Buoy – Learn to Dive Today Blog

A Day on the Bay: A Brydes whale for company

On a beautiful, calm day in early June this year, shortly after dropping my divers in the water, I was visited by a friendly Brydes whale. A Brydes whale – I suspect the same one – had been showing a strong interest in boats in western False Bay over the last couple of weeks.

I knew it was a Brydes whale because of the small, sickle-shaped dorsal fin far back on its spine. This one circled the boat a few times, and then headed straight for me like a submarine on the surface. It pushed a small wave of water ahead of it as it came.

It was a slightly intimidating sight as it ploughed through the water. It was an extremely calm day, so the boat’s motors were switched off. I waited with some anxiety to see what the whale would do.

After a close pass by the boat, the whale circled Seahorse several times, blowing lustily. It came back to the boat repeatedly over a period of at least half an hour. I kept the engines off, and made sure my life jacket was fastened. I hoped the divers might also be able to see what was happening! The whale was not hostile in the least, but an exuberant animal weighing between 12 and 20 tons, moving at speed, could accidentally tip me into the water in a heartbeat.

The whale lifted its head out of the water a few times, showing me the three rostral ridges on top of its head and the grooves under its throat, which also help with confirming its identification as a Brydes whale. Our whale book says that these whales often have small, circular cookie cutter shark scars, specially if they’ve been in tropical waters, but I couldn’t see any.

I find Brydes whales a little mysterious, because they can be seen year round in False Bay and somehow lack the predictability of the Southern right whales and humpbacks whose rowdy presence is apparent close to shore in False Bay between June and November. If you see a whale in the first half of the year in False Bay, it’s almost certainly a Brydes whale.

These whales calve year-round, because they don’t ever go into really cold water (False Bay is at the southern end of their range). This preference for warmer water is probably related to their relatively thin layer of blubber. They eat schooling fish and plankton.

Their blows are low and bushy, as you can see from my photos. They don’t aggregate in big groups like other whales seen along South Africa’s coastline, and you’ll see at most two animals together at a time, if that. These whales are still caught by the Japanese as part of their “scientific” whaling program.

After a while the whale seemed to lose interest, and left me to my thoughts as I waited for the divers (who were gloriously oblivious, it turns out) to surface. While it’s an incredible experience to have an animal like this approach you so close and with such confidence, I am glad it left. Ship and boat strikes are a very real danger to whales, and a whale that is so curious about boats could get itself into trouble in the busy boating areas close to shore in False Bay.

Regulations state that unless you’re in possession of a whale watching permit (and there’s only one operator in False Bay who has one of those), you are not to approach a whale closer than 300 metres, anywhere in South African waters. If a whale approaches you, move away if you can do so safely. If there are divers in the water, your responsibility is to stay close to the divers, so turn off your engines and enjoy the moment!

Testing a shark repellent cable at Glencairn

Signage at Glencairn explaining the test

Perhaps you have noticed some new signage and a little wooden hut at Glencairn beach, where an exciting test – of an electronic cable to repel great white sharks – is underway. The cable is a massively scaled up version of the Shark Shield technology with which many surfers and lifesavers will be familiar. The Shark Shield has been subjected to scientific testing, and is effective in certain circumstances.

The risers on the cable are clearly visible at low tide

The cable is a collaboration between the KwaZulu Natal Sharks Board (who would like an alternative to the gill nets and drum lines currently used to harvest sharks and other marine life off South Africa’s north coast), and the Institute for Maritime Technology (IMT) in Simon’s Town, a division of ARMSCOR. Shark Spotters and the City of Cape Town are assisting with the testing phase, which started in November and will continue until the end of March 2015. A permit has been obtained from the Department of Environmental Affairs.

