Crabs of the British Isles (29,193 t), various swimming crabs (3,180 t), the spider crab "Maja squinado" (1,565 t), the shore crab or green crab "Carcinus maenas" (553 t) and the velvet crab "Necora puber" (193 t). Around 77% of the catch is landed in the United Kingdom, 19% in Ireland, 4% in the Channel Islands, and 1% in the Isle of Man. 62 species have been directly observed in the waters of the British Isles: Three deep-water species have also been recorded near the British Isles, and are likely to occur in the area. These are: Crabs of the British Isles Around 65 species
Introduced species of the British Isles damage. Case studies of impact examples can be found at the Non-native Species Secretariat website. Information on control methods for aquatic species can be found at the GB Non-native Species Secretariat website. One notable example of a species introduced to the British Isles is the grey squirrel from North America, which out-competes the smaller native red squirrel, as well as carrying a virus that is fatal to the reds. The cost of attempting eradication was reported in 2010 to be £14 million. These attempts have been deemed unsuccessful and priority is now being given to preserving the remaining red squirrel