it’d be the plot of a science fiction movie.

The Shark Spotters program doesn’t work

Outcome bias – the tendency to judge a decision by its eventual outcome instead of based on the quality of the decision at the time it was made.

Cape Town’s Shark Spotters program is a world leader in approaches that combine both beach safety and conservation awareness. The spotters cannot force people to obey the flags, however, and the actions of a single selfish, irresponsible, immature individual who endangered not only his own life but that of his eventual rescuers cannot be used to tarnish the reputation of this program. This article gives a good summary of just how impressive the Shark Spotters program is.

I thought it was absolutely shameful (and an outright lie) to suggest that the Shark Spotters have somehow failed, or – as one of the attendees who has “surfed in 30 countries in the world” stated – that the spotters are poorly trained and fall asleep at their posts. Unfortunately this comment was not censured.

A rogue shark or group of sharks is responsible for biting humans and coming inshore to the beaches

Clustering illusion – the tendency to see patterns where actually none exist.

You’ve got to choose: you can’t claim that “ALL sharks are maneaters” and in the next breath claim that a single rogue shark keeps coming into Fish Hoek bay to eat swimmers. If sharks actively sought people as prey we’d see several fatalities a day – at any one time there are about 50 white sharks in False Bay, and if they each wanted a human or three for lunch (a white shark can eat four seals on the trot, no problem), I’d fancy the shark’s chances over yours.

Return Jaws to the video shop and read some proper science writing instead. The Rogue Maneater theory has long been discredited.

The business downturn in the South Peninsula is entirely due to the fear of sharks

Negativity bias – the tendency to pay more attention and give more weight to negative than positive experiences or other kinds of information.

I don’t know if you’ve noticed, but the last few years have been tough. When I fill my car with petrol and hand over R550 for a full tank, it feels as if Armageddon is nigh. As Jenny Trethowan pointed out, we’re still making our way through an economic downturn of note, and businesses everywhere have struggled. Blaming this entirely on sharks is disingenuous.

This statement also ignores the eco-tourism value of sharks. Hundreds of people joined the shark spotter on Boyes drive every day during this recent peak of sightings, scanning the bay and excitedly discussing the possiblity of seeing a shark. Do you think they all went home without having a coffee somewhere, or buying a sandwich?

The large number of sharks currently being spotted inshore is going to persist FOREVER

Disregard of regression toward the mean – the tendency to expect extreme performance to continue.

Shark sightings in False Bay (Jan-Nov 2011)
Shark sightings in False Bay (Jan-Nov 2011)

Source: Shark Spotters recent sightings

Year after year a seasonal peak of inshore sightings of white sharks is observed. Sightings typically peak in October, and then decline somewhat for the rest of the summer. During winter, the white sharks hang out at Seal Island and are hardly ever seen inshore. This same sequence occurs year after year after year. It is driven by the sharks’ search for food (they eat seal pups at the island; when the seal pups get too old, fast and wily they eat the fish that come into False Bay with the warmer water in summer), and possibly by socialising activities and the opportunity to rest in the highly oxygenated waters close to shore. There is no reason to state that THIS year the sharks are going to stay in the surf zone, set up homes there and harrass swimmers year-round.

————-

Having listed the statements above, I realise that there was a disturbing mindset among many of the meeting participants, who seemed opposed to scientific thinking and statistical or evidence-based reasoning. Instead they attached great importance to anecdotes, personal experience (only valuable to the individual unless recorded and shared in an objective manner that recognises shortcomings of perception, memory and understanding) and uninformed generalisations. This kind of thinking is also prevalent in media reports of shark bites, and almost all the conversations I have had with friends and family on the subject (and let me quickly add, I have also been prone to it!).

Unfortunately, as humans we actually can’t help thinking in those ways. We have to actively work against the part of our brain that wants to leap to conclusions based on stories told around the bar or in the elevator, and give it some hard facts to chew on instead. These three cognitive biases capture some of the attitudes I am talking about:

  • Bias blind spot – the tendency to see oneself as less biased than other people.
  • Confirmation bias – the tendency to search for or interpret information in a way that confirms one’s preconceptions.
  • Base rate neglect or Base rate fallacy – the tendency to base judgments on specifics, ignoring general statistical information.

