New eco-friendly shark barrier

Heidi dMBy Heidi dM 5 years ago
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green shark barrier‘Sharksafe’ is the name of the new eco-friendly shark barrier developed by a team of researchers at Stellenbosch University in South Africa.  The Head of the Botany and Zoology Department, Prof. Conrad Matthee, says, “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”.  He says that part of the problem is the existing shark nets which have been designed with the specific purpose to kill sharks.  Not only do the current shark nets kill sharks, but they also unfortunately, result in the death of many other sea animals. According to the KwaZulu-Natal Sharks Board (KZNSB), their average annual catch of sharks in their nets is 591 and only 13.3% are released alive.  Other sea animals included in this average annual catch are 201 rays, 60 turtles, 43 dolphins and 30 fish. “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,” says Matthee. Shark nets in KwaZulu-Natal have evolved since the original 180 m diameter semi-circular enclosure in 1907.  (The enclosure was constructed of steel piles with vertical steel grids placed between them).  In 1952 large-mesh gill nets were laid and in 1957/1958, several coastal towns tried erecting physical barriers in the surf zone, built from poles, wire and netting.  Since then, researchers have been working on developing new ideas like the drum lines that are in place at present and shark-excluding devices such as pingers.  ‘Sharksafe’ is the latest answer to the shark “problem”. When at sea, the ‘Sharksafe’ researchers noted that seals chased by Great White sharks swim into kelp and then the sharks, time and time again, turn away, not entering the kelp areas.  This, and the fact that certain shark species, such as the Zambezi shark found in KwaZulu-Natal, are sensitive to strong permanent magnetic fields, led the team to develop their patent. The structure consists of 3 rows of rigid upright pipes which resemble kelp floating in the water with magnets (to make it more effective for various shark species). It can resist waves up to 7 metres and, according to Matthee, if the right material is used they can stay in the water for at least 20 years with little maintenance.  (At present, KZNSB service their nets every day from Monday to Friday, weather permitting and have 15 ski boats for this maintenance service). Matthee’s final words are clear as to their mission with this structure: “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.” From: http://www.sun.ac.za/english/Lists/news/DispForm.aspx?ID=130

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  Conservation, Science
Heidi dM
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 Heidi dM

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Heidi is a Marine Biologist who has been working in the public aquarium industry as an aquarist and now as a consultant specialising in husbandry, interpretation and staff training. She has also written a series of children's books about the aquarium and fish world called "Abby's Aquarium Adventures".

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