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

Eastern Channel (waters outside 6 nm)


FIP Stage 2

Picture of Scallop, King, scallops

Sustainability rating four info

Sustainability overview

An inshore and offshore Fishery Improvement Project has begun. A stock assessment is currently being produced but current population trends are negative with decreasing landings, effort and productivity since 2012.

There are fewer management measures than the inshore fishery and can include a TAC, landing sizes (100 mm), measures to ban shucked meat, gear restrictions, an effort ceiling for vessels over 15m, closed seasons, closed areas and curfews which are enforced by logbooks, historic data and sometimes survey and Vessel Monitoring System data.

The area is fished by English, Scottish and Irish vessels, therefore, joint management crucial in the fishery. There are a wide variety of bycatch species (including commercial species).?More data are required to determine the direct and indirect impact on vulnerable species.

Dredges can cause significant impacts to the seabed and benthic species, therefore, area closures are used to limit this. The scallop fishery occurs mainly on sand, gravel or pebble/cobbles but there is inadequate management to protect sensitive habitats in offshore fisheries. 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: 0.75 info

There is no harvest strategy at the unit stock level other than a minimum landing size (MLS), which is 110mm (larger than the MLS for most areas around the UK - normally 100mm). However, the effectiveness of MLS at protecting the stock has not been studied and the MLS is not responsive to changes in stock status. There are no TACs. Other management measures include: effort restrictions, e.g. limited licensing; and gear restrictions, e.g. minimum mesh sizes. However, these measures have not considered the stock status and therefore may not prevent over-exploitation.

Stock assessments and adaptive management actions are lacking. There is no defined stock boundary for English Channel scallops which creates conflict when different jurisdictions try to manage the stock. Data on landings, effort, fleet composition, and potentially catch rates are available. A significant number of landings occur from foreign fleets. Monitoring is completed on species productivity, growth rate and maturity.

Both fisheries-dependent and fisheries-independent data are available. Assessments are conducted in ICES level with member state’s scientists. The advice is then reviewed by STECF. However, since scallop stocks are ill-defined, using the advice to apply management is more difficult, which undermines stock management. Whilst a good level of information exists on the Endangered, Threatened and Protected (ETP) species distribution, fleet activity and bycatch information and regulations to protect bycatch, there still needs to be an improvement in catch composition data.

Enforcement duties are conducted by EU member states and measures are in place to reduce the risk of illegal, unreported and unregulated (IUU) fishing. All vessels greater than 12m are required to have VMS and electronic logbook reporting is required. Buyers and Sellers are registered and are required to present sales notes. Marine Management Organisation enforcement officers inspect catches in ports and at sea in association with the Royal Navy Fishery Protection Squadron. Non-compliance is punishable with fines and sentencing, and can be completed at national and EU level.

Capture Information

Criterion score: 0.75 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.

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.


Southall, T. 2016. MSC Pre-Assessment for English & Western Channel Scallop fishery (Scallop Dredge). Prepared for Project UK Fisheries Improvements. Edinburgh, UK.

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:

ICES. 2016. Report of the ICES Scallop Assessment Working Group (WGScallop) 3-7 October 2016 Aberdeen. Available at:

MMO. 2017. Evidence requirement R046: Impact of external pressures on fisheries in Western Waters (area 7). Available at:

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: