Sydney University shark expert comments on harbour shark numbers

2 March 2009

A recent increase in reported shark activity in and around Sydney Harbour has potentially arisen due to commercial fishing bans, changing environmental factors as well as the activities of people, a University of Sydney shark expert says.

Phoebe Hill, a PhD student at the University of Sydney's School of Biological Sciences who has studied Sydney's shark activity, says the warmer water temperatures, increase in fish numbers and water quality may have tempted more sharks into Sydney's waters.

"The end of commercial fishing in the harbour in combination with high water quality and cleanliness means the harbour is becoming more attractive for larger species of shark," Ms Hill said. "As the harbour ecosystem improves, sharks are simply chasing the fish into shallower waters."

Ms Hill also believes shark populations are regenerating in the harbour as the ban on commercial fishing means less sharks are being caught and killed.

She also says the public's renewed fascination with sharks has created a higher awareness and vigilance leading to more shark sightings.

"While the arrival of bull sharks and Great Whites is highly unusual, there has been and always will be sharks in the harbour."

She called the shark attack on navy diver Paul Degelder off Woolloomooloo on February 11 "highly irregular as most sharks are afraid of the bubbles generated by scuba divers."

"Most of this behaviour has been inquisitive more than anything though," she said. "These sharks have been taking bitesout of curiosity not hunger."

Ms Hill has called for more Government investment in shark research not shark nets. "Shark nets trap other animals as well as sharks," she said. "The Government needs to invest in scientific research of these animals so we can track and monitor them and better understand these animals."

She says surfers are particularly vulnerable due to their perceived resemblance to seals and turtles but also due to the fact that they are in deeper waters than most swimmers.

Still, she advises against swimming at dawn and dusk as these are the feeding times of most sharks.

"Sydneysiders need to remember that when they enter the water they are entering a foreign environment that is the shark's territory. People should still feel safe to swim and enjoy the harbour but exercise common sense and caution."

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