Shark attacks increase in El Nino years: Marine biologist
CLIMATE change is bringing more sharks closer to Australia's beaches and increasing the number of shark attacks.
This is one hypothesis of marine biologist Dr Blake Chapman, who's new book, Shark Attacks: Myths, Misunderstandings and Human Fear, is sure to land under the Christmas trees of Northern Rivers surfers next month.
Dr Chapman said global warming was having an effect on these marine creatures.
"We know this affects shark interaction as shark attacks increased in 2009 and 2015 and they were El Nino years," she said.
"This means we had higher water temperatures and change of currents which affects them."
During 2015, the Bureau of Meteorology reported an increase of 2 degrees Celsius to sea surface temperatures, meaning very warm ocean water was pushed towards Australia.
According to the International Shark Attack File, 2015 set a new record for shark attacks around the world, with 98 incidents, including six human fatalities.
The Australian branch of ISAF reported of the 33 shark and human interactions in Australia that year, 22 were unprovoked attacks, with 16 of these from great white sharks and two from bull sharks.
In 2015 Australia recorded 14 unprovoked attacks in New South Wales, four in Queensland, two in Western Australia, one each in South Australia and Victoria.
Dr Chapman said an increase of human activity in the water, from surfers to divers, swimmers to fishers was also a factor.
However, while shark attacks grab the headlines, Dr Chapman said numbers were extremely low compared to other causes of injury and death.
"We have 10 to 20 shark bites per year in Australia and two fatalities annually and while these are very sad and often traumatic circumstances, when you put them in perspective with numbers such as road accidents, these numbers are so low," she said.
"There were 280 drownings in Australian waterways last year, but don't hear about these because of the graphic nature of shark attacks and when we look at the numbers of shark encounters people have, it appears only five per cent are negative."
On the face of scientific evidence, Dr Chapman said globally shark number appeared to be declining, but more ongoing research was needed.
"It is important to acknowledge the age of these scientific studies so we not using reactive evidence as we are seeing a lot of anecdotal reports to suggesting shark numbers are increasing," she said.
"But doing up-to-date studies of shark populations really deserves investigating."
However, Dr Chapman said counting sharks and tracking them, even with electronic tags, was not as straightforward as it sounded.
"Sharks are a migratory species and counting them is very difficult even with tagging," she said.
"White and tiger sharks are highly mobile species and their use areas are known to shift due to environmental variables."
Along with shark attack victims, Dr Chapman conducts research on their effects on first responders who attend the incidents or work with the injuries.
"One of my favourite things is talking - and listening - to people and hearing their shark stories from people who have been affected such as surgeons, paramedics and nurses," she said.
When it comes down to shark nets versus SMART drumlines, Dr Chapman is firmly on the side of the latter.
"I think there is a high degree of psychological comfort with shark nets and we get 40 per cent of the sharks on the beach side of the net," she said.
"I like the way we are moving towards the SMART drumlines and SMART nets."