Contrary to my initial expectations the meeting was conducted in a civilised manner, and despite the flawed thinking on display, for the most part the attendees agreed (or claimed to agree) that a solution to the issue of perceived increased risk owing to shark attacks in False Bay must make sense both from a conservation point of view (not killing sharks) and from a human safety perspective. (As an aside, a topic that was skipped over was the possible role of trek net fishermen in attracting sharks to the beaches… A bit of a political hot potato, methinks!)

Tony has experienced a slight dip in business as a result of the recent shark bite incident at Fish Hoek. Experienced divers aren’t generally fussed, but new and prospective diving students are frequently nervous about sharks and ask a lot of questions. I think that no matter how much income Tony lost, however, he’d be very hard pressed to suggest that killing some of the fauna of False Bay was a valid solution to the problem.

However, at least two of the participants at the meeting – both gentlemen of a certain age who claimed vast knowledge about the world’s oceans and Fish Hoek in particular – clearly favour shark nets, culling, hunting down and shooting the “rogue” sharks who persist in coming into the bay or a similar solution. To say so, however, would have been unpopular once it became clear which direction the consensus was moving.

Some of those with a purely financial interest in the public perceiving Fish Hoek beach and False Bay waters as safe also would have jumped at the idea of a solution that removed sharks from the waters around Fish Hoek – whether that involved killing them or not. Fortunately thinking like this is no longer socially acceptable as it smacks of arrogance about humans’ role on earth, and ignorance about the functioning of ecosystems. Fear of saying something socially unacceptable is a tenuous reason to hold back on expressing a favourable opinion towards a shark cull – it by no means signals or causes a change of mind on the subject – but fortunately it was sufficient of a restraint for the meeting participants to reach an agreement that was in favour of the sharks’ continued existence in False Bay, hopefully in harmony with ours.

I was relieved when the meeting concluded with Mr Wiley stating that the evening’s contributions were sufficient to request the Cape Town Sub-Council in Fish Hoek to allocate funds for a research project to making False Bay, specifically Fish Hoek coastline safer for beach users. I believe that this will take the form of a safe swimming area, but we’ll have to wait (hopefully not too long) and see.

Newsletter: Ever had a bad Monday? Come diving on Tuesday!

Hello diving people

Anemone at Long Beach
Anemone at Long Beach

You will probably have heard about the shark bite that occurred at Clovelly this morning, at the far end of Fish Hoek beach. For a balanced description of the events, you can read what the NSRI says here. At this time of year sharks do move inshore from Seal Island, and as a swimmer or surfer it is essential to pay attention to the Shark Spotter sirens and flags. As divers we are less concerned about sharks, because it’s highly unlikely that a shark will mistake you for anything other than what you are: a noisy, neoprene-clad figure exhaling clouds of bubbles, unlike any other creature in its domain! I have dived extensively with sharks – when I was working in Ponta do Ouro in Mozambique, our first dive of the day was almost invariably to a reef called Pinnacles, where we saw hammerheads and Zambezi (bull) sharks almost daily, and sometimes tiger sharks. They just do not bug divers.

However, it is recommended to avoid flailing around on the surface too much at any time of the year in Cape Town’s waters, even if you’re in scuba gear. Controlled buoyancy and businesslike behaviour when you surface after a dive will contribute to your peace of mind. If you’d like to chat about sharks or are concerned about what to do if you see one while diving, please get in touch (my contact details are below or on the About page). You can also read this post in our Frequently Asked Questions section for more information, and my account of seeing a great white shark while diving. There is a follow-up on that sighting here.

Sharks are a reality of life lived close to and in the ocean, and we are privileged to reside in a country where great white sharks have been protected for nearly 20 years. Increased shark sightings in Cape Town are attributable both to population growth of great whites – back towards their natural levels before fishing for them was popular – and to increased efforts being put into minimising interactions between bathers and sharks, chiefly by the excellent Shark Spotters campaign. For a bit of background and some food for thought, you can read this post about the history of Shark Spotters, and this movie review.

