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. You can view it here, or read through it below.
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.)
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.
I’ve been appallingly tardy in writing about this talk, but recent events in False Bay have reminded me that my notes have been sitting waiting for me to attend to them for several (ahem) months. My diary indicates that the series of talks that it was part of was held in November 2012. Dr Barnett has in fact left South Africa and returned during the time it’s taken me to get to this task. Sorry.
Broadnose sevengill cowsharks (Notorynchus cepedianus) are part of the order Hexanchiformes, which comprises six species. This is a primitive order of modern sharks with six or seven paired gill openings (most sharks have five). Four species are cowsharks, and the others are deep water sharks.
Surprisingly little is known about sevengill cowsharks, but Dr Barnett contends that they should be an extremely important apex predator. They are found worldwide, but not (so far) in the north Atlantic. There are far more of them than there are white sharks, and they eat the same sort of things: fish, rays, seals, and other sharks. Their role in coastal ecosystems is very important.
They are found in coastal waters of countries including (but not limited to) Australia, South Africa, Argentina, and California. There are known nursery areas at the latter two locations. Only one pregnant female has been dissected. She was carrying 82 pups (for context, white sharks bear 2-10 young, hammerheads about 50, whale sharks up to 300, and most other shark species 2-40). Their reproductive cycle is thought to be about two years in length. It is not known at what age these sharks reach sexual maturity.
Sevengill cowsharks are on the IUCN Red List as data deficient (not enough is known about their conservation status). The IUCN Red List website page about the sevengill is informative. They are a target species for recreational fisheries (we often see specimens with hooks stuck in their mouths when we dive at Shark Alley), and a low value bycatch species for commercial fisheries in South Africa. There are several semi-commercial fisheries elsewhere that target them. There is some evidence that the fisheries in California and Namibia are not sustainable.
View Larger Map
For some time, Dr Barnett has been studying the sevengill cowshark population found in the south eastern corner of Tasmania, in the system of bays that makes up the Derwent River estuary. The water here is turbid and there is a wedge of salt water that moves up and down the river with the tide. The river is at most 40 metres deep, and Norfolk Bay is about 20 metres deep. The winter water temperature in the area is 8-13 degrees, and in summer the maximum water temperature is 21-22 degrees. Much like False Bay (except for the river)!
The estuary is a shark refuge area and also includes populations of soupfin and smoothhound sharks, which pup there. The aim of the study has been to determing the population structure, abundance, diet, habitat use, and predator-prey relationships of the cowsharks.
Barnett fished for sharks using long lines with 50 hooks per line, deploying four lines per night. He tagged and released 457 sharks in total, took biological samples and measurements, determined their sex, and flushed their stomachs to see what they’d been eating. Sixteen percent of the females had mating scars (bite marks). He found more sharks each year in summer, and fewer in winter. Do they leave? Or do they not get caught in winter? Of the 457 sharks tagged, 68 (15%) were recaptured, in the same bay as where they were first caught.
Cowsharks are about 50 centimetres at birth, and after a year they are 70-80 centimetres long. The Derwent estuary is not a pupping or nursery ground, based on the measurement distribution that Barnett observed. He caught 60-100% female sharks (depending on what time of year he fished), averaging about 60% females. In winter he found no males, with a few showing up by spring.
Barnett also set an array of 74 VR2 acoustic receivers 800 metres apart, during the period December 2007 to June 2009. He set them along the boundary of the protected area and at entrances to bays and inlets. For the movement study he tagged 43 animals (31 female) with acoustic tags that communicate with the receivers. The process to implant the tag is a three minute surgery. He found that no Norfolk Bay shark moved to the upper Derwent estuary, and no estuary shark moved to Norfolk Bay. This suggests strong site fidelity. There is some overlap between the populations in late autumn, and by winter most of the sharks (including all the males) left the area. After winter the animals returned to where they were tagged.
Pop up archival tags attached to five males and five females located the makes 1000 kilometres north in Jervis Bay, south of Sydney, and the females closer – slightly offshore, with one visiting a depth of 300 metres. The sharks are more active and in shallower water at night, spreading out more. During the day they spend a lot of time close to the seabed, moving up and down in the water column at night.
Barnett tagged several of the sevengill sharks’ prey species, and determined that the sevengills were only in the bay when their prey items could be found there. The fact that the sharks are not breeding in the area suggests that their habitat use is indeed diet related.
False Bay study (ongoing)
Excitingly, broadnose sevengill cowsharks are the subject of a current study in False Bay involving Dr Barnett and local scientists, making use of the array of acoustic receivers that was originally set to study white shark residency patterns. There are also compatible receivers in Algoa Bay, Mossel Bay, Gansbaai, Port Alfred, Port St Johns and on Aliwal Shoal. At least nine sharks have already been fitted with acoustic tags at Miller’s Point, and a hook was incidentally removed from one shark’s mouth.
Miller’s Point is a unique aggregation site: the researchers aim to determine why. Female sharks that look very pregnant are often observed by divers there. The researchers will use the data from the acoustic receivers to try to determine the sharks’ habitat use in False Bay, their seasonal movements, the population structure and the effects of fishing. This will assisst in managing the species. They will also study their interaction with white sharks (with whom they compete for food), and the cowsharks’ predator-prey interactions with other species. This is important for ecosystem management.
Sevengill sharks have been seen and caught at Robben Island in Table Bay, in Betty’s Bay, and in Gordon’s Bay (at night). It is possible to dive with the Betty’s Bay sharks, if you know where they are! It isn’t known whether there are any at Seal Island, perhaps closely sharing that habitat with the white sharks.
Dr Barnett’s results from his work in Tasmania are fascinating because they shed light on broadnose sevengill cowsharks as a species as well as their specific behaviour in the Derwent estuary. So little is known about our local population that the temptation to try to generalise some ideas from his Tasmanian research is irresistible. I hope that the tagging study currently taking place will increase our understanding of these local celebrity sharks, and that it will assist in managing the species and the places they live so as to ensure that the population continues to thrive. Yay science!
On the same evening as Alison Kock delivered an update on the Shark Spotters program, we listened to Masters student Kay Welz speak about her analysis of the reams of data that the Shark Spotters have collected. The range of data under consideration stretched over five years, from 2006 to 2011, and was collected at Muizenberg and Fish Hoek beach by spotters who had done 100 or more shifts each. This set of data was selected for its quality, covering the beaches with the most sightings and the highest risk of a human encountering a shark.
The analysis considered a range of variables, and whether any of these increase the probability of a shark being present during a spotting shift (approximately 4-5 hours long). Presence/absence was used instead of counting sightings per shift, because it’s not always possible to identify whether one shark is repeatedly buzzing the beach, or if it’s multiple individual animals. The variables in the study were:
sea surface temperature (SST)
The results are exciting and point to many avenues for future research. Here’s a summary that I jotted down during the talk:
Sea surface temperature
Sea surface temperatures of 16-20 degrees increase the probability of a sighting. The statistical model used spat out a probability of a shark sighting at Muizenberg eight times higher when the water temperature was 18 degrees than when it was 14 degrees.
This warm temperature range corresponds to the preferred temperature range of many of the white shark’s summer prey items, such as steenbras. It follows that when these fish are in the bay, enjoying the warm water, white sharks follow them.
The study found an increased probability of shark sightings during the time from 3rd quarter (waning) to new moon. The chance of a shark sighting at Fish Hoek is four times higher at new moon than at full moon. This is also probably related to prey activity – perhaps there is more fish activity when there is less light to betray their movements.
The finding was that there have been more sightings since 2009 than in the years prior (2006-2008). Unfortunately the study period is not long enough to be dogmatic about this – it’s quite likely a long term fluctuation. Drawing conclusions on this one is dangerous.
A drive around the south peninsula on a windy day will help explain why this variable didn’t turn out to be significant. The beaches along the False Bay coast are oriented quite differently to one another, and surrounded by mountains at different angles which can influence wind speed and direction. Future studies should, it was suggested, incorporate factors such as wind direction, speed and duration, but at a lag so that the effect of “one day of light northwesterly wind” can be distinguished from “five days of strong southeaster”.
