A day early in April was the date for the annual Freedom Swim, a 7.5 kilometre open ocean cold water swim from Murray’s Bay harbour on Robben Island to Big Bay near Blouberg. As we have in several previous years, we provided boat support for a swimmer.
This entails providing a straight course for the swimmer so as to minimise the distance swum, and keeping an eye on them to ensure that they don’t get too cold or show any other symptoms of hypothermia or distress. It requires communication with race control by radio, and a bit of boat and swimmer dodging in the early stages of the race when the water is thick with activity.
Cloudy skies over Robben Island
Tony waiting for the start
Team de Mooij at the start
Rougher seas closer to Big Bay
Green water close to shore
Table Mountain
There was a 3.5 metre swell on the day, which made the ride out to the island a bit bumpy. As soon as we were in the shelter of the island, however, the sea was flattened as the swell diverted around the island. The water remained calm until we got quite close to shore, at which point the swell picked up. The final stretch from the rocks at Big Bay to the beach must have been very hairy for the swimmers!
Our swimmer, Maryna, swam in a wetsuit. She was part of the Lighthouse Swim relay team we supported last year. The water was relatively warm (13-16 degrees) clear at the island, and we could see kelp and quite far down into the sea. Great red streaks of water, probably an algae bloom, were filled with sea jellies (which stung Maryna, but she continued strongly). These were replaced by murky green water close to the shore, where the swell had lifted the sand particles into the water column.
It was a good day out, and always a pleasure to see Table Mountain in its majesty from the water.
The sea swallow, Glaucus atlanticus, is a type of pelagic nudibranch. Pelagic means it lives in the open ocean, and being a nudibranch makes it a member of the phylum Mollusca. They are also called blue dragons, blue sea slugs, and a few other similar names. Because of where they live, these striking creatures are not frequently seen, so we were lucky to encounter a few of them after a dive at Batsata Maze in the south western part of False Bay, just south of Smitswinkel Bay.
Sea swallow
The blue patterned side of this nudibranch that is visible when viewed from above is actually its underside. The top surface of the animal, which points down, is counter-shaded (like a great white shark). It is a greyish silver colour to blend in with the surface of the sea when viewed from underwater.
Photographing a sea swallow
Sea swallows suck air into a gas-filled sack inside their bodies, for buoyancy. They prey on blue bottles (also called Portuguese man o’war) and retain and concentrate the blue bottles’ venom in their bodies for use against their own enemies. This makes them extremely venomous with the potential to sting badly.
Luckily the intrepid Carel leaped into the water to scoop one into a cup and we could all take a closer look (don’t touch!) on the boat and get some photographs. Afterwards, our visitor was returned safely to the ocean.
They are widely distributed through many of the world’s oceans, and sometimes wash up on the beaches in False Bay. They are unusual, but not earth-shatteringly rare. If we were more social media savvy we would have managed to use this sighting to manufacture the kind of hysteria generated by that facebook page whose title expresses an intense and profane love for “science“, or a few other media channels. But we’re not, so you get this blog post!
One of the joys of having a manoeuvreable, user-friendly little boat is the opportunities that arise to participate in a variety of interesting events. Lately, we have been doing a number of open water swims; not swimming, but providing boat support to a swimmer who is traversing a stretch of open ocean. Last year we did the Swim for Hope around Cape Point, and the Freedom Swim from Robben Island to Big Bay, and several more of the same in 2015.
We used SharkShields at the Swim for Hope events, and with the increasing number of swims that Tony has been supporting we thought it might be time to invest in a SharkShield for use in these events. The SharkShield is a portable device designed to be worn by a surfer, free diver or scuba diver. It has a long antenna which emits an electric current which is intended to repel sharks. When used for open water swimming, the SharkShield is typically attached to the side of the boat with the antenna in the water alongside, creating a radius of 3-5 metres within which the current can be felt by a shark. If you touch the end of the antenna there is a noticeable pinching sensation, so swimmers have to be careful when approaching the boat.
