Great white sharks hold many secrets

Many conservationists believe great whites are disappearing from the oceans, but a scientist says there's a lot we can learn from them.

The great white, witdoodshaai, squalo bianco, grand requin blanc, menschenhai, the man-eater and even the white death.

Humans know many names for Carcharodon carcharias, but much about the world's largest predatory fish remains a mystery.

Great whites are the apex oceanic predator, and are found throughout Australian waters, from the bight to the Torres Strait.

They use the continental shelves like highways, and some can travel thousands of kilometres in a few months.

But no human has ever seen a great white mate or give birth.

There are just a handful of nurseries along the coast where juveniles congregate before they're big enough for the open ocean.

One is off Stockton beach, in NSW, and large numbers of young great whites regularly swim within the surf line, beneath unsuspecting bathers.

But great white attacks are extremely rare given the number of people entering the water each year.

In Australia, there have been nine fatal attacks blamed on great whites since 2002, but Griffith University's Dr Jonathan Werry believes we don't have much to worry about.

There are many theories about why they attack humans - we look like seals when wearing wetsuits, or maybe sharks associate us with food because of excessive chumming by shark cage diving operators and fishing fleets - but none are proven.

Werry sees a pattern emerging from the incidents (he doesn't call them attacks).

He says most incidents have occurred in areas that are far away from known great white nurseries and feeding grounds.

"The sharks involved are just passing through the area," he says. "They're not locals, so to speak.

"Sharks are not crocodiles. Humans are prey for crocodiles every time.

"But great whites may be different to other sharks. We need to do more research on them to find out."

However, Werry says it's very extremely important to preserve great whites, not just because removing them would upset the ecosystem's food chain.

He says great whites' vertebrae, skin and tissue hold a record of the environment, like tree rings or ice cores do.

Great whites can live for up to 70 years and act like oceanic encyclopedias, storing decades of information about pollution levels and fish stocks.

Werry says a four-metre male white was recently found dead with its huge head stuck in a underwater cave off Sydney Harbour.

When researchers ran tests on its body, they found it had been poisoned by a build-up of toxins.

"There were moderate amounts of these toxins in the harbour, but the animal died because of years of exposure, causing an overload in its system," he says.

"If that sort of thing is happening at the top of the food chain, it must be occurring lower down."

Werry believes that if we can learn more about great whites, we can protect them, humans and the oceans.

"It's very hard to study them, but we should try," he says.

"Great whites can still teach us so much."


Share

3 min read

Published

Updated

Source: AAP


Share this with family and friends


Get SBS News daily and direct to your Inbox

Sign up now for the latest news from Australia and around the world direct to your inbox.

By subscribing, you agree to SBS’s terms of service and privacy policy including receiving email updates from SBS.

Download our apps
SBS News
SBS Audio
SBS On Demand

Listen to our podcasts
An overview of the day's top stories from SBS News
Interviews and feature reports from SBS News
Your daily ten minute finance and business news wrap with SBS Finance Editor Ricardo Gonçalves.
A daily five minute news wrap for English learners and people with disability
Get the latest with our News podcasts on your favourite podcast apps.

Watch on SBS
SBS World News

SBS World News

Take a global view with Australia's most comprehensive world news service
Watch the latest news videos from Australia and across the world