Kay pointed out that it is vital to bear in mind that this is not the final word on when you will see sharks near the beaches in False Bay. On a day when the moon is new and the water is 18 degrees no sharks might be sighted, while at full moon with 14 degree water you may see a shark. It’s important to think about this probabalistically; none of this research deals with impossibilities or absolutes, but it enables water users to make smart choices about their activities and the potential proximity of sharks.
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.
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.
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!
Tony and I attended a talk by television presenter and shark scientist Ryan Johnson at the Save Our Seas Shark Centre in Kalk Bay one evening in mid-July, as part of their series of marine-related talks. We were very interested to hear this talk because Johnson worked on the recent Ocearch project in South Africa, which tagged 42 great white sharks in South African waters earlier this year and caused intense controversy for a variety of reasons. The sharks were removed from the water for up to 15 minutes, and biological samples (blood, parasites, muscle biopsies) were taken for 12 reasearch projects as well as fitting a satellite tag to the shark’s fin.
The topic Johnson chose to speak about was “can shark science save sharks?” By his account, the three month long Ocearch expedition, and the criticisms levelled at the project, caused him to question some very fundamental aspects of what he was doing as a scientist. If scientists cannot help sharks, then of what use is their work? Johnson listed some of the criticisms that were levelled at the Ocearch project, and responded to them one by one.
Why must Americans come and do this work? Why can’t South Africans do it themselves? There were 30 South African and 12 international scientists on the project, showing that we do certainly have the scientific capacity to do research on this scale. Funding, however, was never going to be found from local sources.
The scientists weren’t using the best methods. Alternative tagging methods for large marine creatures include the pop-up archival tags (PAT) tags used by the Breede River bull shark project, and acoustic tags, which have been used in False Bay and involve placing transponders on the ocean floor which record a signal when a tagged shark swims past. PAT tags have a life of only three months in Southern African waters because of the rate of algae growth, so no multi-year data would be obtained. They also are only accurate to within 300 kilometres, so no fine scale data would be available either. Acoustic tags require a network of transponders to be placed at locations past which the shark is likely to swim (and at this stage we don’t know what those locations are, for white sharks), and provide no detailed directional information unless the transponders are very close together. Satellite tags (SPOT tags) are by far the best option as they have a life of about five years, and work all over the world.
White sharks are already protected in South Africa, so what’s the point of doing research on them? This is true, but as Johnson later pointed out, they are not protected in any neighbouring countries other than Namibia, and certainly not on the high seas.
It was all done for television sensationalism. I can’t actually remember what Johnson said about this one (I wrote nothing down, so he may have pooh-poohed it briefly and moved on), but I can say that while the visuals of a white shark being wrestled by a fisherman and hoisted onto a platform may be arresting, there was no other way to get the biological samples and apply the satellite tags on an animal this size. Johnson acknowledged that this aspect of the research was not pretty, but that the alternative – no more sharks – is far worse. In response to a question he also acknowledged that deformity of the tagged sharks’ dorsal finswill take place, but that improvements in the positioning of the tags (higher up) and the anti fouling substance used to prevent algae growth will hopefully reduce the deformities from the levels observed during similar research in 2003-2004. The tags will fall off after about five years.Again, it is a trade off between being able to better protect sharks with the knowledge gained from harming a minority of them, or simply not being able to protect any sharks at all. I haven’t seen the show yet, so I’m not sure how much “ocean posturing” went on (it was probably too cold to get the speedos and bikinis out), but there’s no escaping the fact that a lot of science was taking place at the same time. Perhaps we must overlook the human frailty that causes some of us to seek the limelight, and focus on the very exciting research that is taking place now, long after the cameras have stopped rolling.
The idea of a “caring fisherman” is an oxymoron. According to Johnson, the professional fishermen working with Chris Fischer to hook the sharks and bring them on board the Ocearch boat have for years been adherents of the “only keep what you’re going to eat” viewpoint. (I’m not sure you should even take it out the water if you’re not going to eat or tag it, though, but we’ll let that one go.)