Tony and Gerard on Tafelberg Reef
Tony and Gerard on Tafelberg Reef

Sharks aside, the ocean has been kind to us of late. We dived both the Atlantic side and the False Bay coastline this last weekend and had a good 12 metres visibility with 10 degrees at Tafelberg Reef, and at Long Beach we had 6 metres visibility and 15 degree water. Yesterday we dived Partridge Point with some tourists and had 15 degree water with 8 metre visibility, and some friendly and playful seals made the tourists extremely happy. On the way out we saw several whales from the boat, and then on our way back our skipper took us on a tour to see the penguins, oystercatchers, and some other tourists standing on the beach!

Bluefin gurnard at Long Beach
Bluefin gurnard at Long Beach

On Saturday ScubaPro will be holding a dive day. This is taking place at the False Bay Yacht Club in Simon’s Town and there will be five or so dive boats running dives at R100 each. Tonight was the deadline for booking a spot on the boat so hopefully you have all made a plan. We had 12 spots but they are all taken. If you are on the first launch on Saturday (8am), please be at the yacht club by 7am. Directions here.

Basket star on Tafelberg Reef
Basket star on Tafelberg Reef

ScubaPro will have gear available for testing on a dive so if you have finally saved up some hard earned cash to purchase a BCD for example, you could test the one you have had dreams of owning… Oh, no you can’t do that… You need to hand in your old one to test a new one. Or fork out some cash to hire one first so that you can hand it in. Once again the local dive gear suppliers show little or no concern for new divers getting into the sport except to take their money.

Anyway, this is how the day will look:

GOODIE BAGS for every diver booked on a dive with a participating Charter – Please note, only bookings received by Wednesday 28th September are eligible for Goodie Bags. Collect your Goodie bag on registration day.

DEMO GEAR: Hand in your gear and borrow the latest & greatest for a test dive!

SPIRIT of SEALIFE Photo Comp: A fun competition where the picture that best captures the fun & wonder of diving wins, not necessarily the picture that is technically best!

EAT, DRINK & BE MERRY at the Prize Giving Party! Great food and beverages will be available and there’ll be music and a slide show from the Sealife Photo Comp! Prize giving for the photo comp and the lucky draw will take place at 16h30.

WORLD CUP RUGBY on a BIG SCREEN:

Although there’s no Springbok match, we’ll be screening the World Cup matches in the morning (07h00 and 09h30).

WIN OVER R17 000-00 WORTH OF PRIZES: Try any item of demo gear to qualify for the Lucky Draw.

On Sunday I will spend the day at Long Beach as there are six people wanting to experience scuba diving for the first time, so it will be a DSD day.

Close up of a basket star at Tafelberg Reef
Close up of a basket star at Tafelberg Reef

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog

Diving is addictive!

Checking out the kink in the chain at Long Beach
Checking out the kink in the chain at Long Beach

Lecture: Christopher Neff on the politics of shark attacks

One rainy Thursday in June Tony and I attended the first of what will hopefully be a monthly series of talks at the Save Our Seas Shark Centre in Kalk Bay. The speaker was Christopher Neff, a PhD candidate at the University of Sydney. Chris is doing his doctorate on the politics of shark attacks, and was in South Africa to learn more about our Shark Spotters program (and to meet some great white sharks).

He spoke about his doctoral research, and described how perceptions of risk and other factors influence government responses to shark attacks. I was struck by a couple of things:

It isn’t all Peter Benchley’s fault

Sure, Jaws demonised sharks and I don’t think Peter Benchley is wrong to feel some residual guilt about the ensuing panic and slaughter of creatures assumed to be bloodthirsty maneaters. The phrase “shark attack” – as opposed to the previously popular “shark accident” – was invented in 1929 by Australian surgeon Sir Victor Coppleson. He mounted a one man crusade, alerting people to the dangers of sharks, in response to a fatal shark attack off Sydney that year. He published a book on the subject of shark attacks in 1958, and was considered a world authority on the subject. Shark nets were installed on the beaches of New South Wales in the early 1930s in response to the findings of the Shark Menace Committee appointed to study the issue of human-shark interactions.

Shark spotters is unique

We’ve posted before about Cape Town’s Shark Spotter’s program on this blog, and I consider myself fairly familiar with its workings, but Chris’s talk shed new light on the program’s importance and singular success.

