A team of Stellenbosch University (SU) researchers has developed an eco-friendly and probably highly effective shark barrier, known as ‘Sharksafe.’ This is an alternative for shark nets which result in the death of thousands of sharks and other sea animals every year.
Prof Conrad Matthee, Head of the Department of Botany and Zoology and member of the research group that has developed Sharksafe, says that because of existing shark nets shark populations are declining drastically.
“It is estimated that the numbers of certain shark species have decreased by up to 90% over the past 20 years – particularly the number of great white sharks. Sharks are top predators and if they were to be taken out of the ecosystem, the latter will be disrupted. It is for instance speculated that there is a direct relation between the decline in shark numbers and the decline in other bony fish species.”
The problem, he says, is that shark nets have been designed with the specific purpose to kill sharks, but also result in the death of many other sea animals, such as dolphins and sea turtles.
Time has come to find less cruel ways
“Great pressure is currently being put on countries that are using shark nets, to do away with these – among others Australia, USA, Japan, Argentina and South Africa. In addition to destroying the sea life, shark nets are also not 100% safe for humans since they are not placed right down to the seabed and there are also overlapping gap areas where sharks can swim through. So, even though you are safer in an area with shark nets, you are not 100% safe.”
He explains that certain shark species, such as the Zambezi shark found in KwaZulu-Natal, are sensitive to strong permanent magnetic fields, while others, like the great white shark in the Cape waters, do not like kelp at all.
“Members of the team saw how seals chased by sharks swam into kelp and how the sharks time and time again turned away, not entering the kelp areas. Using these concepts we then developed a patent consisting of a rigid upright pipe which resembles kelp when it floats in the water. The structure also contains magnets to make it more effective for various shark species. The pipes are anchored to the seabed and stand upright up to the height of the water level during high tide. Our structure can resist waves of up to seven metres.”
The first test phase of Sharksafe was erected at Gansbaai and is currently redeployed by Mike Rutzen and Craig O’Connell – both part of the research team.
Loose pipes keep sharks out
“In our research we put bait behind the barrier to attract sharks, but no sharks swam through the barrier. In addition to the fact that the barrier looks like kelp to them, they are also being deterred by the magnetic fields. If correctly deployed our barrier forms a ‘cage’ consisting of loose pipes without a net, resulting in no sea animals being caught while sharks are kept out effectively,” explains Matthee.
He envisages that if the right material is used, the barriers will be able to remain in the water for at least 20 years with little maintenance required. “We are already establishing that marine life grows on the cement blocks which anchor the barriers to the seabed, which now forms an artificial reef.”
The research team intends to get permission to fence in the Muizenberg/Fish Hoek swimming beaches at an estimated cost of approximately R10 million each. The current patent consists of three rows of overlapping pipes, but in the deployment phase the idea is to employ five rows of pipes. They would like to implement this in collaboration with the developers of the so-called “mesh nets” which are currently being considered as alternative for shark nets – a finer woven net than the traditional shark nets.
“We hope our green alternative will be supported by the City of Cape Town as it is environmentally friendly and also much safer for humans. It will be wonderful if the Cape beaches which currently enjoy blue flag status, all rather opt for the green alternative as a preferred choice.
“We call our barrier ‘Sharksafe because it keeps people safe from sharks while simultaneously protecting the sharks. For our team it is all about shark research and the protection of sharks. That is the driving force behind this research.”
Sharks not into human meat
Are sharks really such a great danger to man?
“Sharks are not interested in humans as prey,” Matthee says. “Great whites shorter than three metres – about four to five years old – feed primarily on fish. They then change their teeth and get those characteristically large teeth adapted for marine mammal prey. Their diet then changes seasonally from fish to marine mammals. Humans don’t look like a marine mammal in the water, but the sharks are curious in nature leading to some negative encounters with humans from time to time. The problem of course is that one negative encounter can be fatal.”
Matthee adds Rutzen regularly dives with the great whites. A shark tooth once hooked him to such an extent that he bled considerably. The sharks, however, were not interested in him.
“It is like walking into a pizza restaurant and smelling hamburgers – if you feel like a pizza, you will not buy a hamburger, particularly if you never smelled a hamburger before in your life and you don’t associate it with food. The argument therefore is that all shark attacks are merely inquisitive in nature and that sharks are definitely not interested in hunting humans.”
For more information, contact Prof Conrad Matthee at tel 021 808 3957, cell 0844534344 or via e-mail.
Photos:
1. A diver fitting the “Sharksafe” barrier that resembles kelp into the seabed.
2. Seals and other marine life swimming in between the shark barrier.
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