Eight ways humans have tried to avoid shark attacks

Very little is known about great white shark numbers, but sharks worldwide are under threat and conservationists – even shark attack victims themselves – have called for a rethink of the cull. Even though Australia has laws that make it an offense to harm, capture or trade any member of a listed threatened species without a permit, as the Australian federal government has provided permits to fishermen the cull is above board.

Instead of killing rare, endangered and important shark species, we need to take note of other means at our disposal to keep these sea hunters at bay.

1. Shark barrier curtains

The most effective way of protecting beaches is to use a shark barrier, mesh nets and steel curtains set up around popular beaches. But there are issues around the problems with by-catch and the ability to protect only small areas of coastline.

Old Dunsborough beach on the Western Coast has just installed a trial shark protection barrier that extends 100m from the shore and runs parallel with the beach for around 300m. This is the second shark barrier trial on WA beaches, the first at Coogee Beach. No dead sharks, so far.

2. Satellite tracking

Little has been said about the Shark Monitoring Network, set up in 2009 to monitor movements of tagged great whites off the coast of WA. Having trapped and tagged 338 sharks so far, the network uses seabed monitors and satellite technology to provide early warning when tagged sharks swim close to beaches.

3. Imitate dead sharks

Developed by the US Navy in World War II, the “Shark Chaser” relied on the belief that sharks avoided dead sharks, and that copper acetate mimicked the odour of dead, decaying sharks. While early tests suggested promise, further studies showed that sharks were not affected – they were even seen eating the containers.

4. Chemical repellants

Following the Shark Chaser’s failure, chemical repellents were ignored for many years. But recently the work of Dr Samuel Gruber and his team in Bimini Island, Bahamas, has led to the development of semiochemical repellents. These work by chemically triggering sharks’ flight reaction, with some chemicals able even to immobilise some species in very low doses. Clothing and equipment using these repellents are now produced by SharkDefense Technologies since 2009.

5. Compressed air

Developed in Australia in the 1960s, the bubble curtain can be described as a garden hose with holes drilled into it, through which compressed air is pumped. This generates a thick cloud of bubbles, touted as an “impenetrable wall” no shark would cross. Sold to many US hoteliers, in 1961 it was tested and found to be totally inadequate – out of 12 tiger sharks, 11 passed through, and of these some were evidently playing in the bubbles.

6. Mano a mano with knives, Bond-style

 

 

 

 

 

 

 

 

 

 

 

 

While commonplace in films, diver’s knives or even harpoons are highly ineffective tools to stave off a determined shark attack. And equipping swimmers with weaponry or armour would be cumbersome and pretty much eradicate any enjoyment from being in the water.

CO₂-powered drogue darts are used by navies to deter sharks, but in the wrong hands they can cause more harm than good. The CO₂ dart can only be fired from the side or underneath, so in murky waters a shark seen only at the last minute renders them pretty useless.

7. Chainmail armour

The Neptunic™ has been available on the market since the early 1980s. The wearer wouldn’t look out of place on horseback, as it’s essentially a chainmail suit of armour. And while it offers some protection, it’s quite limited. Even the advertising states it is “a last line of defence” and that if bitten “bodily harm can and most likely will occur”.

So it’s not that effective, and for an outlay of more than US$5,000 is probably a bit steep for most beachgoers.

8. Electrical force field

Sharks are highly sensitive to electricity, and when confronted by small electrical currents are startled and tend to swim away. Higher voltages can paralyse or even kill.

 

 

 

 

 

 

 

 

 

 

 

 

 

There have been brisk sales of the Shark Shield electronic shark deterrent in recent years, particularly after a spate of shark attacks in Hawaii last year – eight shark attacks in Maui alone, and 14 across the islands, including the first shark-attack death in the state since 2004. Swimmers and surfers strap the devices that emit electric pulses to their ankles or to their surf boards.

In scientific trials researchers have found these have a deterrent effect on the behaviour of white sharks, but did not deter or repel them in all situations. Nor did it attract them, which is better than nothing.

Other ideas for electrical devices, such as electric fences around beaches or hand-held electric harpoons, have been dropped when development costs far outweighed the practicality or call for these devices.

So while shark barriers are expensive, have limited range, and have been found not to be fully effective on certain targets, is a cull that potentially causes serious harm to important species really the answer?

Sharks have not evolved for several million years as they are apex predators in their own environment. Who are we to encroach on their domain and not expect to – however rarely – get a bite taken out of us?

Nicholas Ray, Senior Lecturer, Nottingham Trent University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

https://www.sharkophile.com/2019/01/01/shark-shield-carroll/