Underwater electric fence not warding sharks off just yet

2015-01-30 08:00
Post a comment 2

Cape Town - While Cape Town's beautiful beaches continue being a major tourism drawcard for the city, a seeming prevalence of shark attacks, especially on the False Bay side of the peninsula, remain a worrisome factor. 

Over the past few years Cape Town's pioneering shark safety programme, Shark Spotters, has played a massive role in alerting bathers to shark activity and assisting in emergencies. 

Positioned at strategic points along the Cape Peninsula, primarily the False Bay coastline, two shark spotters per beach scan the waters for any threat throughout the day. One spotter is placed at an elevated position with polarized sunglasses and binoculars and is in constant radio contact with another spotter on the beach. If a shark is spotted by either, the beach spotter immediately sounds an alarm and raises a white flag with a black shark on.

Now, the raising of flags is central to their system and having a good understanding of what each means could do a lot for bathers' peace of mind. We take a look at the four flags they use and stipulate what each means:

First thing to note is that each of the flags does have a shark on it, which might seem a little intimidating at first, but not all of them mean an actual shark has been spotted. 

But there's still a risk

While the system really has done a lot for increased safety in the water, it does have one weak spot, as a News24 report recently pointed out: human error. A factor which also adds pressure to the actual Shark Spotters' already stressful jobs.

In order to minimise that margin of error, the Sharks Board has spent three years developing a new, environmentally friendly method of keeping sharks at bay, in the form of underwater electric fences. 


Instead of using magnets or physical barriers (such as shark nets that have proven to be hazardous to all marine life), the new system uses an active low-power pulsed electronic field in sea water.

Since October last year one of these electric fences was installed at Glencairn beach, close to Muizenberg to serve as a trial of the new technology. Up until the end of March this year, the fence will be activated on certain days during daylight hours for testing purposes.

By the end of March, the Sharks Board is expected to have collected enough data to establish what the full impact of the underwater electric fence would be.

How safe is it?

Good times #beach #glencairn

A photo posted by Ronel Human (@ronelhuman) on

 
But wait! An electric fence under water?

Sounds kind of dangerous, doesn't it?

Well apparently it's not! Neither to sharks nor to humans. According to the KZN Sharks Board, direct human contact with one of the fence's vertical electrodes would cause little more than a stinging sensation. However, it is currently strongly advised that bathers steer clear of the fence, at least 5 metres away, so as to avoid unintentional contact and obstruction of the experiment. 

Sharks, on the other hand, are highly sensitive to electromagnetic fields and able to move away from the fence easily at the first signs of discomfort.

So, no more shark attacks?

The Sharks Board has made it very clear, however, that at this stage the experimental fence in no way protects bathers at Glencairn beach from shark attacks, as it has not been deployed in such a way to exclude the predators from the beach. 

"It's only covering a very small area so far, so it's not impacting beach safety whatsoever. Thus, our Shark Spotters are still on duty as per usual," Sarah Waries, project manager, at Shark Spotters explained.  


So, in the meantime, until more conclusive data has been gathered about the underwater fences by the end of March, brush up on your Shark Spotter flag knowledge.

Green flag 

This signifies that spotting conditions are good. 

This flag will be raised when the spotters can see clearly in the area where the majority of water users are. 

In other words, it's pretty safe to take to the waters, as any underwater movement will be seen pretty soon. If you're still nervous, just keep an eye on the spotter for any change in flags.

Black flag


Photo: Leather foot on the move

This signifies poor spotting conditions. 

This flag will be raised if they are not able to see clearly what is happening in the area where the majority of water users are. Water visibility is affected by glare, cloud cover, water clarity, swell and wind chop. 

In other words, despite the rather grim colouring, it does not mean that a shark has been spotted at all. However, if you are a little jittery, rather stay clear of the water. 

White flag 

Photo: Cape Point Chronicle

This is the one to watch out for and will be accompanied by the sounding of the shark siren.

The white flag with a solid black shark on will be raised only when a shark has been seen in the vicinity of water users and is assessed to pose a potential threat. The shark's distance from water users, swimming speed and direction of travel will be taken into account by the spotter before raising the flag. 

In other words... uhm... STAY CLEAR OF THE WATER!!!

The flag will remain up for as long as the shark is visible to the spotter and will only be taken down once the entire area has been scanned and no further threat is posed to water users. 

The white flag will also be raised after a serious incident, such as an attack, when the beach is closed.

Red flag

Photo: Shark spotters

The red flag serves as a warning that a shark has been seen recently, that there is higher than usual shark activity or that there are known conditions for high shark activity. 

In other words, there is no immediate threat, but rather safe than sorry. 

This flag will be flown for an hour after a shark has been spotted and if no other sighting is recorded during that time it will be taken down. Either the green or the black flag will then be raised. 

If a shark is seen far from water users, which doesn't pose any threat, the red flag will be raised instead of the white one. 

No flag

This means that shark spotters are not present at the beach you're visiting. No need to panic, though, as the lifeguards on duty are sure to have a system of their own including warning flags and alarms. If you're not sure what to look out for, go chat to them to find out. No lifeguards on duty? You'll have to use your own discretion.


Shark safety tips

It's a known fact that shark attacks have been on the increase in the Western Cape, as well as the rest of the world, over the last two decades. While the reasons are not clear, it could have a lot to do with the increasing number of people in the water at one time. 

So, while it may seem silly to some, it probably is just a good idea to be a little bit shark savvy before diving in. Here are a few tips from Shark Spotters:

1. If you are not fully aware of the risks involved in swimming in the ocean, or not prepared to take the necessary responsibility, rather stay on the beach.

2. White sharks, like all predators, are more likely to identify a solitary individual as potential prey, so remaining in a group is always a good idea. 

3. White sharks rely strongly on their sense of sight to distinguish prey from non-prey. So, avoid entering the ocean when it's dark, the water is murky or at twilight when sharks have to rely on their other senses to hunt. 

4. If you do encounter a shark, try to remain as calm as possible. Panicked movements are sure to increase the shark's curiosity and draw them closer. If you have any form of equipment with you (such as a surfboard), use it to create a barrier between you and the shark. 

5. If you are the first to spot a shark, calmly alert others around you, form a group and leave the water swiftly, but calmly. ALERT LIFEGUARDS IMMEDIATELY. 

Come join the News24 Travel community on Facebook and Pinterest or follow us on Twitter, otherwise subscribe to our weekly newsletter for more useful travel updates.

 

Read News24’s Comments Policy

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
2 comments
Add your comment
Comment 0 characters remaining