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Crab, brown or edible

Cancer pagurus

Method of production - Caught at sea
Capture method - Creel,Pot
Capture area - North East Atlantic (FAO 27)
Stock area - Scotland
Stock detail - Orkney
Certification -
Fish type - Shellfish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is a good sustainable fish to eat. Click on the rating icon above to read more and on the alternatives tab below to find similar fish to eat.


Sustainability overview

Pots or creels have a low habitat impact. They are also a highly selective method of fishing as undersized animals can be returned to the sea alive. Brown crab from fisheries managed by Orkney Sustainable Fisheries (OSF) are a good choice. Their Code of Practice prohibits landing of pre or post moult and berried or egg-bearing female crabs. OSF Ltd intends to go forward for MSC assessment of their fishery in the spring of 2017. The process is anticipated to take 6-9 months.

Biology

The brown crab is commonly found in the North Atlantic Ocean, North Sea, less so in the Mediterranean. It is the heaviest British crab and easily identified by a characteristic pie-crust edge to the carapace or shell. They are found in waters down to 100 m. Brown crabs are highly fecund. Mating activity peaks in the summer when the female has moulted with spawning occurring in the late autumn or winter. Egg carrying females are largely inactive over the winter brooding period before the eggs hatch in the spring and summer. Between 250,00 to 3,000,000 eggs are held by the female for 8 months until they hatch into planktonic larvae. After around five weeks in the plankton, the crab larvae settle on the seabed. Juvenile crabs settle in the intertidal zone and remain in these habitats for 3 years, until they reach 6-7 cm carapace width, at which time they migrate to subtidal habitats. The crab is encased in a hard, rigid shell, which, like other crustaceans, has to be shed at intervals to permit growth. Moulting takes place at frequent intervals during the first years of a crab's life, but only every two years after it is grown and this is mirrored by a slowing of growth rate. Growth is dependent on the frequency of moulting as well as the increase in size on each moulting occasion and it typically takes about four or five years for a juvenile crab to grow to commercial size. They can grow up to about 25 cm carapace width, with the larger specimens inhabiting deeper water. Growth rate varies between areas, and animals will typically reach a minimum landing size of 140mm carapace width at 4 to 6 years old. Environmental variables e.g. sea temperature related to geographical area and fishing pressure affect the size of maturity with animals in more northerly latitudes growing and maturing more slowly. Minimum landing sizes vary around the British coast from 150mm in the Western Channel to 115 mm in Norfolk for example. Edible crabs can live for up to 100 years but average age is around 25 to 30 years, and sexual maturity is reached after approximately 10 years, but can be as early as 3 to 4 years. Female brown crabs in Scottish waters typically mature between 130 and 150 mm CW. In Orkney research has shown that sexual maturity can be reached at 115 to 120 mm. The sex of a brown crab can be determined by the shape of the abdomen; the males being narrow and the females being broad and rounded for carrying eggs. Stock boundaries for edible crab remain poorly understood and both sexes move quite widely at times; females in particular have been shown to travel large distances in relation to spawning activity.

Stock information

Stock area
Scotland

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Stock information
Although some assessment has been carried out on brown crab in the UK and Scottish waters, the status of stocks (e.g. populations, seasonal distributions, etc.) in particular areas is unclear. For the Orkney brown crab fishery, this lack of area-specific information is currently being addressed as part of a Fishery Improvement Project (FIP) working towards meeting the Marine Stewardship Council's sustainable fisheries standard. A pre-assessment of the fishery in 2012 against this standard identified three essential components of a sustainable fishery management system were lacking, namely criteria for sustainable fishing (Biological Reference Points); rules for controlling fishing pressure in response to stock status (Harvest Control Rules); and data on fishing effort that could be used in monitoring and controlling fishery input. To meet these requirements crab fishermen in Orkney have been involved in the Orkney Shellfish Research Project, which underpins the FIP, collecting data to improve biological understanding of the stock and fishing effort. Sampling of fishermen's catches onshore and offshore has been at a high level during 2013, 2014 & 2015 with more than 80,000 crustaceans of the three main target species measured each year and a total of more than 10,000 crabs tagged. Tagging of brown crabs is aimed at understanding the spatial structure of the stock, particularly in relation to movements of spawning females between inshore and offshore grounds. Market sampling has provided data for length cohort analysis (LCA) used for stock assessment purposes. Over the past year over 60,000 individual brown crab were measured and recorded. Observers on vessels have looked at catch composition, live discards (undersize and out of condition animals) and catch per unit effort. There are also a number of smaller projects looking at: lobster habitats; efficiency of escape panels in creels; and monitoring of bottom sea temperatures around Orkney in relation to crustacean catches. Heriot-Watt University carried out the first Orkney shellfish stock assessment in 2014 using data collected during 2013 and by Orkney Sustainable Fisheries (OSF) since 2010. This will allow candidate Biological Reference Points to be identified, providing the basis for designing Harvest Control Rules for the fishery. Indications are that crab stocks in both inshore and offshore areas are being fished within sustainable limits (MSY) and that the fishery will receive an unconditional pass under Principle 1 of the MSC standard for responsible fishing.

