Australia’s Shark Attack Hot Spots Revealed
Did you know you’re more likely to be attacked by a shark after it rains? Australian researchers have revealed the country's shark attack hot spots and when to avoid the water.
World-first study 'Modelling Shark Attacks, Australia' was led by researchers from Macquarie University, with assistance from the Taronga Conservation Society, the NSW Department of Primary Industries and the University of NSW.
The study analysed data of every known shark attack in Australian waters from 101 years' worth of records kept in the Taronga Zoo-curated Australian Shark Attack File.
The likelihood of a shark attack can be predicted using oceanographic and climatic forecasts, said study co-author Nathan Hart of Macquarie's Department of Biological Sciences.
Over the 101-year period to 2015, there were 835 attacks in Australia waters from 12 different species.
“Shark bites are still rare events but they have been increasing substantially over the past 20 years and often occur in clusters,” Hart said.
“One of the key findings is that you can't just lump all sharks together; you get a much better result if you use different models for the different species of shark and this reflects differences in their ecology."
The Big Three
The study found that great white sharks, bull/whaler sharks and tiger sharks are responsible for 75 per cent of all attacks.
All fatal attacks, which account for one-in-four of all shark bites, were attributed to these three types of sharks.
Of the 630 attacks attributed to those three species, researchers analysed the conditions of 531 attacks.
Great white sharks accounted for 237, 160 were by tiger sharks and 132 were by bull/whaler sharks.
Far-North NSW / South-West WA: Great White Hot Spots
Almost one-in-five great white attacks happen on the NSW far north coast, near Ballina and Byron Bay, so researchers looked at the history of sea surface temperatures in the region.
The water conditions at the time of these attacks were cooler than surrounding areas or compared to the same location a year before or after the attack.
“These pockets of cooler water are caused by upwelling events, where dense, cool, and nutrient-rich water gets forced up against the coast," Hart said.
"Such areas of the ocean are highly productive and sharks may be attracted by the abundance of fish or other prey, such as seals, that might follow the fish.”
The south-west coast of Western Australia was also found to be a great white hot spot.
Attacks also peaked after monthly rainfalls of more than 100 millimetres, particularly near river mouths.
Sydney / Northern Australia: Tiger Shark Hot Spots
Sydney is a hot spot for tiger shark attacks, but they are mostly seen around tropical reef locations, particularly in northern Australia.
Like the great white, the risk of being attacked by a tiger shark increases after rainfall.
“In a similar way to what we see with changes in ocean currents, if you have substantial rainfall it washes out nutrients and they are then concentrated where the river meets the sea, so you’re likely to see higher productivity which leads to higher fish populations, so sharks are going to be attracted to that,” Hart said.
East-Coast Queensland / North WA: Bull/Whaler Shark Hot Spots
These sharks are more likely to attack at high latitudes near the east coast of Queensland and along the north of Western Australia.
They are also prevalent in the Whitsundays.
Bull/whaler shark attacks are more likely to happen in summer and within one kilometre of a river mouth.
"Especially with high rainfall, you might also get a very turbid environment close to the river mouth because the water washes down a lot of silt," Hart said.
"This might increase the likelihood of getting bitten by a shark because they can’t see you as clearly and they’re having to rely on their other senses to decide what you are, and so they may end up mistaking you for their normal prey or just biting you out of curiosity."
The researchers hope this information can help authorities predict when the risk of a shark attack is higher and warn those thinking of entering the water with increased patrols, flyovers and signs.
"We don't want people to stay out of the water and we’re not trying to freak them out,” Hart said.
“Rather, we’re hoping to increase education about risk and better target resources that might be deployed in that area to try and keep people safe.”