Friday photo: Scarborough beach (2)

View to the north on Scarborough beach
View to the north on Scarborough beach

Here’s the view on Scarborough beach looking north, towards Misty Cliffs (the mist is visible in the distance). There’s a little river flowing over the beach into the sea, just visible to the left of the boardwalk.

Bookshelf: The Sea Hunters

The Sea Hunters – Clive Cussler

The Sea Hunters
The Sea Hunters

Clive Cussler is best known for his entertaining yet wildly misogynist novels about Dirk Pitt, the man who men want to be, and whom women cannot resist. Apparently he used some of the money he made from the Dirk Pitt series to set up an organisation (it may be an exaggeration to call it that) called NUMA, the National Underwater and Marine Agency, named for NUMA in his novels. Also, he named his son Dirk.

NUMA has embarked on many searches for lost shipwrecks (and the occasional train and cannon) in expeditions spanning a couple of decades. In The Sea Hunters, Cussler recounts not only the details of the searches undertaken, but also a dramatic version of the sinking or wreck of the ship in question. He takes great liberties with dialogue and speculates, in many cases, as to the sequence of events, but these reconstructions are entertaining and add colour to the shipwreck story.

I was frustrated that in most cases, once the wreck was located, the action was over (the cover of the book is deeply misleading). NUMA does not salvage anything, and usually doesn’t even dive on the wreck or uncover it from beneath the mud. Most of the time no human eyes are laid on their findings. Many of the wrecks Cussler finds are from the American Civil War, and are lying in rivers under nearly two centuries of silt, or completely outside the existing course of the stream. There were one or two instances when I wondered why he was so certain to have found the wreck he sought, as a more or less right-sized reading on the magnetometer was deemed sufficient to confirm its identity.

The book is illustrated with a map for each shipwreck, which assisted with my reading of the tales of the sinking of some of the Civil War ironclads and other boats, because the locations of enemy combatants and land fortifications are also marked.

There is a connection to a National Geographic series of which Cussler is a presenter. Adventures of a Sea Hunter by James Delgado also attempts to ride this wave.

If you’re in South Africa you can buy the book here, otherwise try here or here.

Lecture: Alison Kock on Shark Spotters

The Save Our Seas Shark Centre in Kalk Bay held another marine speaker series this November, and Tony and I attended a couple of the talks. One which we enjoyed was given by Alison Kock, research manager at Shark Spotters. Shark Spotters is a beach safety program that Capetonians are rightly very proud of – there’s more about it on the Shark Spotters website, here and here. Alison’s talk focused on some updates as to the research that is going on in False Bay, and extensions of the spotting program.

Updates on the shark spotting program

Between 2004 and 2012 the shark spotters have made more than 1,400 sightings of white sharks, 60% of which resulted in beach closures. The sharks are either resting, passing by, or searching for prey (other sharks, rays, fish) when they come inshore in summer. For spotting to be effective, at least 40 metres of elevation is required from which to observe the beach. The beaches in False Bay differ, in that sightings at Muizenberg resulted in a beach closure only 30% of the time, while at Fish Hoek the beach was closed 80% of the time. This is because of the nature of the surf and sharks’ behaviour at the different beaches.

At Muizenberg, the backline is some 300 metres off the beach, and the majority of the time sharks are cruising along behind the backline or further off the beach. The beach is only closed when sharks enter the surf zone – 74% of the time they are simply swimming past the beach. When a shark is behind the surf zone, the red flag is raised (for High Shark Alert) but the beach remains open.

At Fish Hoek, 61% of the sharks remain behind the breakers, but this is a mere 50-100 metres from the beach. 68% of the sharks are swimming past, but their proxmity to the beach means that more beach closures take place than at Muizenberg. The lookout location at Fish Hoek is on the mountainside, 110 metres above the beach.

