Newsletter: Out of season crayfishing

Hi divers

Weekend plans

Best day for diving looks like Sunday, and it’ll be an Atlantic day. Text me if you want to be informed of any plans to launch.

Shane, Christo, Odette, Gary, Matthys and Otti in Hout Bay
Shane, Christo, Odette, Gary, Matthys and Otti in Hout Bay

Recent diving

The south easter has certainly made itself felt and we have had close to 60 km/h wind in False Bay more than a few days over the last week. This is meant to clear the Atlantic but didn’t really do so last weekend, and we had mediocre viz at best and very surgy conditions launching out of Hout Bay.

I am out in Hout Bay tomorrow on a seal trip so I will have a better idea of the conditions tomorrow evening. Sunday will be the day for diving so text me to book and I’ll keep you in the loop regarding plans.

A seal does some crayfishing in Hout Bay
A seal does some crayfishing in Hout Bay

We attended a talk at the Save Our Seas Shark Centre in Kalk Bay this evening on sevengill cowsharks, and there are big plans from local and international scientists to try and gather data on this species as they are listed as data deficient on the ICUN Red List. There are ways for local scuba divers to assist, especially with a photo ID project, and we will share more about that next week.

regards

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

Diving is addictive!

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Article: GQ on bull sharks at Réunion Island

Nowhere has the fraught and complex relationship between surfers and sharks played out with as much drama as at Réunion Island, a department of France situated in the Indian Ocean off Madagascar. A surfers’ paradise, the island has seen a succession of gruesome attacks by bull sharks on surfers. A decision was made in August 2012 to cull sharks around the island, which was almost immediately reversed as it contravened French law (the sharks are in a Marine Protected Area, where hunting is forbidden).

An article at GQ.com describes the attacks and the community response, and attempts to understand the reason behind the sudden increase in human-shark interactions. It is interesting, as someone outside surfing culture, to get an insight into the impact of these events on the local surfing community. One can sense the frustration and bewilderment of the surfers, particularly because the explanations for increased shark sightings and bites on humans are hard to grasp.

Frédéric Buyle, a Belgian free diver and shark conservationist, even went so far as to theorise that

… bull sharks’ social units are complex enough that the loss of a single individual could send a group into a tailspin of erratic behavior. It’s also possible, Buyle posits, that if an influential individual were to be injured, the others might help it hunt for easy prey—and nothing could be easier prey than an oblivious land mammal on the surface. It’s a leap of imagination to see the tragedy of the attacks in reverse perspective: a beloved bull (do they love one another?), suddenly wrenched from the water, vanishing into the sky; the grieving survivors (do they grieve for one another?) rallying together, making a necessary change.

It’s important to remember that Buyle isn’t a scientist; he has, however, been passionately involved in the events at Réunion, and writes more about them here (in French – use Google translate).

Christopher Neff writes at Save Our Seas and for The Conversation on the emotive issue of shark hunts and culls. While they satisfy our desire for vengeance on the animal or animals that may have bitten water users, there is no scientific evidence that they work. This excellent article on tiger sharks off Hawaii highlights the same point.

Read the full article here.

Lecture: Adam Barnett on broadnose sevengill cowsharks

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 cowshark at Shark Alley
Broadnose sevengill cowshark at Shark Alley

Dr Adam Barnett, a visiting researcher from Deakin University (Australia) and the University of Tasmania, spoke at the Save Our Seas Shark Centre in Kalk Bay, on the same evening that we listened to Alison Kock and Kay Welz speak about white sharks in False Bay. He has been conducting research on broadnose sevengill cowsharks (viewable in frequently clean, shallow water at our local dive site Shark Alley), in Tasmania.

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.

Video still of the hooked cowshark
Video still of the hooked cowshark

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.

Tasmania study


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!

