Thirty years ago, crayfish were little more than a nuisance for the rice farmers of eastern and central China, but the invasive species has become big business for one city. Nearly two of three crayfish eaten in Europe hail from the small town of Qianjiang in Hubei Province. In late May, Qianjiang announced it sold US$190 million worth of the crustacean to foreign buyers in 2015, up 27 per cent year-on-year, becoming the country's largest crayfish export base.
To sharpen its edge in the industry, the town set up a research institute dedicated to breeding crayfish in mid-June, shortly after it opened a vocational school to train cooks in preparing crayfish dishes.
China is the world's largest producer of crayfish, with annual output accounting for over 70 per cent of the world's total, reports Xinhua News Agency.
Native to North America, crayfish were brought to east China's Jiangsu Province by a Japanese merchant in the 1920s. They appeared in the Jianghan Plain, where Qianjiang is located, about 30 years ago.
With fertile land and a large network of rivers and lakes, the plain is an ideal habitat for the species.
They weren't always a welcome addition to the ecosystem, especially for local farmers.
"They pinched off rice seedlings in the paddy fields, and made tunnels in ridges that caused water loss," said Liu Zhuquan from Baowan Village in Qianjiang.
Later, however, villagers came to find the shellfish tasty and started raising them in the paddies in 2001.
Liu said this summer his crayfish have sold for 60 yuan (about $9) per kilogram, while his rice goes for 32 yuan a kilogram -- both much higher than prices elsewhere.
Farming crayfish and rice simultaneously does not require chemical fertilizers, pesticides or result in contaminated water, ensuring safe products. Green farming methods help improve the quality of both crayfish and rice, according to Jiang Youyu, head of Qianjiang's crayfish farming association.
Wang Pinghu from Bao'an Village said he used to earn about 60,000 yuan from his four hectares of rice a year, but his income surged to 250,000 yuan after he started raising crayfish in 2014.
Around 80 per cent of crayfish produced in Qianjiang were exported to Europe and the United States as pre-cooked food products.
Two Qianjiang-based companies, Laker and Huashan, are exempt from local quality checks and may send their crayfish products directly to supermarkets in Europe and the United States.
"In the past, we sent technicians abroad to learn about European people's taste. Now we pay top dollar to get European chefs to work in Qianjiang," said Zheng Zhonglong, general manager of Hubei Laker Group.
In addition to edible crayfish, Huashan Aquatic Food Company also exports chitin, a versatile substance used in medicine, health food and cosmetics. It is extracted from the exoskeletons of crayfish. The exoskeleton accounts for most of the animal's body, and only 20 per cent of it is edible.
E-commerce has helped expand the domestic market for Qianjiang crayfish, with revenue from online sales exceeding 100 million yuan last year. Spicy crayfish dishes are popular across the country to pair with beer on summer nights.
There is still work to be done to improve the industry. One pressing task is to improve crayfish breeds to prevent inbreeding, said Shu Yaxin with Hubei's fisheries research institute.
TheFishSite News Desk