Eriocheir sinensis | Chinese Mitten Crab
Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011. (Note: Regulation 50 not yet enacted).
Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [No. 1143/2014].
First reported in the wild
Invasive species - risk of High Impact
Introduction pathways - 1
Introduction pathways subclass - 1
Ship/boat ballast water
Introduction pathways - 2
Introduction pathways subclass - 2
Hitchhikers on ship/boat
NAPRA Ireland risk assessed
No. A full detailed risk assessment of this species to Ireland has not been undertaken.
In the Great Britain risk assessment, which was used to support Union regulation listing of this species, the summary risk of impact is given as MAJOR but with a LOW level of confidence. See: https://circabc.europa.eu/sd/a/95cd1ad3-a893-4484-a2fd-e25710abb77d/Eriocheir%20sinensis%20-%20GBNNRA.pdf
Number of hectads recorded in
The main distinguishing feature of this crab from others is the mitten-like 'fur' on its two front claws. Legs are long and hairy.
It is a small crab with a carapace (main body shell )of about 5-7 cm across that is brownish to greenish in colour with 4 spines on either side and a notch between the eyes.
There are no freshwater species of crab found in Ireland so it could not be confused with any crab in inland waters.
In the marine environment it is distinguishable from other marine crabs by the presence of dense, brown hairs on the claws.
It is an omnivorous predator that feeds on a wide variety of plants, invertebrates, fishes and detritus (Gollasch, 2009).
Larval stages are in the marine environment that then migrate to estuaries where as developed juveniles they then migrate upstream. Adults migrate back downstream to the marine environment in summer, this migration may take several months during which time they become reproductively mature. Most crabs live to 2 years (Gollasch, 2009).
Notes on impact:
- Forms burrows in river banks, which can lead to soil erosion and damage to the bank, with burrow densities of between 6 and >30 recorded in San Franciso (Rudnick et al., 2003) and estimated to remove estimated 1 to 6% of sediment per 0.5m3 of river bank (Rudnick et al., 2005).
- May compete with the native crab Carcinus maenas in estuaries by excluding them from shelters (Gilbey et al., 2008).
- Likely to have widespread impacts on native fish and invertebrate species as there are no native freshwater crabs in Ireland.
- Has been shown to act as a host for Aphanomyces astaci (crayfish plague) under lab conditions (Schmidt & Schulz, 2014).
Inland surface waters; Coastal; Estuaries
Larvae are found in estuarine and marine waters with juveniles migrating upstream, in some cases over 1,000km inland, before adults return to the sea to breed.
Adults migrating into marine environments to reproduce at 1 or 2 years of age. Populations appear to go through abundance cycles (Rudnick et al., 2003).
Pathway and vector description
Most likely source of introduction is as larvae in ballast water or as adults on ship's hulls (Minchin, 2006), though it is possible they could be intentionally brought to Ireland from Britain as an aquarium or food species and accidentally or intentionally released.
Rapid post invasion spread of 448 km per year has been recorded in Britain (Herborg et al., 2005).
Mechanism of impact
Competition, Predation, Other
Eradication attempts usually meet with limited success (Gollasch, 2011) as it is present in high numbers, is widespread, has a high reproductive capacity and tolerates a wide range of physiological challenges (GSID, 2015).
Prevention is the best method of control (NNSS, 2011). Strict protocols in relation to the management of ship ballast water may help. Education of the general public about the ecological impacts of this crab may help to prevent further spread.
Fyke nets, used to catch eels, have been found to be effective in catching Eriocheir sinensis in the Thames river, London (NNSS, 2011).
Migration screens have limited success (Gollasch, 2011).
Most of their life cycle is spent in freshwater environments and larger estuaries that have hard and soft bottom substrates. r Larvae are found in estuarine and marine waters with juveniles migrating upstream, in some cases over 1,000km inland, before adults returning to the sea to breed.
It has a 'tolerance to temperatures down to 0 degree Celsius, high salinity low oxygen conditions and air exposure for several hours' (Gollasch, 2009).
It can walk over land.
As there are no freshwater crabs in Ireland it cannot be confused with any inland water native species. It's furry 'mitten' claws will distinguish it from crabs in the estuarine and marine environments.