The cable is 100 metres long, and is situated at the northern end of Glencairn beach. Cape Town is an ideal location to test things like this, because Shark Spotters has ten years of shark spotting data that will give a baseline measure for “normal” white shark activity without the cable. When something new (the cable) is introduced into the environment, changes in behaviour relative to the baseline data can be ascribed to its presence. Fish Hoek was originally mooted as an ideal beach to run the test, but the trek net fishermen were concerned for their fishing opportunities and so the test was moved to Glencairn.

The cable is off the end of Glencairn beach

The cable emits a low frequency electrical pulse that – it is hoped – will repel sharks. The electrical output of the cable poses no threat to swimmers or surfers, but for obvious reasons people are requested to keep clear of it for the duration of the experiment. The cable has electrodes on either side of it, supported by vertical risers that are marked by small orange buoys (so the cable runs down the middle of the rows of buoys in the pictures). At high tide the buoys are below the surface, but Tony took the boat past at low tide and photographed them sticking out of the water.

Shark Spotters will be monitoring the cable from the mountain above Glencairn, and a video feed will also be used to closely analyse the movements of any sharks that approach the cable. The risers on the cable (marked by the orange buoys in the photographs on this page) are semi-rigid, designed to minimise the risk of entanglement of any marine life. As it is the end of whale season in False Bay, there is not much risk of a whale visiting this location. Despite that, a boat and crew are on constant standby should an entanglement situation arise.

The position of the cable marked by buoys

The usual Shark Spotters sign at Glencairn

The signs and Shark Spotters flag at Glencairn

The big buoy says "Keep Clear" so we did! — The big buoy says “Keep Clear” so we did!

The cable is just off the end of the beach

There is a full report on the testing phase, with an artist’s impression of the cable underwater, on the Sharks Board website, including a list of frequently asked questions (which should set your mind at ease). There’s also a great post at Round About South that includes pictures of the study area, and of the cable from the KZNSB document.

It’s important to note that this is an experiment, and no additional protection from white sharks is offered or guaranteed while the cable is in the water.

Oh buoy

Our cats (of which we have many, many) find our cars irresistibly appealing, and at the first opportunity will climb inside for an investigation. Tony once got out the gate and into the road with a car full of cylinders for filling, and a very wide-eyed Mini cat, who had climbed into the back of the vehicle while Tony was loading the tins.

Here’s Blue, still a little kitten, checking out (something next to) the buoy that the Divemaster (on our boat and shore dives) takes along with him on a reel and line, floating on the surface to mark the divers’ presence to boaters. She’s in the back of the divemobile. Everything gets a bit salty, and this seems to fascinate the cats – perhaps it’s one step away from bringing an actual fish home for them.

Newsletter: Winter wonderland

Hi divers

Weekend diving

Friday: Launch for cowsharks at 2.00pm

Saturday: Fully booked

Sunday: Boat dives if conditions permit, text or email if you want to be notified

Dive conditions report

We have been really busy with two groups of police divers from far inland. Most of their diving for work is in zero visibility and they have been experiencing some 15 metre viz dives for the second week in a row now. In between this I have also done a few shore dives at Long Beach and had 3 m viz on one day and 10 m viz the next day. There are huge patches of clean and dirty water around in the bay and on Wednesday we saw a few patches of red tide around.

Red tide near Simon's Town — Red tide near Simon’s Town

Dive plans

Winter diving is most definitely different. A huge swell rolled in today so we stayed off the water but will be back tomorrow and plan to do three launches. The third, to cowsharks still has a few spots open and we will leave the jetty in Simon’s Town at around 2.00 pm.

I am fully booked for a charter on Saturday. Conditions for Sunday are a little uncertain. The forecast says north easterly wind and that is seldom pleasant to dive in so we will make a call early Sunday as to whether or not we will launch.

Text or email me if you want to dive.

We attended a talk on Monday evening on orcas and dolphins and it is always so interesting to hear researchers and scientists talk so passionately about their subjects. There is also an exciting new research collaboration called Sea Search that is starting in False Bay towards the end of this year.

regards

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

Diving is addictive!

