The weather forecast predicts that we are soon to be lashed with 50 km/h winds, a 7 metre swell, and no small amount of rain. It seldom is as bad as the forecasts claim, however the swell size and direction will hammer False Bay. Despite Sunday’s weather looking peachy, I don’t think the ocean will be, so we will plan for a dry weekend… It is winter after all.
Shark Spotting at Fish Hoek beach
Shark Spotters supporters program
We are proud to announce that we have signed on as official supporters of Shark Spotters. We are Silver partners, and for larger businesses there are higher levels of support on offer. (We are hoping to encourage some of the other dive centres to consider supporting Shark Spotters, too…) Individuals can also sign on to the supporters program, or donate in many different ways.
We’ll write a blog post with more information soon – but in the mean time, we’re very happy to be contributing to the important work of Shark Spotters. If you’d like to as well, visit their website to find out how to lend your support, or drop me an email and I’ll connect you with the right people.
Manta: Secret Life of Devil Rays – Guy Stevens & Thomas Peschak
I found this book to fill a significant gap in my manta ray knowledge, which was (to be honest) virtually nonexistent. Author Guy Stevens is founder of the Manta Trust and a Save Our Seas project leader, and has spent 15 years in the Maldives studying these enormous, charismatic elasmobranchs. The Manta Trust co-ordinates global manta research efforts, with the aim of protecting and conserving mantas and their relatives.
Manta
The photographs in this book are by Thomas Peschak, co-founder of the Manta Trust, with whose extraordinary work you should be familiar. (If not, look here, here and here.)
Everything you might want to know about mantas is here, without being glib about the fact that there is still much we do not understand about these animals. The text covers their biology, life histories, threats to their survival, an identification guide, and numerous accounts by field scientists who study mantas and devil rays. (It was hard not to be envious reading some of the day-in-the-life bits!)
This is a beautiful, substantial book. Get it here.
Nicole: The True Story of a Great White Shark’s Journey into History – Richard Peirce
Nicole’s story is not new, and can be summarised briefly. She was a great white shark, tagged in Gansbaai near Dyer Island in November 2003. In February 2004, Nicole’s tag popped off as scheduled, 11,000 kilometres from where she was tagged, in a location off Western Australia. In August 2004 Nicole was again identified in Gansbaai, having made the return journey.
It was the first, furthest and fastest recorded transoceanic migration by a white shark. Its most important consequence was that it provided scientific grounds to advocate for extended protections for white sharks, outside of South Africa’s territorial waters.
Nicole
The book Nicole chronicles Nicole’s journey, and the work of the researchers who studied her, many of whom have gone on to illustrious careers (but be warned, the names of several of the scientists are subject to creative misspellings). The book beautifully put together, with a lot of photographs. This and the simple, vivid writing style make it an ideal gift for shark-obsessed youngsters. In imaginative interludes the author describes what Nicole might have experienced as she swam to Australia and back.
The scientific paper describing Nicole’s migration can be found here (paywalled) and here (pdf), and there’s some excellent information about Nicole on Michael Scholl’s White Shark Trust website. He was the researcher – now CEO of Save Our Seas – who identified Nicole’s distinctive dorsal fin on her return to Gansbaai. Read a review of Nicole and an interview with the author here.
It feels very much as though winter has arrived (minus the rain), mostly in the early mornings. When daytime temperatures rise into the twenties, it’s not totally unpleasant! Sunday is one of those days, and we will launch from Simons Town jetty at 9.30 and 12.30. Both sites will be a maximum depth of 18 metres as I have a bunch of Open Water students to qualify.
The organisers of the 2015 Southern African Shark and Ray Symposium made an effort to include the public in the celebration of False Bay, the marvelous ecosystem on our doorstep.
#LoveFalseBay speaker evening
The first event to do this was a free speaker evening, held at the Bluebird Garage in Muizenberg on Monday 7 September. Hundreds of people attended; I took the photo above before the room got so full that no one could move!
Eleven speakers presented short talks about False Bay. We heard about the whales, sharks, orcas, and invertebrates and how they are being studied; about transformative social work taking place in the waves; and about what we can do to care for the bay.
Photographic exhibition
Also taking place starting during the week of the symposium and continuing all summer, is a free public photographic exhibition of Joris van Alphen and Mac Stone’s images of False Bay, taken last summer. You can visit the exhibition along the catwalk between Muizenberg and St James. It’s in the same spirit as the Sea-Change exhibition that was up in Sea Point last summer, and I am excited that it will allow non-diving residents of Cape Town to see some of what goes on under the surface!
Welcome evening
Shark & Ray Symposium welcome evening
Storify, which I originally used to curate the tweets about this evening, is dead. However you can access the story as a pdf by clicking this link.
The first, hosted by the staff of the Two Oceans Aquarium, was about safe and ethical handling protocols for sharks and rays. Scientists apply tags, take samples and measure animals in order to learn about them, and some contact is inevitable. It is vital to do all the work as quickly as possible, and with as little stress to the animal as possible. I didn’t attend this workshop, but comments from participants indicated that it was extremely useful and practical, with a hands-on section conducted outdoors.
The second workshop, hosted by the team from the Save Our Seas Shark Education Centre in Kalk Bay, was about science communication, which is dear to my heart. I tweeted quite a lot of detail from this workshop (keep reading…), and it was fantastically useful.
The final workshop was hosted by the Save Our Seas Foundation and its CEO Michael Scholl (also known as “the drone guy”!), and dealt with automated identification of sharks from the shape of their dorsal fins – FinPrinting! I didn’t attend this workshop either, and would be interested to hear more about it.