Localized. - it has been recorded on three occasions in Ireland from Waterford harbour. One individual was recorded in 2006 (Minchin, 2006), a further 16 crabs in 2009 (A. Cullagh, pers comm. 2009) and 2 crabs in 2021. One of the crabs caught in 2021 was of a berried (reproducing) female.
The 2006 and 2009 sightings, were first detected by fishermen highlighting the valuable role of citizen scientists is early detection. In 2006, Mr. James McCartan reeled the crab in when when angling for cod in the winter. He photographed it and returned it to the water (not knowing what it was) but sent photographs to the authorities which triggered rapid response to catch specimens (J. McCartan, pers comm. 30th May 2020). In 2009, Chinese mitten crab were caught and reported by eel fishermen (A. Cullagh, pers comm. 2009).
Distribution frequency in Ireland
Native to Russia, China & Japan (Gollasch, 2009).
Date of first record category
Fifty year date category
Records submitted to Data Centre in 2021
The following map is interactive. If you would prefer to view it full screen then click here.
How can you help
Please report sightings of any type of crab found freshwater environments such as rivers and lakes. If possible take a photograph or specimen to confirm its identity.
If you see or catch a crab with mitten-like furry front claws in an estuary or in the marine environment, please report it and if possible take a photograph or specimen to confirm its identity.
If you come across this species in the live food trade, report it to National Parks and Wildlife Service.
Do not release it to Irish waters.
Management information for this species in Ireland has not been developed yet.
Once populations have established, trapping of crabs is not effective at controlling crab numbers or in limiting damage to riverbanks from burrowing (Gollasch, 2009 & 2011).
Delivering Alien Invasive Species In Europe (DAISIE) project list this as one of the 100 Worst Invaders in Europe.
Invasive Species Specialist Group (ISSG) of the SSC- Species Survival Commission of the IUCN -International Union for Conservation Nature list it in 100 of the World's Invaders globally.
Chinese mitten crab is considered a delicacy in China, Japan, Korea, Singapore and Taiwan.
Gilbey, V., Attrill, M. J., & Coleman, R. A. (2008). Juvenile Chinese mitten crabs (Eriocheir sinensis) in the Thames estuary: distribution, movement and possible interactions with the native crab Carcinus maenas. Biological Invasions, 10(1), 67-77.
Global Invasive Species Database (GISD) 2015. Species profile Eriocheir sinensis. Available from: http://www.iucngisd.org/gisd/species.php?sc=38 Site accessed 27 September 2017.
Gollasch, S. (2009) Eriocheir sinensis Milne-Edwards, Chinese Mitten crab (Varunidae, Crustacea) In: DAISIE Handbook of Alien Species in Europe. Springer.
Gollasch, S. (2011): NOBANIS – Invasive Alien Species Fact Sheet – Eriocheir sinensis. – From: Online Database of
the European Network on Invasive Alien Species – NOBANIS www.nobanis.org, Date of accessed 02/12/2016).
Herborg, L. M., Rushton, S. P., Clare, A. S., & Bentley, M. G. (2005). The invasion of the Chinese mitten crab (Eriocheir sinensis) in the United Kingdom and its comparison to continental Europe. Biological Invasions, 7(6), 959-968.
Minchin, D. (2006) First Irish record of the Chinese mitten crab Eriocheir sinensis (Milne-Edwards, 1854) (Decapoda : Crustacea) Irish Naturalist's Journal, 28(7):303-304.
Non-native Species Secretariat (NNSS). (2011). Eriocheir sinensis – Chinese mitten crab. Risk Assessment (risk assessment prepared for Great Britain).
Rudnick, D. A., Hieb, K., Grimmer, K. F., & Resh, V. H. (2003). Patterns and processes of biological invasion: the Chinese mitten crab in San Francisco Bay. Basic and Applied Ecology, 4(3), 249-262.
Schrimpf, A., Schmidt, T., & Schulz, R. (2014). Invasive Chinese mitten crab (Eriocheir sinensis) transmits crayfish plague pathogen (Aphanomyces astaci). Aquatic Invasions, 9(2), 203-209.
Chinese mitten crab Invasive Species Alert post [issued May 2021]
More detailed description of the life history and biology of Eriocheir sinensis in Dittel, A. I., & Epifanio, C. E. (2009). Invasion biology of the Chinese mitten crab Eriochier sinensis: A brief review. Journal of Experimental Marine Biology and Ecology, 374(2), 79-92.