Believe It Or Not, Aussie Shark Numbers Have Plummeted
The number of sharks swimming along the Queensland coast has dropped by more than 90 per-cent in the past 50 years.
A fresh push for a shark cull was sparked in November after a spate of attacks, including a fatal bite in the Whitsundays. Politicians, boaters and tourist groups said the attacks were because there are simply too many sharks off our coasts.
Researchers from the University Of Queensland and Griffith University have now debunked those claims, revealing some species are actually quickly disappearing from our oceans.
Baited drumlines and nets were first put in the water in 1962 to reduce the risk of shark attacks. They now stretch along nearly 1800 kilometres of the Queensland coastline.
Scientists have been recording the number of hammerhead, great white, tiger and whaler sharks caught over this 55-year period, and the results -- published in the Communications Biology journal -- are surprising.
“What we found is that large apex sharks such as hammerheads, tigers and white sharks, have declined by 74 to 92 per cent along Queensland’s coast,” said George Roff, marine ecologist at the University of Queensland and lead author of the study.
“And the chance of zero catch – catching no sharks at any given beach per year – has increased by as much as seven-fold."
But it's not just the number of sharks decreasing, with the data also showing the sharks being caught are smaller in size.
“The average size of sharks has also declined – tiger sharks and hammerhead sharks are getting smaller," Dr Roff said.
Researchers are confident climate change is not to blame for the sharp drop, and instead suggest over-fishing is responsible. That includes recreational and commercial fishing as well as shark control programs in Queensland and NSW.
While the animals are often perceived as a danger to the public, experts say they're essential to coastal ecosystems.
“Sharks play important roles in ecosystems as scavengers and predators, and they are indicators of healthy ecosystems," said Dr Chris Brown, from Griffith University’s Australian Rivers Institute.
"These declines are concerning because they suggest the health of coastal ecosystems is also declining."
There are calls for authorities to take steps urgently to conserve shark populations before it’s too late.