Asian shore crab (Hemigrapsus sanguineus and H. takanoi)
Native to the NW Pacific, both species of Asian shore crab were first identified in the UK in 2014 (although it is now known that H. takanoi was already present in 2013). They are small squarish shaped crabs with three ‘teeth’ on either side of well-spaced eyes. H. sanguineus has clearly banded legs and purple-red spots on its claws, whereas the upperside of H. takanoi has small brown spots. They occur on muddy and rocky shores and in sheltered estuaries and port areas, they have also been found in oyster reefs. There have only been a few sitings of these species in the UK but they are extremely common along the NW coast of Europe and there is a high risk of further arrivals and spread through ballast water, hull fouling and larval dispersal ( larvae can survive up to 55 days in water column). They can out-compete the native shore crab Carcinus maenas and could have a negative impact on prey species such as juvenile mussels and oysters so potentially affecting spat supply in shellfish farms.
Risk of introduction to area: HIGH
Environmental risk: HIGH
Economic risk: MEDIUM
Image: J. Bishop © MBA