I was particularly struck by the uniqueness of the Shark Spotters program in the world. In response to the fatal 1929 Australian attack mentioned above, a program functionally identical to our Shark Spotters (observers watch for sharks, and warn bathers to exit the water) was proposed. The program never took off, and the reasons for this – chiefly stemming from a lack of agreement by stakeholders and their conflicting aims – form part of Chris Neff’s PhD studies.

In other countries (such as Australia) and even in parts of South Africa (Durban), shark nets are popular and are widely considered to be very successful. Brazil used hooks laid on the ocean bottom near the beaches, and Hawaii has recently taken down all the interventions that could kill sharks in order to protect humans (nets among them, I think).

The Cape Town Shark Spotters program was started in 2004, and since then just under 1 000 sharks have been spotted in the waters around the Cape Peninsula. The proposal to start the program succeeded where the 1929 Australian proposal did not, for several reasons:

Strong backing

The City of Cape Town, surf lifesavers, the trek fishermen, and community groups all backed the proposal. South Africa has a strong history and cultural ethic of wildlife conservation, and the proposal for a shark spotting program dovetailed nicely with this.

Agreement among proponents

It was agreed that any management program should address all the problems raised by human-shark interactions:

  1. altering human behaviour
  2. restoring confidence to enter the water
  3. conserving the sharks

The shark spotting suggestion deals with all of these issues equally well. (Shark nets, for example, answer the first two concerns but not the third one.)

Feasibility

The local trek fishermen have been watching for sharks from the top of Elsie’s Peak for decades. They had thus proved the feasibility and affordability of the solution.

Trek net fishermen at Muizenberg
Trek net fishermen at Muizenberg

(Tony took the picture above from the top of Boyes Drive, next to the Shark Spotter’s hut.)

Comprehensiveness

Shark Spotters answers public concerns about going into the water, as well as environmental concerns, because no sharks are killed as a preventative measure. Shark Spotters use a siren to encourage people to get out of the water when a shark is sighted, and provide them with information when visibility is too poor to identify sharks in the water (via a black flag – see the image below). Hourly water use around shark warnings indicates that the public has developed a high level of trust in the program, as surfers and swimmers return to the water when the all-clear signal is given. (Initially this was not the case – the beach would empty after a shark sighting.)

Cape Town’s topography and ocean conditions make it uniquely suited to this type of effort. There are elevated geographic features such as hills and mountains from which observers can watch for sharks, and the water is clear. Durban installed shark nets over 50 years ago, and while the bycatch is appalling (dolphins, turtles, etc) this seems to satisfy the stakeholders that Durban’s large number of water users, drawn by the warm waters lapping the coast, are protected. What’s more, the tiger and bull sharks common on the KZN coastline are not endangered, whereas the local great white shark is. A shark net solution for Cape Town would fly in the face of all conservation principles.

Black Shark Spotters flag flying at Fish Hoek indicating poor visibility
Black Shark Spotters flag flying at Fish Hoek indicating poor visibility

Tony and I appreciated Chris’s philosophy on information sharing, and particularly his comment in closing that “while my research is independent, the funding is not.” Too much research is conducted using donations from the public, and then kept secret. Unless you paid for the research yourself, it’s not yours to keep! We’re grateful to Chris for sharing.

Bookshelf: South Africa’s Great White Shark

South Africa’s Great White Shark – Thomas P. Peschak & Michael C. Scholl

South Africa's Great White Shark
South Africas Great White Shark

I don’t know why we didn’t get hold of this book earlier. We have spent months and months of trying to get information about shark movements in False Bay – the only good sources of information are commercial operators, such as Apex Predators, and Shark Spotters.  Many South African based shark researchers whose work is frequently mentioned in newspapers, online and in conversation – usually preceded by the words “they plan to…” or “they’re about to…” are as easy to get information from as it is to open a giant clam with your bare hands. We find this hugely frustrating as regular users of the ocean – in my mind, I compare it to withholding news of traffic conditions, jams and accidents from road users. It’s even more frustrating because a lot of the work is publicly funded (and because a run-in with a shark can be a lot more hazardous to your health than an hour in a traffic jam).

Thomas Peschak is a photographer and marine biologist who spends several months of the year in Cape Town. The photos in this book are his, and he was also involved in much of the research.

