Eriocheir sinensis has hairy claws with white tips which make the crab appear to be wearing \"mittens\", hence its common name (Gollasch, 2006). Its scientific name Eriocheir sinensis means \"\"Chinese woolen hand\"\" (The Natural History Museum, 2005).
Native European crabs lack the mitten crab's dense hairy claw covering and square-shaped carapace; no similar species occurs in Europe (Gollasch, 2006).
Crab specimens have also been used as bait for eel fishing, food for cattle and chicken, fertiliser for agriculture and material for the production of cosmetics (Gollasch 1999, in Veilleux & de Lafontaine 2007).
Throughout its life, the Chinese mitten crab will occupy different ecosystems depending on its life stage (Veilleux & de Lafontaine 2007). Adult crabs are found in fresh, brackish and salt waters, but oviparous females are normally found in greatest number in saltwater (Rudnick et al. 2003, Veilleux & de Lafontaine 2007). Larval stages are found in the open water of bays and estuaries. Juvenile crabs are uncommon in open water but are found in tidal tributaries within a few kilometres of open water and in freshwater (Rudnick et al. 2003, in Veilleux & de Lafontaine 2007). Around the world, the highest densities of crabs are principally found within estuaries and the lower part of rivers (Cohen & Weinstein 2001, Rudnick et al. 2003, in Veilleux & de Lafontaine 2007).
Principal source: Rudnick Halat & Resh 2000; Gollasch 2006; Veilleux & de Lafontaine 2007
Compiler: IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Dr. Stephan Gollasch, GoConsult, Grosse Brunnenstrasse 61, 22763 Hamburg, Germany
Publication date: 2009-08-03
Recommended citation: Global Invasive Species Database (2024) Species profile: Eriocheir sinensis. Downloaded from http://iucngisd.org/gisd/species.php?sc=38 on 05-10-2024.
Ecosystem Change: Adult crabs migrate out of freshwater systems to reproduce and die in estuaries. This may constitute a substantial vehicle for exporting biomass out of the freshwater ecosystems, which may impact the food web, particularly when very large densities of crabs are migrating (Rudnick and Resh 2005)
Reduction in Native Biodiversity: is an opportunistic omnivore which will consume aquatic plants, algae, detritus, fish eggs and a variety of macroinvertebrates (Panning 1939; Hoestlandt 1948; Gollasch 1999; Rudnick et al. 2003).
Predation: The predation on fish eggs might be of concern (CMCWG 2003, in Veilleux & de Lafontaine 2007); however, given that fish material made up only 2.4 % of crab gut contents analyzed in Germany (Thiel 1938, in Veilleux & de Lafontaine 2007), the impact on adult fish populations is presumably low. E. sinensis could also reduce populations of native invertebrates through predation and alter the structure of benthic communities (Normant et al. 2002).
Competition: The crab's consumption of native species, including macroalgae, invertebrates and fish may result in significant declines in these species as well as in the crab's competitors (Gollasch 2006). Crayfish species, particularly rare or endangered ones, could be negatively affected by very abundant crab populations because of the freshwater habitat and diet shared by both species (Veldhuizen and Stanish 1999, Rudnick et al. 2000, in Veilleux & de Lafontaine 2007).
Threat to Endangered Species: The Chinese mitten crab's impact on endangered salmonids in California is of concern (IEP undated).
Physical disturbance: Burrowing activity of crabs results in damage to dikes and increased river embankment erosion (Gollasch 2006). The significant amount of sediment removed in areas with high densities of burrows can cause weakening and even collapse of banks (Panning 1938, D. Rudnick Pers. Obs., in Rudnick Halat & Resh 2000). This burrowing is of particular concern where waterways are controlled by human-made levees; weakening or destruction of such levees from extensive burrowing could pose serious threats to flood control and water supply efforts (Rudnick Halat & Resh 2000).
Economic/Livelihoods: The monetary impact caused by this invader in German waters is approximately 80 million Euro since 1912 (cost calculation adjusted from Fladung Pers. Comm., in Gollasch 2006). In general economic concerns arise over the stealing of bait by the crab and the damage to fishing gear (Panning 1939; Rudnick & Resh 2002). In California (USA) E. sinensis has become a major nuisance to anglers, taking a variety of baits including ghost shrimp and shad (Washington Sea Grant Program 2000). E. sinensis reproduces and migrates in such numbers as to block water intakes in irrigation and water supply schemes. Large numbers of downstream migrating crabs become trapped in holding tanks meant to keep fish out of turbines of water diversion plants. This has increased fish mortality and high costs are required to prevent the crabs' entry (Siegfried 1999).
Human Health: Effects on human health in Europe are not reported, however, the crab is the second intermediate host for human lung fluke parasite (Paragonimus westermanii) in Asia (Gollasch 2006).
Bioaccumlulation: E. sinensis has the potential to bioaccumulate inorganic and organic contaminants that then may be passed up the food chain (Rudnick Halat & Resh 2000). This type of bioaccumulation has been documented in E. sinensis populations in Asia (Che and Cheung 1998, in Rudnick et al 2000).
Preventative Methods:\r\nMethods to minimise future spread of the mitten crab are quite limited (Gollasch, 2006). Migration barriers and eradication programmes have shown limited success (Gollasch 2006). Certain guidelines and regulatory instruments may however be applied in areas where the species does not yet occur (Gollasch, 2006). For further details see the Ballast Water Management Convention of the International Maritime Organization (www.imo.org) and the Code of Practice for the Introduction and Transfer of Marine organisms of the International Council for the Exploration of the Sea (www.ices.dk).\r\n
Physical Control: Trapping of crabs has not been found effective in reducing the damage caused to river banks and the feeding on trapped fish (Gollasch, 2006). In order to prevent the migration of the crab up rivers in Germany electrical screens were installed on the river bottom in the 1930s to 1940s and pulses were used to disable and kill the crabs, but this met with little success (McEnnulty et al., 2001).\r\n
Information and awareness:\r\nThis invader has occurred in Europe for almost 100 years and this is why some believe it is a native species (Gollasch, 2006). Awareness raising initiatives have been so far limited to publications in journals (Gollasch, 2006). The general perception is that not much can be done to manage the mitten crab (Gollasch, 2006). \r\n
Knowledge and research: The first mass development of mitten crabs in Germany in the 1930s prompted many studies in the North Sea region, however, comprehensive studies in the Baltic are lacking (Gollasch, 2006). As the crab is only collected occasionally in Baltic waters no substantial research on the invader developed (Gollasch, 2006). However, invasion biology in general is a research topic in almost all Baltic countries (Gollasch, 2006). A network of researchers who deal with mitten crabs published a joint article on mitten crabs findings in the Baltic (Ojaveer et al., 2007).\r\n
Integrated Management: Zoologists at the Natural History Museum (London, UK) have suggested that commercial fishermen should target this species and export it to China where it is considered a delicacy (Owen, 2003). Clark et al (2009) also suggest commerical harvesting of the crab in the River Thames Estuary.