How To Prevent Shark Attacks

In light of the most recent shark bite fatality in Western Australia (WA) last week, there have been renewed calls for a cull of large sharks to protect ocean users. Environment minister Greg Hunt has said he wants to reduce the risk of attacks. So what is the best way to reduce that risk?

Picture: Getty Images

Are shark bites increasing?

There is no denying that each of these events is a tragedy and our sympathy is, of course, with the family and friends of the victims. However, based on statistical data, the number of shark related fatalities is negligible when you consider the vast and increasing number of swimmers entering our coastal waters every year.

Research has shown the number of shark bite incidents occurring each year appears to be directly related to the amount of time people spend in the sea. Given that Western Australia has the fastest population growth of any Australian state, there is likely to be an increasing number of people venturing out into our coastal waters every year. Thus, the likelihood of someone encountering a shark increases and with it a corresponding increase in shark bite incidents.

Politicians and the public are often quoted in the media saying shark numbers in WA have increased. But most experts would agree that there is no evidence to support such a statement.

Data gathered by Surf Life Savers WA has been used to suggest an increase in the number of sharks in WA, by stating that more sharks were sighted in 2012/13 (285 sharks) than in 2011/12 (247 sharks).

However, when you account for the number of hours that the helicopter patrols were out looking for sharks (2012/13: 751 hrs; 2011/12: 620 hrs) we find that they sighted the same number of sharks per hour of patrolling (approximately 1 shark every 2.5 hrs).

In fact, research shows that the number of attacks per million people in Australia almost halved from approximately 60 per million people between 1930/1939 to approximately 30 per million people between 2000/2009.

Does culling work?

So often the argument in favour of a cull comes down to the emotional question of who is more important: a human or a shark. Rather, we need to ask the question, will culling sharks actually reduce the risk of an attack?

The answer is no. In fact, when shark culling was carried out in Hawaii, between 1959 to 1976, over 4,500 sharks were killed and yet there was no significant decrease in the number of shark bites recorded.

Culling has been the primary shark mitigation policy of the New South Wales Government for over 60 years, through the use of "shark" nets. But a report by the Department of Primary Industries showed that 24 of the 38 (63 per cent) attacks in the state, between 1937 and 2008, occurred at netted beaches.

Pre-emptively killing sharks is a response based on emotion rather than of scientific data.

How to reduce personal risk

We take a calculated risk whenever we enter the ocean, but the risk is quite small when compared to other daily activities. For example, new research shows that rip currents are the cause of an average 21 confirmed human fatalities per year in Australia, compared with 7.5 for cyclones, 5.9 for bushfires, 4.3 for floods, and 1 for sharks.

With the correct information, we can make an objective judgement as to whether or not we accept the risk to enter the oceans.

The WA Department of Fisheries recently released a report on how to reduce your personal risk of being bitten by a shark (and you can find more information at the International Shark Attack File).

  1. Stay out of the water if sharks have been sighted in the area.
  2. Stay close to shore (within 30m of the water's edge).
  3. Don't go in the water alone (stay in groups).
  4. Avoid water temperatures lower than 22C.
  5. Avoid water depths of greater than 5m when swimming or surfing.
  6. Avoid swimming after heavy storms, or in low light conditions (dusk and dawn).
  7. Avoid swimming if there are seals, dolphins, whales or baitfish nearby.

What the government can do

The WA Government are in a difficult situation. They genuinely want to protect ocean users, but at the same time they are well aware there is no "magic bullet" to prevent shark attacks across the large expanse of the WA coastline.

Their investment in monitoring and research has been a very positive step towards reducing shark bite incidents in the region, but the use of lethal control measures and the threats of a major cull of sharks is not the answer.

Instead, we need to better understand exactly what causes sharks to bite people, what factors are responsible for them venturing closer to shore and more about their biology and life history. Recent research has found, for example, that sharks' diving behaviour is affected by temperature and the moon, that female white sharks have different movement patterns to males, and that Australian white sharks have home territories they always return to.

This kind of research helps us better understand where sharks will be and how they're likely to behave. More of the same could help us develop strategies to coexist with these important apex predators and continue to enjoy the ocean safely.

The WA Government should also consider placing more emphasis on educating people about the risks, such as the times of day and conditions under which attacks are most likely to occur.

They could also put warning signs at beaches known to be frequented by "dangerous" sharks. We are unaware of a single beach in WA that has information boards related to the risks associated with encountering potentially dangerous sharks. This strategy is common practice in California and other places frequented by large sharks.

