Electrical field to repel sharks

2013-09-26 00:00

THE safety of bathers from shark attacks at popular beaches throughout the province may rest on technology being developed by a maritime defence research unit.

The research was initiated by the KZN Sharks Board (KZNSB), which has a history in developing and patenting electrical shark repellents. The board is looking at developing a shark repellent cable that would be charged with an electrical current that could surround an entire bathing area with an electrical field.

Coastwatch, a coastline lobby group, is fully behind the concept if it comes to fruition.

The cable technology is being developed by the Institute for Maritime Technology (IMT), a division of Armscor. It usually performs defence research for techno-military support, products and services for the Department of Defence and Military Veterans.

The development is being funded by the provincial Department of Economic Development, to which the sharks board reports.

If it is successfully developed, it could mark the demise of the controversial shark net that has protected bathers for well over half-a-century but has been known to catch and kill dolphins, turtles and even baby whales.

KZNSB head of research, planning and development Geremy Cliff said while the concept would change the landscape of protecting bathers from sharks, the development of the project is still far from conclusion.

“IMT is undertaking the research and development. They have the expertise and have put a lot of time into this project. The prime motivation behind the project is that it is environmentally friendly compared to the shark nets,” said Cliff.

In total, the board has 37 locations where they place nets over an area of 320 km, of which 23 km is protected through a combination of the nets and drumlines.

The KZNSB currently checks the nets five times a week. Most of the nets used are just over 210 metres long and run a depth of six metres with stretched mesh of 51 cm.

Durban has 17 nets that are each 305 m in length, covering all the popular swimming beaches between the Umgeni River and the harbour entrance.

Since the installation of nets in Durban in 1952, there have been no fatalities as is the case at all the beaches where nets are now present. All recently recorded fatalities in KZN have taken place at unprotected beaches.

The Sharks Board is no stranger to the use of electrical fields to repel sharks. In 1996 they developed the SharkPOD. The unit was specifically designed for use by scuba divers and repells sharks within a vicinity of 1,5 metres of the diver. According to KZNSB, the field appeared to affect sharks’ sensory and neuromuscular systems.

“Whether we use nets or if this new technology is successful, the business of repelling sharks will remain costly. We were hoping to start with tests this year. The test will most likely be in the Western Cape as their beaches are better protected [from the elements]. Developing any such product for the KZN coastline is difficult.

“They must take into account our turbulent surf, rip currents and our spring tides. They must also consider the elements and of course it must be ascertained what strength electrical current can be used, the safety and effect on bathers and whether it can ultimately repel sharks,” said Cliff.

Coastwatch spokesperson Di Dold said while they do not like the by-catch associated with nets, they understand their value when it comes to tourism.

“We would like a more effective manner in repelling sharks and would fully support an electrical solution. However, protecting our bathers is necessary. Small coastal towns would lose their tourism trade if beaches were not protected,” she said.

IMT would not discuss the project, stating they had a non-disclosure agreement with KZNSB.

• jonathan.erasmus@witness.co.za

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