Tuesday, December 23, 2008

Is your fear of sharks based on facts or fiction?

Shark attacks are the stuff of nightmares and horror movies. Steven Spielberg's Jaws has a lot to answer for.

It's probably the thought of something menacing watching us from below - razor sharp teeth bared and soulless eyes masking an insatiable hunger for flesh. If Spielberg is to be believed, from the moment we set foot in the water, our life span can be measured in moments.

Yet history shows us the
chances of being attacked are extremely unlikely - you are far more likely to drown or be killed in a car smash on your way to the beach.

Each year, over summer, reports of
shark sightings dominate the news and old fears are raised anew.

This year is bound to be the same. As the weather heats up, Kiwis flock to the beaches in their thousands and, with more eyes at the beach, shark sightings are inevitable.

Already a half-tonne mako has been caught off Nelson and a 2.4 metre thresher shark scared swimmers out of the water in the Bay of Plenty. Kite surfers on their way across the Cook Strait also recently reported surfing past a two-metre shark.

Few creatures capture the imagination or instil such a sense of fear as the shark, but scientists believe that fear is unreasonable.

New Zealand has around
66 different sharks species and very few of them are dangerous to humans.

NIWA shark expert Malcolm Francis tries to put the threat of an attack into context:

"Humans are a top predator ourselves and we don't like the idea that there is another predator out there that is bigger and stronger than we are and might eat us.

"But, having said, that there's a lot more people killed every year by tigers, lions, hippos round the world than there are by sharks and yet we seem to have this real fear of sharks and what they might do to us."

He points to the fact millions of people are in the water over summer, surrounded by sharks, yet the attack rate is incredibly low.

According to the Conservation Department, there have been 13 fatal shark attacks recorded in New Zealand in the last 170 years - the last was 32 years ago when a spear fisherman was attacked at Te Kaha in the Bay of Plenty.

"That just indicates to me that they're not really considering us as food at all," he said.

Francis says that, if sharks wanted to eat us, we would never be able to go in the water.

"They are out there in numbers and they are all around the coast ... it's extremely likely that when we have been in the water, there has been a shark there that's ignored us."

Francis likens shark attacks to plane crashes: "When they happen they're horrifying and particularly nasty but
the chances of them happening is extremely low," he said.

A diver for over 30 years himself, Francis says he has only ever seen three sharks while in the water - none of them dangerous.

Scientists have identified most attacks happen during daylight on adult males aged between 18 and 30 - the group that happens to spend the most time in the water and the time-of-day they tend to be there.

The only places Francis says to avoid swimming are near seal colonies, and dead animals. Spear fisherman should also get speared fish out of the water straight away, or at least keep them as far away from their bodies as possible.

People should also try to swim in groups and not too far from shore, to ensure help is at hand should they be bitten.

Most attack fatalities are the result of blood loss from a bite, rather than the shark eating its victim, he says. They will attack, bite their victim, and back away for up to 15 minutes - a defence mechanism he says they have built up to protect themselves from the teeth of seals, their main source of food.

This often allowed the victims' companions time to get them out of the water and do first aid.


Though more eyes at the beach inevitably mean more sightings, Francis says it's true there are more sharks around over summer.

Populations in coastal areas increase as sharks come in to breed and feed, though most will be small and harmless.

The chances of bumping into a big, dangerous shark are remote - but if you see one, it pays to get out of the water, Francis says.

It appears a lot of the fear and misinformation about sharks comes from a startling lack of scientific information.

The shark which the general public know most about - the great white - scientists actually know very little about.

New Zealand is recognised as one of the world's hot spots for the apex predator, along with the waters off California, in the United States, and South Africa, Australia and Japan.

However, Francis says that, despite their fearsome reputation, great whites are extremely cautious. When Francis and his team tried to attract sharks with blood and bait in the water, some would circle the boat for hours, deciding whether or not to take the bait.

This suggests they are curious but selective when choosing their prey, he says.

NIWA, the Conservation Department and Dr Ramon Bonfil from Shark Tracker/NABU in Germany, have been tagging great whites with satellite tags since 2005.

Though the data is still sparse, the research has yielded some surprising results and Francis believes they are making progress.

After analysing the data from 10 tags, scientists were surprised to find great whites were leaving New Zealand and heading from the Chatham Islands to Tonga - a journey of over 3000km.

Scientists can only guess why the sharks undertake this epic journey, but believe it must be to chase food - probably humpback whales.

What science has told us is that shark numbers are drastically low. Nineteen of the world's shark species are listed as vulnerable, 17 endangered, and four critically endangered, according to the 2000 World Conservation Union Red List.

Four New Zealand sharks - including the basking, spiny dogfish, whale and great white - were listed as vulnerable.

Humans kill more than 100 million sharks worldwide each year, in recreational and commercial fishing.

Though Great Whites have been protected in New Zealand since 2007, many are still caught in nets and on long lines by commercial fisherman.

There is no penalty for accidentally catching sharks, but fishermen must report it to the conservation department within 24 hours.


Knowledge is essential in order to ensure their survival. Francis believes that, if we can identify when and where sharks are, we can design management measures to reduce shark by-catch in fisheries.

"[Sharks] don't really have the reproductive capacity to bounce back very quickly so unless we take the pressure right off, it's going to be hard for the populations to increase back up to normal."
Scientists believe the shark population is going down, but don't know the rate of decline.

One thing is certain: sharks across the globe are in danger of being wiped out. There are already vast areas of the ocean where sharks have been fished out, Francis says.

Francis believes people have a moral imperative to protect sharks. But only further research and policy change will save them.


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