The book is small and thin (under 100 pages), but covers white shark biology, behaviour and interactions with humans – with a focus on Southern African populations. Tony devoured it in a day, reading most of it aloud to me, and I read it straight after he did. There is confirmation and refutation of many of the bits of information – usually frustratingly vague – that are passed around as fact in diving circles and general discussion with interested parties.

At the back there is a section on how to avoid unpleasant human-shark interactions, and what to do if you see one. The authors have advice for swimmers, divers, kayakers and spearfishermen (in a word, don’t do it!). Interestingly, they advise against urinating in your wetsuit or going in the water while menstruating or bleeding from a wound. This is erring on the side of caution – I don’t necessarily think there’s a huge problem with either of those in general – but if you’re diving somewhere near Seal Island such as the SAS Fleur, an area trafficked by sharks, it’s probably wise to be wise. The rest of the advice to divers confirms what Tony tells people when he does a shark briefing – stay together, breathe slowly, stay at the bottom, and make your way out in a dignified manner when the opportunity arises.

Buy the book here.

I would recommend that instead of making a donation to shark research in Cape Town – since we have NO IDEA where that money goes – you buy this book. Or donate to Shark Spotters, since their work is visible, open to public scrutiny, and clearly directly useful. Or both!

A primer on shark spotting

Wonderful and vital work is being done by the Shark Spotters team. Their aim is to reduce in-water interactions between sharks and humans. Shark Spotters is a registered nonprofit organisation that employs a team of spotters along the False Bay coast and at Noordhoek on the Atlantic coast of the Cape Peninsula. The program has been in action since 2004, and from somewhat ad-hoc beginnings is now supported by the WWF and City of Cape Town. They also work closely with the NSRI. You can spot the Muizenberg spotter on top of Boyes drive, and more team members at other high-up vantage points around the peninsula.

New signage

New signage was erected in late 2010, but not one of the people (friends and family) I’ve spoken to is quite clear on the meanings of the different warning flags. This is a matter of life and… well, a toothy bite to an extremity at best, or death at worst. So I thought it was important to put a little refresher up on the blog. Read, and learn!

Red dots indicate beaches where shark spotters are on duty
Red dots indicate beaches where shark spotters are on duty

There are four flags, each with a different meaning:

  • green means visibility for spotting is good, and no sharks can be seen
  • red means a shark has been seen recently but the spotters can’t see it any more
  • black means visibility for spotting is poor but no sharks can be seen
  • white with a black shark on the flag means a shark has been sighted and swimmers should get out of the water. A siren will be sounded.
Shark Spotters flags
Shark Spotters flags

The above information was taken from the Shark Spotters website, here. There’s more information about shark behaviour on the website at this link. The Shark Spotters blog is updated frequently with a list of sightings.

What does this mean for you?

You should be cautious if a red or a white flag is flying, and you plan to use the sea. A black flag is quite common in False Bay, especially in the middle of the day when it’s sunny, and when it’s  windy, so it’s hard to be prescriptive about what you should do then!

Relevance for divers

I don’t think that divers should be unnecessarily concerned about shark sightings, but I do think this should inform our activities in the water. It’s never a good idea to thrash around on the surface for any length of time, but particularly during high shark activity periods. If you’re doing a shore entry, swim all the way up the beach before surfacing. Avoid long surface swims – manage your air consumption carefully. If you’re boat diving, don’t mess around – get back into the boat quickly, and help the other divers to do so as well.

Tony has seen two great white sharks while diving since he’s been in Cape Town. Both times the shark checked him and his students out, and swam away. Both times he said that prior to sighting the shark there was an eerie, quiet feeling underwater and there were no fish or other marine life about. The first time he thought it might have been a coincidence, but when it happened again, we decided that it probably wasn’t coincidental. Trust your gut – if you feel uncomfortable, stay on the bottom, and make your way out of the water.

Most of all, though, remember that if you do see a shark while diving, it’s an incredible privilege. We are visiting the sharks’ domain, and they deserve our respect and awe.

Who to follow

twitter

So I am sick in bed today while Tony enjoys the sea and southeaster with students. In the absence of my diving fix, I have to rely on the Internet to feed my currently short attention span. Enter Twitter.

To me, Twitter incorporates my favourite feature of Facebook – constant stream of bite-sized news and views – and leaves out all the other guff (Farmville, Zombie Vampire Slayers, Are You Feeling Hot Today?).

