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 Inshore (0-6nm)
Certification — 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 is predicted to enhance monitoring and management in the fishery. Currently there are a lack of data on the population size of Channel scallops and stocks are ill-defined. There are some negative population trends: landings, effort and productivity have all decreased since 2012. Management measures include effort restrictions, limited licencing and technical measures (minimum mesh sizes). The inshore fishery is enforced well, using Vessel Monitoring Systems (VMS) and patrols. There are a wide variety of bycatch species caught and more data are required to understand both the direct and indirect impact of the fishery on Endangered, Threatened and Protected species such as skates, rays and sharks. 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.

The ICES Scallop working group have attributed recent declines in scallop recruitment, particularly in the Eastern English Channel, to environmental fluctuations, particularly regarding changes in average sea-surface temperature in early summer.

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

The local IFCAs enforce the following management measures per district:

Southern (Area 7d and e)
Minimum landing sizes: 10.0cm shell width in 7e and 11.0cm shell width in 7d. Gear restrictions: 12 dredges per boat with a spring loaded tooth bar; the dredge mouth must not exceed 85 cm in overall width; tow bar restrictions; 7pm-7am fishing curfew.

Sussex (Area 7d)
A closed season from 1st June to 31st October in every year; no scallop dredging within 3 nautical miles of the shoreline; the dredge must be spring loaded ‘Newhaven’ type (‘French’ or paravane type scallop dredges are banned); and there are designated MPAs (Beachy Head West, Kingmere and Utopia).

Kent & Essex (Area 7d and 4c)
Minimum landing size: 11.0cm shell width; bycatch restrictions depending on landings obligation; gear restrictions: 12 dredges per boat with a spring loaded tooth bar; the dredge mouth must not exceed 85 cm in overall width; tow bar restrictions.

IFCAs apply management controls within 6nm of the English coastline. There is no evidence to suggest that scallops inside these areas are not genetically influenced by offshore stocks and therefore improved management between inshore and offshore stocks is required.

There is some information available on stock structure, however, this has not yet been used to define stocks or complete a stock assessment. Data on landings, effort, and fleet composition, and potentially catch rates are available. A significant number of landings are by foreign fleets. Species productivity, growth rate and maturity are monitored. Both fisheries-dependent and fisheries-independent data are available. Assessments are conducted at ICES-level with the 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 IFCAs and 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. 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 responded to with fines and sentencing, and can be completed at national and EU level. There appears to be no evidence of systematic non-compliance.

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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Sussex IFCA. 2011. Inshore Fisheries and Conservation Authority Species Guide. Available at:

Southern IFCA. 2017. Byelaws. Available at:

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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: