Sydney Shark Kills Swimming PADI Instructor

Locals were shocked when PADI diving instructor Simon Nellis was chomped up by a ten-foot great white shark in Sydney's Little Bay in mid-February. It was the first fatal shark attack in New South Wales since 1963. The 35-year-old was not scuba diving, but rather out for his regular exercise swim, and suffered catastrophic wounds. Not all of his wetsuit-clad body has been recovered.

As expected, some people called for culling all sharks or at least killing the responsible shark, but it is improbable that the actual shark might be identified given their vast range. She's probably long gone. Thankfully, the public now realizes the intrinsic value of sharks and their essential role in the ecosystem.

So, how would you spot a marauding shark? An aircraft with observers can survey a lot of coastline but relies on clear water, so detection rates are low. Beach towers need to be at least 120 feet high to give an effective view - far higher than existing towers.

Baited drumlines and shark nets are deployed at more than 50 New South Wales beaches, killing nearly all the sharks and other marine animals they capture. Scientists have experimented with orca calls and novel sounds to deter sharks, but they do not work on all shark species. Physical barriers to segregate swimmers from sharks must withstand the ocean's power; previous efforts have failed.

Across the world off a Colombian beach, at San Andres in La Piscinita, an Italian male tourist, 56, died of blood loss after being bitten by a tiger shark while snorkeling on March 17.

It's comforting to know that scuba divers rarely suffer unprovoked shark bites.