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更新时间:2018/3/18 10:50:24 来源:本站原创 作者:佚名

Can technology save you from a shark attack?

In mid-January this year, during the heat of the Australian summer, shark scientist Charlie Huveneers set off towards the Neptune Islands, near the mouth of South Australia’s Spencer Gulf. Here, about 250km (156 miles) south-west of Adelaide, is one of the Australia’s largest aggregations of great white sharks, and also the centre of the nation’s cage-diving tourism industry, which brings in around AUS$8m (£4.5m).

今年1月中旬,正值澳大利亚夏季最炎热的时候,鲨鱼科学家查理·胡芬尼尔斯(Charlie Huveneers)启程前往南澳大利亚斯宾塞海湾(Spencer Gulf)口附近的内普丘恩群岛(Neptune Islands)。这里位于阿德莱德(Adelaide)西南250公里处,是澳大利亚最大的大白鲨聚居地之一,也是澳大利亚鲨笼潜水旅游业中心,每年带来大约800万澳币收入。

Over 18 days, Huveneers – who heads the Southern Shark Ecology Group at Adelaide’s Flinders University – tested a series of commercially available shark deterrent devices to determine their effectiveness in repelling the ocean’s most feared predator. Over many long days at sea, his team observed sharks from its boat and with cameras below the waves. During 300 trials, they studied sharks approaching potential prey some 1,500 times.

在18天的时间里,阿德莱德弗林德斯大学(Flinders University)南部鲨鱼生态小组(Southern Shark Ecology Group)组长胡芬尼尔斯测试了市面上的一系列驱鲨设备,以判断其对海洋中最可怕的这种掠食动物的驱赶效果。团队每天长时间停留在海上,从船上和水下摄像机观察鲨鱼。在300个测试中,鲨鱼靠近潜在猎物大约1500次。

The work they are doing to test repellents is vital. Shark attacks are increasing in Australia, and more of these devices are being sold than ever before, but very few models have been independently tested to match manufacturers’ claims.


“Personal shark repellent or deterrent devices are the ‘holy grail’ of shark bite prevention, but the efficacy of some of the most popular products is questionable, and most have never been subjected to scientifically rigorous independent testing,” says Carl Meyer, a shark ecologist at the Hawaii Institute of Marine Biology in the US.

"个人驱鲨器是防止被鲨鱼攻击的'圣杯',但是一些最受欢迎的产品的效果却存在问题,大多数都没有经过科学、严谨的独立测试,"美国夏威夷大学海洋生物研究所(Hawaii Institute of Marine Biology)的鲨鱼生态学家卡尔·迈耶(Carl Meyer)说。

These devices can be beneficial, as long as people understand their level of effectiveness and how much they actually reduce the risk of attacks, Huveneers says. He warns that some devices “might create a false sense of security and lead people to put themselves in riskier situations”.


While shark attack fatalities in Australia have remained fairly constant, at an average of around one a year, the number of bites per year doubled when researchers compared the period between 2000 to 2015 with 1990–2000. Specific clusters of attacks have led to public outcries for the authorities to do more. In Western Australia (WA), 15 fatalities since 2000 led the state government last year to offer a controversial AUS$200 (£112) rebate towards purchasing a AUS$750 (£421) electrical repellent – the Shark Shield FREEDOM7. In November, they put another AUS$200,000 (£112,000) towards this scheme.

在澳大利亚,鲨鱼攻击导致身亡的事件数量基本保持稳定,平均大约一年一例。不过研究者发现,如果把1990-2000年和2000-2015年进行比较,会发现每年鲨鱼咬人事件的数量翻了一番。一些密集发生的鲨鱼袭击事件导致公众呼吁相关部门加强措施。在西澳大利亚州,2000年以来发生了15起鲨鱼攻击导致身亡的事件。州政府去年推行了一项有争议的政策,每购买一件价格750澳元的电驱鲨器——Shark Shield FREEDOM7——就能获得200澳元的退款补助。11月,他们又为这项计划追加了20万澳元的拨款。

But do these devices actually work? Huveneers says he supports the WA government for selecting one of the only repellents independently tested by scientists. As reported in the journal PLoS ONE in 2016, he was part of a team including University of Western Australia scientists, that tested it in South Africa. By attaching the electrodes to baits in waters abundant with white sharks, they showed the FREEDOM7 repelled them 90% of the time, but was only effective to about 1m out from the device.

