A local consumer watchdog has received 15 complaints related to hairy crabs since the start of September, 25 percent more than last year, local media reported Monday.

The Shanghai Consumer Rights Protection Commission found that half of the complaints were about coupons, which consumers buy to exchange for hairy crabs at stores or by delivery, said Fan Qiang, an official from the commission's complaints department.

Fan said the most common complaints were about stores that refused to honor unexpired coupons or stores that delivered dead crabs or crabs that were smaller than the coupon guaranteed. "In one case, a customer found that each of the crabs he ordered was 50 grams lighter than what he had paid for," Fan told the Global Times.

Consumers need to be wary when using coupons because many websites are currently selling them at a discount. "Consumers who have crabs delivered should thoroughly check the packages before accepting them. If there is a problem, they should try to negotiate with the seller or report the issue to us immediately," Fan said.

Yang Weilong, chairman of the Suzhou Yangcheng Lake Crab Association, advised consumers to avoid coupons entirely. "I really suggest that consumers buy crabs directly from stores, rather than trying to save money by buying them with a coupon because they might receive poor quality crabs," Yang told the Global Times.

The association has punished several stores that consumers have complained about and issued warnings to others to prevent problems from occurring, Yang said.