Collaboration between scientists leads to amazing things, like the massive acoustic tracking system that covers the entire south and east coasts of South Africa.
You can tell a lot about what an animal is doing, without necessarily being right next to the animal all the time, with some clever technology and mathematics (yay maths!)
There are tiger sharks that are partially resident off Ponta do Ouro, Mozambique. They are being tracked and studied. Something to bear in mind next time you visit!
Sharks that cross borders (e.g. tiger sharks, great white sharks) are hard to conserve and face huge risks when they move out of protected areas.
False Bay’s great white sharks are incredibly well understood (great work has been done in the last 5-10 years), and at the same time the more we know, the more questions there are!
We are beginning to get a better understanding of sevengill cowsharks in False Bay and research is ongoing. Plus, did you know there’s a huge sevengill population around Robben Island?
Many of the shark and ray populations around South Africa’s talks are not comprised of separate groups of animals (e.g False Bay’s white sharks, Gansbaai’s white sharks and so on), but interbreed all along their range. This means you can’t protect one aggregation site and expect the species to survive and thrive – you have to think about threats along the entire range of the animal. This was a common theme in the genetics talks (which is a difficult subject to explain to peasants like me).
Juvenile hammerhead sharks aggregate in Mossel Bay at certain times of year! (This wasn’t the point of what was an excellent talk, but I was excited to hear it.)
We had exceptional conditions last Saturday and again on Tuesday, and I’m not just saying that because we had cake on the boat on both days… It was clean, cold and spectacular. It is the time of the year for that. This weekend, somewhere out there someone is going to have spectacular conditions… They are just not going to be near us. Sadly the forecasts have big swell from different directions, varied wind speeds and a different opinion on cloud cover. For us it mean we will not plan anything specific. We will however be ready to rock and roll on Sunday, at very short notice… If things change.
On a more serious note: check out the summaries of the talks presented at the shark symposium this week. It’s not often one gets such a good look “under the hood” at what work is being done, much of it right on our doorstep in False Bay, to understand sharks and how to protect them. There are many people, in science, government and industry, who are working hard on all sorts of shark-related things – like ways to keep humans safe from sharks without harming the sharks, ways to manage shark populations sustainably, and on understanding how sharks interact with the rest of the ecosystem. Clare has also written a short summary of the first day of the symposium if you want a broad overview.
Be sure to head down to the walkway between Muizenberg and St James to see a great outdoor underwater photography exhibition sponsored by Save Our Seas which is a tie-in to this week’s symposium. It’ll be there through the summer.
Earlier this week I had the great privilege of attending the 3rd Southern African Shark and Ray Symposium, which was held from 7-9 September at the Blue Horizon Estate above Simon’s Town. I am not a shark scientist (these days I am probably best described as a lapsed mathematician) but have an interest in the subject so I went to listen. If I had to provide some bite-sized takeaways from the first day of the symposium, jotted down without applying any of the science communication principles I learned at the workshop yesterday, it would be these:
Shark mitigation – avoiding negative interactions between humans and sharks – is HARD and a lot of smart people are working on the problem.
The City of Cape Town is a world leader in shark mitigation efforts, along with Shark Spotters. They really think about the problem, and care about both people and sharks.
If you are not blessed with high coastal terrain and surface-swimming sharks (which would permit a shark spotting program like Cape Town’s one), other shark mitigation measures are in the pipeline… From orca-patterned surfboards (and wetsuits?) to shark exclusion nets to large-scale electrical repellent cables.
The KZN Sharks Board catches a lot of sharks, rays and other animals in their gill nets and drum lines, and this is upsetting and far from ideal. But they facilitate an incredible amount of scientific study, too – their catches do not go to waste.
The KZN Sharks Board is committed to finding measures other than gill nets and drum lines to keep bathers safe, and they are actively working on the problem (refer to the electrical shark repellent cable I mentioned above).
Sometimes scientific research doesn’t look the way you expect or imagine. Ruth Leeney of Protect Africa’s Sawfishes spent months on the ground interviewing Mozambican villagers in the far north of the country to assess the population status of sawfish in Mozambique. She collected data that no one else could have obtained by other means!
Smaller, less charismatic sharks, like catsharks, need more love. There are also whole families of sharks that divers don’t see (such as dogfish) and hence aren’t really aware of. They are caught prolifically as by-catch and not much is known about them. But some smart people are working on this!
There are motivated, talented scientists working hard in South African government departments to protect our marine resources and making recommendations to manage them sustainably. (There’s also many a slip ‘twixt cup and lip, but they are trying very hard.)
Technology – be it cameras, software, or tags – is enabling great leaps in our understanding of what’s out there, which will enable us to protect and conserve things better.
Ocean acidification as a result of climate change could affect sharks directly, by actually wearing away their denticles (tooth-like structures on their skin). Denticles protect sharks and help them to swim faster.
