Keep­ing the sharks at bay

SA’s un­der­wa­ter elec­tric fence could be the an­swer

The Witness - Wheels - - FEATURES PLANET -

DOZENS of peo­ple are at­tacked by sharks ev­ery year. Fear among tourists is rife and in­dus­try prof­its are tak­ing a hit. A new un­der­wa­ter elec­tric fence — de­vel­oped and tested in South Africa — aims to stop sharks from get­ting close to bathers.

Nasief Jaf­fer, a 24- year- old surfer, emerges from the ocean, surf­board ex­pertly tucked un­der one arm. He is at Muizen­berg beach, one of South Africa’s top hol­i­day des­ti­na­tions.

A black flag fea­tur­ing the white out­line of a shark is flap­ping in the wind be­hind him. “Cau­tion”, the flag in­di­cates. “Shark- spot­ting con­di­tions are poor.” Un­per­turbed by the dis­claimer, Jaf­fer shrugs. “I go surf­ing sev­eral times a week. I trust the shark spot­ters,” he says.

The Shark Spot­ters is a beach- safety or­gan­i­sa­tion that aims to pro­tect swim­mers and surfers from at­tacks on Cape Town’s popular south­ern penin­sula. The At­lantic Ocean around Cape Town is home to the largest Great White pop­u­la­tion in the world, the most danger­ous and ag­gres­sive of all shark. For 10 hours each day, shark spot­ters take up po­si­tions on moun­tains over­look­ing nine popular beaches, search­ing the wa­ter for preda­tors. If they see a shark, they alert a col­league on the beach, who sounds a siren and raises a white flag. Within min­utes, ev­ery­one clears out of the wa­ter.

But the Shark Spotter pro­gramme, although lauded as a suc­cess, has a ma­jor weak­ness: hu­man er­ror.

“It’s a highly re­spon­si­ble job. It’s very stress­ful, es­pe­cially on days with poor visibility,” says shark spotter Liesel Lott, while scan­ning the ocean with binoc­u­lars.

Pres­sure mounts dur­ing the sum­mer, which is the sharks’ in- shore hunt­ing sea­son. “We ex­pect to sight sharks ev­ery day at this time of year,” says Shark Spot­ters field manager Mon­wabisi Sik­weyiya.

Over the past decade, more than 1 700 sharks have been spot­ted near the beaches of Cape Town’s south­ern penin­sula alone, most of them Great Whites. Some as close as 50 me­tres to the shore.

Na­tional con­ser­va­tion and re­search or­gan­i­sa­tion the Sharks Board records an av­er­age of six shark at­tacks per year in South Africa. That might not sound like much, but ev­ery ac­ci­dent raises fears, and mem­o­ries of Steven Spiel­berg’s iconic movie Jaws.

“Shark at­tacks have huge im­pact on tourism,” says Sharks Board chief sci­en­tist Geremy Cliff.

On South Africa’s east coast, nets pre­vent the preda­tors from get­ting too close to the shore. But the mesh­work catches not only sharks, which drown when im­mo­bilised, it also kills other sea an­i­mals, in­clud­ing dol­phins, tur­tles and rays.

As a re­sult, the Sharks Board has spent the past three years de­vel­op­ing an en­vi­ron­men­tally friendly so­lu­tion to keep sharks at bay: an un­der­wa­ter elec­tric fence that harms nei­ther hu­mans, sharks nor any other marine an­i­mal. The fence con­sists of a ca­ble fixed to the sea floor from which ver­ti­cal ca­bles rise to the sur­face. The ca­bles emit a low- fre­quency sig­nal, cre­at­ing an elec­tric fence that repels sharks whose noses are ex­tremely sen­si­tive to elec­tric­ity.

If hu­mans accidentally touch the ca­ble, they feel only a tin­gling sen­sa­tion. Two 100- me­tre- long pro­to­types have been in­stalled at Glen­cairn beach, 12 kilo­me­tres from Muizen­berg. A high- def­i­ni­tion cam­era on a peak op­po­site the bay films wa­ter ac­tiv­ity to show if the fence ef­fec­tively repels sharks.

“It’s a world first. The de­sign stretched our tech­ni­cal ca­pa­bil­ity,” says Claude Ra­masami, project manager at the In­sti­tute for Mar­itime Tech­nol­ogy which de­vel­oped the fence.

In­stalling elec­tric­ity safely in wa­ter, an ever- shift­ing sea bot­tom, the force of the waves pound­ing the equip­ment and cor­ro­sion, all add to the dif­fi­culty.

By the end of March, the Sharks Board hopes to have suf­fi­cient data to prove the elec­tric fence is work­ing.

“If we’re suc­cess­ful, it could be in­stalled around the globe,” says Sharks Board project manager Paul von Blerk, who is over­see­ing the trial phase. Ini­tial data in­di­cates pos­i­tive re­sults, he adds. This would, for ex­am­ple, make bathing safer in the United States, which recorded 47 un­pro­voked shark at­tacks in 2013, or in Australia, where 10 ac­ci­dents were re­ported that year, ac­cord­ing to the In­ter­na­tional Shark Attack File of the Florida Mu­seum of Nat­u­ral His­tory.

Even surfers like Jaf­fer say they would wel­come the elec­tric fence. “I’d feel much safer,” he ad­mits.

— Sapa- dpa.


Bathers are in­formed about the shark- spot­ting pro­gramme at Muizen­berg beach, Cape Town. Could an elec­tric fence make bathers even safer from shark attack?

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