Shark exclusion net at Fish Hoek

Fish Hoek is to be the site of a trial shark exclusion net that will be tested in the next month or two, all going well. It’s important to understand that this is an exclusion net, not a gill net, and the team in charge of the trial have been mandated to design and construct a net that will not lead to bycatch of any marine species. The aim is not to kill sharks and reduce the population, thus reducing the chance of interactions with people (this is what the Durban nets do), but rather to build a “wall” in the sea to keep them out of a specific area of Fish Hoek Bay in order to make it safe for swimming.

The other important thing to remember is that nothing like this has ever been done before.  Owing to the strength of the wind and swells that we experience in Cape Town’s summer, and the presence of large amounts of kelp in False Bay which can foul the net, the net will only be deployed on calm days and will be removed overnight. The net has been designed and is being constructed at the moment, but the process of deploying and removing it (to be handled by the trek fishermen) will be a learning experience initially. If the initial prototype has flaws, the City of Cape Town is determined to iron them out and make it work. It would be courteous and generous of the media and other observers to recognise that this is a world first, and to allow for an initial period of change and possible disruption as the net is tested and refined.

New spotting locations

Earlier this year, Caves at Kogel Bay (on the eastern side of False Bay beyond Gordon’s Bay) was added as a spotting beach. This is a popular surfing location and the water is relatively deep as much of the coastline in that location is rocky cliffs. There have been numerous sightings there since spotting commenced, confirming that this site seems to be on a route that white sharks take in and out of False Bay.

Monwabisi Beach on the northern end of False Bay is the site of up to 10 drownings per year, owing to dangerous rip currents that are, in part, a result of artificial structures constructed for swimming (see the satellite image below). Shark Spotters is adding Monwabisi Beach to the list of regular beaches that have spotters on duty. This is an exciting development and will be particularly important if the proposed oceanfront development along Baden Powell Drive takes place.

[googlemaps https://maps.google.com/?ie=UTF8&ll=-34.074071,18.687294&spn=0.006185,0.009645&t=h&z=17&output=embed&w=425&h=350]

SharkShield research

South African researchers collaborated with scientists in Australia to test the effectiveness of SharkShield, a portable device for use by surfers and divers and intended to repel sharks with a magnetic field. The South Africa researchers towed a seal decoy at Seal Island with the SharkShield attached, while the Australians tested it in natural predation situations. They found that the device does not attract sharks (this I imagine would be the absolute minimum functionality required before one even considered using it!). The device repelled some sharks, but not all of them, and its effectiveness depended on the shark’s state of mind. The range of its effectiveness was found to be about 2 metres diameter from the object. The full research study is available here.

Safety tips

Sign at the end of Fish Hoek beach
Sign at the end of Fish Hoek beach

Alison concluded her talk with some shark safety tips, of which it’s good to remind oneself of once in a while (specially in summer):

  • Be aware of your surroundings. The presence of dolphins, bird activity, or fishing may indicate that white sharks will be in the area. Don’t let the cute dolphins distract you and get your guard down!
  • Check out recent sightings. Visit the Shark Spotters facebook page, and make sure you understand the flag system and read the signs at the beaches you visit.
  • Don’t swim at night, in low light (sunrise and sunset), or in murky water (such as at a river mouth) or poor visibility.
  • Stay in shallow water. Three quarters of shark activity at our beaches is behind the backline.
  • Avoid high risk times and areas when you go swimming.
  • Stay in groups – don’t get separated or swim out far beyond the other water users.

De Kelders drip cave

Entrance to the drip cave
Entrance to the drip cave

On our way home from our short stay in De Kelders, Tony and I walked down the steps to the entrace of the drip cave (“drupkelder”), a cave on the shore which has a large freshwater river running through it that supplies the town of Gansbaai with fresh water. We weren’t able to go inside (it was by appointment and I think the person with the key was at the shopping mall).

The view from the cliff above the cave
The view from the cliff above the cave

The cliffs at De Kelders are riddled with caves, but this one is apparently quite unique because of the freshwater river inside it. It also contains beautiful stalagmites and stalagtites. It was visited by Lady Anne Barnard in 1798, and has recently (date uncertain) been threatened by a property development (which may or may not be the fairly unsightly building that currently stands on the land above the cave). I was interested to see in the article about the property development that there was concern that the whales would be chased away from the coast by the bright lights from such a large building.

Tony going down the steps
Tony going down the steps

The concrete structures around the entrance to the cave are related to its use as the water supply for Gansbaai, while the wooden poles are part of a restaurant facility that the owners of the land planned to erect. Probably better that they didn’t.

Friday poem: Murray Dreaming

A little boy captivated at the aquarium – but by the freshwater exhibit, rather than the impressive predators…

Murray Dreaming – Stephen Edgar

It’s not the sharks
Sliding mere inches from his upturned face
Through warps of water where the tunnel arcs
Transparent overhead,
Their lipless jaws clamped shut, extruding teeth,
Their eyes that stare at nothing, like the dead,
Staring at him; it’s not the eerie grace
Of rays he stood beneath,
Gaping at their entranced slow-motion chase

That is unending;
It’s not the ultra-auditory hum
Of ET cuttlefish superintending
The iridescent craft
Of their lit selves, as messages were sent,
Turning the sight of him they photographed
To code: it is not this that left him dumb
With schoolboy wonderment
Those hours he wandered the aquarium.

It is that room,
That room of Murray River they had walled
In glass and, deep within the shifting gloom
And subtle drifts of sky
That filtered down, it seemed, from the real day
Of trees and bird light many fathoms high,
The giant Murray cod that was installed
In stillness to delay
All that would pass. The boy stood there enthralled.

Out in the day
Again, he saw the famous streets expound
Their theories about speed, the cars obey,
Racing to catch the sun,
The loud fast-forward crowds, and thought it odd
That in the multitudes not everyone
Should understand as he did the profound
Profession of the cod,
That held time, motionless, unknown to sound.

In bed at night,
Are his eyes open or is this a dream?
The room is all dark water, ghosted light,
And midway to the ceiling
The great fish with its working fins and gills
Suspended, while before it glide the reeling
And see-through scenes of day, faintly agleam,
Until their passage stills
And merges with the deep unmoving stream.

City warns beach users of inshore movement of sharks over the summer season

Here’s the seasonal media release issued yesterday by the City of Cape Town and Shark Spotters reminding beach users that, as the southeaster starts to blow, the white sharks move inshore from Seal Island. The sharks do the same thing every year, but it’s excellent practice to remind water users every year in early September that they might have company and to be extra vigilant over the summer months.

The press release is a fascinating read – particularly the recent results that have been obtained relating to the confluence of certain sea conditions and lunar phase with increased shark sightings.

CITY OF CAPE TOWN

4 SEPTEMBER 2012

MEDIA RELEASE

City warns beach users of inshore movement of sharks over the summer season

The City of Cape Town would once again like to remind all beach users that the time of year is approaching when a seasonal increase in the presence of white sharks in the inshore area is expected.

This seasonal change is not recent in its occurrence or unique to False Bay. Similar trends are recorded in Gansbaai, Mossel Bay and California – all areas that white sharks are known to frequent.

Shark sightings recorded by the Shark Spotters have consistently shown a seasonal increase during the period from September to April, peaking in mid-summer. Typically shark sightings start in late August and the City is therefore appealing to all beach users to be aware of the expected increase in shark presence in the inshore area over the summer months.

White sharks are present in the Cape’s waters all year round and the possibility of encountering one of these animals at any time is minimal. However, beach users should always remain vigilant.

The graph below shows the sightings recorded over the last six years of shark spotting, clearly indicating seasonal trends.

Seasonal trends in shark sightings over the last 6 years
Seasonal trends in shark sightings over the last 6 years

The data has also shown that shark sightings increase significantly at beaches where a whale carcass has stranded. These sightings may persist for up to a week after the whale carcass stranding. The City will therefore close relevant beaches where there has been a whale stranding, and appeals to residents to understand this precautionary approach.

Kayakers and surf-skiers specifically are asked to be cautious of the area between Sunnycove and Glencairn Beach, and swimmers are urged not to use the water off Jaegers Walk in Fish Hoek as this is considered a high-risk area. The City has erected warning signs along Jaegers Walk.

Surfers are asked to be especially vigilant in the areas between the Sunrise Beach and Macassar Beach area during the summer months, as research has shown these to be areas of highest shark presence in False Bay in summer.

Update on exclusion net trial programme

The City’s Environmental Resource Management Department is on track to trial the exclusion net at Fish Hoek during the 2012/2013 summer season. It is currently planned that the trial could take place from January 2013 onwards as certain matters are still being finalised. This includes:

  • on-going discussions with the trek net fishing rights holder at Fish Hoek beach, to ensure that the exclusion net does not impact on his fishing activities; and
  • finalisation of the permit required from the Department of Agriculture, Forestry and Fisheries

before any trial can take place.

Shark Spotting programmes are operational at the following areas:

Summer (From start of school holidays, 28 September 2012 until 9 April 2013):

Muizenberg corner 7 days a week from 08:00 to 18:00
St James 7 days a week from 08:00 to 18:00
Fish Hoek 7 days a week from 07:00 to 18:45pm
Noordhoek (The Hoek) 7 days a week from 08:00 to 18:00
Clovelly Weekends, public and school holidays from 10:00 to 17:00
Glencairn Weekends, public and school holidays from 08:00 to 18:00
Kogel Bay – Caves 7 days a week from 08:00 to 18:00

Winter:

Muizenberg corner 7 days a week from 08:00 to 18:00
St James 7 days a week from 08:00 to 18:00
Fish Hoek 7 days a week from 08:00 to 18:00
Noordhoek (The Hoek) 7 days a week from 08:00 to 18:00
Caves 7 days a week from 08:00 to 18:00

 

Shark Spotter research yields new information

In addition to providing a safety service, the Shark Spotters collect valuable information that contributes to a better understanding of white shark coastal occurrence and behaviour. This information can in turn be used for local awareness campaigns to enhance beach safety.

More than 1 300 shark sightings have been recorded since the programme began in 2004. Previous analysis of the sightings has demonstrated a clear seasonal trend in occurrence, with most sightings taking place over spring and summer (September to May) for all beaches. The most sightings were reported in Muizenberg, when compared with Fish Hoek, St James, Clovelly, Glencairn and the Hoek (Noordhoek). In addition, most of the sightings, i.e. 73.8% took place behind the surf zone in deeper water.

A recent study, which used the information collected through the Shark Spotter programme, conducted by University of Cape Town (UCT) Masters graduate, Kay Weltz, in collaboration with Alison Kock (Shark Spotters), Prof. Colin Attwood (UCT) and Dr Henning Winker (UCT) investigated the influence of environmental variables on white shark sightings at Muizenberg, St James and Fish Hoek. The study found a significant relationship between shark sightings and water temperature at all three beaches. The analysis demonstrated increased probabilities of shark sightings as water temperature approached and exceeded 18⁰C.

The influence of the lunar phase was consistent with an increase in sightings just before or at new moon at Muizenberg and Fish Hoek. No significant relationship was found for the lunar phase at St James, which is likely due to a shorter time series of data available for analysis.

The relationship between shark sightings and warmer water temperature is more than likely linked to an increase in prey availability. Similarly, the increase in sightings just before or at new moon is likely to be the result of an increase in prey availability (although the mechanism influencing this remains unclear).

Finally, the study found that the number of shark sightings changed each year, with no trend evident between 2004 and 2008; however, it identified an increasing trend of more sightings over the last three years at all three beaches. This increase is suspected to be either due to more sharks using these inshore areas or sharks spending more time at these sites over this period. Continued monitoring will provide a valuable tool for assessing and hopefully explaining this trend in the long-term. Individual spotters, cloud cover, wind direction and wind speed were also considered, but were not found to significantly influence shark sightings.

None of the variables, such as water temperature and lunar phase or year, influence the ability of spotters to detect sharks and therefore represent actual shark behaviour in the inshore area at these beaches. The finding that individual spotters, cloud cover, wind direction and wind speed had no significant relationship with shark sightings provides evidence that the Shark Spotting programme is an effective warning system.

These findings of the Shark Spotting data are being written up for publication to be submitted to a recognised scientific journal.

Although these findings provide us with more information to increase safety, beach users should bear in mind that these are trends. White sharks have been recorded in the inshore area in all environmental conditions, including in very cold water temperatures and at full moon.

“This research and the other research that has been made possible through the data collected by the shark spotter programme shows that the City is committed to doing everything possible to improve the safety of beach users, while recognising the important role that white sharks play in our natural environment. While this research is still new and underway it gives us important insights and demonstrates the value of the shark spotter programme”, said Alderman Belinda Walker, Mayoral Committee Member for Economic, Environmental and Spatial Planning.

Shark safety tips

Beach users are encouraged to use areas where Shark Spotters are on duty and to take the time to speak to the Shark Spotters on the day they visit the beach to find out about recent sightings and activity as well as the current conditions which determine the effectiveness for shark spotting.

Beach users are also requested to please take the time to familiarise themselves with the Shark Spotter signage and to ensure that they understand the four flag warning system. They should be aware of the use of a siren to close the beach.

It must be borne in mind that no safety measure is 100% effective. Although the Shark Spotting programme has been successful, it remains vulnerable to human error, weather conditions and water quality issues.

The following tips can help reduce the risk of attack:

  • Do not swim, surf or surf-ski when birds, dolphins or seals are feeding nearby.
  • Do not swim, surf or surf-ski near where trek-netting, fishing or spear fishing is taking place.
  • Do not swim in deep water beyond the breakers.
  • Do not swim if you are bleeding.
  • Do not swim near river mouths.
  • Do not swim, surf or surf-ski at night.
  • Do not swim, surf or surf-ski if there has been a whale stranding nearby.
  • If a shark has recently been sighted in an area where no Shark Spotters are present, consider using another beach for the day.
  • First-time visitors to beach areas should ask the local law enforcement official, life guards or locals about the area.
  • Obey beach officials if told to leave the water.
  • For those who are kayaking or surf-skiing far out to the sea, consider paddling in groups and staying close together (in a diamond formation).
  • Consider using a personal shark shield when you go surfing or kayaking.
  • Pay attention to any shark signage on beaches.

For more information on the latest shark sightings and research please visit: www.sharkspotters.org.za. The public are encouraged to report any sightings of white sharks to the Shark Spotting programme via this website.

End
 
Issued by: Integrated Strategic Communication and Branding Department, City of Cape Town
 
Media enquiries: Gregg Oelofse, Head: Environmental Policy and Strategy, Environmental Resource Management Department, City of Cape Town, Tel: 021 487 2239 or Cell: 083 940 8143
 
Alison Kock, Research Director: Shark Spotters programme, Cell: 072 661 9516
 
Alderman Felicity Purchase, Chairperson: Subcouncil 19, City of Cape Town, Tel: 021 784 2001 or Cell: 083 629 0829

Bookshelf: Shoreline

Shoreline
Shoreline

Shoreline: Discovering South Africa’s Coast by Jeannie Hayward, Jaco Loubser, Claudio Velásquez Rojas

Sometimes I do things in the wrong order, and reading this book (I think) is an example of that. It’s the companion volume to locally-produced series Shoreline, of which I have only watched one episode while having a raucous conversation with my sister about whether her former junior school rival had aged well.

Like the television series, Shoreline the book is divided into chapters by location, traversing South Africa’s 2,800 kilometres of shoreline from the Orange river to Kosi Bay. Much of the text is taken directly from the television program, for which the script was written by the brilliant Tom Eaton. Magnificent photographs by Claudio Velásquez Rojas, who worked with Thomas Peschak on Currents of Contrast. The aerial photos in particular are incredible – much of South Africa’s coast is dramatically rocky with gorges, cliffs and free-standing formations such as Hole in the Wall at Coffee Bay, and seeing it from an unusual angle is very special.

The book is not solely focused on the marine and coastal wildlife and plants found along our shores, although many species are singled out. There is evidence of extremely early human settlement and family groups along the South African coastline, where the poly-unsaturated fatty acids available from marine species such as limpets would allow large-brained humanoid inhabitants of the sea caves along the southern Cape coast to thrive. There is thus a strong archaeological focus to the volume, and the marriage between natural history and anthropology, geology, oceanography, zoology, botany and archaeology is beautifully achieved. The communities that currently inhabit the shoreline and utilise its resources also feature, and I enjoyed learning of the fish kraals at Kosi Bay, the fish traps built by 19th century farmers along the Wild Coast, and the Thembe-Tonga people, who harvest red bait and other invertebrates from rock pools at full and new moon. The book also touches on subjects such as the KwaZulu Natal shark nets, Knysna seahorses, the diamond industry on the West Coast, and a number of other special interest subjects that apply to different sections of our coast.

As soon as I finished reading this book I made plans for a midweek break at De Kelders for me and Tony later this year (during whale season) and I have been plotting how we can explore some of the Wild Coast without going missing or getting stuck in the mud. The South African coast is compelling and varied, and it seems that one could travel it for a lifetime without getting bored. This beautiful book showcases the beauty, variety and history of our coast in spectacular fashion.

There are some representative photos here. A short review can be found here. I’d recommend it for locals as well as for tourists who want a coffee table volume to take home as a souvenir – this one has substance, as well as the requisite pretty pictures.

You can purchase a copy of the book here.

Friday poem: The Crocodile

If you’re concerned about the connection of crocodiles to diving, I suggest you check out this link.

Hearty thanks to Bernita for suggesting Lewis Carroll for our Friday poems.

The Crocodile – Lewis Carroll

How doth the little crocodile
Improve his shining tail,
And pour the waters of the Nile
On every golden scale!

How cheerfully he seems to grin!
How neatly spread his claws,
And welcomes little fishes in
With gently smiling jaws!

Friday poem: Move

This poem appears in the front matter of Carl Safina’s book Song for the Blue Ocean. It reflects a yearning -as humans faced with a bewildering array of choices – for the apparently sure destiny of living creatures such as turtles and salmon, both of which have homing instincts that take them back to where they were born. Something to reflect on as we approach the turning of another year.

I tell you this to help you in reading this poem, not to categorise her, but Alicia Ostriker is an American poet whose Judaism and feminist leanings inform her work.

Move – Alicia Ostriker

Whether it’s a turtle who drags herself
Slowly to the sandlot, where she digs
The sandy nest she was born to dig

And lay leathery eggs in, or whether it’s salmon
Rocketing upstream
Toward pools that call, Bring your eggs here

And nowhere else in the world, whether it is turtle-green
Ugliness and awkwardness, or the seething
Grace and gild of silky salmon, we

Are envious, our wishes speak out right here.
Thirsty for a destiny like theirs,
an absolute right choice

To end all choices. Is it memory,
We ask, is it a smell
They remember,

Or just what is it—some kind of blueprint
That makes them move, hot grain by grain,
Cold cascade above icy cascade,

Slipping through
Water’s fingers
A hundred miles

Inland from the easy, shiny sea?
And we also—in the company
Of our tribe

Or perhaps alone, like the turtle
On her wrinkled feet with the tapping nails—
We also are going to travel, we say let’s be

Oblivious to all, save
That we travel, and we say
When we reach the place we’ll know

We are in the right spot, somehow, like a breath
Entering a singer’s chest, that shapes itself
For the song that is to follow