Crab, brown or edible

Cancer pagurus

Method of production — Caught at sea
Capture method — Pot or creel
Capture area — North East Atlantic (FAO 27)
Stock area — Eastern English Channel
Stock detail — 7d: Sussex IFCA District (0-6nm)
Picture of Crab, brown or edible

Sustainability rating three info

Sustainability overview

Updated: November 2020.

This stock is data limited and the status of the brown crab stock in the Eastern English Channel is currently unknown. There is concern for biomass and no concern for fishing pressure. Landings per day appear stable and brown crab has a low vulnerability to fishing pressure. Management measures in place include a ban on the landing of berried and soft crabs, and a minimum conservation reference size of 140mm carapace width. Management in this area includes a 300 pot limit inside the 3nm limit, and a total maximum of 600 pots within the 6nm limit. Pot fishing is considered sustainable as it is selective for larger individuals and has minimal impact on the surrounding environment.

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

Criterion score: 0.5 info

Brown crab is widely distributed in coastal waters of the Mediterranean, Atlantic, English Channel and North Sea. CEFAS defines five Crab Fishery Units for England and publishes stock status reports for each area every 2 years.

This stock is data limited and the status of the brown crab stock in the Eastern English Channel is currently unknown. No reference points have been calculated. There is concern the biomass and no concern for fishing pressure.

A length-based assessment (how many animals at a given size there are in the population from one year to the next) was not feasible due to insufficient data. Although with large uncertainty, landings per day appear stable from 2010-2018 for the <=10m fleet and brown crab has a low vulnerability to fishing pressure.

Management

Criterion score: 0.5 info

This assessment is for the brown crab fishery in the Sussex Inshore Fisheries and Conservation Authority (IFCA) district. There are management measures in place for this fishery, but they are not fully effective in managing the stock. This stock is data limited and management would benefit from a better understanding of the stock. Sussex IFCA have a vessel length limit of 14m in place for the district. . All vessels registered in the UK must have a domestic fishing vessel license to fish within the UK EEZ for sea fish that will be sold. No new licenses are being issued. All commercial vessels under 10m, with a shellfish license, are required to complete Monthly Shellfish Activity Return (MSAR) forms for the Marine Management Organisation (MMO). These must include the catch and retained weight each day along with the date, name of the vessel, vessel registration number, gear type, area and port of landing. All vessels over 10m do not need to complete MSAR as they will be completing an EU logbook of catches. For all vessels, effort is reported as days fished, and not as pots fished. In Sussex IFCA district, you must have a commercial permit to fish for crabs and lobsters. Crab and lobster fisheries are not limited by EU Total Allowable Catch (TAC) regulations or national regulations, and therefore are not limited in the number of crabs they can take. Sussex IFCA have a pot limit in place in order to reduce fishing pressure. Only 300 pots may be placed within the 3 nautical mile limit, with a total maximum of 600 pots within the 6 nautical mile limit.

In this area, there is a Minimum Conservation Reference Size (MCRS) of 140mm carapace width in place. According to CEFAS, in the Eastern English Channel, 96-99% of males and 60-86% of females should be sexually mature at this size. National legislation in England and Wales also prohibits the landing of berried and soft crabs. In addition, when using pots or creels, a maximum of 1% by weight of the total catch of brown crabs landed may consist of detached claws. For all other gear types, a maximum of 75kg of detached claws may be landed. In many areas, market preference can also have influence on the crabs which are landed, as those having an unclean appearance, due to disease or discolouration, or those missing both claws can be seen as unmarketable.

In the Sussex IFCA district, permit holders cannot fish for crab or lobster using a pot which has a chamber with an entrance designed to restrict escape, unless the pot is fitted with an escape gap located in the exterior wall of the pot, or if there are multiple chambers in the pot, an escape gap must be fitted to each chamber. This will allow small immature crabs and lobsters, which have not had a chance to breed, to escape.

