Fish – Page 62 – Learn to Dive Today Blog

Shark tale

As a freelance instructor I dive at Long Beach behind Simon’s Town railway station several times a week. Long Beach is an ideal training site as it offers protection from the weather under most conditions, visibility is almost always 5 metres plus and it is one of the easiest shore entry dive sites around the Cape Peninsula.

On Wednesday 25 August I was on a training dive with three students. I briefed them as usual and off we went. The visibility was around 6–8 metres and I was surprised to find nothing to show them. Around the barge, over the fishing boat, down the inner pipeline, nothing to be seen. I was starting to feel the place was barren, and it was very strange. Suddenly a klipfish came racing across the sand faster than I believed they could swim and I half expected a seal to be close behind as I had seen one on the surface before we started the dive, but nothing. I honestly couldn’t find anything, no shysharks, no pipefish, no crabs, no octopus and I can almost guarantee I will find these creatures there on any dive. Not even the hundreds of busy little hermit crabs were scurrying around and I could not find any movement. I started to think that perhaps the water had been poisoned by some ship or something weird and all signs of life had moved off somewhere else.

We were just reaching the western end of the outer pipeline, about 60 metres offshore and at a depth of around 5 metres when I looked up and less than five metres away was a 2-3 metre great white shark. She was just cruising very, very slowly and must have seen us long before we saw her. I was most awestruck by the shark’s graceful poise and her girth. The other impressive feature was the length of the pectoral fins. She circled slowly around us and them slowly swam away, close above two other divers in the water not too far from us, and disappeared.

What to do when you see a shark?

Well, we all have our own theory and during briefings we always tell divers what we will do and how we will react. But will we react the way we think we will, and how will we deal with divers that panic?

I always brief divers as to what I will do and what they should do, and this is what we did. We all dropped to the sand, me first as I saw it first. I pulled my buddy, the most jumpy student, down and deflated his BC well before he saw it, I then pulled the other pair closer and dumped their air. It was a family and the youngster was 13 years old. He saw the shark but did not know what he was looking at. We then swam slowly back to shore without seeing the shark again. The first thing they said was ”I thought you said you never see great whites here!” so I had egg on my face as I had just said that – honestly – as I had never seen a great white there before! Oh well… I will need to modify my dive briefing slightly now!

In all reality the shark had been watching us for a while, possibly thinking “man, they make a noise.” According to the Introduction to Sharks course offered by SharkLife (it’s free and fantastic – do it now!), sharks are highly sensory creatures. Sharks have eyes on either side of their heads, which means they have a nearly 360 degree visual field (compare that to the approximate 120 degree width of your visual field when wearing a scuba mask). They have a small blind spot directly in front of their snouts – too small for you to hide in! – and another one just behind their heads. They can focus their eyes at a range of distances, and have excellent vision even in low light conditions. Sharks also have excellent hearing, augmented by a “lateral line” which extends along their bodies and provides additional sensory information. Their sense of smell is likewise highly developed. In a great white shark, 18 percent of its brain mass (largest percentage of all sharks) is devoted to the processing of olfactory (smell) information. As if this arsenal of highly developed sensory organs is not enough, sharks also have electroreceptive cells called Ampullae of Lorenzini located around their snout and head area. These cells can detect tiny bioelectrical impulses given off by muscle movement of potential prey (which is why it’s a bad idea, as a spearfisherman, to swim along with dying fish attached to your belt). The Ampullae are sensitive to temperature, and are also used in navigation.

Anyway… the shark swam a circle wondering what on earth we were looking for, and then swam off looking for something to eat. Clearly she did not find our presence worthy of investigating or for that matter munching. This just shows that divers that are slowly swimming along with good buoyancy, looking at the marine life in the ocean are just not on a sharks’ to do list.

Great white shark in Mozambique — A great white shark I photographed in Mozambique

Divers seldom get to see great whites. I have been diving for 18 years and have only seen three on a dive. I have done over 100 dives at Long Beach in the last year without seeing one and numerous dives at other dive sites in Cape Town, including at Sunny Cove where I was sure I would see one. Without a single sighting. So remember: stay calm, stay together and enjoy the moment because it is not something you get to experience too often.

If you want to chat about this, please email me!

FAQ: If I bleed in the water, will I attract sharks?