New research on white shark residency patterns in False Bay

I’ve been a bit slow off the mark on this one – the paper was published in late January of this year – but here you go: some exciting new research on the white sharks of False Bay has been completed. The study was a long term one (sharks were tracked over a nearly three year period using acoustic tags and receivers situated throughout False Bay) and reveals that female white sharks in False Bay tend to stick around – at Seal Island in winter, and inshore around the beaches in summer – meaning that the area is a critical one for conservation of these animals.

Here is a synopsis of the paper, courtesy of one of its authors, Shark Spotters research manager Alison Kock. Emphasis mine:

Female great white sharks show high residency to inshore coastal area

Seal colonies are well established white shark aggregation areas, but a new study shows that inshore coastal areas (not associated with seals) can be equally as important for white sharks and that use of aggregation areas can differ between the sexes, which has important management implications.

The researchers described their findings in a paper published online January 28 in PLOS ONE (http://dx.plos.org/10.1371/journal.pone.0055048). The study was conducted in False Bay, South Africa where the scientists tracked 56 tagged white sharks of both sexes ranging in size from 1.7 to 5 meters over a period of 32 months.

“We found that white sharks showed high levels of residency to the seal colony over autumn and winter as expected, but we were very surprised to learn that female sharks showed equally high residency at inshore areas during spring and summer and that males were notably absent,” said Alison Kock, who led the study as part of her PhD research at the University of Cape Town (UCT). Kock explains that “the shift from the island in autumn and winter to the inshore region in spring and summer by female sharks mirrors the seasonal peaks in prey abundance including juvenile seals at the island in winter and a range of migratory fish along the inshore during the warmer months”.

White sharks are threatened apex predators and despite South Africa enacting protective legislation in 1991, there is limited knowledge available on how best to make such protection effective. Currently no critical area conservation plans exist for False Bay, or anywhere in South Africa. This study confirms False Bay as a critical area for white shark conservation and identifies that females are particularly at risk, due to their frequent use of the inshore areas of the Bay, which are impacted by fishing, pollution, and damage to natural habitat from coastal development.

Furthermore, the finding that female sharks frequent the inshore regions during spring and summer when recreational use peaks highlights the need for ongoing shark-human conflict mitigation strategies such as the Shark Spotter program in Cape Town, for which Kock serves as the research manager. The Shark Spotters aim to improve public safety while simultaneously conserving this vulnerable shark population.

Although the study focused locally, its findings have broad conservation and management implications because it highlights the need for understanding how behavioural patterns differ between sexes of the same population as this can influence a particular sex’s susceptibility to threats. Co-author, Justin O’Riain, Associate Professor of behavioural ecology at UCT welcomed the findings as an important contribution to the broad field of predator spatial ecology,   “We have a wealth of such information for land predators and these results provide an important step in narrowing the knowledge gap between marine and terrestrial systems and assessing the extent of our generalities”.

In addition to Kock and O’Riain, the co-authors of the paper are Katya Mauff, a statistics professional at UCT, Michael Meÿer and Deon Kotze from the Department of Environmental Affairs, Oceans and Coasts Branch and Charles Griffiths, Professor of marine biology at UCT. This research was funded by the Save Our Seas Foundation and the Department of Environmental Affairs provided research equipment and ship time. The National Research Foundation (SA) provided bursary funding for Alison Kock.

The paper is available on PLOS ONE, an online journal which is both peer reviewed and international, as well as being open access. Those last two words are golden ones for peasants like me who don’t have access to journal articles that live behind paywalls. Open access journals make scientific results and studies freely available to everyone, including non-scientists. The pie is made higher and everyone benefits from the knowledge and insights that have been obtained. This is a wonderful thing. More scientists should publish like this.

Anyway, read the full paper here.

Ways of talking about sharks

Yesterday we read an interview with George Burgess of the International Shark Attack File. The very name of the file – containing the word “attack” – says something about our view of sharks. When writing here, I try to avoid using the phrase “shark attack” (sometimes it’s impossible to come up with an alternative!) because very often what happens when a shark bites a person isn’t an attack: it’s a case of mistaken identity involving teeth, or it’s an exploratory test to see whether you’re one of its prey items, for example. This is not to minimise the experience of a person who is bitten by a shark, but to acknowledge that from the shark’s perspective something else entirely may be going on.