The UK Fisheries Act came into force in January 2021 and requires the development of Fisheries Management Plans (FMPs). There are no details yet on how and when these will be developed. FMPs have the potential to be very important tools for managing UK fisheries, although data limitations may delay them for some stocks. MCS is keen to see FMPs for all commercially exploited stocks, especially where stocks are depleted, that include:
Targets for fishing pressure and biomass, and additional management when those targets are not being met
Timeframes for stock recovery
Technologies such as Remote Electronic Monitoring (REM) to support data collection and improve transparency and accountability
Consideration of wider environmental impacts of the fishery

Capture Information

Criterion score: 0 info

In the UK, brown crab and European lobster are fished together in a mixed fishery with seasonal and regional variation of target species taking place. The key fishing season for brown crab in the UK takes place from May to December. Crabs are caught in pots, also known as creels, and can be fished individually or as part of a fleet of up to 100 pots, depending on the size of the boat and crew. Pots are portable traps made 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 becomes trapped.

Pot fishing is considered sustainable as it is selective for larger individuals and has minimal impact on the surrounding environment. In brown crab fisheries, there is no legislation or regulation to standardise the type of pot used. They tend to be highly selective as undersized animals can be returned to the sea alive and survival rates for non-target organisms are thought to be high. More than half of the bycatch caught are predicted to survive, although there is little available research to prove this. Measures to further reduce bycatch include the use of escape panels to allow undersize animals and bycatch to escape pots.

Habitat impacts from potting are low but can occur during deployment, soak time or hauling of the pot, impacting the benthic habitat and associated species through contact with the pot or end weight, or by scouring from ropes. Research that has taken place suggests that while some damage does occur, it is unlikely to be significant unless potting intensity is high (defined as approximately 30 pots per 500 square metres). Most damage occurs where traps are set in rocky habitats that are home to corals, sponges, sea whips and other large emergent species. These habitats and species provide nursery areas, refuges from predators and habitat for the settlement of invertebrate spat.

In some circumstances, there can be instances of ghost fishing, when lost fishing gear continues to fish and can entangle a variety of species, but this can be minimised by using appropriate gear and release devices.

References

Cefas. 2020. Edible crab (Cancer pagurus). Cefas Stock Status Report 2019 18 pp. Available at https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/928793/Crab_assessments_2019..pdf [Accessed on 01.12.2020].

CBI. 2020. Entering the European market for crab. Available at https://www.cbi.eu/market-information/fish-seafood/crab/market-entry [Accessed on 01.12.2020].

Gall, S.C., Rodwell, L.D., Clark, S., Robbins, T., Attrill, M.J., Holmes, L.A. and Sheehan, E.V. 2020. The impact of potting for crustaceans on temperate rocky reef habitats: Implications for management. Marine Environmental Research, 162, p.105134. Available at https://www.sciencedirect.com/science/article/abs/pii/S0141113619308657 [Accessed on 08.12.2020].

ICES. 2017. Report of the Working Group on the Biology and Life History of Crabs (WGCRAB), 1–3 November 2016, Aberdeen, Scotland, UK. ICES CM 2016/SSGEPD:10. 78 pp. Available at http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/SSGEPD/2016/01%20WGCRAB%20-%20Report%20of%20the%20Working%20Group%20on%20the%20Biology%20and%20Life%20History%20of%20Crabs.pdf [Accessed on 01.12.2020].

ICES. 2018. Interim Report of the Working Group on the Biology and Life History of Crabs (WGCRAB), 6–8 November 2018, Jersey. ICES CM 2018/EPDSG:09. 13 pp. Available at http://ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/EPDSG/2018/WGCRAB%20-%20Report%20of%20the%20Working%20Group%20on%20the%20Biology%20and%20Life%20History%20of%20Crabs.pdf [Accessed on 01.12.2020].

ICES. 2018. Interim Report of the Working Group on the Biology and Life History of Crabs (WGCRAB), 8–10 November 2017, Brest, France. ICES CM 2017/SSGEPD:09. 30 pp. Available at https://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/SSGEPD/2017/01%20WGCRAB%20-%20Report%20of%20the%20Working%20Group%20on%20the%20Biology%20and%20Life%20History%20of%20Crabs.pdf [Accessed on 01.12.2020].