As for the first and second day of the symposium, I created a storify timeline that compiles tweets and images from the day. Storify is no more, so you can view it here (large pdf).
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.)
You can read a summary of all the day two talks in this quite large pdf – Storify died.
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.
Sharks
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.
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.)
Taking pictures at Batsata Maze
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.
Working at Batsata Maze
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.
The boat at Simon’s Town harbour
Tony’s “don’t take my photo” face
Joris and his bodyguard in the water
The guano-stained cliffs at the south end of Smitswinkel Bay
Stand up paddle boarder in Smitswinkel Bay
Working near Millers Point
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.
I’d suggest you read through my write up of Dr Barnett’s talk last November. There’s a lot of background information on these beautiful animals in that post.
Cowshark with a small external tag
Why tagging studies need to be done
Here is an explanation, in relatively simple terms, of why cowsharks are tagged for scientific research. Tell your friends.
We don’t know much about sevengill cowshark behaviour and habitat use in South Africa’s waters. Actually we know almost nothing.
Because we don’t know for sure where they mate, give birth, and rest, we don’t know how best to protect them.
We can’t protect every bit of coastal water and every species of fish. Because why? Because we live in the real world, where there are extensive commercial interests, finite amounts of funding, and a lack of resources and will to police things.
We can’t go on suspicions and gut feel when deciding which areas and species to protect. This is because there are extremely limited resources (see above), and designating a certain area an MPA or a no-fishing zone needs iron-clad justification. Just try and tell an angler that he can’t fish somewhere, without giving a reason.
Scientific research provides us with facts, on the basis of which wise and informed decisions can be made.
The way to find out, scientifically, where sevengill cowsharks go, and what they do there, is to tag them. There is no other way to find out what they do when they’re not swimming around you at Shark Alley. The ocean is (ahem) quite large.
Once we know where they go, we can find out how to protect them. The most important sevengill habitats to conserve are those related to reproduction. The fact that Shark Alley is in an Marine Protected Area isn’t enough: the sharks don’t give birth there, and there is almost no policing of MPAs in South African anyway. A baby sevengill is about 45 centimetres long. Have you ever seen one less than a metre long at Miller’s Point? I thought not.
If you enjoy diving with the sevengills (from the shore or a boat), if you enjoy photographing them and winning photo competitions with your images, if you make money from taking other divers to see these sharks, or if you’re in favour of making the best effort to get the maximum results with the very limited conservation resources that are available in South Africa, then I hope you can see that this is vital research for the future of the species.
What sort of tags are used?
There are two types of tags suitable for use on sevengills. The primary one is acoustic tags, which send out a ping every two minutes. Receivers placed in False Bay and around South Africa’s coast (many of them part of the Ocean Tracking Network) register and save these pings when a shark is close enough (up to 500 metres away in deep, still water; significantly less in shallow, noisy areas). The data is downloaded from the receiver after retrieving it from its position in the sea.
Acoustic listening device
Acoustic tags are about the size of your little finger and are surgically inserted into the shark’s abdomen. The procedure takes approximately two minutes and the incision heals remarkably fast (as animals that bite each other during mating, it’s in a shark’s best evolutionary interest to be a fast healer). Their battery life is measured in years, so a tagged shark can provide data over multiple reproductive cycles. This is how large scale movement patterns are picked up, much like the white shark research in the US that I wrote about recently. This enables scientists to identify what the sharks use different areas for.
The other type of tag that has been used on three of our local sevengills so far is a pop up archival tag (PAT). Meaghen McCord explained these tags to us when she talked about her research on bull sharks in the Breede River. These tags are applied externally and programmed to release from the shark and float to the surface after a certain number of days. On the surface, they broadcast their location and start transmitting some of the data that they’ve collected. The full suite of data, including diving depths, is only accessible if the tag is physically retrieved.
What results have been obtained so far?
So far seventeen female cowsharks have been tagged with acoustic tags. The tagging was done in March, at Shark Alley. Blood and tissue samples, from which hormone levels can be obtained (to indicate a readiness to mate, or pregnancy, for example), were also taken.
Three PAT tags were deployed. One popped up after 48 days far out to sea on Agulhas Bank, the other came off after 88 days between Gordon’s Bay and Pringle Bay, and the third came off after 136 days close to Silwerstroom Beach on the West Coast, just before Langebaan. The cowshark whose tag popped off on Agulhas bank had spent most of its time at depths between 10 and 60 metres. The West Coast shark had spent the bulk of its time between 10 and 40 metres’ depth. The False Bay shark, interestingly, recorded most of its time at depths of between 40 and 60 metres – pretty much the maximum depth you can get in False Bay. So it didn’t just hang out at Shark Alley while in False Bay!
More detailed results will be made available on the Shark Spotters blog. It’s early days yet!
How you can help
Go and like the Spot the Sevengill Shark – Cape Town page on facebook. Then get your camera out and go for a dive, or dig through your photo library. The researchers are looking for photographs of sevengills taken from above, with the following accompanying information: the date, the shark’s gender (males have two external claspers, females have smooth abdomens), and the location. Software and some human intervention (when the computer falls over) will be used to identify sharks by the markings on their bodies. This will enable the researchers to build a database of shark individuals, and to track their presence at the known aggregation sites visited by recreational scuba divers.
There is a slightly similar citizen science project on sevengills happening in San Diego. It’s very exciting for us to be able to advance the cause of a species that is so charismatic and beloved by the Cape Town diving community.
