Category Archives: News

Latest News

Shark Diving Unlimited Nominated Best Adventure Activity

Shark cage diving in Gansbaai
Shark cage diving in Gansbaai, South Africa


Shark Diving Unlimited has been nominated the best adventure activity for the second year running in the Lilizela Tourism Awards.

The Awards which recognise fair and responsible tourism companies, nominated the company for the second year in a row.

Shark Diving Unlimited takes great care in providing enjoyable shark cage diving trips for all people regardless of their ability, age, or monetary situation.

Based in the Great White Shark capital of the world, Gansbaai South Africa, the company also tries to give back to the ocean, by supporting a number of scientific field research studies on the Great White Shark.

To vote please visit:

New software will standardise data collection for great white sharks


Shark Diving Unlimited is very pleased that the latest scientific paper we sponsored for Dr Sara Andreotti of Stellenbosch University, has been published.20160407-_mg_5811

The lack of a standardized procedure for collecting data about elusive and hard to find species like the great white shark has to date seriously hampered efforts to manage and protect these animals.

But now a marine biologist, an applied mathematician and a software developer from Stellenbosch University joined expertise to develop a custom-made software package, called Identifin, which may offer a solution to this problem.

Dr Sara Andreotti, a marine biologist in the Department of Botany and Zoology at SU, have collected over 5000 photographic images of the dorsal fins of white sharks along the South African coastline as part of her research. This is because the trailing edge of the dorsal fin provides a unique trade, analogous to a human fingerprint.

Over six years she managed to manually build a database with information on when and where an individual white shark was sighted. In those cases where she was able to collect a biopsy from the shark, the genetic information was linked to its profile.

But she was doing all this manually on her personal computer.

“I nearly lost my head. I quickly realised that in the long term updating the database was going to consume more and more of my time. That is when I headed over campus to the applied mathematics division and asked for help. I was stunned when they became all excited about my data,” she laughs.

Prof. Ben Herbst, a specialist in machine learning, and Dr Pieter Holtzhausen, a software engineer then busy with his PhD in Applied Mathematics, were literally overjoyed to be able to work with Dr Andreotti’ s data base.

Dr Holtzhausen explains: “We used an algorithmic technique called dynamic time-warping to match the fingerprints. With this technique, any data that can be turned into a linear sequence can be analysed. The technique is often used in speech recognition software.”

The image recognition software they developed, called Identifin, compares a semi-automatically drawn trace of the back edge of the dorsal fin to existing images in the database. The images in the database are then re-arranged and ranked by probability of match. If there is a match, the database photograph in the first position will be the correct one.

This is what the interface of the Identifin – fin matching – program looks like. A researcher takes the original photograph (a) and indicates the top and the bottom of the fin. The software then automatically traces the notches pattern (in red). Image: courtesy Dr Sara Andreotti.

The researcher then asks the software to match the traced photograph with existing images from the sharks’ database. Image: Sara Andreotti

However, while working with Michael Meyer, a marine scientist from the Department of Environmental Affairs, and shark conservationist Michael Rutzen from Shark Diving Unlimited, Dr Andreotti realised that the software needed some more tweaking if it were to fit the ideal of sustaining a large database for the long-term monitoring of the white shark population.

“The software had to be capable of quickly matching the fin identification of a newly photographed shark with a possible existing match in the database, and to automatically update the sharks’ id catalogue. The database also had to be user-friendly and structured in such a way so that different researchers can use it over the long term,” she explains.

The custom-made software uses the complete database for comparing the matches and then organises them in order of similarity, from left to right. There is also an embedded function in the software to create a matrix of the history of recaptures. This information can be used to estimate population numbers. Image: Sara Andreotti

While there is still room for improvement, the success of the first trials boosted their hope that in the near future they will be able to use Identifin to monitor white shark populations on a large scale.

“Previously, while at sea, I had to try and memorize which shark is which, to prevent sampling the same individual more than once. Now Identifin can take over. I will only need to  download the new photographic identifications from my camera onto a small field laptop and run the software to see if the sharks currently around the boat have been sampled or not.

“By knowing which sharks had not been sampled before we can focus the biopsy collections on them. This saves us both time and money when it comes to genetic analysis in the laboratory,” she adds.

Dr Andreotti says to date the lack of standardization of data collection has been a major limitation to combining datasets of worldwide distributed species: “We hope Identifin will offer a solution for the development of a South African and then global adaptive management plan for great white sharks.”

The next step is to adapt Identifin for the identification of other large marine species and help other researchers facing the same kind of struggles.