Tony testing some SharkShields in the pool
Proper scientific testing of the device in Australia and South Africa indicates that it is by no means foolproof, and does not work in all situations, but it seems to have a certain usefulness if your visiting white shark is in the right frame of mind. The paper reporting the results of the SharkShield tests says:
Our study assessed the behavioural effects of the electric field produced by the Shark Shield Freedom7™. The study was performed in two locations and tested two distinct approach and behavioural situations to assess whether the response to the Shark Shield™ was consistent across behaviours. The electric field did not affect the proportion of static baits consumed, but significantly decreased the number of breaches, and surface interactions on a towed seal decoy.
The authors suggest that since breaching requires significant energy outlay, sharks may be more cautious to mount a breaching attack in the presence of anything out of the ordinary (I’m paraphrasing). Even with knowledge of the device’s usefulness only in certain situations, it still provides great peace of mind to swimmers while they swim in parts of the ocean where sharks are known to be mobile, such as False Bay.
The Freedom7 SharkShield unit outside its neoprene case
Tony was able to examine and test several lightly- to well-used Freedom7 SharkShields to see which of them worked, and what the battery life was like. In the process he shocked himself several times, which provided great entertainment to me and caused some consternation to the cats, who were themselves strolling around alarmingly close to the antennae. The unit itself is filled with something that looks like glycerin, to keep it pressurised and protect the electronics. The red switch at right turns the device on and off, and red and green lights indicate whether it’s on, charged, and functioning. A wet hand applied to the end of the antenna also gives information on whether the device is functioning…
The shark repellent cable that was tested at Glencairn this summer is a massively scaled up version of these retail SharkShields. It is essential that development and testing of non-lethal shark mitigation devices continues, to provide an alternative to measures such as the KwaZulu Natal shark nets, and the French government’s shark fishing activities at Reunion in response to multiple shark bite incidents at the island.
Shark Alley is a special and unusual dive site just south of Millers Point. It is an aggregation site for broadnose sevengill cowsharks, predators who feed on seals and a variety of other animals. They can grow to three metres in length. These sharks seem to use this site as a resting area (though we aren’t sure – research is ongoing) and their behaviour is typically docile and relaxed. For this reason it is a great place to dive, as the sharks come close enough to get a good look at them but do not behave in a threatening manner.
There has never been a serious incident involving a diver and a shark at this site, but there have been a few incidents. Clare has had her pillar valve gnawed on by a feisty young male shark while on a dive here a few years back, and early in May a diver was bitten on the arm by one of the sharks. That latter bite made the newspaper (the shark drew blood and the NSRI was summoned), but I am sure that there have been other more minor incidents here that didn’t get reported.
Young cowshark
This got me thinking about a protocol for diving with these animals. Shark dives all over the world are governed by safety protocols and guidelines, usually put in place by dive operators themselves (examples here and here). We do have a set of standards that we adhere to when visiting this site and mention in dive briefings, but I’ve never written them down all together before. I am a firm believer in self regulation, whereby the industry regulates itself so that we don’t end up with a bureaucrat in an office telling us we can’t dive with cowsharks without (for example) a special permit, or (heaven forbid) ever again!
Cowshark passing a diver
So here’s our protocol – how we choose to regulate ourselves when diving this site. It’s not a set of hard and fast rules that everyone has to follow, but it’s how we choose to approach dives at Shark Alley, a little bit like Underwater Africa’s diver code of conduct, but for cowshark diving. You are welcome to use these principles yourself, and I’d like to hear any suggestions you have to improve them or for points I may not have thought of.
Do a positive entry (i.e. with your BCD fully inflated) if you are diving off the boat, so you do not risk landing on a shark in mid water. If there is a thermocline, the sharks typically swim above it, and may be shallower than you expect.
Descend slowly in a controlled manner, looking below you at all times. Ensure that you are carrying sufficient weight (you should be able to kneel on the sand if necessary).
Do not feed the sharks. Don’t carry anything edible (sardines, for example) in your BCD, and do not chum from the boat. This includes washing the deck off at the dive site if you’ve just been fishing or on a baited shark dive. Chumming is both illegal (you need a permit) and unsafe, especially if there are divers in the water.
If you have students in the water, perform skills away from the sharks (if possible, avoid conducting skills at this site).
Some sharks will show a keen interest in your camera and flash or strobes. Do not antagonise them by putting a camera directly in their face. If a shark is showing undue interest in your photographic equipment, hold off taking pictures for a moment while it swims away.
Move out of the sharks’ way if they swim towards you. (Here’s a video of Tami doing just that.) Cowsharks are confident and curious, and often won’t give way to divers. Respect their space and move far enough away that they won’t rub against you or bump you as they swim by.
Be alert for any strange behaviour by an individual shark or the sharks around you. Be aware of your surroundings and don’t become absorbed with fiddling with your camera or gear. If a shark does become overly familiar (bumping or biting), gather the divers together in a close group and abort the dive in a controlled manner.
Do not dive at this site at night or in low light. This is probably when cowsharks feed (though we aren’t sure), and as ambush predators their behaviour is likely to be quite different in dark water when they’re in hunting mode.
Do not dive at this site alone. When diving in a group, stay with the group and close to your buddy.
I am not writing this protocol down to make people afraid of diving with cowsharks in Cape Town. But I do think it’s important to remember that this is a dive that needs to be taken seriously, with safety as a priority. Because we can visit this site whenever we want to, it’s tempting to become blasé about what an amazing experience it is, and also about the fact that these are sharks that need to be respected.
In conclusion! Unlike great white sharks, cowsharks (and blue sharks, and mako sharks, and and and…) are not protected in South Africa, so it’s not illegal to fish for them in permitted fishing areas (i.e. outside no take zones, etc). One of the cage diving operators in Gansbaai even used to use cowshark livers in his chum… If you want to make a difference in the lives of cowsharks and ensure they’re still here for us to dive with in future decades, consider writing a letter to the relevant government minister (make sure it’s the current one, in the new cabinet) and also to the shadow minister from the opposition party, requesting protection for more shark species in South African waters.
It’s not Jellyfish Lake in Palau by any stretch of the imagination, but we had some impressive jellyfish action in False Bay during September and October this year. I filmed these two videos at Outer Photographer’s Reef, at the safety stop.
These purple beauties are compass sea jellies, but we also saw impressive blooms of box jellyfish that lasted for several weeks, right into November. It’s possible that this congregation of sea jellies was caused by a quirk of a current somewhere, that herded them all into False Bay and then prevented their departure. There’s also the possibility that they found something nice to eat in False Bay, perhaps because of the large volume of sewerage that gets pumped out into the ocean all around this special piece of coastline.
Scientists aren’t actually sure what causes jellyfish blooms, but ultimate causes seem to be warmer oceans and increased nutrient loadings in coastal waters as a result of human activities.
Box jellies can deliver a nasty sting – it’s the luck of the draw whether it’s bad or not, but if it is, you can suffer for days. It’s also distinctly possible that with repeated stings you will become more sensitised to their venom. So take care!
Wind, walkers and waves will mean we are diving on Saturday in False Bay starting real early, i.e. 7.00 am at the Yacht club. We plan to dive Atlantis and the Brunswick.
On Sunday there will be way too much traffic and road closures to make an early start possible and I don’t think the wind will allow anything later in the day. I am really keen to do a double tank dive to Justin’s Caves or to dive North and South Paw, but will make that call on Saturday afternoon once we have a better idea of the wind (which looks iffy) and the viz.
Week’s diving
The last week has been spent driving instead of diving as all our cylinders were due for their annual medical examination. We did cancel last weekend’s dives due to the wind being a little stronger than I like to launch and dive in, but the guys that did go out reported really good conditions.
Divers near the jetty in Simon’s Town
We are just home from a really good night dive and all in all we were 19 divers. We dived below and around the jetty in Simon’s Town and had passable viz and a great deal of jellyfish to contend with. Thanks to all those folks from far and wide (including OMSAC!) that joined the fun. The aim with Diversnight International is to have as many divers in the water at 2013 as possible, world wide, and then to eat cake. The numbers since this event started are:
2005: 351 divers in Norway.
