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Scallop by Sarah McCartney


Scallops have two large shells joined at the bottom by a hinge and inside they have a juicy white muscle which attaches to both shells. Scallop meat is prized for its delicate taste and texture. 

Sustainability Overview

The best choice are diver collected scallops which are collected with minimal damage to the seabed, however the quantity landed is very small and the majority of scallops landed to Cornwall have been collected using scallop dredges.
Scallop populations in Cornish waters are poorly studied but are unlikely to be overfished due to the rapid growth of this species. The impact of scallop dredging on the environment is the main concern with this fishery as the heavy toothed dredges used dig into the sea bed and disturb and damage habitats and species.  Cornwall Inshore Fisheries and Conservation Authority have placed many restrictions on scallopers in Cornish waters however  there is still room for improvement and with improved spatial management of productive scallop grounds the future of this fishery could be far more sustainable.  It is encouraging that the industry is working on a Fisheries Improvement Plan which sets an ambitious target to improve the sustainability of this important fishery.  The latest large scale study on scallop populations in our area (CEFAS) show that stocks are likely to be just below maximum sustainable yield in some areas and near MSY in other areas, meaning it is hard to say it is a sustainable fishery. More research is still needed. 
According to MMO data a total of 478 tonnes of scallops were landed to Cornish ports in 2019 with a value of £748k. 
Updated July 2023

Sustainability ratings for this species

Diver Collected

7e and f (Inshore Cornwall: 0-6 nm)

Diving using scuba apparatus is a low impact method of collection of shellfish.

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Scallop Dredging

7f.l (7f) Bristol channel - outside 6nm

Scallop dredges are heavy duty metal framed, toothed nets that are pulled over the seabed to target scallops which live buried in the sand or mud seabed.

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Scallop Dredging

England (English Channel - Offshore West: 7e.O) (7e)

Scallop dredges are heavy duty metal framed, toothed nets that are pulled over the seabed to target scallops which live buried in the sand or mud seabed.

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Scallop Dredging

English Channel - outside 6nm Cornwall: 7e.I (7e)

Scallop dredges are heavy duty metal framed, toothed nets that are pulled over the seabed to target scallops which live buried in the sand or mud seabed.

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Scallop Dredging

English Channel - Inside 6nm - 7e.I (7e)

Scallop dredges are heavy duty metal framed, toothed nets that are pulled over the seabed to target scallops which live buried in the sand or mud seabed.

Learn more

How we rate fish

Cornwall Good Seafood Guide rates fish on sustainability using a scale of 1 to 5.

1, 2 and 3 are recommended, Fish to avoid are rated 5.

We use the system devised by the Marine Conservation Society (MCS) so our scores are comparable with the scores produced by MCS for the UK and fisheries from all around the world. For more information on scoring click here.


Scallops are bivalve molluscs. They live buried in the surface layer of soft seabeds; sand mud and gravel and maerl. They filter feed on plankton and detritus. Scallops are able to move by rapidly closing their shell which forces jets of water out of the back of the shell and propels them along. 
When a scallop is resting on the seabed and feeding its shell opens by up to 2 centimetres and the mantle with thousands of tentacles is visible. A ring of eyes all around the shell further improve the sensory ability of scallops to detect predators. 
Scallops 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, and a three year old scallop can produce between 15 and 21 million eggs each year! (Marlin)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. 
Due to rapid growth and high reproductive rate scallops have a low vulnerability to fishing pressure 26% (Cheung et al 2005, source

Stock Info

Stocks of scallops in UK have long been understudied. A recent large scale government funded stock assesement carried out by CEFAS carried out in 2017 and 2018 showed that scallop stocks in our area are likely to be close to sustainable levels but it is a very complex situation and more research is needed. This is the first time a project of this scale has been carried out and it is hoped that if it is continued it will show an improving situation regarding stocks of scallops. The work has identified 5 important scalloping areas in the Western Channel and one smaller area off the north Cornish coast in area VIIf (Trevose Bank). 

Seafish Risk Assesement for scoring seafood has analysed scallop fisheries in the South west and estimate that there is a moderate risk for this stock. The Seafish responsible sourcing guide states that Periodic intensive fishing by large (>15m) ‘nomadic’ boats from England and Scotland in recent years has threatened the viability of small-scale inshore fleets that rely on local beds. Number of boats fishing for scallops in area VII increased by 26% between 2002 and 2014.(MMO)

Landings of scallops in Cornwall have dropped significantly from a previous rate of  1-2000 tonnes per year to less than 500 tonnes for 2020 and 2021, for the first time in nearly 30 years.