Diving has been a little on the lean side the past few weeks but that is all set to change tomorrow. The wind dies, the swell is hammering another beach somewhere else, and the forecast is for day time temperatures above 20 degrees. Okay maybe 20.1 degrees, but still, it’s up there. Saturday is going to be best for diving as Sunday looks wild and windy again, so we will launch from Simon’s Town jetty at 10.00am and 12.00pm. I do know there were reports of 15 metre visibility and 4 metre visibility on the same day in the same bay, so I reckon we will go out and look for some clean water and then decide where we dive.
There is not much to say about this BBC Earth production, other than that it is excellent, contains shark and ray footage unlike anything you’ve ever seen before, and you must watch it. The DVD is now available in South Africa (and of course in the rest of the known world), so you have no excuse.
It was filmed over two years, and from the thousands of hours of footage, three episodes were distilled. The focus is on elasmobranchs, which is slightly broader than the title suggests (but Shark is more catchy). There is a fourth episode devoted entirely to how the series was filmed, including interviews with the camera operators, which was fascinating. I enjoyed seeing the gear they used – as a scuba diver – as much as I did getting an insight into how they framed their shots and told the stories of the different species. A repeated realisation I had watching this episode was how close one has to get to the animals to obtain the kind of footage required for a broadcast-quality production!
I admit that I was frustrated by the brevity of the series – just when I got into it, it seemed to end – but I understand the desire to show only the very best material, to hold viewers’ attention, and to stay focused on the message (which is essentially that sharks are misunderstood and more important, complex and interesting than you may have thought). The series has a strong scientific bent, explaining how scientists’ work assists with conservation and management measures, and how it illuminates the lives of sharks beyond them simply being a potential threat to beach goers. Individual scientists are interviewed in the field, and are shown taking samples, tagging and observing the animals they study. Not all of those scientists were men, ensuring that the program will inspire a new generation of shark scientists of both genders. Thank you, BBC.
The BBC’s Shark was apparently a welcome addition to Discovery’s Shark Week 2015 – a complete departure from the made-up, mendacious fluff that has been served up on that channel in previous years. Long may it last!
Jean-Marie Ghislain is a Belgian photographer who has had the privilege to visit far flung places on earth, and to dive with charismatic megafauna of all descriptions. This book is a beautiful collection of images of all kinds of sharks, taken from South Africa to Guadaloupe. The images were taken using natural light only. The level of detail in some of the photographs is almost comparable to the pictures in Beautiful Whale.
There are several images of our local broadnose sevengill cowsharks, and I have enjoyed being able to show them to friends who aren’t familiar with these sharks (my own photos are pretty poor)!
The photos are entirely black and white, which lends a solemnity and luminosity to the sharks’ bodies that is very beautiful. There is almost no text, and one doesn’t miss it. At the back of the book, a mosaic of the photos presents information on the type of shark, the camera settings and a few sentences on the taking of or the motivation for the picture.
The photographs reveal that author is of the school of thought that advocates touching sharks, and some of the photographs even depict illegal dives outside the cage with great white sharks at Isla Guadalupe. This is a great pity and should not be mistaken for an activity that has any conservation benefits for sharks whatsoever.
You have probably all read this article, and if you haven’t you should. South African-born social anthropologist Ceridwen Dovey does an excellent job of introducing and interrogating the various shark bite mitigation measures available in the New Yorker, no less. The subject has been in and out of the news with increasing frequency for at least two years, owing largely to sensational reports of sharks repeatedly biting people in Australia and Reunion. The Western Australian response to a spate of shark bites at beaches in the state has been to fish out sharks using nets and drumlines – the same approach taken by the KZN Sharks Board here in South Africa.
Dovey speaks to Christopher Neff, who thinks deeply about the language we use to speak about shark bites, and their political and social ramifications. Cape Town’s amazing Shark Spotters program gets a mention, as does the SharkShield. There are many non-lethal measures currently in testing – not all of them as location and species dependent as Shark Spotters (which works because Cape Town’s great white sharks are a surface-swimming species and are visible from high ground close to the coast). It is a hopeful time for relations between sharks and humans, as long as the scientific impetus is not allowed to flag.
The first winter swell arrived last weekend and hung around all week. It is dropping off and should be gone by the weekend. We had a good trip out to Dungeons last Saturday and no matter how often I go I am always awed by the impressive skills on display from the surfers and the jet ski drivers.
This weekend we are fully booked as we have a group of police divers from the Northern Cape who have booked several days’ diving from the boat, and on Sunday the boat has been chartered for a swim from Milnerton lighthouse to Big Bay.
If you’re free on Sunday, the annual Paddle Out for Sharks is taking place. The aim is to raise awareness about shark conservation issues. The Cape Town event is taking place at Long Beach, Simon’s Town.
One of the joys of having a manoeuvreable, user-friendly little boat is the opportunities that arise to participate in a variety of interesting events. Lately, we have been doing a number of open water swims; not swimming, but providing boat support to a swimmer who is traversing a stretch of open ocean. Last year we did the Swim for Hope around Cape Point, and the Freedom Swim from Robben Island to Big Bay, and several more of the same in 2015.
