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Scallop, King, scallops

Pecten maximus

Method of production - Caught at sea
Capture method - Dredge
Capture area - North East Atlantic (FAO 27)
Stock area - Isle of Man
Stock detail - All Areas
Certification -
Fish type - Shellfish

Sustainability rating Click for explaination of rating

This fish, caught by the methods and in the area listed above, is not the most sustainable choice of fish to eat. Click on the rating icon above to read more and on the alternatives tab below to find more sustainable fish to eat.

Sustainability overview

The overall trend for fisheries in the Isle of Man is one of increasing abundance over the last 10 years. The fishery is well-managed with a seasonal closure in force. There are also various effort restriction measures in place, along with a series of closed and restricted fishing areas.


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

Stock area
Isle of Man

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Stock information
The scallop populations around the Isle of Man are probably the most comprehensively studied in British Isles waters. Data surveys are carried out annually by the Manx Government, in conjunction with the University of Bangor, with a view to conducting more formalized stock assessments. No quotas are currently in place for Manx scallops, although a minimum size limit of 110mm is in place, compared with 100mm for most UK waters. There have been no obvious declines in landings with an overall trend of increasing abundance over the last 10 years.


There is an annual seasonal closure from June to October. Also strict effort control in 3 and 12 n mile zones with regulations controlling boat size, fishing hours, and various technical measures governing the gear. Restricted areas protect inshore scallop stocks; the oldest has been maintained as a spawning refuge since 1989. Vessel satellite monitoring (VMS) is also obligatory for this fishery (

Capture information

Scallop dredging is a significantly more damaging method of fishing compared to manual harvesting by divers. Dredging can cause considerable disturbance of the seabed leading to damage to important habitats and reduced biodiversity. The impact of dredging and of other towed gears on the seabed however is largely determined by how exposed the seabed is to natural disturbance i.e. wave action. Consequently less exposed areas such as those found in inshore waters are more vulnerable to the effects of dredging. These effects can however be mitigated by a combination of technical conservation and spatial protection measures such as permanent and rotational closures. A typical or standard scallop dredge, known as a Newhaven dredge, comprises a heavy steel frame, with a mesh net top and belly rings of interlocked steel forming the cod end. At the front of the dredge a toothed bar is present which penetrates the seabed, removing the recessed scallop and flipping it into the body of the dredge. Dredges are used in series, connected to a rigid wheeled bar and may have up to 20 dredges per bar. Typically two dredge-bar units will be deployed, one on either side of the vessel. Non-target species, such as echinoderms (starfish, urchins etc.), crabs and undersized scallops are often taken as bycatch or damaged in situ. When undamaged, undersize scallops can be returned live to the sea. A project to assess new dredge types - the ecodredge - with less invasive teeth and rollers instead of belly rings will commence shortly in the Moray Firth. Management measures drafted for Special Areas of Conservation (SACs) and Marine Coastal Zones (MCZs) are likely however to recommend no demersal towed gears in areas where the seabed habitat type is a protected or sensitive feature e.g. reef. There are also access restrictions in some areas for towed gear to protect nursery and spawning areas e.g. Start Bay. Closures have also been introduced in some areas e.g. Devon to reduce conflict between mobile gear including dredges and static gears such as pots and gill nets. The number of dredges is also limited by fisheries management legislation. Within 6 miles of the coast the number of dredges per bar is dictated by the local Inshore Fisheries Conservation Authority (IFCA). Between 6 and 12 miles the new harmonised English and Scallop Orders limit the number of dredges to 8 per side of the vessel. The gear mesh or ring size should be as selective as possible to allow juveniles to escape. The minimum landing size for scallop in EU waters is 100mm, except in the northern Irish Sea (Isle of Man), Eastern English Channel and Welsh waters where it is 110 mm.

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