There are currently no industry led seasonal closures and few restricted areas for scallopers in Cornish waters but these have proven to be effective in other parts of the UK for management of scallop stocks and habitats. Scallop dredging has a direct physical impact on the seabed and it is important that some areas are left undredged to allow vulnerable seabed habitats to recover and to provide protected brood stocks and nursery areas for scallops. 
This is a regulated fishery but there is currently no quota providing a cap on quantities of scallops caught.
There are technical measures including gear and effort restrictions and a minimum landing size of 100mm shell width. 
A 7pm-7am curfew applies preventing scallop dredging at night within Cornwall and Devon IFCA's. Scallops have to be landed whole, it is illegal to cut them out of the shells at sea.
Effort is capped through restrictive licensing and local Inshore Fishery Conservation Authority (IFCA) permit. Within Cornish waters CIFCA have placed a restriction on the number of dredges used per boat inside 6 mile limit of 12 per vessel and restrictions on mesh size on dredges and length of dredge bar.
The Western Waters effort regime places an upper ceiling on the number of kilowatt days (KWdays) fished by vessels larger than15m in length, towing dredges for scallops. Within the UK this pool of effort is administered by the Marine Management Organisation (MMO) in a system which sets a maximum number of days (per quarter) that any vessel with a scallop entitlement may fish, these limits being revised on a quarterly basis. In recent years this effort cap has been limiting.
There are 40 vessels fishing in Devon and Cornish waters that have Vessel Monitoring Systems (VMS) fitted voluntarily either to engage in the Lyme Bay pilot project or by those vessels that fish nomadically in Welsh waters where its use is compulsory. VMS provides fisheries management agencies with accurate information about the location and activity of regulated fishing vessels and it is a cost effective  tool for the successful monitoring, control and surveillance of fisheries activities. The length and power of vessels scalloping within Cornish IFCA waters is restricted to 18.28 m (60ft) and 221 kw (300hp).  A Voluntary Scalloping Good practice guide has been developed by the Scallop association and many local boats adhere to this.
Diving for scallops commercially can only be undertaken from a licenced fishing vessel and divers must adhere to minimum landing sizes, fill in a shellfish data return for CIFCA and must adhere to HSE regulations governing safety. 
Unfortunately the Fisheries Improvement Plan (FIP) for king scallops has shown no real signs of changes in management of the fishery despite 5 years of development, however it is hoped that a harvest strategy and improved management may be included in the national Scallop Fisheries Management Plan (FMP) which is in development.

Capture Info

The majority of scallops (98%) are caught using scallop dredges. A very small quantity are collected by divers. Scallop dredges are steel framed nets that are pulled along the seabed. Spring loaded teeth act like a rake cutting into the seabed and flipping scallops up and into a net. The teeth can hinge backwards to prevent the dredge snagging on the seabed if it hits rock or wreckage. Use of these ‘Newhaven dredges’ have a well-documented impact on the seabed (Sewell and Hiscock) particularly the first time an area is fished but in some areas which have already been dredged the additional impact can be argued as far less. Fragile habitats such as maerl beds and seagrass beds are particularly vulnerable to damabe by scallop dredging, as are fragile invertebrates such as sponges, bryozoans and corals.

Scallops are also collected by divers in shallow waters (less than 30m). Diving for scallops is very selective and has no impact on the wider environment.(Sewell and Hiscock) 



Assessment of king scallop stock status for selected waters around the English Coast 2021/22
ICES. 2019. Scallop Assessment Working Group (WGSCALLOP)
Scallop survey trial Portloe Cornwall IFCA 2019
Scallop stock assesement English Channel 2017 CEFAS
Fisheries Improvement plans through Project UK 
CEFAS Red bag scheme final report July 2014
Ecological Risk Assessment of the effects of fishing for South West fisheries; ICES Divisions VII e,f,g &h Seafish 2014
MMO Landings data
UK scallop fishery good practice guide – Shellfish association and Seafish industry authority
Cheung, W.W.L., T.J. Pitcher and D. Pauly 2005 A fuzzy logic expert system to estimate intrinsic extinction vulnerabilities of marine fishes to fishing. Biol. Conserv. 124:97-111 source
SEAFISH Responsible Sourcing Guide: Scallops. Version 3 – January 2013

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