It’s not all about socialising and keeping up with your online friends… It’s also useful for news, activism, and informative updates from individuals and organisations whose work interests you. If you want to beef up the list of users you’re following, check out our “followees”!

Diving

Learn to Dive Today: @learn2divetoday (of course!)

PADI: @PADI

South Africa

SANCCOB – the organisation that rescues, cleans and protects our coastal birds: @SANCCOB

Two Oceans Aquarium, Cape Town: @2oceansaquarium

Shark Spotters for reports of shark activity in False Bay: @SharkSpotters

World Wildlife Foundation South Africa: @WWFSouthAfrica

Conservation & Agencies

NOAA’s National Ocean Service: @usoceangov

NOAA’s Ocean Explorer educational program: @oceanexplorer

Project Aware – conservation agency by divers: @projectaware

Save Our Seas: @saveourseas

World Wildlife Foundation: @WWF

Whale & Dolphin Conservation Society: @whales_org

NASA (they do ocean exploration too!): @NASA

Ocean Information Center (OCEANIC) at the University of Delaware College of Earth, Ocean and Environment: @oceandata

The Smithsonian Institute: @smithsonian

Smithsonian Ocean Portal: @oceanportal

Sea Shepherd Conservation Society (because everyone can do with a bit of radical extremism to spice things up now and then!): @seashepherd

Ocean Conservancy: @OurOcean

Ocean Institute: @oceaninstitute

Oceana: @oceana

Photography

Bonica Snapper video cameras (the manufacturers of Tony’s newish toy): @bonicahddv

Fiona Ayerst, underwater photographer who offers courses: @Fayerst

Orms (more awesome camera equipment, knowledgeable sales staff and a top-notch D&P facility): @OrmsdDirect

SA Camera (very reasonably priced photographic equipment, including underwater housings): @SAcamera

Scott Kelby, author of fantastic photography books: @scottkelby

Writing & Television

National Geographic: @NatGeoSociety

Urban Times Oceans: @UT_Oceans

The Guardian Environment section: @guardianeco

PBS NOVA will keep you up to date with science news and cool gadgets: @novapbs

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!

Exploring: Sunny Cove

Tony has been wanting to dive Sunny Cove practically since he first set foot in Cape Town, having read in an old book on South African dive spots (The Dive Sites of South Africa – Anton Koornhof) that seahorses had been found there in the sea grass. Tony loves seahorses.

I put my foot down, repeatedly, until it was the dead of winter and the Sharkspotters website told me that not a single great white had been seen patrolling the coast for a couple of months. Sunny Cove is at the end of Jagger Walk, the catwalk that runs along the western edge of Fish Hoek Bay. It’s the site of at least one fatal munching by a great white, and I didn’t want to take any chances.

Sunny Cove railway station
View from the bridge over the railway line towards the dive site

It’s a shore entry, and we parked on the road at the bottom of the steps over the railway line. It’s quite a strenuous walk over the bridge with all your kit on. We spent a while figuring out where to get in – you have to clamber over some rocks, and make your way through dense kelp before getting to a clear spot. Once we decided where to get in, we were glad to be wearing thick wetsuits, otherwise we would have been scraped and scratched quite liberally! There is a huge submerged concrete block just where we got in – at first I tried to swim over it, but realised it was in only a few centimetres of water, and made my way around it. (Fortunately there was no one on the shore with a camera!) Cape Town shore diving is hard on your kit.

Sunny Cove
Our entry point is on the far left, almost out of the photo, where the straight piece of rock sticks out.

The actual dive site is aptly named. The sun streams in through the kelp, and the sea floor looks a lot like Shark Alley near Pyramid Rock – lots and lots of urchins, with pink-encrusted rock formations. We saw a little bit of sea grass, and spent a lot of time examining it for signs of life, but didn’t even find a pipe fish, let alone seahorses! There’s a lot of invertebrate life on the rocks – feather stars, brittle stars, abalone – and we saw quite a few fish.

We did see the deep channel that the sharks probably use to get in and out of Fish Hoek Bay. We were hoping to spot the beacon that records movements by tagged sharks past Sunny Cove, but no luck there. We did not explore much to the south of our entry point – that’s on the to do list (along with more sea horse hunting) for another shark-free day.