We will never completely prevent shark attacks, however, with better education and improved investment in monitoring and research we can reduce the risk and frequency of these tragic events.

Ryan Kempster is a shark biologist at the University of Western Australia. Shaun Collin is Winthrop Professor/WA Premier's Research Fellow at the School of Animal Biology and the Oceans Institute at the University of Western Australia. Ryan Kempster is affiliated with the University of Western Australia. Prof. Shaun Collin receives funding from the Applied Research Program (Shark Hazard Mitigation) administered by the WA State Government. He is part of The University of Western Australia (School of Animal Biology and the Oceans Institute).

The ConversationThis article was originally published at The Conversation. Read the original article.

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Comments

    How about just not swimming in where sharks live.

      So point one in "How to reduce personal risk" in the article?

    Has any ever thought that maybe it's the sharks culling humans in response to the increasing number of human attacks on sharks?

      http://www.troll.me/images/keanu-reeves-conspiracy/woah-thumb.jpg

    While they're off cleaning the ocean to make it safer. May I suggest they also flattern the entire country and cover it in a soft foam like substance as people often hurt themselves falling or tripping over.

    When can I pick up my government issues bubble packaging to wrap myself in when I get up in the morning. Getting up from my mattress build floor level with by foam floor. It helps to reduce injury from falling out of bed.

    I look forward to the great sun monocle being deployed to protect peoples eyes and skin from excessive sun damage.

    Thank you glorious leaders for such wonderful innovations to keep us safe... Oh wait, someone just drowned at the beach. Can some body please build a wall to keep the ocean out of the beaches to ensure people don't drown. Why isn't the government doing anything to stop this??? It's dangerous to go to the beach!!!

    Oh wait, yes it's dangerous to go to the beach and one of the risks among things like skin cancer, falling on rocks, drowning, heat stroke, swallowing too much water, sitting on a suringe, cutting your foot on a rock/broken glass, jumping off a rock and hurting your head/spine, being dumped from a wave into shallow surf, being hit by a surfer, falling on your surfboard, being caught in a rip tide, damage to your retina from staring at the sun and many other things is shark attacks. Shark Attacks is just one. It's a known danger. It's also a tiny small problem that due to it's nature gets a lot of press when it happens.

    Leave the sharks alone. It's just a tiny risk swimming at some places, by all means take precautions, but don't go out there killing sharks for basically the only purpose of avoiding the people of pretty much doing nothing by taking minor precautions when swimming at a beach where there could be sharks.

    Last edited 29/11/13 10:48 am

    Your hundreds of times more likely to killed by a fellow human either accidently or deliberately than a shark.
    Not to mention things like dogs,cows and kangaroos.

      Sadly, the government has repeatedly rejected my proposal to start culling humans.

    I like to stand in the middle of the street but the cars are a problem, I vote we should get rid of cars.
    Obviously horrible for all concerned (except the shark maybe) if someone gets attacked but culling isn't going to solve any problems, more likely create more (like a bloom of jellyfish), just something that is what it is and have to accept it.

    If you suggested that people go jogging across the Serengti they'd say it was a stupid idea. There's lions, cheetahs, leopards and a host of animals that could kill you. Yet the same people will happily swim in the ocean and are surprised (and outraged) when a shark takes a bite out of someone.

    Considering you have a massively higher chance of being killed in a car accident on the way to the beach than being killed by a shark at the beach itself, culling is simply a kneejerk reaction to appease the hand wringers. Sharks live in the ocean, when you enter the water you accept the risk.

    A few people are killed by some sharks and suddenly we're talking about culling them. Meanwhile more people die from drunk drivers and yet no-one suggests culling any of them. Yes, yes, human life is worth more than the life of an animal, I get that. But the sharks are in their own habitat, minding their own business, and doing what comes naturally. They only (occasionally) attack humans because they've mistaken them for seals or other food. Instead of culling the animals, people need to take responsibility for their own safety and do whatever they can do minimize the risk of shark attack (which is already pretty low anyway).
    I feel sorry for the people who have died and their families, but culling the sharks isn't going to do anything other than give people a false sense of security. Real life is not like Jaws.

    I would just like to vote in favor of the sharks.I myself for many years took part in a shark hunt in NZ every year.The prizes were great and a lot caught and killed.This was in the 70s and 80s.Now they stopped the hunt this year due to the fact that for over 400 plus anglers in nearly 300 boats over three days.ONE yes only ONE legal size shark ,that being over 20kg was caught.I feel we have done enough damage and since being here in Australia for seven years have not caught a single shark of any size.They have run out of food and we are now on the menu.

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