Date of introduction and origin
Eriocheir sinensis was most likely introduced from
the Low Countries of Europe. It was first collected in Germany in
1912 (Clark 1986). The date of introduction to Britain is thought
to be 1935 and this species was first introduced into the Thames at
Chelsea in Greater London (Ingle 1986) and later to the Humber
catchment in Yorkshire. This species' natural range is south-east
Asia where it is found from China (26·N) to the Korean Peninsula
(40·N) and Japan.
Method of introduction
This species may have been introduced by transport of small
crabs or larvae in ballast water or through transport of adult
crabs clinging to ships' hulls. Introduction may have been
associated with scrap-metal yards on the Thames and Medway in
Essex, and barges from the continent (P.F. Clark pers.
Reasons for success
Rate of spread and methods involved
Its dispersal is likely to be through pelagic larvae and
mobile adults; the rate of spread is not known.
In Britain this species occurs in the Humber, Thames and
Medway estuaries (Clark 1986). It has also been reported
specifically from the River Ancholme, a tributary of the Humber
since 1976, and the River Wharfe and River Ouse in Yorkshire since
1986, where it is caught in nets laid by eel fishermen (B.
Helmsley-Flint pers. comm.). European populations can be
found from Finland to France (Ingle 1986).
Factors likely to influence spread and distribution
Currents may take the larvae onto the coasts of Europe. This
species may be preyed on by pike Esox lucius, eels
Anguilla anguilla and brown trout Salmo trutta
(P.F. Clark pers. comm.). Limited reproductive success may be a
limiting factor to its spread in Britain.
Effects on the environment
For most of its life E. sinensis lives in fresh
water. During August adult crabs migrate seawards and gather in
large swarms to breed in estuaries (Panning 1939). When population
densities are high, E. sinensis causes considerable damage
to soft sediment banks through burrowing which increases erosion
and might affect flood defences. This species is an intermediate
host for the mammalian lung fluke Paragonimus
Effects on commercial interests
It may damage the nets of eel fishermen. Damage caused to
river banks may increase repair costs.
Control methods used and effectiveness
Those caught in eel nets are destroyed. It may be possible to
use biological control through maintenance of fish populations
leading to increased predation.
Parasite-free individuals, have a small commercial value: In
the Japanese restaurant market E. sinensis was worth
£20/kg in 1995.
Increases in population in the Thames in recent years may be
attributable to drought conditions during 1989-1992 having
facilitated greater settlement of young crabs (Atrill & Thomas
in press). Adults occupy an essentially freshwater habitat but must
migrate to mate and release larvae in the saline mouths of
estuaries, congregating as they do so. Young crabs in turn migrate
up estuaries (Barnes 1994).
Atrill, M.J., & Thomas, M.R. In press. Long-term
distribution patterns of mobile estuarine invertebrates in relation
to hydrological parameters. 30th European Marine Biology Symposium,
Barnes, R.S.K. 1994. The brackish-water fauna of
northwestern Europe. Cambridge, Cambridge University
Clark, P.F. 1984. Recent records of alien crabs in Britain.
Naturalist, 109: 111-112.
Clark, P.F. 1986. North-east Atlantic crabs: an atlas of
distribution. Ross-on-Wye, Marine Conservation Society.
Hayward, P.J., & Ryland, J.S. eds. 1990. The
marine fauna of the British Isles and north-west Europe. 2
vols. Oxford, Clarendon Press.
Ingle, R.W. 1986. The Chinese mitten crab Eriocheir
sinensis H. Milne Edwards - a contentious immigrant. The
London Naturalist, No. 65:101-105.
Panning, A. 1939. The Chinese mitten crab. Report of the
Board of the Regents of the Smithsonian Institution (Washington)
(1938), 361 - 375 plus 9 plates. (publication 3508.)
Acknowledgements (contributions from questionnaire)
P.F. Clark, Natural History Museum, London.
B. Helmsley-Flint, The Environment Agency, Northumbria and