EXPERT TOPIC
CHINESE RIVER CRAB
EXPERT TOPIC
Chinese river crab
by Rebecca Sherratt, Features Editor, International Aquafeed
The Chinese river crab (Eriocheir sinensis), also referred to as the Chinese mitten crab, is named so due to its furry claws, which are said resemble mittens.
T
he species is considered relatively new to the aquaculture industry, having only being produced for aquaculture purposes since 1989. As well as China, this crustacean can also be found in temperate waters along Korea, Japan, Taiwan and Eastern Russia. Much commercial production of Chinese river crabs is carried out in China. This crustacean is typically marketed live, although in recent years processed products have entered the market. Exports are primarily focused within Japan, Hong Kong and Korea. Market rates suggest Chinese river crab is gaining more international attention, as export numbers increased by 70 percent in 2004, compared to the previous year. These rates have continued to increase year-onyear as the Western market establishes itself. Chinese river crabs typically reside in inland water bodies connected to estuaries. Upon reaching sexual maturity, they relocate to downstream estuaries to reproduce. The species is omnivorous, feeding on small fish, mussels, worms and aquatic plants. One of the issues most prevalent in Chinese river crab production is the myriad of diseases they can become subject to. Particular diseases to be wary of include Shiver disease, Shell ulcer disease and Sacculina disease, all of which can be caused by a variety of factors such as parasites, viruses and bacteria. Treating these diseases can be very complicated, whilst some diseases (such as Shiver disease) currently have no known cure, so ensuring farm hygiene conditions are optimised is crucial. In 1995, 41,516 tonnes (t) of Chinese river crabs were farmed for aquaculture purposes. In 2005 this number increased to 378,376t and again to 812,183t in 2016.
Introduction to aquaculture
The Jiangsu province of China first saw an increase in Chinese river crabs following the release of crab seed into lakes in the 1970s. The stocking of seed also began in small lakes along the Yangtze River. The farming of Chinese river crabs was a relatively humble business until it expanded in the 1990s. In this period, crab seed was introduced to various shallow lakes, paddy fields and earthen ponds across China. Nowadays, the Chinese river crab is a key species in Eastern freshwater farming and have also been reportedly farmed in Germany and the US. This crustacean has been seen as a key contributor to the income of rural farmers in China. Farming of Chinese river crab is still often carried out on a small scale by independent farmers but, in recent years, advances have been made in producing large-scale production facilities, special feed additives and artificial propagation solutions. The aim of these emerging technologies is to improve survival rates, animal welfare and production efficiencies. Another unique farming method that has been established in China is integrated rice-aquaculture 54 | November 2020 - International Aquafeed