There was no public participation or information provided. Shark cage diving operators in Mossel Bay were only informed two hours before the Ocearch crew started work in the area that they were going to be operating nearby, and we are all familiar with the complete PR debacle that took place when the project came to Cape Town. Johnson admitted several times that they “dropped the ball significantly” on this, and said that while public participation is not necessary (I agree – it’s a ridiculous idea to ask a generally uninformed public whether they think science should be done), keeping the public informed absolutely is both courteous and necessary.
The participants took part in the research for financial gain. According to Johnson, none of the scientists got paid a cent, and Chris Fischer himself is not very financially flush either. There is no way for me to know anything about this, and I have no opinion on it.
The government has no ability to enforce whatever recommendations the scientists make based on the research, so why do it? This is a poor argument – the mandate of science is to provide research regardless of whether the will or means to act on it exists. At some future time the government may remove its head from the sand on these issues, and at that time scientists will be ready with data and analysis.
The project had no academic credibility. There were 30 local shark scientists involved (the majority of the community), and during the course of several workshops and discussions the project was discussed with academics in order to determine whether everyone would be involved. The consensus was a fairly resounding yes, by all accounts.
Johnson acknowledged that several of the criticisms of the project, especially regarding the complete absence of communication on what was planned and what the scientists were doing, were valid, but reiterated that the opportunity to do research like this, with funding provided by the History Channel (over $5 million), is simply a once in a lifetime event. It seems that everyone has learned something about bridging the apparent disconnect between scientists and the general public in South Africa. Hopefully these lessons are taken to heart!
As pointed out earlier, the criticism that bothered Johnson the most was that the research was purely academic and couldn’t contribute to the conservation of the animal. This prompted him to ask several questions, which he shared with us.
White sharks have been protected in South Africa since 1991 on the basis of a “precautionary principle”. What can this research add apart from simply satisfying academic curiosity?Will it have tangible benefits to the conservation status of white sharks in South Africa?
White shark capture rates in the KZN “bather protection” nets between 1978 and 2008 suggest that the population is stable. The average size of captured sharks, however, is dropping significantly, indicating that the breeding stock is being depleted. Female white sharks take 15 years to reach sexual maturity (the age at which they will start to breed), and a rapid, sudden population decline is possible if these mature females have mostly been fished out (by whatever means).
Moreover, while white sharks are protected here and in neighbouring Namibia, protection simply on a national scale is not effective. Dorien and Lyla Grace are examples of tagged sharks that have ventured far out of South Africa’s EEZ (territorial waters) and are thus exposed to uncontrolled fishing, longlining and finning by foreign vessels. Perseverance, another of the Ocearch sharks, has ventured to the edge of the continental shelf into waters patrolled by longliners.
Regarding the question of whether white sharks are targeted in South Africa, Johnson observed that the KZN nets take about 30 white sharks per year. (Stop and think about that number. It’s enormous.) Three tagged sharks have already extensively utilised this coast: Edna, Nico, and Luis Antonio, who spent almost three months chilling just off Richard’s Bay in what might be an as yet unidentified aggregation area. Very large white sharks have been caught in the shark nets there (over 4 metres in length), and this has potential consequences for the entire white shark population.
The role of the recreational fishing community was raised in the question of whether white sharks are captured incidentally in South Africa, but I think also ought to be examined in terms of whether it targets white sharks deliberately. Fisherman Leon Bekker of George, who was photographed (by Ryan Johnson, in fact) hauling a white shark out of the water by the gills and posing for photos with it for 15 minutes claimed he had caught the fish by accident and it was washed ashore, but much evidence indicates that a minority of recreational anglers deliberately seek out white sharks, using heavy tackle and special hooks, in order to feel more manly by subjugating another living creature, one presumes. Classy guys.
Johnson did point out (and Meaghen McCord has echoed this point in talks I’ve heard her give) that the majority of recreational anglers are keen to be legal and to operate on the side of the law and of conservation data. I hope this is true and that the local fishermen who use the internet and post in angling forums are a minority. That’s all I’m saying.