但是,这些设备真的有效吗?胡芬尼尔斯说,他支持西澳大利亚州政府选择了一款经过科学家独立测试的驱鲨器。根据期刊PLoS ONE在2016年的一份报道称,胡芬尼尔斯和西澳大学的科学家组队在南非测试驱鲨器。他们在白鲨聚集的海域安装了带电极的诱饵,结果表明 FREEDOM7的驱赶成功率为90%,但是有效范围仅限设备周围一米左右。

The Shark Shield takes advantage of the fact that sharks have sensory organs around their snouts called ampullae of Lorenzini, which enable them to detect prey via the weak electric fields they emit. But an artificial electrical field can be used to overwhelm the organs, causing the shark discomfort. This is what a Shark Shield does, by generating a field between two electrodes on an antenna. The charge is produced by a unit worn on the swimmer’s ankle, with the antenna and electrodes trailing behind.

Shark Shield驱鲨器利用了鲨鱼口鼻部分名为"劳伦斯壶腹"(Lorenzini)的感官——它能发射微弱的电场以探查猎物。但是人工电场能够超过该感官的负荷,让鲨鱼感到不适。这就是Shark Shield驱鲨器的原理:通过天线上的两个电极制造出电场。游泳者把产生电荷的设备戴在脚踝上,后面拖着天线和电极。

It is one of several repellent devices that use an electric field. And while there are other approaches, Meyer agrees that electrical repellents have the greatest potential.


“Sharks have a highly sensitive electroreceptive system that may produce an avoidance reaction if over-stimulated by a man-made electric field,” he says. “Widely-spaced dipoles can effectively shroud your entire body in an electric field.” However, a problem with many existing products is that the field covers little more than a diameter of 1m, meaning it can’t protect the whole body.


The repellents recently tested at the Neptune Islands included several untested electrical devices, magnetic deterrents, and a kind of surfboard wax meant to mask the smell of the surfer with natural products such as clove oil and cayenne pepper.

最近在内普丘恩群岛(Neptune Islands)测试的驱鲨器包括几种此前未经测试的电驱鲨器、磁力驱鲨器,还有一种冲浪板蜡。它是用丁香油和辣椒粉等天然产品遮掩冲浪者的体味。

The idea behind magnetic deterrents – such as wristbands containing strong magnets produced by a company called Sharkbanz – is that they work in a similar way to the Shark Shield, creating a field that overwhelms a shark’s ampullae of Lorenzini.

磁力驱鲨器——比如Sharkbanz公司生产的强磁腕带——的原理类似于Shark Shield驱鲨器,它会产生一个磁场,超过鲨鱼的劳伦斯壶腹的负荷。

While the theory is sound, a magnetic field becomes very weak even just a few centimetres from the device, says Meyer. “A shark might, or might not, avoid eating your wrist-worn device, but the rest of your body is certainly unprotected.”


Other approaches have been to develop devices that produce the sounds of hunting killer whales (a predator of sharks), or wetsuits and surfboards with camouflage that mimics the banded patterns of venomous and unappealing prey, such as sea snakes.


Some research suggests that auditory repellents are ineffective, or sharks quickly get used to them.


“Shark hearing is optimal at low frequencies and poor-to-non-existent at the higher frequencies typical of orca calls,” says Meyer. Meanwhile, research in Queensland has revealed that sea snakes are in fact very commonly found in the stomachs of tiger sharks, so perhaps not so unappetising.