Contact details

Dr Sara Andreotti


Mobile: 072 3219198


Dr Pieter Holtzhausen


Mobile: 084 998 6386


Additional reading

Andreotti S, Rutzen M, Wesche PS, O’Connell CP, Meÿer M, Oosthuizen WH, Matthee CA (2014) A novel categorisation system to organize a large photo identification database for white sharks Carcharodon carcharias. African Journal of Marine Science 36:59–67. Available online at

Andreotti S, Heyden S von der, Henriques R, Rutzen M, Meÿer M, Oosthuizen H, Matthee CA (2016) New insights into the evolutionary history of white sharks,Carcharodon carcharias. Journal of Biogeography 43:328–339. Available online at

Andreotti S, Rutzen M, Walt S van der, Heyden S Von der, Henriques R, Meÿer M, Oosthuizen H, Matthee C (2016) An integrated mark-recapture and genetic approach to estimate the population size of white sharks in South Africa. Marine Ecology Progress Series 552:241–253. Available online at


Issued by Wiida Fourie-Basson, Media: Faculty of Science, Stellenbosch University, 021 808-2684,

Witness Nature’s Greatest Spectacle – An Airborne One Tonne Shark Right Next to Your Boat.


There’s no greater sight than a 1 tonne Great White Shark launching itself out of the water, right by your boat, in hungry pursuit of a seal.  Shark Diving Unlimited in Gansbaai, South Africa runs breaching trips from May to August each year so that you can witness this spectaculr behaviour.

Breaching is thought to be part of the Great White Shark’s hunting behaviour and only occurs in the South African winter months.  It is thought that they only exhibit this activity in one place in the world, Gansbaai, two hours South of Cape Town.   During winter visibility is excellent in this region and tours are especially popular with photographers and those who want to enjoy the majesty of these animals but don’t want to get their feet wet.

Breaching trips head out at first light and last approximately 2-3 hours.  An artificial seal is towed behind the boat to entice this apex predator to breach and guests then brace themselves for this rare spectacle with cameras at the ready.  During their visit guests are treated to breakfast, snacks on board and a light lunch after the trip.

Mike Rutzen, well known shark behaviourist, conservationist and owner of Shark Diving Unlimited, was the first person in the world to witness this behaviour from both above and below the water in his documentary Great White Shark: A Living Legend.

The first time I saw this behaviour my heart skipped a beat, it is truly magnificent and right up there with observing  lions hunting  or fighting.  The great white shark is worth a lot when slaughtered for its jaws and teeth, but alive it is truly the greatest sight

Great White Sharks are listed as Vulnerable by the IUCN Red List and are primarily being threatened by baited hooks, which are used by the government to protect swimming beaches, by hooking (and in most cases killing) sharks.  Poaching for the shark’s valuable jaws and teeth is also a huge problem in the preservation of this species.

Shark Diving Unlimited uses most of its profits to fund scientific research, in collaboration with Dr. Sara Andreotti, a marine biologist at Stellenbosch University.  Together, they have been attempting to preserve the great white shark through a series of studies on their behaviour and genetics.

Shark Breaching trips are  10 000 ZAR per boat ride for 1-8 people and the cost is split between all the guests on any given trip.   It is also possible to book an exclusive breaching trip for 10 000 ZAR.  In addition, those wishing to go shark cage diving can do so all year round at a cost of  1500 ZAR.  Return transfers from Cape Town are 450 ZAR per person return.

To book please email us at or call us all hours: +27 (0) 82 441 4555



Shark Finning: the facts

Shark finning, or simply finning, is the brutal practice of hacking off a shark’s fins for food, normally used for the Asian delicacy, shark fin soup.

Once their fins are hacked off, the sharks are thrown back into the sea. They then die slowly and painfully as they starve to death, get eaten by other fish or suffocate because they cannot swim properly and enough oxygen into their gills.

Tens of millions of sharks are killed every year at a rapid speed to keep up with the demand for shark fins on the black market. This cruel practice has caused sharks to become endangered worldwide. Several species are now at a critically endangered level with almost 95% of their population killed off since the 1970s.

  • Blacktip Sharks have fallen by 93%;
  • Tiger Sharks by 97%;
  • Bull Sharks, Dusky Sharks and Smooth Hammerheads by 99%.

Many people are unsupportive of the decline of sharks and the cruelty of finning. This is due to two factors.

  1. The shark is not a ‘loveable’ animal and is unjustly seen as a monster. Because of the movie industry, notably Jaws, sharks such as the Great White are seen as vicious man-eaters. This is an unfounded stereotype used only to promote movies and television and to entertain people. Unfortunately, many people have taken this image to heart. However, when one actually reads about sharks in scientific reports, journals and articles, one finds that they do not seek out humans for food and are actually docile creatures. It has been proven that the odds of a shark killing you are extremely slim and there are many other animals much more violent and dangerous than sharks.
  2. People are ignorant of the importance of sharks. Coupled with their publicity as terrifying monsters, people do not educate themselves about sharks and some are indifferent to shark finning. The consequences of the decline in sharks are dire. If sharks become extinct, the ocean will lose a key part of its eco-system. As an apex predator, the shark is integral in keeping certain populations at bay. A lack of sharks on the east coast of the USA has seen a decline in shellfish because sharks are not there to balance the small shark, ray and skate populations who mainly eat shellfish. Imagine if all lions were extinct; there would be an overpopulation of herbivores.

How you can help

Luckily, there are many compassionate people and organisations that are banding together to fight the shark fin trade, especially in the USA. In South Africa, shark finning is illegal but there are many other countries where it is not, such as Mozambique. You can aid the international campaign by visiting these sites and signing the petitions or donating money to end shark finning.


Shark Diving Unlimited is one organisation that, not only advocates for sharks, but uses their resources for research and conservation; educating the public on the importance of these animals. With another amazing Shark Week behind us, let us all take action and help preserve the species.




Shark Week 2013: Why you should support the campaign against shark finning

Shark fin soup is a delicacy that tens of millions of sharks have been killed for. Here are a few facts about shark fin soup that will hopefully prompt you to support the banning of shark finning.

Why are sharks killed for their fins?

Sharks are caught and their fins are hacked off for the Asian delicacy, shark fin soup. Their fins are used to make a gelatinous soup that is tasteless and contains no nutritional value. Shark fin soup is also highly expensive; one shark fin can cost up to $400. Shark meat itself is of low value therefore shark finning is done on the boat after which the sharks are thrown overboard where they die from suffocation, drown or are eaten by other fish.

Why should people care?

Shark finning has killed tens of millions of sharks to date. At this moment, every species of shark is endangered. The systematic destruction of the species has serious consequences for ocean’s eco-system. Sharks are necessary apex predators who have been around for 300 million years. They regulate the population of other species of fish and mammals by eating them as prey.

What can you do?

  • Support organisations that work to preserve sharks such as Shark Diving Unlimited
  • Sign petitions and support legislation that work to ban shark finning
  • Refuse to eat in restaurants that serve shark fin soup or shop where shark fins or shark products are sold
  • Spread the word by letting everyone know about the importance of campaigns against shark finning
  • Keep an open mind and educate yourself on sharks by watching educational programs or better yet, embark on shark cage diving trip.

Watch this video on how humans are destroying the ocean’s eco-system.




Conservation Talks 2012

2012 got off with good start as Mike has been invited to do conservation talks and presentations from several universities and institutions.

First up we have the Atlantis, The Palm, in Dubai, where Mike and many others like Steve Kaiser, Rima Jabado and Robert Bennet discussed measures to conserve sharks in the UAE waters. They focused on the damage at the top end of the marine food chain.


From the left: Steve Kaiser (vice president of marine science and engineering at Dubai’s Atlantis hotel, The Palm, which houses the world’s third-largest aquarium). Michael Rutzen (shark expert and conservationist, owner of the eco-tourism shark cage diving company Shark Diving Unlimited). Rima Jabado (Marine Biologist, busy creating a catalogue of the sharks species, some of which have never been described before, in the United Arab Emirates waters for her PhD Project). Robert Bennett(Manager, Large Exhibits at Atlantis aquarium, The Palm)

This event made some big waves as it hit news channels around the world, a clip below shows some interviews with Mike and Rob on City 7 News.

Media Watch

Newspapers also welcomed the events as it made frontpage news on many of the tabloids in the UAE. Below just to name a few that had published the events




Please visit the Atlantis Blog for more events and information that are run by Atlantis, The Palm in Dubai.


This year Shark Diving Unlimited sponsored the field work for PhD student Craig P. O’Connell from the University of Massachusetts Dartmouth, providing the materials and logistics for his project.

This project was authorized by the Department of Environmental Affairs of South Africa, cooperating with Prof. C.A. Matthee (Stellenbosch University), Sara Andreotti (PhD student, Stellenbosch University) and Michael Rutzen (Shark Diving Unlimited) as field work supervisor.

The aim of this project is to find an alternative non-killing solution to the anti-shark nets to protect both beach goers and sharks around our coastline.

It was great to have Craig in our team and we’re looking forward to see him back in South Africa.

