"For a crab weighing at 175 grams, the retail price will be 200 yuan ($32.70) per kilogram, up from 100 yuan per kilogram last year," he said.

Yang, from the Yangcheng Lake Hairy Crab Association, said the reason is simple: this summer's heat wave. Crab breeders expected a bumper harvest this year, but the sweltering heat this summer flattened production. Yang said the catch this year equals last year's haul of around 2,100 tons, or 16 million crabs.

He added that hairy crabs sold before Tuesday at cheaper prices are most likely not from the lake. "This date is carefully calculated to guarantee the quality of the delicacy," he said.

Online sales of crabs have been popular for several weeks. Wu said online sales are putting added stress on the Yipin Lotus restaurant's bottom line.

Industry insiders said some of the crabs sold online cannot be from Yangcheng Lake, which is generally believed to be the best location for breeding the animals.

Contact the writers at xieyu@chinadaily.com.cn and xujunqian@chinadaily.com.cn