An Australian shark expert made a chilling prediction that environmental circumstances had become perfect for shark attacks on swimmers in Australia's Sydney Harbor, just days before January 18, when a bull shark mauled a 12-year-old boy.

Joel Nacarrow, owner of Hunter Shark Jaw Restoration, said that heavy rain, with murky water caused by river run-off, had created the perfect conditions for bull sharks. They thrive in brackish conditions, can tolerate freshwater, and are known to swim up rivers. He urged swimmers to stay clear of dirty water, river mouths, and low-visibility surf.

Unfortunately, the boy didn't heed the warning. Nico Antic was swimming with five friends at Nielsen Park and leaping into the water from a 20-foot-high Jump Rock when a bull shark attacked him. He died five days later from his injuries.

A day later, only a few miles away, an 11-year-old boy had a close call when his surfboard was chomped, and the same day, a surfer was left in critical condition after being attacked off Manley, one of Sydney's northern beaches. The following day, another surfer was rushed to the hospital after a shark attack near Port Macquarie.

Ironically, the presence of sharks indicates a healthy ecosystem.

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