Verdict: Shallow, easy dive but a fairly tricky entry and exit. Infrequently dived, so rather more lush and unspoiled than busier sites. Videos of our dive are here and here.

[youtube=http://www.youtube.com/watch?v=DaxvdFG4Fdg&w=540]

Dive date: 4 July 2010

Air temperature: 21 degrees

Water temperature: 13 degrees

Maximum depth: 10 metres

Visibility: 6 metres

Dive duration: 32 minutes

FAQ: What about sharks?

You had to ask! I’m glad you did. As divers, we are venturing into the sharks’ domain, and it’s a risk we take. This might sound scary, but it’s important to bear a few things in mind. First, the ocean is a big place. It’s very unlikely that we’ll meet a shark, unless we go looking for them. Second, even though sharks are wild animals, they don’t like to eat people. Great white sharks need a huge amount of energy to keep their incredibly powerful bodies warm and mobile. That’s why they eat seals – conveniently packaged in a very thick layer of calorie-rich, nutritious blubber. Humans just don’t have the same appeal. That’s why many shark attacks are “bite and release”: the shark takes an exploratory nibble, because he thinks you’re a seal, and when he realises you’re not as tasty and fatty as he thought, he lets go and swims away. Unfortunately, with so many sharp teeth, a shark’s exploratory nibble can hurt you quite badly.

You might be thinking that what you’ve just read proves it’s a terrible idea to dive where sharks are found… especially since we often see seals on our dives in Cape Town. What’s to stop a shark from getting confused between a diver in his black wetsuit, and a sleek little seal? The answer to this relates to how great white sharks hunt. Their hunting technique is to launch themselves from the bottom of the ocean, up towards the seal on the surface. This enables them to reach enormous speeds and to take the seal totally by surprise. Often the shark will breach right out of the water with the seal in its mouth.

Why doesn’t this worry us? Because we spend most of our time on the bottom. For one thing, sharks can’t usually get underneath you to attack. There isn’t much chance of the shark mistaking you for a meal – in fact, it’s more likely that if you see a great white, he’ll just cruise right on by without paying you any attention. Another reason is that the places we dive that are frequented by seals (Partridge Point, Duiker Island in Hout Bay, the Clan Stuart, Long Beach for example) simply aren’t deep enough for a shark to mount an attack. They prefer to get their snacks out at Seal Island in the middle of False Bay (where the shark cage diving takes place), where there is a deep channel around the island perfect for hunting.

There has never been a great white shark attack on a diver in the Cape, despite the attacks we have had on swimmers, spear fishermen and surfers. That’s because surfers and swimmers are usually flailing around on the surface, and spear fishermen are usually dragging a handful of dead or dying fish behind them sending out distress signals to all the predators in the vicinity, so you can forgive the shark for getting confused and thinking they were a meal! You can see some general shark attack statistics (for the whole world) here.

If you dive with me, I will give you a shark briefing if I feel it’s necessary. I’d also like to encourage you to join me sometime for a dive at Shark Alley in front of Pyramid Rock in False Bay. This is a shore entry site where sevengill cowsharks can be seen in large numbers, with near certainty. They are beautiful creatures, up to about three metres long, and are not harmful to divers. We swim to the sandy patch among the kelp where they like to hang out, and then sit on the sand and wait for them to visit us. They are curious, and swim very close to take a look, and then swim away. It’s breathtaking – in a good way! You can see some videos of past dives I’ve done with these sharks on my YouTube page. Diving with these magnificent creatures will change your perception of sharks in general, and may also help you to master any shark-related fears you may have.

Sevengill Cowshark near Pyramid Rock
Sevengill cowshark at Shark Alley, near Pyramid Rock. These curious sharks will approach to within a few feet of divers to get a closer look.

For information on shark spottings in Cape Town, visit Sharkspotters (here too). For information on the relative risks of a shark attack compared to other things (lightning strikes, bicycle accidents, etc – the home improvements section is highly recommended!) go here.

As of yesterday (25 August) I can speak from first hand experience – after a just under a year in Cape Town, I was buzzed by my first great white shark. She circled us, and then left. It was awe-inspiring, and left me feeling honoured to have encountered one of these incredible creatures. I mentioned it in my newsletter today.

(This information also appears on my website, here.)