2006: 889 divers in Denmark, Norway and Sweden.
2007: 1859 divers in Denmark, Estonia, Finland, Iceland, Norway, Sweden and also Svalbard.
2008: 2183 divers in Denmark, Estonia, Finland, Iceland, Norway, Sweden, Egypt, Indonesia, France, Spain, Faroe Islands and Belgium
2009: 2749 divers, 218 divesites and 20 countries
2010: 1700 divers, 175 dive sites and 22 countries
2011: 2577 divers, 196 dive sites and 24 countries
2012: 2322 divers, 231 dive sites and 25 countries
If you think the water is cold here, you should feel it in Scandinavia in November, where this event started!
Brave jellyfish warriors at Diversnight
Prizes
Congratulations to Bianca, who won two boat dives in the Diversnight lucky draw this evening! Also congratulations to Esti who has won a Nitrox Specialty course in the October boat divers’ lucky draw.
We will have another draw for boat divers in November and one in December. To enter, come for a boat dive. You’ll win a Nitrox course, or, if you’re already Nitrox certified, you’ll win two boat dives!
Gear
Sometimes I have students and former students who want to sell some gear secondhand. If you’re looking for gear, let me know and I might be able to put you in touch with someone. The details of the transaction are up to you! At the moment I know someone with a Suunto D6i dive computer and a regulator set for sale. If you’re interested drop me a mail and I’ll hook you up.
I think I prefer this article on octopus (the language is a bit less fruity, for one thing), but giant Pacific octopus are cool enough that even the most offensive writing about them can be interesting. A specimen has been weighed at 71 kilograms, but they usually weigh about 15 kilograms and can have arm spans of over four metres.
One octopus off San Juan Island grabbed a diver’s legs and held him underwater while he struggled, long enough that the diver used up most of the air in his tank and nearly died—as if the octopus knew that divers have only a certain amount of breathing time. Another octopus in Washington waters pounced on a diver, flaring its tentacles in a hunting gesture. The diver fended it off and swam away, but the octopus followed, crawling toward him on the ocean floor, and pounced again. Luckily, this octopus was small—but bizarrely aggressive for its size.
If you’re skeptical about the source of the above information, it’s from a Canadian Field-Naturalist journal article. An interview with Dr Roland Anderson, one of the authors of the journal paper, sheds further light on the “cold intelligence” of cephalopods (when kept in aquaria, they are notorious escape-artists), and their depressing sex lives (have sex once at the age of 3-5 years, then go mad and die). Anderson says giant Pacific octopus are not as smart as dogs or cats, but they are smarter than the average pet bird.
The article concludes with a discussion on cooking octopus. Kind of hard to contemplate after pondering their intelligence and remarkable physiology…
The four episodes of this History Channel series cover waves, tides and currents, predators, and pressure – all powerful features of the ocean that can be sensationalised (some more easily than others) and presented for shock value and as imminent threats to human life. Full advantage is taken of this fact.
This very American offering doesn’t boast the measured, mellifluous tones of Benedict Cumberbatch or Steve Toussaint as narrator, but the line-up of (mostly in-studio) guest narrators is quite impressive. Bruce Parker (The Power of the Sea), Susan Casey (The Devil’s Teeth and The Wave), David Gallo (scientist presenter of the TED Talk I mentioned here), Scott Cassell (student of the Humboldt squid), Richard Ellis (writer of a number of ocean history, art and sciencebooks), and Neil Hammerschlag (shark scientist) were familiar to me, as was big wave surfer Ken Bradshaw, from this article. The strange, uncomfortable way in which the studio narrators were filmed, with silent close ups interspersed with talking, was very annoying and must have been incredibly embarrassing to shoot. Or perhaps the cameraman took the footage when the narrators didn’t realise they were being filmed.
