Brown Crab

 Brown Crab

  • Scientific name: Cancer pagurus
  • Also know as: Edible Crab
  • Size: Up to 11 inches (27cm) across carapace
  • Distribution: Found throughout the North East Atlantic.

The brown crab is a large species of crab found all around the British Isles. It is extremely commercially valuable meaning that a significant fishery has built up to catch this species.

Description

The brown crab is by far the largest crab species in British waters, with the carapace of a fully grown adult being around 20cm across, and in exceptional specimens can be 30cm across and weigh 9lbs. The upper shell of the crab is oval shaped and usually an orange-red colour with paler undersides. Like all of the crab species in British waters they have eight legs and two, very large and powerful claws, with the pincers usually being tipped black. One of the most distinguishable features of this species of crab is the pattern which runs along the edge of the carapace which is usually described as resembling a pie crust. Due to the very large and powerful claws the brown crab can cause a very painful nip to humans it comes across.

Distribution and Habitat

The brown crab is distributed all around the British Isles and is found in areas where there are rocks and weed to provide cover. The crab will hide in cracks and under weed and emerge to forage for food. They are found throughout European waters with their distribution ranging from Norwegian waters down to the northern coastline of Africa, although they only have a very limited presence in the Mediterranean and are absent from the Black Sea.

Feeding and Behaviour

Like all crab species they are voracious consumers of anything they can find. They will happily feed on dead marine organisms and shellfish such as mussels and will use their strength and power to ambush other crabs, especially the common shore crab. Smaller, younger brown crabs tend to live in the intertidal zone, with crabs moving into deeper water as they get older and grown in size. The largest, fully-grown brown crabs will live in water down to around one hundred metres deep. Brown crabs need to be around 15cm across the carapace before they can reproduce. Brown crabs will shell and enter the peeler phase often in their first few years of life when they are growing rapidly, but this slows down to shedding their shell once a year or less as they get older. It is thought that brown crabs have a natural lifespan of 30 to 40 years, and in exceptional circumstances could possibly live for significantly longer.

Commercial Importance

Brown crabs are extremely commercially important and the brown crab fishery in British waters is one of the largest crab fisheries in the world, although a large proportion of the catch is exported to France and Spain. The brown crab provides white flesh from the claws and brown flesh from its body. Around one third of the overall weight of the crab is edible as crab meat. Despite the importance of this species there is very little known about overall stock numbers, or the extent to which current fishing intensity is depleting stocks.

Sorting crabs Ffionphort

Fishermen sorting different crab species they have caught in Ffionphort, Scotland.

Crabs are caught by lowering baited crab pots into the sea. This is one of the most selective methods of commercial fishing and allows small, undersized and berried (egg carrying) females to be returned to the sea. However, the brown crab fishery could be threatened by more mechanised methods of fishing with are less selective. Anywhere selling brown crabs with a carapace of 13cm or under should be boycotted as there is no possibility that crabs of this size would have been able to reproduce before capture and they should have been returned to the sea.

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