Scallop, King, scallops

Pecten maximus

Method of production — Caught at sea
Capture method — Dredge
Capture area — North East Atlantic (FAO 27)
Stock area — Northern Ireland
Stock detail — All Areas
Picture of Scallop, King, scallops

Sustainability rating three info

Sustainability overview

The Agri-Food and Biosciences Institute (AFBI) conduct annual scallop surveys but there is no current evaluation to say if the stock is healthy.

The Northern Ireland fleet is managed by the Conservation of Scallops Regulations through gear restrictions which are enforced via patrols-at-sea and VMS data, however around half of vessels fishing for scallop are below 12m and therefore, don’t use Vessel Monitoring Systems.

Scallop dredging is one of the most destructive bottom-towed year methods and it is unknown how this impacts bycatch in the region. There has been controversy over how scallop dredging has impacted some ecosystems, e.g. in Strangford Lough, evidence has shown that the ecosystem has undergone substantial degradation due to scallop dredging. There is little regulation thought there are scallop bans within inshore Marine Protected Areas for 3 significant sites - Strangford Lough; Rathlin Island; the Skerries and another five smaller sites. Additionally, the AFBI have implemented a seeding project by identifying potential sites which will act as breeding grounds for scallops.

Biology

King scallops are bivalve molluscs found in a range of depths from shallow waters in sea lochs to over 100m. They inhabit sandy-gravel and gravel seabeds. They have 2 shells or valves, the upper being flat, and the under or right valve, cup shaped. They are hermaphrodites (i.e. both male and female) and become fully mature at about 3 years old (80 to 90mm in length). Spawning occurs in the warmer months, from April to September. The species can grow to more than 20cm in length and live for more than 20 years, although average sizes are in the range of 10-16cm.

Stock information

Criterion score: 0.5 info

Stock Area

Northern Ireland

Stock information

The Agri-Food and Biosciences Institute (AFBI) conduct annual scallop surveys and have found very few one and two-year-old scallops though The Ards Peninsula has a larger proportion of megaspawners (20% of the population). There are insufficient biomass and fishing mortality data to evaluate the stock status.

Management

Criterion score: 0.5 info

The Northern Ireland fleet is managed by the Conservation of Scallops Regulations through gear restrictions (6 dredges per side max; 9 teeth per dredge max; minimum tooth spacing; belly ring diameter of 75mm min; a minimum mesh size of 100mm in the netting cover; the prohibition of French dredges), a curfew and an MLS of 110mm. These are enforced via patrols-at-sea and VMS data, however around half of vessels fishing for scallop are below 12m and therefore, don’t use VMS.

Capture Information

Criterion score: 0.5 info

Generally, scallop dredge bycatch includes commercial species such as crabs (spider and brown), monkfish, queen scallop, cuttlefish, rays, plaice and sole and non-commercial species such as starfish, echinoderms, small crustaceans, bivalves, hydroids and bryozoans. In the English Channel bycatch represents around 20% by weight. Additionally, much of the mortality is not recorded in vessel surveys: over 75% of the megafauna encountered by scallop dredges remains on the seafloor.

Dredges can cause considerable impact on benthic habitats and is a significantly more damaging method of fishing compared to manual harvesting by divers. This can lead to damage to important habitats and reduced biodiversity depending on how much mortality is caused by the fishing method and the recovery rate of the biota effected. The impact can be highly site specific. Scallop dredging presents a greater impact to the biota: hydraulic dredges can remove 41% of biota and penetrate the seabed by on average 16.1 cm. The impact of dredging on the seabed vary with different seabed types and how exposed the seabed is to natural disturbance i.e. wave action.

Typically, less exposed seabed areas such as inshore waters and vulnerable habitats are more vulnerable to the effects of dredging. Destroying maerl beds substantially reduces biodiversity, seabed stability, local nursery areas and therefore commercial fisheries. Soft sediments are generally much less sensitive to disturbance, depending on their sediment structure, morphology and presence of vulnerable features. More naturally stable seabed environments are generally more sensitive to ecological disturbance. Therefore, seabeds and ecosystems naturally adapted to disturbance by currents and storms e.g. in soft mud / sand sediments are less likely to incur long-term damage. Mixed sand and mud habitats generally have diverse benthic communities with a high biomass. Therefore it is important to determine the localised impact of scallop dredging on the ecological community.

The most common habitats for scallop dredging in the area is on sand, gravel or pebble/ cobbles. However, there are vulnerable marine ecosystems (VME)s within the area including reefs and seagrass beds. It is important to monitor the impact of scallop dredging on these habitats and bycatch species because scallop dredging can damage horse mussel beds. However, there are no ETP strategies in place for these identified species. There has been controversy over how scallop dredging has impacted some ecosystems in Northern Ireland, e.g. in Strangford Lough, evidence has shown that the ecosystem has undergone substantial degradation due to scallop dredging. There is little regulation thought there are scallop bans within inshore MPAs for 3 significant sites - Strangford Lough; Rathlin Island; the Skerries and another five smaller sites. Additionally, the AFBI have implemented a seeding project by identifying potential sites which will act as breeding grounds for scallops.

References

Hiddink, J.G., Jennings, S., Sciberras, M., Szostek, C.L., Hughes, K.M., Ellis, N., Rijnsdorp, A.D., McConnaughey, R.A., Mazor, T., Hilborn, R., Collie, J.S., Pitcher, C.R., Amoroso, R.O., Parma, A.M., Suuronen, P., Kaiser, M.J., 2017. Global analysis of depletion and recovery of seabed biota after bottom trawling disturbance. Proc. Natl. Acad. Sci. 114, 8301-8306. doi:10.1073/pnas.1618858114

Howarth, L. M. & Stewart, B. D. 2014. The dredge fishery for scallops in the United Kingdom (UK): effects on marine ecosystems and proposals for future management. Report to the Sustainable Inshore Fisheries Trust. Marine Ecosystem Management Report no. 5, University of York, 54 pp

Bangor University. 2017. Fisheries and Conservation Science Group: Scallop Fisheries: Fishery. Available at: http://fisheries-conservation.bangor.ac.uk/iom/scallops.php.en#fishery-tab

ICES. 2016. Report of the ICES Scallop Assessment Working Group (WGScallop) 3-7 October 2016 Aberdeen. Available at: http://ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/acom/2016/WGScallop/01%20WGScallop%202016%20Report.pdf

MMO. 2017. Evidence requirement R046: Impact of external pressures on fisheries in Western Waters (area 7). Available at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/647357/Impact_of_external_pressures_on_fisheries_in_Western_Waters__area_7_.pdf.

Sciberras, M., Hinz, H., Bennell, J., Jenkins, S., Hawkins, S., Kaiser, M., 2013. Benthic community response to a scallop dredging closure within a dynamic seabed habitat. Mar. Ecol. Prog. Ser. 480, 83-98. doi:10.3354/meps10198

Seafish. 2017. Seafish Economic Analysis: UK king scallop dredging sector 2008-2016. Edinburgh, UK. Available at: http://seafish.org/media/Publications/Scallop_report_FINAL.pdf

http://www.sealifebase.org/summary/Pecten-maximus.html

https://www.daera-ni.gov.uk/articles/inshore-fisheries-policy

https://www.gov.uk/government/publications/fishing-regulations-the-blue-book/section-c-legislation-applicable-in-welsh-and-northern-irish-zones