Leaner pickings are predicted in the new season's batch It's bad news for crustacean lovers: hairy crabs brought in from the mainland this autumn will not only be thinner, but also more expensive. The smaller size is linked to the hot summer weather having reduced the appetites of the crabs, and recent flooding has also meant there are fewer fat crabs on offer. Bound with water grass, the green hairy crabs are starting to turn up in shops specialising in Shanghainese delicacies. Branded by many shops as 'big gate crabs from Lake Yangcheng', most of the crabs are, in fact, from elsewhere. The lakes near Shanghai - such as Lake Yangcheng - are thought to be too polluted for the crabs to be good enough for the Hong Kong market. As a result, some city merchants are going as far afield as Xinjiang to collect their haul. Albert Chan, owner of Wah Kee Wing Cheong Ho, a shop selling hairy crabs, said that the quality of the crustaceans now depended more on where the baby crabs came from than the lakes they were farmed in. He said the best ones are fully-grown crabs of the wild baby crabs from the lower reaches of the Yangtze river. However, more than 90 per cent of baby crabs now come from hatcheries. 'In Shanghai, it is still very hot. The temperature of the lake surfaces in early September was well over 30 degrees Celsius. At this time of the year, normally it is about 25 degrees. In such weather, the crabs don't have an appetite and won't get big enough to develop their new shells. If they don't develop their new shells, they won't get bigger and fatter,' Mr Chan said. It takes more than a year for a crab to grow fat enough for the Hong Kong market. A crab changes its shell four times before it is fully grown. 'The most ideal [lake water] level is 1.5 metres because the water grass where crabs find their food is about 1 metre high. 'This year, because of the flooding, the water levels of some lakes are as high as 3 metres. Some of the crabs escaped from their farms. For those remaining in the lakes, the prospect of getting fatter is bleak because they have problems getting food. The water grass in the lake cannot grow well if the water level is too high and sunlight cannot penetrate,' Mr Chan said. For those who find the crabs tasty, timing is very important. According to old Chinese sayings, female crabs are better to eat in September because their fat is still soft; in October, male crabs are better. Male and female crabs are differentiated by their belly shapes: the female's is round, while the male's is pointed. In Chinese, hairy crabs are called big gate crabs because of the system used to catch them before they began to be commercially produced. Bait was put inside a box-like trap placed in river shallows. The crabs would climb over the walls of the trap - the big gates - take the bait, and then find themselves trapped.