Zhejiang authorities found many shark fins sold in the market are artificial products and some contain excessive levels of cadmium, a toxic metal.

The industry and commerce department in Zhejiang province conducted a check of shark fin soup, a popular dish often served at luxurious banquets. The inspection found many restaurants serve artificial shark fins made of edible gelatin and seaweed gum. Restaurants purchase the "shark fins" at a low price, but they are sold for up to 1,000 yuan ($160) a bowl in restaurants and hotels.

An employee at a workshop in Wenzhou, Zhejiang province, processes shark fins on Sept 9. Yi Xin / for China Daily

Similar results were found in an investigation by the province's consumer rights protection agency, which randomly selected about 10 samples of shark fin soup collected from local restaurants for DNA testing. No shark was found in any of the soups.

The consumer rights protection agency also found that about one-third of dried shark fin in the province's markets contained excessive cadmium and methyl mercury.

Local news website Zjol reported that ocean pollution can lead to high levels of metals in the sharks.

Experts said excessive ingestion of mercury will harm pregnant woman and the development of the fetal brain and nervous system.

Insiders said such artificial shark fins are widely available in local wholesale market.

"Many restaurants and hotels have bought 'shark fins' from me," said Lin Wenyu, a businessman at a seafood wholesaler that sells "vegetarian" shark fin (artificial shark fin) at the Shanghai Tongchuanlu Seafood Market.

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