Regarding incidental capture of white sharks, in the last 10 years there have been about five white sharks voluntarily surrendered to authorities after accidental capture by fishermen. No one is under any illusion that these are the only sharks that have been captured by accident in the past decade – fishermen are generally afraid to hand over a protected species if it’s caught by accident and most will toss it overboard, or the fins and jaws are valuable enough to tempt many people to hang onto their catch. We have no idea of the impact of long lining, purse seine fishing and trawling, and accidental entanglement. The white shark killed by whelk farming gear (warning – horrible photo) earlier this year is a case in point.
Johnson also questioned whether our Marine Protected Areas (MPAs) are effective. He showed a map of the De Hoop MPA, with a large white shark aggregation area stradding the boundary as these creatures took advantage of the massive fish stocks in the area. Clearly the MPAs are of benefit to fish that don’t range very far (as Colin Attwood pointed out), but white sharks have enormous migratory paths and may spend very little time in protected waters.
Towards the end of his talk, Johnson touched on something that has bothered me about shark conservation in South Africa, but also internationally. There seems to be a disproportionate amount of rivalry, posturing, jockeying for media coverage, and misguided competition between individuals who SUPPOSEDLY have only sharks’ best interests at heart. Johnson observed sadly that this type of infighting “makes shark killers smile”.
In response to questions Johnson shared a bit of insight around the tension that existed between cage diving operators (some of whom bizarrely objected to television coverage of the very “product” they are selling – at high prices – to visitors from around the globe, and have failed to recognise what a boon the real-time tracks of the tagged sharks are to their presentations to guests prior to embarking on a trip), the conditions attached to the permit granted by the Department of Environmental Affairs (DEA), the presence of very professional government observers and vets on board the Ocearch vessel, and the ridiculous controversy over the “five tons of chum“, which was drummed up by an uninformed (or deliberately obstructive) local cage diving operator.
We found this interesting, as it provided much colour and understanding about the events of the torrid couple of weeks when the DEA revoked and then reinstated the Ocearch permit, but at the same time I must observe how saddening and disappointing it is to find such a complete lack of co-operation and open communication between all parties concerned: the DEA, Ocearch, conservationists, scientists, and eco-tourism operators. What is it about sharks that seems to bring out the worst, most self-interested aspects of the personalities involved?
Having depressed myself thinking about this topic again, I’ll close with a quote from an Ocearch press release in which the names of the scientists working on the project were released for the first time (only after a fire storm of controversy erupted when a bodyboarder was bitten by a white shark in False Bay):
Knowledge generated in this way can capacitate resource managers to effectively mitigate threats to this species by developing effective conservation and management measures. Such knowledge may, for example, include identification of areas where white sharks are vulnerable to exploitation, identification of habitats that are critical for mating, birthing, and feeding, and insight as to whether our white shark stock can adequately be conserved locally or whether regional or international cooperation will be necessary.
Let’s obtain that knowledge, analyse it, and act on it. Please, thank you.
The South African coastal waters are under threat from a number of directions. Resource extraction (mining, oil drilling and the like) carries a danger of catastrophic pollution and spills, and the craft used for these activities are often vectors for alien species. Aquaculture, which may seem like a good idea, also threatens to introduce alien species to sensitive areas of the coast, and generates huge amounts of pollution too. Municipal failures such as sewerage spills, plastic pollution, and most of all fishing are the other big threats to the integrity of the ocean habitat. A future threat to our coastline is phosphate mining (the phosphate would be shipped to China and Australia to rehabilitate farmland), and demersal trawl fishing is a constant threat to large areas of the coastline.
The scale of fishing in South Africa’s coastal waters is terrifying: 800,000 tonnes of marine life is harvested annually. About 300 species (including invertebrates such as abalone and rock lobster) are targeted, but about 550 are impacted, many as bycatch. To put that in perspective, there are about 2,200 fish species found around our coastline.