Christopher Neff, the Australian researcher whose talk Tony and I listened to at the Save Our Seas Shark Centre a year or two ago, has recently published a report with Dr. Robert Hueter, proposing a classification system that will promote more accurate reporting on interactions between humans and sharks.

The researchers propose three categories of incidents involving sharks: sightings, encounters, and bites (fatal and non fatal). They state that they are reluctant to use the phrase “shark attack” unless the motivation of the shark involved is not in doubt in the opinion of experts – a rare situation. These labels are intended to assist the public in gauging the level of risk entailed in going into the sea. The use of more accurate language would also aid discussion of the conservation of sharks.

Read a summary of the report here. The full report can be downloaded here.

What do you think? Is it all semantics, or are the words important?

Lecture: Alison Kock on Shark Spotters

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

Updates on the shark spotting program

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

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

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

Shark exclusion net at Fish Hoek

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

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

New spotting locations

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

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

SharkShield research

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

Safety tips

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

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

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

Proposed shark net at Fish Hoek beach

I have read so many stupid things on the internet about the shark exclusion net that is to be trialled at Fish Hoek beach starting (hopefully) in January 2013, that I sigh loudly to myself, roll my eyes, and wonder about reading comprehension and literacy.

In an effort to lower my blood pressure and spread some information (as opposed to wild-eyed rumours based purely on the words “shark net” and a vigorously professed love for sharks), here is a helpful article explaining the extent and purpose of the proposed net. Exclusion nets are currently used in Hong Kong (you can see a photo here), but the unique challenges of the Fish Hoek environment (the bay faces into the prevailing summer wind, and there is a lot of kelp in the area which could foul the net) mean that the project needs to be thought out very carefully for Cape Town – hence the delay.

Fish Hoek Beach
Fish Hoek Beach

Here is a press release from the City of Cape Town, explaining in detail what the net will be like. I quote (emphasis mine):

An exclusion net is not the same as shark nets currently used in KwaZulu-Natal.

Exclusion nets are small meshed nets designed to act as a barrier to sharks preventing them from entering an enclosed area. In the proposed trial the area that would be protected would be kept to a minimum, but large enough to provide a recreational space and training area for the life-saving club. As such the area would be less than the size of two rugby fields and would run from just off Jaggers Walk on the south of the beach diagonally across to the Law Enforcement offices on the beach. The small mesh of the nets prevents capture or entanglement of marine species and the net acts only as a barrier.

Shark nets on the other hand are used along the KwaZulu-Natal coastline and are essentially fishing devices known as large meshed gill nets that entangle and catch sharks, reducing the local shark population and, by fishing for sharks within the vicinity of a protected beach, reducing the risk of shark attack. They cover large geographic areas and are further out at sea than exclusion nets. These nets are not species selective and hence also result in a range of other marine species becoming entangled.

Shark Spotters have neatly summarised the difference between gill nets (the KZN type) and exclusion nets here. Here’s a thoughful piece by Christopher Neff that discusses current and proposed uses of shark nets worldwide.

Tell your friends, and pay heed to the Shark Spotters.

Lecture: Ryan Johnson on whether science can save sharks

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 fins will 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).

Dorien
Dorien

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.

Luis Antonio
Luis Antonio

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.

Lecture: Colin Attwood on the effectiveness of South Africa’s Marine Protected Areas

Colin Attwood is a professor in the zoology department at the University of Cape Town with a special interest in Marine Protected Areas. Tony and I attended a talk by him at the Save Our Seas Foundation Shark Centre on the same evening as the talk about Baited Remote Underwater Video Stations (BRUVS) in False Bay. The two talks dovetailed nicely, since the aim of the BRUVS project is to enable more effective monitoring of our Marine Protected Areas.

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.

Giant roman at Photographer's Reef
Giant roman at Photographer’s Reef

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.

Lecture: Baited Remote Underwater Video Stations (BRUVS) in False Bay

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”!