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Exploring: The shark exclusion net at Fish Hoek beach

One Tuesday in early December, Tony escorted some members of the media – Murray Williams of the Cape Argus, and Bruce Hong of Cape Talk radio, on a dive along the inside of the shark exclusion net at Fish Hoek beach. It was just before the start of the school holidays, and since the net has been trialled multiple times by now and is working well, it’s a good time to raise awareness of the additional beach safety and – importantly – peace of mind that the net offers. I tagged along as photographer.

Over-under view of the exclusion net at Fish Hoek

The net at Fish Hoek beach is a world first. It has a fine mesh that is highly visible underwater, and is designed not to catch anything – unlike the shark gill nets in KwaZulu Natal. The net is put out in the morning and retrieved at the end of the day, but only when sea conditions allow it. The south easterly wind can bring huge quantities of kelp into Fish Hoek bay which would foul the net, so when there is a strong south easter the net cannot be deployed.

If you’re a water person, please educate yourself on how the net works, and its intention, and share it with your friends. Even now, nine months after the trial started, I hear uninformed comments from people who have not bothered to do any reading about the net, and assume it’s the same kind of net as the ones in Durban. It’s not. The whole idea is that nothing – no sharks, no humans, no klipfish – gets hurt. Shark Spotters and the City of Cape Town have been very clear on this from the start. I had a bit of a rant about this late last year.

Murray dives down to check out the exclusion net

I digress. We went to the beach, got suited up, and went to check out the net. It was spring low tide, so at its southernmost end we were in about 2 metres of water. The net is high enough that when the tide comes in and the yellow floats rise with the water level, it simply unfurls further downwards, making an unbroken curtain. The lower portion of the net rests on the sand, with two parallel weighted lines to ensure that it lies flat. You can see that in the photo above Murray is gripping one of these leaded lines, and that there is a fairly large amount of net waiting on the sand for higher tides.

Entering the water watched by some schoolboys on an outing

The net hangs down like a curtain and rests on the sand

We stuck close to the net, and didn’t see much marine life on the sandy bottom. I spotted a large sand shark (when I say I “spotted” him, I mean that I almost landed on top of him). We were mutually surprised, and he zipped away into the bay, sliding neatly under the bottom of the net. I also saw a box jelly cruising along the net. Given my recent history with box jellies, I kept clear! The sea floor in the area where the net is deployed is level, sandy and free from rocks. There’s more life on the catwalk side, where beautiful rock pools wait to be snorkelled.

We were accompanied by Monwabisi Sikweyiya, who is the Field Manager of Shark Spotters. He is a hero and I always feel a bit star-struck when I see him (although he has no idea why – he probably just thinks there’s something wrong with me). He swims along the net regularly – someone does each time it is deployed, actually – to make sure that it’s released properly and hanging straight down.

Swimming inside the net is completely voluntary. When a shark is seen in Fish Hoek bay the Shark Spotter still sounds the siren and the flag is raised to clear the water. The Shark Spotters team are still waiting to see how a shark will respond to the net when it swims close enough to be aware of it. So far none of the local sharks have come close to the net, as the summer season when sharks move inshore has only just started. Tony was half hoping that we’d be swimming along inside the net, look out through the mesh – and blammo! – see a great white shark. But we had no such luck, if that is the right word.

You can read the article that Murray Williams from the Argus wrote after the dive, here.

Dive date: 3 December 2013

Air temperature: 22 degrees

Water temperature: 17 degrees

Maximum depth: 2.3 metres

Visibility: 4 metres

Dive duration: 25 minutes

Liveaboard diving: Getting in

Just when we thought we’d tried all the possible ways to get in and out of the water from our Red Sea liveaboard, we learned a new one. We jumped in off the dive deck while the boat was on anchor or idling precariously near a cliff, or rolled backwards off Zodiacs. We used tail lines in a variety of configurations, did short surface swims, and generally felt like action heroes.