Please look at this short video of video of Craig’ s field work


New Sharksafe Barrier System to protect both sharks and people

Not only are sharks strikingly beautiful, but without sharks patrolling the seas marine ecosystems would be thrown entirely off balance. Sharks weed out weak and sickly prey, keeping other species fit. Additionally, sharks keep the ocean healthy by feeding on prey species, ensuring that they don’t become overabundant. In essence, the shark is one of evolutions most impressive success stories.

Yet, sharks are feared and in some cases ostracised. For many, the great white shark is considered a dangerous predator with a penchant for human flesh – films like Jaws and Open Water have simply perpetuated this gross misjudgement. Going shark cage diving is one of the best ways to dispel misconceptions for yourself, but due to a somewhat crippling public fear of shark attacks, preventative measures such as shark nets have become the norm in coastal areas.

As an apex predator, the great white shark has been a protected species since 2005 under the Convention on International Trade in Endangered Species (CITES, Appendix II) and the Convention for Migratory Species (CMS); furthermore, due to rapid population declines, the species is listed as vulnerable to extinction according to the International Union for the Conservation of Nature (IUCN, Category VU A1cd+2cd; Dulvy et al. 2008)

While protecting swimmers from potential shark attacks, shark nets actively injure sharks and have led to the strangulation and suffocation of all kinds of sea animals. As traditional shark nets have unquestionably caused more harm than good, an eco-friendly shark barrier called Sharksafe which will not only shield swimmers, but protect marine life too, has been developed.

The project is the result of a huge collaborative effort between the PhD candidate Craig O’Connell from the University of Massachusetts Dartmouth, Dr. Conrad Matthee and Sara Andreotti from Stellenbosch University, and Mike Rutzen of Shark Diving Unlimited. The team have been developing the Sharksafe Barrier since 2011, each contributing their areas of expertise and, in some instances, funding.

The Sharksafe Barrier is constructed from rigid pipes that emit a magnetic barrier which, when erected on the seabed, resemble seaweed. These features are effective in two ways: sharks are sensitive to magnetic fields and it will deter them from attempting to swim through the barrier, and great whites seem to particularly detest kelp and tend to avoid it – an observation made by Rutzen, who has an intimate understanding of great white behaviour.

The Sharksafe Barrier’s deployment cost which amounts to R10 000 000, is built to sustain functionality for over 10 years while withstanding up to seven metre swells and requiring a maximum of one check-up per year. Therefore, besides being environmentally friendly and long-lasting, the associated manual labour once the barrier is deployed will be minimal .

Under the guiding eye of Rutzen et al. the Sharksafe barriers have been exclusively erected at Dyer Island in Gansbaai by Shark Diving Unlimited vessels, who also offer shark cage diving. Stellenbosch University has patented the system. In the long run, it is hoped that this new alternative to shark nets may actively reduce the number of related marine life deaths and curb the few shark attacks which actually occur.


The Kings of Chaos dive with the king of the sea

Rockstar royalty has touched down in South Africa! On Monday, June 10th, three of the eight iconic rock musicians touring the country joined Mike Rutzen and the Shark Diving Unlimited team in Gansbaai for a quick shark diving expedition before heading to Jozi for the next Kings of Chaos show, taking place this Saturday.

The Shark Diving Unlimited team was pleased to host the following musical legends: Glenn Hughes of Deep Purple, Ed Roland of Collective Soul and Myles Kennedy of Guns n Roses. All of these rockers are avid conservationists and Rutzen happily skippered the trip himself. The shark diving trip was quite a success, with idyllic weather conditions and a lively group on board.

Mike Rutzen rescues juvenile Blue Shark

On Saturday morning 18 May, False Bay Yacht Club members notified Mike on Shark Diving Unlimited’s research sailing vessel “Catalyst”, that a young Blue Shark was swimming bewildered and confused in the shallows in the marina at Simon’s Town.

With fellow club members John and Nina, they sprang into action, commandeered the club ferry and hauled the young fellow into the boat.

They then proceeded to take the shark out beyond the SA Navy harbour wall and set him free.

The shark was approximately 1.3 metres in length and was sexually mature. He had two holes, most probably from a gaff, in in his lower body near the head. He showed signs of extreme stress, but still seemed quite strong. Mike’s assumption is that a fisherman had caught him, brought him back from the trip and then decided to throw him overboard in the jetty/marina area.

Michael says “the problem is that most shark species are considered commercial fish within the Republic of South Africa’s borders, even though some of them are protected by Cites”.

A big thank you to all who helped in this endeavor.