The Chinese Mitten Crab, Eriocheir Sinensis, on the Yorkshire Coast

The Chinese mitten crab, Eriocheir sinensis, is a medium sized crab, unmistakeable when found; its colour is a light greenish-grey to brown, with a box-like carapace which in large specimens may reach over 70mm in width. The front of the carapace between the eyes, bears a concave central notch; the sides of the carapace have four, not very prominent, teeth. The legs are long, with an extreme span nearly five times the carapace width, and with dense setae along the distal half of their length.

The chelipeds are the most notable feature of this crab, being clothed in a dense fur of long setae, this feature having given the crustacean its name of mitten crab.

This crab is a native of China, and is typically a fresh-water species that migrates to saline waters in order to breed, the larvae developing in the sea.

The species first appeared in Europe in 1912 when it was found in Germany, but was not found in Britain until a specimen found in the Thames at Chelsea in 1935 became the first to be recorded here; only since the 1970’s has the crab made a slow but steady advance elsewhere in the country.

First recorded in the Humber in 1976, it has now ascended many of its tributaries, and is now found through South Yorkshire; in 2008 a specimen gained publicity by being taken from the River Don almost in the centre of Doncaster. Further north its presence was first confirmed in the River Tyne in 2001, and to the west, the first Irish record was confirmed in January 2006.

An unconfirmed report was received in 2008 that a specimen had been taken by a fisherman in Bridlington Bay, but in early 2009 a living crab was collected from Bridlington Bay, with a number of other marine specimens, during our survey of Brama brama along the coast. This is the first known occurrence of the crab from the sea area off the Yorkshire coast; the specimen is now preserved in the crustacean collection at Scarborough.

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