I am an enthusiastic practitioner of giant strides. It makes me sad that there are so few giant stride opportunities in Cape Town. These divers, on a liveaboard close to ours, were diving a wreck called the El Miniya. Their boat was tied up to the wreck at her stern. The divers jump into the water, and then swim along the side of their liveaboard to get to the stern line, before descending onto the wreck.

[youtube=”http://www.youtube.com/watch?v=OnKHqri7GNc&w=540″]

Here are some of the divers on our liveaboard doing giant strides into the warm darkness of the Red Sea for a night dive:

[youtube=”http://www.youtube.com/watch?v=qf9GLLNq0lc&w=540″]

A tidy deck

Lines, mooring ropes, anchor ropes and any other piece of rope on a boat has an uncanny knack of getting knotted, tangled or generally in the way. There are a multitude of ideas and ways of keeping ropes tidy and in order, and every skipper has his own theory.

Seahorse is a boat used mostly with new students – for some, we provide their first ever boat ride – we often have people doing completely unheard of things with ropes including tossing them overboard without tying them off. I have tried to make sure I reduce the likelihood of a mishap so amongst other things I have marked the deck Port and Starboard, and the lines on the pontoons are colour coded: red for port and green for starboard.

If there is a line on the boat that should not be untied, the knots are covered with insulation tape and the most recent addition to the rope organisation system on board are these bags for keeping mooring lines off the deck and out of the way. Fenders are attached permanently at the stern to avoid them going overboard unclipped, and it is the same up front in the bow.

I have also recently moved the life jackets from the hatch in the bow to these two grey bags on the stern for easier access. The O₂ unit will now move into the hatch in the bow, as it is a little more sensitive to salt water.

Life jackets live in bags next to the engines

Great white shark at the Clan Stuart wreck – video

To close off Cape Town’s Shark Week, here’s the 11 second video footage that diver Vladislav Tomshinskiy (thank you Vlad!) took of the shark as it swam past the divers the second time. The bubbles at the end of the video belong to Craig (far left, with the buoy line) and Christo. Please enjoy this beautiful video of one of the ocean’s most brilliant predators, swimming curiously and gracefully past a group of awe-struck divers who are all amazed and grateful for having had the experience.

[youtube=”http://www.youtube.com/watch?v=F_h-3q9zm20&w=540″]

Local shark scientist Alison Kock of Shark Spotters says that from the video the shark looks to be a female (she said that if it was a male you’d expect to see claspers as it turned to swim away, which one can’t) and that she’s between 3 and 3.5 metres long. According to a recent study, most of the sharks seen at inshore locations by the Shark Spotters during the summer months are large females, who tend to be in False Bay year-round.

It’s not clear whether the shark was disturbed by the divers’ bubbles (as Christo speculates), and whether that was what caused it to swim away when it did. That flick of the tail says “I’m outta here!” and is something we’ve seen when observing these animals from the surface (on cage diving and research boats). The acceleration and turning abilities of white sharks is remarkable.

I’m interested by the bubbles because it’s an oft-repeated mantra by the shark cage diving operators (all over the country) that sharks are scared of scuba bubbles, and this is why you have to breath hold or snorkel in the cage. In July we did a cage diving trip in False Bay with African Shark Eco-Charters, who allow their clients to view sharks from the cage while on scuba, and they certainly don’t see fewer sharks than any other operator. Also, the sharks who swam past us in the cage were totally not bothered by our bubbles (of which there were many).

I therefore wouldn’t bet my reputation (or maybe I should, just to get rid of it…) on the “sharks don’t like bubbles” theory, but there may be far more nuance to it than we know. The shark in this video practically got a spa treatment on its tummy from Christo and Craig’s regulators… Perhaps to scare a shark away using air bubbles you need to get really close. But I don’t plan to test that theory unless I have to!

Weekend dive plans

Tales of Surf Rescue

Weekend dive plans

Shark Spotters fundraiser

Weekend diving

Dive conditions report

Dive plans