Management

Crab and lobster fisheries are not subject to EU TAC regulations or national quotas although there are measures in place to restrict the fishing effort through kW days at sea for boats over 15m. EU technical conservation measures include geographically varying minimum landing sizes (MLS) and restrictions on the amount of crab claws that can be landed. Orkney Sustainable Fisheries (OSF) Ltd was established some 8 years ago to take over the running of the local lobster hatchery and carry out shellfish research. The fishery currently employs 4 shellfish researchers and has a number of management projects underway alongside a major 4 year shellfish research project looking at inshore fishing activity in a marine spatial planning context, as well as running the UK's first Fishery Improvement Plan (FIP) for local crustacean species. The FIP for the Orkney brown crab fishery is the only recognised FIP for brown crab in the world. The fishery is in the 4 year FIP to enable it to obtain Marine Stewardship Council (MSC) certification. All processing is done in co-operatively owned factories on the islands and only brown crab that is caught by the boats owned and registered in Orkney, fishing out of and landing into Orkney ports are processed. Recently the fishery announced that they are applying for EU Product Designation of Origin (PDO). Benefits to the consumer are fish of known origin from a monitored and sustainable fishery. To demonstrate OSFs commitment to sustainable fishing a Fishermen's Code of Practice is in place, specifying best practice for fishing, handling and storage of shellfish. The legal limit of 140 mm carapace width ensures that females have the opportunity to spawn at least once before entering the fishery. OSF applies further precaution by applying a larger MLS of 153 mm. The Code of Practice also requires that only hard shelled, heavy and crabs in good condition are landed. Under the Code landing of pre or post moult crabs; berried or egg-bearing female crabs; crabs exhibiting "black spot"; cripple or one-clawed crabs; or other visibly diseased crab is prohibited. OSF Ltd intends to go forward for MSC assessment of their fishery in the spring of 2017. The process is anticipated to take 6-9 months.

Capture information

A crab pot is a portable trap made up of wood or steel wire and plastic. The crab is baited into the initial part (the chamber) and moves into the secondary part (the parlour) where it is trapped. Pots or creels have a low habitat impact. They are also a highly selective method of fishing as undersized animals can be returned to the sea alive. The fishery have notified that undersized or "out of condition" target species are returned alive. The fishery also has very little bycatch, starfish and hermit crabs, are returned to the sea alive. Measures to further reduce bycatch and environmental impact is the trial of escape panels to allow undersize animals and bycatch to escape creels. The fishery harvests 25-30% of the total Scottish brown crab catch.

Read more about capture methods


References
http://assets.wwf.org.uk/downloads/orkney_brown_crab_fip_action_plan_2013.pdf?_ga=1.217609366.1415573881.1445252840
http://www.gov.scot/Topics/marine/marine-environment/species/fish/shellfish/BrownCrab
http://www.orkneycrab.co.uk/index.php
http://www.arkive.org/edible-crab/cancer-pagurus/#text=All
Http://producerexchange.marksandspencer.com/news/ms-support-ground-breaking-shellfish-research-project-orkney
Http://www.wwf.org.uk/what_we_do/changing_the_way_we_live/food/seafood__responsibility_and_stewardship/orkney_brown_crab_fip/
Http://assets.wwf.org.uk/downloads/orkney_fip_annual_review_reprt_2014.pdf?_ga=1.223752667.1738140489.1446129726
Http://www.orkneysustainablefisheries.co.uk/wp-content/uploads/2014/12/Orkney_FIP-2014.pdf

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