Unlike BBC documentaries, which tend to rely purely on incredible photography and fluent narrative to convey information, the History Channel favours a CGI-heavy approach that we encountered in Treasure Quest,Deep Sea Salvage, and also in the National Geographic SharkMen series.For the subject matter of this series – particularly the sections on waves, tides and currents – it was very appropriate and informative. The first episode, devoted to tsunamis, rogue waves and “monster waves”, made good use of CGI to illustrate the concepts as they were explained. The series was produced shortly before the Japanese tsunami of 2011 (there is a hastily tacked on “thoughts and prayers” disclaimer) and features interviews with a survivor of a tsunami in Samoa. I am fascinated by rogue waves – the whole episode could have been devoted to them but they don’t make for good television – we only have indirect evidence of their existence. Also, I could have done with more footage of giant ships battling storms, but that’s what youtube is for…
The least interesting and most irritating episode was the one devoted to the ocean’s top predators, which suggested that orcas are a serious threat to humans. As evidence, the cases of captive killer whales drowning and injuring their trainers at marine theme parks were cited. No mention was made of the psychosis that these whales suffer from as a result of confinement in a small, barren, completely unnatural environment. An incident in which orcas inexplicably rammed and sank a yacht in the Pacific Ocean is also described and re-enacted. Whether the orcas did what they did because they wanted to kill the people on board is highly debatable. There is also a half-hearted attempt to paint whales as potentially vicious killers, recounting incidents when sperm whales rammed whaling boats in the 19th century. More power to the sperm whales, I say.
The other dangerous predators were (predictably) white sharks, Humboldt squid, saltwater crocodiles and Australian box jellyfish. There was a small environmental message at the end of this episode, mentioning that squid will probably end up the top predators in our oceans if current trends – fishing out large predatory fish and global warming in particular – continue.
The third episode, on the immense pressures that objects in the deep ocean are subjected to, was very interesting to Tony and me as divers. A confusing interview with a diver whose brother got DCS on a wreck dive leaves (I suspect) much out. Were they even qualified divers? Why was he surprised that his brother felt unwell and confused as to the cause after he popped to the surface from 30 metres after a 30 minute dive?
The bulk of the third episode, however, recounts a 1981 experiment called Atlantis III in which three volunteers were taken in a saturation system to a simulated depth of 686 metres while breathing Trimix 10 (70% helium, 20% nitrogen and 10% oxygen). It took 31 days for them to decompress. The chief of the experiment, Peter Bennett, was the founder and former CEO of DAN. There’s a more information about the project here – worth a read (download the pdf slowly), and a briefer account here.
The series concludes with an episode on tides and currents, including rip currents. The massive tidal range of Morecambe Bay in the United Kingdom, is discussed at length. At low tide, up to 300 square kilometres of mudflats is exposed, and flooded again when the tide comes in. The guides who escort people out onto the mudflats when the tide is out seem like charming individuals – it is recommended not to wander around at low tide without local guidance. In 2004, the rising tide trapped and drowned 23 Chinese immigrants who were working the cockle beds – with such a large expanse of land to cover, the rising tide comes in at great speed. There is also a harrowing re-enactment of a father and his two sons getting washed out to sea in a rip current in Kauai that should make you think twice about swimming at beaches with warning signs on them.
You can get the DVDs here if you’re in South Africa. Foreigners, go here or here.
Last Saturday, 14 September, Tony took a group of four Russian tourists (all very experienced divers in their forties and fifties), Divemaster trainee Craig, and experienced Cape Town diver Christo, for some boat dives. Their first dive was an hour-long dip at Photographer’s Reef, in very nice visibility. By the time they were ready to do a second dive, the wind had come up a bit, and they decided to visit the wreck of the Clan Stuart, which is close to shore and relatively sheltered.
The dive site
The Clan Stuart is most often dived from shore, but involves a crossing of a busy road in full dive gear, climbing over a low wall, crossing small dunes and a railway line, and then a scramble over some rocks onto the beach. Then there’s usually a breaker to get through – no mean feat at the best of times. One of the Russian divers has a prosthetic leg, which would have complicated the surf entry somewhat (and ended up complicating their exit slightly).