South Africa has a fairly extensive network of MPAs, covering 19% of our coastline. 9% of the coast falls within no-take zones, where nothing is to be removed by fishing or other methods. If one rather measures the extent of our MPAs as a percentage of our exclusive economic zone (EEZ) which extends 200 nautical miles off our coastline, they cover only 0.4% of South Africa’s territorial waters, and only 0.16% of our EEZ is a no-take zone. The west coast of the country is largely neglected, but other than that the MPAs are distributed quite evenly around the coastline.
Marine protected areas protect habitats and ecosystems, as well as commercially important fish populations. They do this by preventing fishing in nursery areas and locations where spawning takes place, as well as by preserving the genetic structure of the population. They allow research into the effects of fishing to take place by providing areas that aren’t fished to compare with areas that are. They also enable non-consumptive activities such as scuba diving, whale, seal and seabird viewing, and coastal tourism to take place.
One interesting aspect of MPAs that Prof Attwood pointed out is that they are used for crowd control. Anyone who has seen the number of vehicles on the beach at Sodwana during high season might think that this is terribly destructive and not what an MPA should look like. What is in fact taking place is that 95% of the people are being funnelled through 5% of the MPA, constraining the damage done by human activities to a very restricted area.
Redundancy in Marine Protected Areas, as in engineering, is a good thing. If a species exists in more than one MPA, it is less vulnerable to habitat destruction and catastrophic events such as oil spills. One of Prof Attwood’s students has done work on whether all our marine species are adequately protected (i.e. appear in at least one, and preferably more than one MPA). The results are sobering – of the 225 shore species surveyed, 26% of them do not live in any of our MPAs and 85 species only exist in one MPA. Of the inshore species surveyed (230), 33% are not in an MPA. 25% of the 145 estuarine species surveyed do not live in any of our MPAs, and of the 446 species found out in up to 500 metres on the deep continental shelf, 78% of them are not in an MPA. Only two MPAs (Pondoland is one) cover any of these species at all!
Prof Attwood then gave us a rapid tour through the important scientific studies that have been conducted in South African MPAS. It was only in the last 20 years that the scientific community shook off its skepticism that Marine Protected Areas – underwater, without fences – would actually work. The results are very heartening, and numerous studies have confirmed MPAs efficacy. Fish are more abundant, and populations of heavily exploited fish recover remarkably rapidly and thoroughly when fishing pressure is removed. I first read about this in Charles Clover’s book End of the Line, where he describes an MPA in New Zealand, at Goat Island, and what a delight and amazement it is to the locals and tourists who get to encounter abundant fish in knee deep water.
Roman inside the Goukamma MPA (8 x 1 nautical miles in dimension, along the coast near Knysna) are on average larger, and change sex later. Roman change from female to male at a certain age, but fishing pressure outside the MPA has forced a physiological change in the fish: their sex-change takes place at age 8 instead of the usual 10 years. The roman inside the MPA are thinner and in poorer condition than those outside the reserve, where fewer fish means less competition for prey. This is at first blush a strange result, but makes complete sense given the higher density of fish inside the MPA – and perhaps these “thinner” roman are fit, compared to the chubby, overfed ones outside the MPA! Prof Attwood pointed out that MPAs are not good for all species – the example here is the crinoids (feather stars) that romans love to eat. Inside the MPA there is a significantly lower density of feather stars than outside, where fewer roman prey on them.
The talk concluded with a map showing analysis of where South Africa’s next MPA should be located. It’s possible to identify critical locations where species that are not widespread live or breed, and these are the areas that should be protected. Tony and I both found this talk extremely inspiring and encouraging, as Prof Attwood does not do the kind of science that gets shelved somewhere and forgotten about. The results of his work are useful in policy making, legislation and decisions about the protection and use of our common marine resource, and he is active and willing to participate in that aspect of marine conservation.
One of the projects currently sponsored by the Save Our Seas Foundation is Baited Remote Underwater Video Stations (BRUVS) in False Bay. The project involves deploying cheap video cameras in underwater housings mounted on specially constructed tripods, with a bait container filled with 800g-1kg of sardines nearby. The camera and bait are positioned so that anything that comes to investigate the bait is captured on camera. If two cameras are used to get a stereo image, the dimensions of the fish and other marine life can be calculated. The camera films for one hour, and then is retrieved back onto the boat and deployed elsewhere.