We used SharkShields at the Swim for Hope events, and with the increasing number of swims that Tony has been supporting we thought it might be time to invest in a SharkShield for use in these events. The SharkShield is a portable device designed to be worn by a surfer, free diver or scuba diver. It has a long antenna which emits an electric current which is intended to repel sharks. When used for open water swimming, the SharkShield is typically attached to the side of the boat with the antenna in the water alongside, creating a radius of 3-5 metres within which the current can be felt by a shark. If you touch the end of the antenna there is a noticeable pinching sensation, so swimmers have to be careful when approaching the boat.
Proper scientific testing of the device in Australia and South Africa indicates that it is by no means foolproof, and does not work in all situations, but it seems to have a certain usefulness if your visiting white shark is in the right frame of mind. The paper reporting the results of the SharkShield tests says:
Our study assessed the behavioural effects of the electric field produced by the Shark Shield Freedom7™. The study was performed in two locations and tested two distinct approach and behavioural situations to assess whether the response to the Shark Shield™ was consistent across behaviours. The electric field did not affect the proportion of static baits consumed, but significantly decreased the number of breaches, and surface interactions on a towed seal decoy.
The authors suggest that since breaching requires significant energy outlay, sharks may be more cautious to mount a breaching attack in the presence of anything out of the ordinary (I’m paraphrasing). Even with knowledge of the device’s usefulness only in certain situations, it still provides great peace of mind to swimmers while they swim in parts of the ocean where sharks are known to be mobile, such as False Bay.
Tony was able to examine and test several lightly- to well-used Freedom7 SharkShields to see which of them worked, and what the battery life was like. In the process he shocked himself several times, which provided great entertainment to me and caused some consternation to the cats, who were themselves strolling around alarmingly close to the antennae. The unit itself is filled with something that looks like glycerin, to keep it pressurised and protect the electronics. The red switch at right turns the device on and off, and red and green lights indicate whether it’s on, charged, and functioning. A wet hand applied to the end of the antenna also gives information on whether the device is functioning…
We felt quite sorry for them – November and December are historically months of appalling visibility and surface conditions in False Bay thanks to the south easterly winds that prevail, and November always seems to play host to at least one massive storm to top things off! Despite having to work with the worst of what False Bay has to offer, the two of them have produced some incredible images, and I’ve admired their persistence and creativity in dealing with murky visibility and adverse surface conditions. (You can follow them on facebook to get regular updates – Mac and Joris.)
Joris was on the boat just before Christmas, getting some of the final set of photographs that he needs for his reef fish story. On this particular trip he wanted to photograph fish on the hook: False Bay is the site of both commercial and recreational fisheries, land and sea-based. Our aim was to track down a Kalk Bay fishing boat that he’d worked with twice already, but they were nowhere to be found (despite being large and yellow, and despite us searching all the way down to Cape Point)! Hailing them on the radio was futile as they likely did not want to broadcast their position.
As a consolation prize, Joris and his personal shark spotter Brandon were able to spend time in the water with three recreational fishing boats. The first two were at Batsata Maze/Smits Reef at the southern end of Smitswinkel Bay. The crew of both boats were using handlines to catch roman and hottentot. The sea was quite choppy and working in close quarters to a pitching boat strewn with fishing lines was challenging. The fishermen were very kind and co-operative! Brandon’s presence was necessary because Joris was on the surface, absorbed in his work, next to boats that were hauling twitching fish onboard, and throwing back fish guts and bits of bait (basically chumming). All these things are very interesting to men in grey suits.
The third boat we found fishing with rod and reel on Caravan Reef, the large, shallow reef that lies close by to the south and east of the wreck of the SAS Pietermaritzburg. We were now a bit further north in the bay, and the large swell that we’d experienced at Cape Point and Smitswinkel Bay had been modified and reduced on its path towards Muizenberg. It was calmer in the water, though the visibility was still only 2-3 metres. Joris was looking for split shots, with fish half in and half out of the water, and it seemed to be getting easier.
I had a great day tagging along on the boat, but my interest in the scale and nature of the fisheries in False Bay was piqued, and if I manage to find out anything of interest I’ll share it here. Did you know that both commercial and recreational fishermen visit the reefs that we dive on, and remove the fish that we like to look at? Those in the no-take zones are obviously exempt (apart from the occasional chancer or ignoramus), but we found commercial fishing boats inside Buffels Bay in the Cape Point nature reserve, close to shore. There was a fisheries patrol boat close by, but they were not prevented from fishing there. I found this puzzling and troubling, because when we visited the Cape Point reserve as recreational divers, we had to jump through a variety of bureaucratic hoops just to be allowed to drive a boat through the reserve with dive gear on board! Never mind taking fish out of the water! More to follow on this subject – and perhaps Joris’s story will also help us to understand this issue better.