Taxonomy

Eriocheir sinensis | Chinese Mitten Crab

Distribution

Status

Conservation status

Not Assessed

Legal status

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].

Native status

Non-native

First reported in the wild

2006

Invasiveness

Invasive species - risk of High Impact

Irish status

Intercepted

Introduction pathways - 1

Transport Stowaway

Introduction pathways subclass - 1

Ship/boat ballast water

Introduction pathways - 2

Transport Stowaway

Introduction pathways subclass - 2

Hitchhikers on ship/boat

Invasive score

21

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 

Species Biology

Identification

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.

Diet

It is an omnivorous predator that feeds on a wide variety of plants, invertebrates, fishes and detritus (Gollasch, 2009).  

Ecology

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).

Habitat

Inland surface waters; Coastal; Estuaries

Life stages

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.

Reproduction

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

Broad environment

Freshwater

Habitat description

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.


Species group

Vertebrate

Native region

Temperate Asia

Similar species

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.

Distribution

World distribution(GBIF)

Irish distribution

Intercepted - it has been recorded on two occasions in Waterford harbour and on both occasions the animals have been removed. One individual was recorded in 2006 ( Minchin, 2006) and a further 16 in 2009.

Distribution frequency in Ireland

Not present

Native distribution

Native to Russia, China & Japan (Gollasch, 2009).

Temporal change

Date of first record category

2001-2010

Fifty year date category

2001-2050

Records submitted to Data Centre in 2017

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.


Further information

Management information for this species in Ireland has not been developed yet.  

Once populations have established, trapping of crabs is not effective  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.

References

Publications

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.

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.

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.

NOBANIS Fact sheet

CABI Datasheet

Global Invasive Species Database

DAISIE Factsheet

Additional comments

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.

Images