Huveneers adds that surfers and surfboards, seen by sharks cruising along the sea bottom, may merely appear as dark silhouettes at the surface, so colours and patterns are often irrelevant.


Chemical repellents have also been created and trialled over the years, with one currently marketed product being an aerosol spray called Anti-Shark 100, made by Shark Tec, which says it is “derived from putrefied shark”.

还有化学类驱鲨器,已经试验多年。市场上现有的一种产品是Shark Tec公司生产的名为Anti-Shark 100的气体喷雾,据称它"是由腐烂的鲨鱼制作而成"。

There is some evidence that sharks steer clear of the ‘necromone’ chemicals produced by other decomposing sharks, Huveneers says. “The reason for sharks to be deterred by this smell is unknown, but from an evolutionary perspective, it makes sense to leave an area where a conspecific [same specis] has recently died, as it might indicate danger.”


Still, while many chemicals are irritating or unpleasant to sharks, they dissipate rapidly into the water column, he says, limiting their effectiveness.


“You’d have to see the shark coming and then release this aerosol into the water, and a lot of sharks prefer sneak attacks,” says Blake Chapman, a shark researcher at the University of Queensland and author of Shark Attacks: Myths, Misunderstandings and Human Fear. “So, having a device where you have to see the shark first, and then release some sort of cue that it doesn’t like and leave… I can’t imagine that it’s going to buy you a lot of time.”

"你必须看到鲨鱼靠近,才会把喷雾释放到水中,但是很多鲨鱼更喜欢偷袭。"昆士兰大学的鲨鱼研究者、《鲨鱼攻击:迷思、误解和人类的恐惧》(Shark Attacks: Myths, Misunderstandings and Human Fear)一书作者布莱克·查普曼(Blake Chapman)说,"所以,如果要使用这种设备,你首先要看到鲨鱼,然后释放它不喜欢的信号,让它离开……我无法想象你能争取到多少时间。"

Chapman argues that no repellent device can ever be entirely effective. “I wouldn’t put my life in the hands of any of these devices,” she says. “It comes down to a shark’s motivation. If you have a 3m to 5m great white, bull or tiger shark that’s starving, I can almost guarantee that nothing we’ve discovered, and probably nothing we will discover for some time, will deter that shark.”


She also questions whether it’s likely that a large shark will abort an attack, a metre out from a prey item, once it has committed to swimming at high speed towards it.


Huveneers admits that repellents are unlikely to stop highly motivated sharks, but says the South African trials showed that sharks are highly manoeuvrable and can and will abort attacks at very short distances from potential prey.


He does, however, note that people need to be aware that repellent devices are often only effective in specific locations, for specific activities. Therefore, a device that may show some use for repelling white sharks from attacking surfers off the coast of Cape Town might be completely ineffective at protecting scuba divers from lurking bull sharks in Sydney Harbour.


“I see the refinement of electrical-current based devices as the best bet for effective personal shark repellents, but I don't see any device ever being 100% effective,” agrees Meyer.


Chapman says that in the future current technologies may evolve into more effective means of stopping investigative bites, but argues that the most effective tool is education. “People taking time to understand these animals and the situation will alleviate so many more events than any technology could… Just be smart about where you swim,” she says.


Research is, for example, uncovering clues on shark movement patterns that might reveal what times of the day and year are best for reducing the risks associated with various activities in the sea.


Despite the increase in shark incidents in WA in recent years, some estimates suggest the chance of being bitten by a shark off Perth is still only about one in 30 million. To put that into perspective, you’re about 100 times more likely to be struck by lightning.


Nevertheless, Chapman says that if shark repellent devices allow people to feel comfortable entering the water, then it’s already a great outcome. “These things may or may not work, but the chances of being bitten is so small, that if it’s giving you peace of mind to go out there and do your activity then it’s doing its job.”