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Scientists try to manipulate shark senses to prevent attacks


Researchers rely on the intelligence and learning ability of animals to create alternatives to slaughter.

The Australian government recently authorized shark slaughter on the east coast of the country due to the increasing number of attack deaths. There have been seven in the last three years, compared with 20 in the last century.

Killing will protect bathers, according to the Australian government. 'We are confident that the measure taken is the right one. We'll move on, 'said Western Australia State Prime Minister Colin Barnett.

But scientists disagree with the measure. In an open letter, 100 researchers ask it to be reviewed because of its environmental impact and the unlikelihood of finding the shark that caused a specific attack.

"Every scientist I talk to agrees that killing is not the right thing to do," says Rodney Fox, who survived a white shark attack 50 years ago and has since become a staunch defender of these animals. "We have to learn to live with them instead of just killing them because we are afraid of being attacked."

Sharks have been around for at least 400 million years and over that time have evolved into a wide variety of species, many of them peaceful. Even so, the fear of being attacked is the first thing that comes to mind when meeting one of them face to face. In fact, the sharks should be scared.

A quarter of all shark species and their relatives, stingrays, are threatened with extinction, according to a recent report by the International Union for Conservation of Nature (IUCN).

The reason is predatory fishing, especially for larger species. Millions of sharks die this way every year.
Meanwhile, a person's chances of being killed by a shark are less likely than they are to die from lightning, a bee, or a car accident.

So scientists are looking for new ways to deal with the problem of human shark attacks for the good of both species. "We want to protect humans and sharks at the same time," says Shaun Collin, who leads a team of neurobiologists who are trying to learn to think like these fish.

They study how sharks' brains and five senses work to test nonlethal ways to prevent them from approaching or attacking people. One is an outfit that makes a human like a poisonous sea snake, which is usually avoided. by sharks. The outfit has white and black stripes, like the snake. Because sharks see poorly, the stripes are large enough to be detected at a distance.

The idea was suggested some years ago by marine biologist Walter Starck and is now being tested. Barrels full of dead fish are covered with clothing and thrown into the sea to see how sharks react.

So far the results have been positive, according to Nathan Hart, professor at East Australian University. "It works like a seat belt," Hart explains. "It reduces the risk of attack to some extent, but not to zero."

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Another strategy tested by scientists is to prevent sharks from entering certain areas where it would be safe to swim. One of these techniques involves placing a perforated pipe at the bottom of the ocean and pumping air into it to create a curtain of bubbles in the water.

Sharks can see and hear bubbles and feel them through the line that runs along the side of their body, a kind of sense that many fish have. "It's a system known as 'distant touch,'" says Hart. "It detects vibrations and low frequency sounds in the water."
This would discourage the shark from crossing the bubble curtain. However, tests with tiger sharks have shown that at some point these animals sometimes decide to test the curtain and cross it, suggesting that they have the ability to learn.

Marine biologist Eugenie Clark of the Mote Marine Lab in Florida was one of the first to demonstrate this skill in the 1950s. She trained sharks to press their snouts against a target or use them to ring bells for food.

This sign of intelligence indicates that they can learn not to attack humans. I personally witnessed this when I was on the Fiji Islands and dived with about 100 bull sharks, a species known for its aggressiveness.

As I prepared for the dive, where there would be no cage or protection, I didn't know how I would react to them. But just being in the water made my fear go away. I saw how a bull shark can be calm and graceful.

Local inhabitants taught the animals to approach each diver and to gently pick up a piece of meat that is offered to the shark. That is, they learned to behave in exchange for food. "They know us very well," the diver Papa told me. 'That's good: they know what's going on.'

In this way, the inhabitants are not only trying to change sharks' bad reputation, but also to prove that a live shark is far more valuable than a dead shark.

(//g1.globo.com/nature/news/2014/04/scientists-Try-manipulating-tubaro-senses-to-block-attacks.html)