Scallop, King, scallops

Pecten maximus

Method of production — Caught at sea
Capture method — Dredge
Capture area — North East Atlantic (FAO 27)
Stock area — England
Stock detail

Western Channel Inshore (0-6nm)


FIP Stage 2

Picture of Scallop, King, scallops

Sustainability rating three info

Sustainability overview

A Fishery Improvement Project has begun in the Channel fishery which aims to improve data collection to improve management. A stock assessment is currently being produced but current population trends are negative with landings, effort and productivity have all decreased since 2012. The Western Channel North (from Penzance to Bournemouth) typically has slower growth rates compared to the east or south.

Inshore waters are generally managed using effort restrictions, limited licencing and technical measures (minimum mesh sizes). The fishery is enforced well using Vessel Monitoring Systems (VMS) data and patrols.

There are a wide variety of bycatch species caught and more data are required to determine the direct and indirect impact on vulnerable species. There is scientific consensus that dredges present a greater risk to seabeds habitats and species opposed to other bottom trawl gears. In the inshore waters, there has been significant protection by the IFCAs to reduce the risk of fishing in vulnerable habitats through spatial management.

Of concern is the use of bottom towed fishing gear in Marine Protected Areas (MPAs), especially sites to protect seabed features or where an appropriate impact or risk assessment has not been undertaken to demonstrate that the activity has no significant effect to the site.


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


Stock information

The scallop stock in ICES Area 7 are poorly defined which the ICES Scallop Assessment Working Group is currently trying to improve. There are no reference points for the stock. Landings, effort and productivity have all decreased since 2012. MLS is above the size at maturity, and therefore, is unlikely to impair recruitment.

To determine the stock status for scallops, researchers need to define the level where the stock is sustainable and/or where the stock population is at risk. These levels are called reference points. In the absence of reference points, it is difficult to determine how healthy a population is.

There is no conclusion regarding the stock status because there has been little interpretation of the data (e.g. no reference points).


Criterion score: 0.5 info

Capture Information

Criterion score: 0.5 info

Scallops represent the majority of landings from dredges, followed by monkfish, sole, plaice, turbot, brill, cuttlefish, brown crab. The main discard species include crabs, dogfish, Nursehound, Dragonet, Green sea urchin, Starry ray, Smelt, Ocean quahog and starfish. Some sensitive species are caught, including starry ray, common skate (Dipturus batis), thornback rays, porbeagle and nursehounds.

Dredges can cause considerable impact on benthic habitats and is a significantly more damaging method of fishing compared to dive-caught methods. 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. Mixed sand and mud habitats generally have diverse benthic communities with a high biomass. Conversely, 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. Soft sediments are generally much less sensitive to disturbance, depending on their sediment structure, morphology and presence of vulnerable features.

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, seagrass beds and horse mussel beds. There is a partial ‘strategy’ through EU, UK and local management regimes to protect habitats. European Marine Sites (SACs & SPAs) are designated throughout the English Channel.

English inshore and offshore marine habitats are relatively well-studied to understand where OSPAR priority habitats (VMEs) are present, and where fishing vessels coincide (vessels over 12m in length are monitored using VMS, and smaller vessels can be monitored e.g. by using surveillance data.

At a local level, the local IFCAs conduct surveys to determine and designate vulnerable features e.g. restrictions on dredging in the IFCA areas and a ban on shellfish dredging within the designated European Marine Site at Lyme Bay.


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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

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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: