Saturday, August 19, 2006

Culling sharks and using nets are unacceptable

Proposals to cull sharks or put up nets are irrational and emotive responses to recent attacks along the False Bay coast and will not be viable solutions.This is the view of Lesley Rochat, executive director of the AfriOceans Conservation Alliance and a member of the city's shark working group.

She said recent encounters with the predators had created overnight "shark experts" and a new type of opportunist who received media recognition for coming up with radical, yet unrealistic and ill-informed solutions. "Of course we are concerned about the shark encounters, but they have been occurring worldwide for aeons.

'snake and dog bites are responsible for more deaths in SA'"So too have snake bites and dog bites - which are responsible for more deaths in South Africa annually than shark bites."Rochat said that in searching for a solution, the working group had taken into account the suggestions of people on the street. "Firstly, nets are not a solution - not because they are too expensive or for some other 'pro-shark' hidden agenda, but rather because experts from the Natal Sharks Board say that they will not work in our waters.

"Not only will they not significantly lower the risk of an encounter, but also between June and December they would be catastrophic for the whales that visit our coast and for all other marine life throughout the year."She said electronic repellent devices had also been considered to protect beaches, but the technology was not yet available worldwide.

"Only shark shields for individuals are available and an option to be considered by some water users."Rochat said culling would also be pointless because the remaining sharks would still pose a threat unless they were all killed off, which was obviously not possible."There is also a popular perception that there is a rogue shark which is responsible for all the encounters, yet globally there is no evidence that a shark becomes a rogue or man-eater. If this was the case then people would be eaten regularly and this is simply not happening."

Rochat said the city of Cape Town's Shark Spotting Programme had proved to be a successful early warning system. "It does however have its limitations, such as bad visibility days and human error. And not all beaches are conducive to spotters because they need an elevated vantage point."She added that all the recent encounters had occurred beyond the breakers while there had been none on swimmers in the waves, so it appeared that there might be a safe zone.Recent attacks include the one on lifeguard Achmat Hassiem, who lost his foot off Sunrise Beach on Sunday.

This was followed by an incident where a shark chewed through a surfer's leash off Danger Beach near St James.Alison Kock, a student at the University of Cape Town doing a PhD on Great White sharks in False Bay, said shark attacks were very rare.The number of deaths and injuries attributable to sharks was dwarfed by other causes of injury and death associated with aquatic recreation and work at sea. "There were only 59 attacks worldwide resulting in four deaths last year - amazing considering the literally billions of human hours spent in the sea."

Kock said that shark populations were on the decline worldwide, with many species at less than half of their original size."White sharks, which by definition have relatively tiny populations because of their place as large apex predators, are even more vulnerable."Kock, who spends upwards of 70 days a year on the water studying the Great Whites in False Bay, said researchers still did not know enough about them.Other safety options which have been investigated by the Natal Sharks Board include exclusion nets, fine-meshed nets that create an exclusion zone.

According to Gregg Oelofse, the city of Cape Town's environmental policy and research co-ordinator, exclusion nets had been used in Hong Kong with success but required calm sea conditions. While they might be effective in certain conditions in Cape Town, they would be expensive, would secure small areas, be maintenance intensive and could be adversely affected by the Western Cape's high kelp loads.

Oelofse said research into the use of early warning sonar devices was under way but was currently prohibitively expensive. He added that research had found there was no current evidence to link cage-diving with White shark attacks.


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