Shark fin soup is a popular seafood for most Guangdong residents since it is considered capable of increasing potency.

It is a must-have at luxurious dinners.

Consumption of the delicacy in this province's capital city Guangzhou amounts to hundreds of tons each year, and shark fin is believed to be the most expensive seafood in the world.

At Garden Hotel, a local five-star hotel, a bowl of shark-fin soup is sold at 600 yuan (US$72), and the hotel can sell 50 bowls a day.

A manager of the hotel's kitchen told China Daily that each bowl uses 200 grams of shark fin, and the hotel consumes 10 kilograms a day.

Despite special fondness for the expensive soup in the city, warnings from an international wildlife protection organization have been issued that eating too much shark fin can cause sterility in men.

"Shark fin may cause sterility because of mercury and other heavy metals contamination," said Victor Wu, an officer at the United States-based WildAid, "and the risk to men is much higher than women."

According to Wu, besides sterility, shark fin can also cause central nervous system problems and kidney diseases.

Wu's words smashed people's imagination of the ideal function of shark fin in the diet.

Song Zhou is a manager at a French-owned company in Guangzhou.

"I often eat shark-fin soup when I attend various business banquets," said Song.

He said WildAid's warnings make it less likely he will eat as much shark fin soup in future.

Wu said the reason why shark fin contains mercury is seabourne pollution. Exposure to mercury used to be mainly an occupational hazard rather than an environmental one. More recently, mercury has also become an environmental pollutant. This has occurred through industrial use of mercury in the manufacture of plastics, paper and batteries with the resultant discharge of contaminated effluent into lakes, rivers and the sea.

Lots of marine organisms have been contaminated by mercury polluted sea water.

Shark is at the top end of the food chain in the deep sea. Eating numerous polluted small fishes and organisms have left sharks contaminated by mercury.

Wu said a survey made by the Thai Government showed that seven in 10 shark fin samples were contaminated by mercury. And cooking cannot remove mercury.

Wu said it was impossible to stop the worldwide trade of shark fin currently, even though lots of illegal trade behaviours exist in many countries, such as fin smuggling.

"The key point is letting people know the source of fins is limited, and eating a bowl of shark-fin soup would increase the risks of getting sick," said Wu. And it was WildAid's focus.

In collaboration with Guangzhou Association of Science and Technology and Guangzhou Ocean World, WildAid held an public exhibition in Guangzhou on Tuesday to display lots of pictures on introduction of sharks and shark fin.

(China Daily May 21, 2005)