Article: Outside on shark repellents

A recurring but seemingly never-resolved question that intrigues shark researchers and management entities is that of whether there exists a reliable, non-lethal shark repellent.

Such a shark repellent would solve all manner of management problems: organisations like Shark Spotters exist partly to navigate that tense, thin line between sharks killing people and people killing sharks.

Furthermore, there would be a significant financial payoff associated with a successful patent of such a product. (I do not mean to suggest that this is the primary motivation for doing this kind of research, but untested, untestable products like this cannot possibly be marketed with anything else in mind.)

Life-size model of a white shark
Life-size model of a white shark

There are several ideas that have been either proposed, tested, or marketed. The SharkShield has been tested (not just by us), with mixed results. A shark repellent wetsuit has certainly been well publicised (there’s even a TED Talk), but, like medicines for pregnant women, I can’t see how it can be properly, ethically tested in order to state with some degree of certainty, in a statistical sense, that it works. The test described here has N=2, and there wasn’t a human in the suit.

I digress. Outside Online has an interesting article this month about the efforts by Eric Stroud, a pharmaceutical consultant, who – after much experimentation – settled on several compounds found in decaying shark flesh, which seem to work well as a repellent of about 30 species of mostly coastal sharks. The compound can also be synthesised, although the real thing, from a dead shark, apparently works better. Stroud’s financial backers travelled to Mossel Bay to visit Oceans Research, a multi-disciplinary research organisation with several shark scientists on its staff, to test the chemical on great white sharks. The article provides an overview of the history of shark repellent technology, and brings us up to date with this new chemical alternative. It’s early days…

Read the full article here. And remember, kids, that while the only thing that will keep you completely safe from a shark is not going into the sea at all, there are a bunch of simple, sensible things you can do to reduce your chances of meeting a man in a grey suit. Do them!

Bookshelf: The Soul of an Octopus

The Soul of an Octopus: A Surprising Exploration Into the Wonder of Consciousness – Sy Montgomery

The Soul of an Octopus
The Soul of an Octopus

Naturalist and author Sy Montgomery delves deep into the life and times of octopus. The intelligence of these animals is relatively well known, but in The Soul of an Octopus Montgomery chronicles what might be called the “personalities” of several animals that she interacts with at Boston’s New England Aquarium, other aquaria, and reefs in the wild. The idea of an animal as apparently simple as an octopus having a personality may seem to be dangerously renegade. But, as we’ve seen, it may be an idea whose time has come. If you’re interested in this, Carl Safina’s Beyond Words is a good place to go after this book.

In addition to being a love letter to the octopus she meets, Montgomery’s book is a chronicle of the importance of aquariums and the people who work at aquariums: volunteers, in particular. This aspect of the book specially moved me, as I could identify with the ways in which the author and her friends at the aquarium were enriched and changed by their time as volunteers.

The Soul of an Octopus is thus more a speculative meditation and a memoir than a scientific treatise on cephalopods. I loved this book and recommend it to readers whose expectations regarding its content are calibrated appropriately. For a sample of Sy Montgomery’s writing about octopus, this article from Orion magazine is excellent. You could also read The Guardian‘s review.

You can get a copy of the book here (South Africa), here or here.

Just want to look at octopus? You could look at this one pretending to be a piece of kelp, this tiny baby one, this one in the warm, clear waters of southern Mozambique, and this one at night.

Newsletter: Rinse and repeat

Hi divers

Weekend dive plans

Saturday & Sunday: Check conditions the day before, and make a call

Filling station for boats on Sandhamn
Filling station for boats on Sandhamn

As weekends go at this time of year, this one is a weirdo. There is meant to be a 6 metre swell tomorrow, so diving might not be good… But the predicted swell is very westerly so diving may be good. There might be little wind on Saturday with a lot of swell, and more wind on Sunday with less swell… Weather sites disagree violently.

The plan is to check conditions tomorrow afternoon and decide for Saturday, and rinse and repeat on Sunday. If you’re keen to dive, let me know and I’ll keep you posted!

Odds & ends

About this week’s photo: we continue with last week’s theme of marine filling stations. We saw this one on the island of Sandhamn in the Stockholm Archipelago.

On Wednesday 16 August (next week), a book about Nicole, the great white shark that was tagged off South Africa’s coast and swam all the way to Australia and back, will be launched at Kalk Bay Books. Sounds interesting. Event details here.

regards

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

Diving is addictive!

Newsletter: Life aboard

Hi divers

Weekend dive plans

Staying dry

The swell peaks at 8 metres with 18 second period tonight. It starts to drop off during the following few days, however I doubt the conditions will have settled enough on Saturday for training dives. Sunday has some south easter so we will have a dry weekend.

SA Agulhas II berthed in Cape Town
SA Agulhas II berthed in Cape Town

SA Agulhas II open day

Visit the East Pier Quay at the V&A Waterfront on Saturday (24 June) to get a rare opportunity to go aboard South Africa’s state of the art polar research vessel, SA Agulhas II. A little bit more info from the Department of Environmental Affairs is available here (pdf). We visited the ship a few years ago – read more about that visit here.

regards

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

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Newsletter: Transformation

Hi divers

Weekend dive plans

Saturday: Boat dives at 9.00 and 11.30 from Simons Town jetty (maximum depth 18 metres)

This week we launched on Monday, Tuesday and again today. Monday and Tuesday were pleasant as there was no swell or wind to worry about, however the visibility was pretty lousy. Mostly pea soup around Roman Rock and a little further south and 4-5 metres in Smitswinkel Bay.

One day of westerly wind, not even that strong, and False Bay transformed. On the wreck of the Princess Elizabeth this morning the visibility was 20 metres plus. It is quite astonishing how quickly things change.

I think the viz will remain for the weekend and Saturday is probably going to be the best day. There’s less wind on Sunday but a lot more swell and therefore surge to deal with. I have students to qualify so both dives will be to a maximum depth of 18 metres. Most likely to Alpha Reef and the northern part of Roman Rock.

Gathering around the shot line in Smitswinkel Bay
Gathering around the shot line in Smitswinkel Bay

Shark Spotters fundraiser

Get the details of the next Shark Spotters fundraiser, happening on Wednesday 31 May, here. Book directly with the Two Oceans Aquarium. Greg Bertish, author of The Little Optimist, will talk about his adventures, and about the early days of the Shark Spotters program. We have donated an auction item/lucky draw prize!

regards

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

Diving is addictive!

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Newsletter: Business as usual

Hi divers

Weekend dive plans

Saturday: Launching from Simons Town jetty at 9.00 and 11.30 am

Sunday: Launching from Simons Town jetty at 9.00 and 11.30 am (suitable for Open Water divers)

It is the time of year where we have more decent days for diving in a week than we experience during the windy summer months. This weekend looks pretty good for both days in False Bay. Not much wind or swell, and while it is doubtful this visibility will be in the double digits, it should be decent.

I will launch from Simons Town jetty at 9.00 and 11.30 am on Saturday and Sunday. Saturday will be for qualified divers, and you get to choose where we go. Sunday will be mostly students’ qualifying dives so max 18 metres, suitable for Open Water divers.

Musselcracker at the Two Oceans Aquarium
Musselcracker at the Two Oceans Aquarium

Shark Spotters fundraiser

Check out the details of an upcoming Shark Spotters fundraiser here. It promises to be an inspirational and enjoyable evening.

regards

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

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Newsletter: Never easy

Hi divers

Weekend dive plans

Boat dives on Saturday or Sunday, swell permitting

The weekend outlook is not that easy to call. A 4 metre, long period swell is due tomorrow. How much of it arrives and precisely when is difficult to say, as the forecasts on the more frequently used weather sites are quite different.

Hout Bay was surprisingly flat today when I went to take a look (the boat had its annual SAMSA survey today) and False Bay had far more swell than expected. For both days this weekend the wind is favourable, so it all really hangs on the swell.

I would like to launch either Saturday or Sunday but will make that decision midday tomorrow. If you’d like the option of diving, reply to this mail, sms or Whatsapp me.

Sandy the turtle checks out her reflection
Sandy the turtle checks out her reflection

Last weekend we dived in the I&J Ocean Exhibit at the Two Oceans Aquarium. It’s an experience that comes highly recommended. The picture above is of Sandy, a rescued green turtle whose shell was badly damaged by a boat propellor, looking at her reflection in my camera lens.

regards

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

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Newsletter: Turtle time

Hi divers

Weekend dive plans

Sunday: Boat dives from Simon’s Town jetty at 10.00 and 12.00, likely to Roman Rock (suitable for Open Water divers)

The weekend looks good for diving. We’ll be boat diving on Sunday. If you want to join us, you know what to do!

Green turtle on the move
Green turtle on the move

Turtles

It’s that time of year when turtle hatchlings get caught up in currents that bring them to Western Cape shores, where it’s too cold for them to survive. If you find one on the beach, please keep it dry and warm, and get it to the Two Oceans Aquarium as soon as possible. Read more about what to do on the aquarium blog here, and here.

regards

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

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Newsletter: To the point

Hi divers

Weekend dive plans

Sunday: Boat dives from Hout Bay harbour

I am short of time today so I will be brief and to the point. Sunday looks like the best option for diving, and Hout Bay looks like the best location. Text or email me if you are keen to dive.

View towards Misty Cliffs from Scarborough Beach
View towards Misty Cliffs from Scarborough Beach

Good news

Reports are that the sevengill cowsharks at Millers Point have cautiously reappeared – I think they’ve possibly been absent since March! We look forward to verifying the reports when False Bay’s visibility is a bit cleaner.

regards

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

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Newsletter: Still waiting

Hi divers

Weekend dive plans

Sunday: Possible launches out of OPBC in Granger Bay

We are still waiting for the non stop south easter to stop blowing, or to at least ease up. False Bay is grumpy to say the least, but the Atlantic is clean and cold, around 9 degrees celsius.

Dwarf sperm whale at the V&A Waterfront
Dwarf sperm whale at the V&A Waterfront

Sadly the wind does not really ease off until late on Monday so I am unable to commit to launching this weekend just yet. On Saturday afternoon we will make a final call as to whether we can dive on Sunday but it would most likely be Table Bay, most likely North and South Paw. If we can go to Hout Bay then we may visit the Aster and the Katsu Maru as there may be some respite from the wind inside the bay.

Text or email me if you want to be on the list.

regards

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

Diving is addictive!

To subscribe to receive this newsletter by email, use the form on this page!