The idea for these cameras and the initial development work took place at the Australian Institute of Marine Science, where BRUVS have been used for biodiversity surveys on the Great Barrier Reef, and have several advantages over the traditional methods used for surveying marine life. Transects swum by scuba divers are limited by diving safety margins, weather conditions, availability of divers, and the fish identification skills of the divers involved. Moreover, the bubbles released by the exhalations of the divers attracts some species and repels others. Controlled angling surveys – partnerships between specially trained fishermen and scientists – can harm species that are fished out from the deep ocean (their swim bladders expand as they are pulled up through the water column, and this necessitates treatment on the surface if the fish is to survive), are not suitable for large creatures, and can be destructive.
Tony and I attended a talk at the Save Our Seas Shark Centre in Kalk Bay by Lauren de Vos of the University of Cape Town, one of the researchers on the project. She explained that the relative cost-effectiveness of the BRUVS makes them an ideal monitoring tool for South Africa’s marine protected areas. The weight of the rig is such that it is easy to retrieve and deploy, and the cost is well within the budgetary constraints faced by the managers of our MPAs.
The data collected is visual, accessible, and can be subjected to rigorous analysis to obtain relative abundance measures for all the creatures that appear on film. It can also be archived, and sent around the world. It is also very useful for educating the public about marine conservation, and “brings our MPAs to shore” in a very real sense.
The BRUVS are being piloted in False Bay, which is an important region for several reasons. There is great diversity of habitat (several kinds of reef, covering 17% of the bay, sand, etc.), it is on the doorstep of a growing urban community, and has a long history of both consumptive and non-consumptive human activity. We know that our bay has incredible diversity of species, but it is important to monitor whether the MPAs are working, and to keep an eye on areas that are vulnerable and potentially over-exploited.
Lauren showed us some of the footage collected so far, and it was wonderful to see shysharks and catsharks nosing at the bait cannister, an octopus sailing in to take a look, sevengill cowsharks rubbing themselves against the camera housing, and a spearnose skate headbutting the rig. I hope that this tool can be well-used by those managing our marine protected areas!
There is another article about the project here with some photos of the rigs underwater. There are some videos on the project here. I recommend “Foiled by an Octopus”!
Biomimicry is the practice of learning from nature, and then attempting to emulate nature’s solutions in solving problems that humans face. The biomimic can imitate (in increasing order of sophistication) form or shape, a natural process, or an entire ecosystem.
The talk made me feel as though I was attending my first meeting at a cult – the woman who “founded” the modern biomimicry movement, Janine Benyus, was repeatedly and reverently referred to as “our teacher”, and there is clearly a shared vocabulary and phraseology that goes beyond mere scientific convenience. Excessive devotion aside, the talk was mostly concerned with explaining biomimicry by means of examples, some of which are very exciting. My favourite examples are those inspired by water and the creatures that live in it.
When feeding, humpback whales use a technique called bubble curtains to concentrate their food in a small area. To achieve this, they somehow manage to turn their double-decker bus sized bodies in ever decreasing circles. They are able to do this because of the tubercules – knobbly bumps – on the leading edges of their very long pectoral fins. The tubercules influence the water flow over the fin, allowing their fins to function at a steeper angle than a straight-edged fin would. They provided increased lift and decrease the amount of drag experienced by the whale.
Wind turbine blades manufactured with tubercules on their leading edges are able to operate in both higher and lower speed winds than conventional turbines. Industrial fan blades and aircraft wings have also been constructed using this insight.
You wouldn’t say so, but the humble boxfish is a miracle of streamlining. Taking the shape of the boxfish’s body as a template, engineers at Daimler (well, Mercedes Benz) designed an incredibly fuel-efficient concept car that happens also to be quite cute to look at. Furthermore, the hexagonal bony plates that hold the boxfish in a stable shape were also transferred to the car’s design, resulting in a weight reduction without loss of safety and strength.
