The future of shark cage diving
Shark cage diving is a scary idea for some, and a dream experience for others. However, this recreational activity may soon come to an end. A recent study by Stellenbosch University (SU) revealed that “the white shark population around the South African coast line has such a low level of genetic diversity that it may seriously jeopardise their capability to survive into the future.”
Enver Duminy, CEO of Cape Town Tourism, says that while various shark cage diving operations include an educational element in their tours, it is important that these companies “subscribe to ethical practices aligned with conservation so that this incredible experience remains available to visitors, and, more importantly, so that all forms of the marine ecosystem are protected.”
Any impact that dwindling numbers may have on the shark cage diving sector, will also impact on tourism. “Bear in mind that shark diving tours as well as trips to seal island provide an extensive contribution to the tourism economy and that this segment of the industry supports families and communities across Cape Town, especially those who live and work close to the sea,” says Duminy.
The future of shark cage diving
The research has suggested a possible impact on the shark cage diving industry as white shark numbers seemingly deplete (see below for more). “If better measures won’t be put in place to protect great white sharks, it is likely that the cage diving industry could collapse in the near future,” stresses Michael Rutzen from Shark Diving Unlimited.
Chris Fallows from Apex Shark Expeditions, notes that the recent data released by SU is concerning. “Not only is this a magnificent predator that is vital to the well-being of a balanced eco system but it is now the golden goose in a shark cage diving and eco-tourism industry that has redefined the value of a living resource over a dead one.”
But these depleting numbers don’t necessarily mean an end to shark cage diving. Marine Dynamic Tours notes that the current findings may lead to an increase in people participating in the activity, as opposed to a decline. No evidence is currently available to illustrate one way or the other, with Marine Dynamic Tours stating that operations are continuing as usual.
The technicalities of shark cage diving
Some people have voiced concerns about the treatment of sharks in relation to shark cage diving, however, Marine Dynamic Tours emphasised that sharks are not lured to an area but rather found in their natural environment.
“All operators work in an area which is frequented by sharks. The abundance of Cape fur seals in the area is an attraction for the sharks – Geyser Rock has an estimated 60 000 Cape fur seals. Sharks are naturally found in the shallows. The area is not a popular swimming area in comparison to more populated areas. Our science aims to understand behaviour of sharks so we can better advise and thereby protect beach goers,” said Marine Dynamic Tours.
Fallows agrees that there is a misconception that great white sharks are lured in for shark cage diving. “Great whites have an inshore seasonal movement irrespective of cage diving operations. It is more pertinent to look at what effects commercial shark fishing, as sanctioned by our government, has had on the natural summer prey of the white sharks and perhaps consider the risks associated with prey depletion rather than perpetuating a poorly substantiated argument that it is because of cage diving boats putting a few pieces of fish in the water, a long way away from the coast, that is the cause for shark attacks.
“If this were the case then any fishing boat, fish cleaning station, trek net, research boats, spear fishermen etc. is doing exactly the same thing when they use fish to attract sharks to catch, or catch fish in their nets or on their spears which attract sharks. Do the sharks know the difference?” asks Fallows.
Cape Town Tourism says there’s an apparent decline in shark numbers from the 1990s to now. “Shark behaviour specialist Michael Rutzen stated that in the 90s, if he’s gone out to his usual spot close to Dyer Island, there would have between 20 and 48 sharks around his boat; if he went out today, he’d have three.”
The research by SU estimated that there are only about 500 white sharks in South Africa. However, a statement by the White Shark Research Group notes that estimating how many sharks there are is challenging.
“We cannot see the sharks most of the time and they move around a lot. To overcome these challenges, scientists need to use complex methods and make assumptions when collecting, analysing and interpreting the data. Different methods and assumptions can lead to different results.
“Although the recent study led by Stellenbosch University is a genuine attempt to estimate the population, there is reason to believe that this contribution needs rigorous examination and testing with further work. This would not be the first time that estimates of population sizes of white sharks and other species have been disputed. It is a consequence of the difficult nature of such investigations,” explained the White Shark Research Group.
The depleting numbers could have quite a drastic impact on the shark cage diving industry. Fallows points out that without white sharks there will be no documentaries and no tourists interested in this experience.
The role of the shark cage diving industry in conservation
“Marine Dynamics believes Science Saves Sharks (#ScienceSavesSharks). If we can better understand this species we can better protect them. It is also crucial to change perceptions and this is done daily by our passionate team and expert crew that includes a marine biologist on board every trip logging crucial observational data,” said the company.
In addition it noted: “Marine Dynamics and the owner established Dyer Island Conservation Trust operate a dedicated research boat that is instrumental for research. Activities include tagging and tracking of great white sharks, behavioural surveys, environmental parameter monitoring (oxygen, salinity, temperature, depth, water sampling), population studies and assistance with strandings and rescues. In addition, all commercial trips have a marine scientist on board – research activities on board these trips include photo fin identification, recording of shark GPS positions and biometrics (size, location etc.), and any unusual abnormalities or behaviour of the sharks.”
Apex Shark Expeditions is also involved in conservation efforts. Fallows says: “We have been involved in the promotion of the great white shark as a magnificent predator with each and every one of our Apex Shark Expeditions guests. In addition to this, we have either hosted or facilitated more than 50 international documentaries focusing on these predators, which have been seen by hundreds of millions of people across the globe. Whilse entertaining there has been a strong conservation message in each one of these shows. We have also authored or co-authored more than a dozen scientific papers on the predatory habits of the False Bay great whites and have also published a book on the majesty of the animal.”
According to Marine Dynamic Tours, the company contributes approximately R1 million to the support of research and conservation. This is through direct financial support, equipment and logistical support, marketing and other means.
Apex Shark Expeditions makes substantial donations to various conservation causes according to Fallows. These are not only aimed at shark conversation, but other projects too as was anti-elephant poaching and various upliftment projects.
Problems with the study
“One of the assumptions made in the recent study is that the Gansbaai aggregation site represents the entire South African white shark population. However, we are not convinced that this is true. Overwhelming scientific evidence shows that white sharks are separated by size and sex during part of their lives and that not all white sharks visit Gansbaai. It is therefore possible that the recent estimate underestimates the total population size. Furthermore, the study has not provided evidence on the current trend of the population, whether it is decreasing, increasing or stable,” revealed the White Shark Research Group.
To overcome this issue, the White Shark Research Group will be working in all major aggregation sites in South Africa. The scientists will combine the data collected from the various sources “to produce a population estimate which we believe would better reflect a national estimate.”
While there are concerns that the figures stated in the SU research may be inaccurate, the White Shark Research Group did acknowledge that white shark number are low and they are vulnerable to the impact of humans. “Every effort should be made to ensure that the current legislation is applied and the population conserved, but future management and conservation actions need to be based on the best available numbers and further research is needed to resolve outstanding questions.”
Fallows believes its the current systems and legislations in place that add to the threat against great white sharks. “Why is it such a big surprise that these sharks are on a downward slope when the governing body of our South African coast line, the department of agriculture forests and fisheries, issues shark longlining permits, has to be pushed by the public to follow up on illegal fishing for great whites and above all, allows the world’s largest great white shark culling machine, the Natal Sharks Board, to kill between 11-60 great whites per year?”
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