Hollywood has a lot to answer for!

For the girls

I get asked this question quite often by girls who are worried about diving while menstruating. The short answer, which should make you breathe a sigh of relief, is no – regardless of what feminine hygiene products you prefer to use. (While we’re on the subject – forgive me boys – but tampons are perfectly safe to use while scuba diving and nothing strange or frightening happens to them inside your body on a dive. If you’re really worried, and there’s no reason to be, use a Mooncup – get one at Wellness Warehouse.)

DAN has a useful answer to this question on their international website. The research that has been done indicates that menstruating women are at no greater risk of shark attacks than men, or women who aren’t on their period.

What you should be aware of is that if you’re a woman, you’re more susceptible to dehydration during your period, which in turn increases the risk of decompression sickness. There is also research that indicates that the use of oral contraceptives may marginally increase a woman’s risk of DCS. So be sure to stay hydrated, do your safety stops, dive conservatively – and enjoy your diving!

For the boys (and the girls who are still reading)

Sharks are not interested in human (mammal) blood – they prefer fish! And what’s more, unless you’ve experienced massive trauma (in which case I doubt scuba diving will be the first thing on your mind), only miniscule quantities of blood will be leaking out into the water – whether it’s because you’ve got a cut or scratch on your body, or (if you’re a girl) you’re menstruating.

(To clarify, in case you’re puzzled: I took these photos of the signs on the restroom doors at the Southern Sun Grayston hotel in Johannesburg with my dodgy cellphone camera while I was there for a conference in June. I’ve been itching to use them since, and frankly didn’t have time to organise a photo shoot of a woman in white trousers frolicking alone on a beach!)

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.)

Newsletter: Diving, a way of life

Hi everyone

The water has been very pleasant this week. The viz yesterday was 8 meters and I had three students on a dive. We were extremely lucky to see a great white swim gracefully by us. The most impressive feature for me was the shark’s girth, it was massive, solid looking and very sleek without a single blemish or scar. I felt honoured to have seen such a majestic creature, so close (it swam by less than three meters away), in its own domain, and very grateful that sharks tolerate us in their space. According to this website there has only ever been one incident of a diver being attacked and that was on the surface.

Diving this weekend

Saturday I have a few Discover Scuba experience students so I will be at Long Beach in the morning.

At 2.00pm we plan to dive the Clan Stuart providing the swell allows or alternatively we will do a navigation adventure dive at long beach and swim the navigation route found here. There is an unidentified huge anchor somewhere out there, as well as a 22 metre yacht and an old shipping container (Jeff’s box).

Saturday night conditions will be perfect for an adventure night dive and we meet in the parking lot at Long Beach at 6.00pm to decide where to dive.

I am trying to find ways of getting more people interested in the ocean, diving and conservation.

So these are my plans:

I am running a special introduction to scuba diving for anyone interested in the experience. For the month of September I will conduct Discover Scuba experiences for anyone that’s keen for the small amount of R350 per person, 7 days a week, minimum two people at a time. Anyone signing up for the Open Water course after this event will receive a full credit of this amount on their course.

I will also run a special Advanced course during September providing there are four people that all do the course at the same time. The normal price is R2400, but for the month of September it will be only R2000. Remember this is five dives, two of which will be boat dives where we will dive a wreck and do a mandatory Deep dive. Both these dives will in reality be deep dives so you gain more experience in this area. The remaining three dives can be a combination of Peak Performance Buoyancy (can you swim through three hoops at different depths without using your inflator hose?), Search and Recovery (lose it, find it and raise it with a lift bag), Photography, or Night diving, to name a few, but must include a Navigation dive. If you have done adventure dives with me in the last 12 months this will count as a credit towards your course.

Two Divemaster candidates start September (both bossy type girls so I hope I survive that!!) and Open Water course starts 11 September.

During September we will have a world clean up day and I plan to rally every one of you to join me on a dive with a garbage bag to clean up one of our dive sites… details next week, you may be lucky and get your picture in the newspaper… in a wetsuit and dive gear!

Be good and have fun

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

Bookshelf: Books about sharks

Sharks! All about sharks! Get some actual, scientific facts here. You can dive as deep as you want into the subject – here’s a wide selection of shark books for you to choose from.