Shark skin (I)
Speedo’s Fastskin LZR racing swimsuits first came to the attention of the general public at the 2008 Beijing Olympics, where a large number of the swimming records were toppled by athletes wearing these suits. Inspired by sharks’ skin, which is covered in enamel-plated denticles that actively push water away from the surface of the skin, these suits use different kinds of fabric over different parts of the body, just as a shark’s skin varies over its body.
Airbus is working on incorporating shark skin-inspired coatings with their airplane fuselages, to reduce fuel consumption.
Shark skin (II)
Sharks are the only slow-moving ocean creatures that don’t foul (i.e. get barnacles, algae and other small passengers adhering to them). Not only does shark skin have impressive streamlining qualities, but the configuration of the ridges on the denticles is such that bacteria and algae are discouraged from settling and breeding. Imitating the roughness qualities of sharks’ skin led to a coating that is used on high-touch surfaces such as in hospitals, restaurants and restrooms, thus reducing bacteria build-up by as much as 80%. The coating can also be used on boats. All of this reduces the need for toxic chemicals to remove bacteria and other fouling organisms, which is kinder to the environment, too. Sharklet Technologies is one of the companies working on this.
Aquaporins are proteins embedded in cell membranes that regulate water flow. Aquaporins allow only water molecules to pass through, resulting in totally pure water. Instead of requiring high pressure and energy to treat water (desalination, for example), aquaporins use the properties of the water molecules to restrict the types of molecules they permit to pass through. This technology has medical applications, for example in conditions that result in fluid build up in parts of the body, and can reduce the energy required to desalinate water by up to 70%.
Lotus leaves exhibit superhydrophobicity – they’re very afraid of water. Water does not dissipate on their surface, owing to the microtopography (essentially the texture) of the leaves. Airbus, a leader in biomimetic design, has been incorporating material based on lotus leaves on their airline seats, carpets, and on bathroom surfaces. This makes the surfaces easier to clean and more hygienic.
Also working with this principle, Stocorp makes building exterior coatings that repel rain and are easy to clean.
If you’ve ever run and then emptied your own bath – and I assume, unless Queen Elizabeth II is reading this blog, that you have – you’ll be aware that water likes to travel in vortices. These are swirling pathways that are typically logarithmic spirals (i.e. the ratio between successive spirals is constant). Inspired by natural water flow and the golden ratio, the Pax Group “froze” a vortex shape and used it to create an impeller (to the untrained eye – me – it looks just like a PROpeller, except it apparently pulls rather than pushes water). The uses of this design are many, but the one I liked the most was to mix huge tanks of liquid. A self-reinforcing pattern of fluid flow is set up, and because of the golden ratio encapsulated in the impeller blades, all interference is constructive. A tiny handbag-sized impeller can do the same job as a propeller the size of a compact car. The design can also be used to replace fans of all shapes and sizes.
Water bears look like polar bears, except with too many legs. They’re also called tardigrades and moss piglets, and apart from being cute (some think), they have incredible powers of survival, if you will. They can be frozen to near absolute zero (-273.15 degrees celcius), heated to 150 degrees celcius, dessicated so that only 3% of their water content remains and left in that state for over 10 years, be exposed to 1000 times the amount of radiation that a human can withstand, and survive the vacuum of space. You could do all those things to me… and I’d die – but if you do them to a waterbear, and then drop it into a glass of water when you’re done, it’ll simply reanimate and toddle away.
Imitating the ways in which waterbears do all these things enables us to create vaccines that don’t need to be refrigerated constantly (a huge issue in the third world)
Venus flower basket
The venus flower basket is a deep ocean sponge that manufactures its own magnificent glass-like silica structure from silicic acid that it extracts from sea water. It’s 1000 times stronger than glass and endures pressure of up to 300 times atmospheric pressure on the ocean floor. It exists at temperatures below 4 degrees celcius. Even the most basic knowledge of how the glass we use in our windows and other objects is made will convince you that the feats performed by this sponge are something quite special. The sponge is of interest in fibre optic research, because man-made fibre optics are brittle and require high temperatures to be forged.