Marine Management Organisation. 2018. Statutory guidance: Minimum Conservation Reference Sizes (MCRS) in UK waters. Available at https://www.gov.uk/government/publications/minimum-conservation-reference-sizes-mcrs/minimum-conservation-reference-sizes-mcrs-in-uk-waters#crustaceans [Accessed on 01.12.2020].

Mesquita, C., Dobby, H., Pierce, G.J., Jones, C.S., Fernandes, P.G. 2020. Abundance and spatial distribution of brown crab (Cancer pagurus) from fishery-independent dredge and trawl surveys in the North Sea. ICES Journal of Marine Science, fsaa105. Available at https://academic.oup.com/icesjms/advance-article/doi/10.1093/icesjms/fsaa105/5880823 [Accessed on 01.12.2020].

Moffat, C., Richardson, H. and Roberts, G. 2020. Natural England marine chalk characterisation project. Natural England Report NERR080. Available at http://publications.naturalengland.org.uk/publication/5385776319954944#:~:text=Natural%20England%20Marine%20Chalk%20Characterisation%20Project%20(NERR080),England%20on%202%20March%202020%20.&text=Marine%20chalk%20is%20protected%20within,marine%20chalk%20as%20a%20feature [Accessed on 01.12.2020].

Nautilus Consultants. 2009. Final Report: Future Management of Brown Crab in UK and Ireland. Available at https://www.sff.co.uk/wp-content/uploads/2015/09/Nautilus-Brown-Crab-Management-FinRep.pdf [Accessed on 01.12.2020].

Palomares, M.L.D. and Pauly, D. Editors. 2020. SeaLife Base. Cancer pagurus, edible crab. Available at https://www.sealifebase.ca/summary/Cancer-pagurus.html [Accessed on 01.12.2020].

Seafish. Pots and traps – Brown Crab. Available at https://www.seafish.org/responsible-sourcing/fishing-gear-database/gear/pots-and-traps-brown-crab/ [Accessed on 07.12.2020].

Stevens, B. G. 2020. The ups and downs of traps: environmental impacts, entanglement, mitigation, and the future of trap fishing for crustaceans and fish, ICES Journal of Marine Science. Available at https://doi.org/10.1093/icesjms/fsaa135 [Accessed on 08.12.2020].

Sussex Inshore Fisheries and Conservation Authority. 2015. Shellfish Permit Byelaw. Available at https://secure.toolkitfiles.co.uk/clients/34087/sitedata/files/Shellfish-Permit-Guidance-.pdf [Accessed on 01.12.2020].

Sussex Inshore Fisheries and Conservation Authority. 2019. Shellfish Permit Catch Returns Data Summary 2019. Available at https://secure.toolkitfiles.co.uk/clients/34087/sitedata/files/Research/2019-Shellfish-Catch-Return-Report.pdf [Accessed on 01.12.2020].

Sussex Inshore Fisheries and Conservation Authority. 2020. Species Specific Fisheries Information Reports. Available at https://secure.toolkitfiles.co.uk/clients/34087/sitedata/files/Research/Species-Specific-Fishery-Information-Reports.pdf [Accessed on 01.12.2020].

Sussex Inshore Fisheries and Conservation Authority. Shellfish Permit Catch Returns Guidance. Available at https://secure.toolkitfiles.co.uk/clients/34087/sitedata/files/Research/SP-Catch-Returns-Instructions-2018.pdf [Accessed on 01.12.2020].

UK Government. 2020. Manage your fishing effort: Western Waters crabs and scallops. Available at https://www.gov.uk/guidance/manage-your-fishing-effort-western-waters-crabs [Accessed on 01.12.2020].

UK Government. 2020. UK sea fisheries annual statistics report 2019. Available at https://www.gov.uk/government/statistics/uk-sea-fisheries-annual-statistics-report-2019 [Accessed on 07.12.2020].