Big bite: A bull shark (Carcharhinus leucas), the species thought to have been responsible for the attack at Woolloomooloo Bay.
Credit: Wikipedia/pterantula
SYDNEY: The recent increase in shark attacks around Sydney may be due to a variety of factors that are drawing the predators closer to shore, say experts.
"There is no evidence that shark numbers are increasing," said Mark Meekan, a fish biologist at the Australian Institute of Marine Science in Darwin. "We could simply be seeing more sharks closer to shore this year where there is more chance that they could interact with people."
Phoebe Hill, who studies sharks at Sydney University, agrees. Cleaner water and commercial fishing restrictions, which have led to increases in fish stocks, could be key factors responsible for the increased number of sightings around the harbour, she said.
Shark attack plan
The scientists' conclusions come as the New South Wales Department of Primary Industries today put forward a number of new proposals designed to reduce shark attacks. These include a new shark-tagging program, the use of GPS to monitor shark nets and a list of recorded attacks at each beach since 1900.
Extensive shark-tagging programs would be a good idea, said Hill. "We could then learn sharks' movements over time and potentially predict those movements more easily."
The recent attacks in Sydney have hit headlines around the world. Two days ago, a teenage boy surfing with his father off Avalon Beach became the third victim in as many weeks. On 12 February, a 2.5-metre great white mauled a surfer at Bondi Beach – the first shark attack at the beach in almost 60 years. The day before that, a navy diver fought off a shark in Sydney Harbour's Woolloomooloo Bay.
State-wide in NSW, there have been five attacks in just over two months, compared to eight for the whole of 2008.
Change of diet
Great whites of around 2.5 metres are starting to change their feeding diet, switching from eating mostly fish to feeding to marine mammals such as dolphins and seals, and this might help explain the Bondi attack, said Ian McDonald, NSW Minister for Primary Industries. Surfers, who venture into deeper water than swimmers, also more closely resemble a seal than a swimmer, said Hill.
To minimise the risk of a shark attack, both Meehan and Hill advise people to stay out of the water at dawn and dusk, when the recent attacks all occurred. Sharks feed at this time, and poor light levels can increase the risk that a shark will mistake a person for its usual prey. Aerial shark patrols also find it harder to spot the animals at this time.
