Wednesday, August 23, 2006

New electronic shark repellent may prevent shark attacks

Being bitten by a shark must be a terrifying experience. I have been surfing for 28 years, and go out in False Bay at least twice a week. I also work for a science-based organisation - WWF - that seeks to protect and enhance the wellbeing of humans by trying to ensure we do not irresponsibly destroy the environment.It is in this context that I express my deep empathy with Achmat Hassiem, the 24-year-old lifeguard whose foot was severed by a Great White last Saturday, and I have nothing but admiration for the courage shown by him and his fellow lifeguards in serving their community.

But it is with disappointment that I have read the illogical, knee-jerk reaction from a narrow sector of the public. Their reaction is even more astounding in light of the calm and rationality shown by the Hassiem family, who declared that Achmat would be back in the water at his first opportunity.In the media-induced aftermath of this event, many different public perspectives have emerged: from the primal position of "let's start killing sharks", through the philosophical viewpoint of "man is entering the domain of the shark", to the protectionist perspective of "sharks have an equal right to exist on this planet".

But, whatever your view, I think we need to bear three basic criteria in mind when considering how we respond to this situation. Based on best-available knowledge, we need to be sure that a proposed response:Has a practical chance of reducing the level of risk significantly.
Is proportional to the level of the threat to society.

Will not cause disproportionate damage to the very environment that has attracted such high numbers of water-users to our beautiful city in the first place.In light of these criteria, I would like to consider some of the arguments and inferences put forward in the media over the past days.
"We should start selectively culling sharks": Selectively culling sharks will only work if you are dealing with a relatively localised and resident population. Culling efforts will reduce the density of the local population, and therefore the statistical risk of attack.

But research of tagged Great Whites in False Bay has shown that these animals move frequently between locations along the coast of South Africa and even all the way to Australia. False Bay, therefore, appears to have an open population of Great Whites and selective culling will not be effective in significantly reducing the level of risk to recreational users.

"We should introduce shark nets": A surprisingly little known fact is that shark nets do not function as protective barriers between sharks and humans. They function as very effective fishing nets that kill large numbers of sharks (and many other creatures) until they significantly reduce the local densities of more resident shark species, like Zambezi and Tiger sharks.This strategy in unlikely to be effective in False Bay because of the migratory nature of Great Whites. Furthermore, during our spring and early summer months, our waters are graced with one of nature's true spectacles: Southern Right whales. Shark nets and whales are a bad combination. Entangled whales would suffer a slow death by starvation, and nets would be unserviceable for long periods.

"Sharks are preying on humans": The overwhelming majority of shark attacks around the world are no more than an inquisitive investigation rather than a predatory attack. These animals are supreme predators equipped to take out large prey, and yet most encounters with humans can be described as "bumps" in their terms. Sharks have never - and will never - "prey"on humans on a predictable and repeated basis.

"All bathers are at high risk of shark attack": Different water-use activities carry very different risk profiles. All the recent attacks in False Bay have involved ocean-users practising extreme sports and venturing far distances offshore. These ocean-users are all aware and have accepted this level of risk because of the enjoyment these sports provide. Most importantly, though, these extreme activities carry a very different risk profile compared to bathers wading waste-deep in the inshore area.

It's a bit like striking the fear of imminent mortal danger into the hearts of all day-hikers on Table Mountain, following a rock-climbing accident on an extreme rock face of the mountain.In considering a way forward, I need to commend the rational approach that has prevailed within the City of Cape Town and the Department of Environmental Affairs and Tourism.

More than eight months ago, these parties approached WWF South Africa to facilitate a process of drawing together the best-available scientific evidence in South Africa (if not the world) to inform the development of a policy to manage Great Whites and the recreational safety in the waters of the Western Cape. This culminated in a successful workshop at the end of May, the proceedings of which will be made public on September 12.

These recommendations have also informed the development of a draft policy by the city that will be adopted and released for public comment at the same time. I am confident that this policy walks the middle road of rationality, practicality and logic and will provide water-users with options that suit the level of risk they wish to expose themselves to.Unfortunately, like too many things in life, no quick-fix, blanket solution exists. Several technological options are being investigated, like electronic barriers and sonar detection devices.

None of these is operational yet and, for now, the novel shark-spotter programme remains a kingpin of the city's strategy.Although still in its infancy, the programme has been highly successful at the beaches where it is operational, and is very likely to be expanded in the near future, with the help of the city, WWF and the Table Mountain Fund.Ultimately, however, our personal safety can only be our own personal responsibility.

The first thing each individual recreational water-user needs to do is to make a conscious decision about what level of risk we wish to expose ourselves to. Once we have made this decision, we need to start behaving accordingly.At the individual level, a number of measures exist through which we can all decrease our risk of an encounter with a Great White. A recent innovation is a personal electronic shark repellent device, called a Shark Shield. These devices, costing about R2 500, are available for surfers, swimmers and divers.

Under test conditions with Great Whites in heightened predatory behaviour, these devices were proven to reduce the risk of attack by more than 80%. In an already low-probability scenario (of encountering a Great White), a further reduction in risk by more than 80% would decrease one's risk to almost zero.Now this is where I have a problem with human logic. An average dedicated surfer owns at least two surfboards (at about R2 500 a pop) and about two wetsuits (at about R1 500 each) and spends at least R6 000 a year on fuel and car maintenance getting to and from surf spots.

By comparison, the cost of a electronic shark repellent does not seem prohibitive. These devices are certainly affordable for the small but vocal group of surfers that are advocating that we go out and hunt sharks - a course of action that has a much higher financial and environmental cost, and one that is totally ineffectual.Is it purely coincidental that in the alternative scenario, someone else will need to carry the financial costs, or is it just that electronic shark repellents don't look cool?

Other measures exist for occasional bathers, who cannot afford such devices, to reduce their risk. The further offshore you venture, the higher your risk. Don't swim alone, at dawn or dusk, when the waters are murky, or in areas where there are signs of high fish activity (birds diving, dolphins and seals are feeding). Bathe at beaches where shark-spotters and lifesavers are on duty.

Bathers should take note of the flags that indicate whether shark-spotters are on duty and if the visibility is adequate.Finally, the most significant action that all recreational water-users can take to reduce their risk is to drive more carefully on the way to the beach. Statistically, you stand a far greater chance of being involved in a car accident on the way to the beach than being attacked by a shark.

I say this not to make light of a serious issue, but merely to make the point that on a daily basis we engage in many activities that carry far higher risks to our personal safety and survival. In these situations we all make daily decisions about the level of risk we wish to expose ourselves to (for example, the manner and speed at which we drive, our exposure to violent crimes, whether we smoke, how much alcohol we consume).

Why should the oceans be any different?The relative success of humans compared to other species on this planet is largely attributable to our ability to logically process best-available information and to make rational and practical decisions based on this, for our own safety and survival.Let's not allow a media hype to cloud our strongest trait. Achmat Hassiem and his family haven't.


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