Two crabs sit next to a stack of brand labels at a market in Beijing on Sept 7. The vendor claimed the hairy crabs were caught in Yangcheng Lake. Provided to China Daily

BEIJING - Diners hoping to enjoy a traditional Chinese delicacy this fall should look out for a special brand label that guarantees the dish is authentic.

Hairy crabs are one of the most sought-after ingredients at this time of year and those caught in Yangcheng Lake in Jiangsu province are considered to be among the tastiest.

However, the market has been proliferated with fakes in recent years, prompting many fans to stop eating them.

To combat the problem, the Yangcheng Lake Crab Association in Suzhou, a major city in Jiangsu, on Sunday released to the media the design of this year's authentic brand ring, inside which there will be a serial number for each crab.

"There will be the special trademark in front of the ring and the company brand on the back," said Yang Weilong, director of the association. "By opening the plate from the back, customers will find a designated number."

To check the authenticity of the crab, customers can call 9510-5881 or (0512) 6573-5581 to verify the serial number. Yang said that any phone number prefixed with 400 or 800 is not genuine.

The ring is being kept secret by the government and will be distributed to members of the association on Sept 17 to coincide with the start of the crab fishing season.

About 250 to 280 tons of Yangcheng Lake crab will be shipped to Beijing in the coming weeks, Yang added.

"If they aren't checked for authenticity by the trade association and don't have the brand rings, crabs on the market can't be called Yangcheng Lake crabs," he said.

Yangcheng Lake is regarded a good place for crab farming because of its natural surroundings.

"The water quality is one of the essential factors," Yang said, who added that the size and taste of the crabs this year will be the best in a decade, although prices will be about 20 percent higher due to increased costs.

The crabs were not available for Mid-Autumn Festival, which fell on Monday this year, but the gift vouchers are selling well, said Chen Zheqian, a sales manager at a franchised store in Beijing's Fangzhuang.

"My family have hairy crab every year in autumn," said Wang Zhenyan, a customer from Shanghai. "The best variety is from Yangcheng Lake, but they are expensive."

The high prices are largely the reason why there are so many copies of the brand on the market.

"I had Yangcheng Lake crab almost every autumn when I was young, but I haven't had it for years," said Zheng, who is also from Shanghai and was having seafood hotpot to celebrate Mid-Autumn Festival with his family on Monday. He did not reveal his full name.

"I don't trust the brand any more. Too many fake ones are on the market," he added.

Authorities constantly change the branding mark to stay ahead of the fraudsters. However, authenticity remains a problem.

"If customers order today, the crab will arrive in Beijing on Wednesday," a salesperson at an online Taobao store told China Daily on Monday. "The small crabs don't have the brand ring, but bigger ones do. Customers can order the ring separately."