Some fin really special

Twelve beaches across Hong Kong were closed last week after bathers spotted the black fin of a suspected whale shark slicing through the water.

While it is wise to get out of the sea until one knows what kind of shark it is, most people have little knowledge about these marine beasts.

At least a dozen types of sharks have been recorded in Hong Kong waters over the past 150 years. And some of these creatures are now considered extremely rare, verging on extinction, says Tracy Tsang Chui-chi, a senior programme officer on sharks with WWF Hong Kong.

Tsang says summer is a high season for shark sightings because the predators move up the coast as the seas warm, and back down when the waters cool. Sai Kung and Stanley are prime sighting areas.

The most commonly found species are blacktip reef, grey reef and bamboo sharks. But tiger, whitecheek, hardnose, spottail, milk, grey sharpnose and spadenose sharks, as well as hammerheads, also prowl the city's seas.

Sharks have been responsible for 10 fatal attacks across the territory since records have been kept, reports the Shark Attack File website, which monitors such incidents worldwide.

The last and worst assault happened in 1995 when three swimmers died over 10 days. It was suggested that a great white, the world's largest ocean predator, might have been the culprit behind the local attacks, but this was never confirmed. This torpedo-shaped giant with a powerful tail can grow up to eight metres long and weigh up to 3,400kg.