It should be mentioned that according to the Diving the Cape Peninsula and False Bay page about the Clan Stuart on wikivoyage, scuba divers have reported seeing white sharks on the Clan Stuart in 2010 and 2011. We did a very uncomfortable dive there in early 2012 during which we were swarmed by white steenbras, behaving in a manner which made us suspect shark presence, although we didn’t see a shark (and we couldn’t get out of the water fast enough). I’ve added the Clan Stuart to my winter-only dive site list, which includes anything near Fish Hoek or Glencairn, and especially Sunny Cove.
The dive
Very shortly after rolling into the water at the Clan Stuart, the divers encountered a curious great white shark, which circled them twice and then swam off. It was not aggressive at all. Tony saw the shark on the surface after it had circled the divers, as it came quite close to the boat. One of the Russian divers, Vladislav Tomshinskiy, had a video camera and the presence of mind to film the shark as she swam past, both times. The first bit of footage is very blurry; in the second, the shark is clearly visible as well as the bubbles of Christo and Craig, who was holding the buoy line. From the footage local shark expert Alison Kock estimates the shark to be 3 to 3.5 metres long, and a female.
Craig and Christo acted calmly, got the divers into a small group, and when the shark had left them alone, swam them close to the bottom, over the wreck and onto the beach, where Tony and I fetched them in our cars. Our Russian visitors were thrilled to have seen a white shark and perhaps would have liked to continue the dive at the Clan Stuart, but we judged it prudent to go elsewhere and they finished the day at Roman Rock.
Advisory issued by City of Cape Town
We notified Shark Spotters, who informed the City of Cape Town and issued a shark advisory. If something similar happens to you, please let Shark Spotters know – they log all encounters between people and white sharks, for public awareness and research purposes.
Why talk about it?
There is always the chance that scuba divers in Cape Town waters will encounter a white shark, but very few such encounters actually occur. Tony almost always mentions sharks in his dive briefings (if I close my eyes I can practically recite the shark bit: “This is Cape Town, and we do have great white sharks here. It’s very unlikely that we’ll see one, but if we do, this is the plan…”). He speaks from experience, having encountered white sharks at Long Beach on two separate occasions. He’s been told by one or two of his divers that talking about sharks in a dive briefing is scary and they don’t want to hear that there’s a chance of seeing one – but ignoring the fact that encounters like this one at the Clan Stuart can happen is short sighted. Both Craig and Christo have heard the shark briefing tens of (and in Christo’s case possibly more than a hundred) times, and as a result had some idea of what to do because they can probably also recite Tony’s briefing to themselves without having to think too hard about it.
Hopefully the example set by the divers on this particular day will provide comfort that an encounter with a curious white shark need not be catastrophic, and show that there are things you can do to minimise your chances of a negative outcome. Also, it serves as a reminder that sharks don’t swim around looking for people to eat. This shark had probably never seen a diver before, and was understandably curious about these noisy creatures in its realm. It wasn’t looking for a meal. All six the divers behaved calmly and with discipline, not panicking or doing anything that would endanger themselves or their buddies. They were also all completely awe-struck by the experience of seeing the shark in its natural habitat, and variously remarked upon its grace, how quickly it turned, the powerful wash of water from its tail fin, and how majestic it looked.
Over the next few days we’ll feature accounts of the event from Tony, Christo and Craig, as well as the video footage that Vlad took of the shark. I hope that this can contribute to white shark awareness and safety in the diving community.
I think it’s a timely occasion to do this, as the City of Cape Town has recently released its annual safety tips and reminder that white sharks move inshore during the summer months. This inshore movement is related to the availability of fish such as white steenbras, and a number of other factors. Sharks are a reality of life and scuba diving (and surfing and swimming…) in Cape Town; an informed community of water users will enable us to appreciate and protect these animals whilst promoting water safety and a realistic assessment of the risks.
What’s coming up?
We’ll have reports on the incident from a few different perspectives. Also, I’ll post the video of the sighting taken by Vlad. I’ll update these links as the posts go live over the next few days:
