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 — Territorial waters (0-3nm)
Picture of Scallop, King, scallops

Sustainability rating four info

Sustainability overview

The Isle of Man’s Department of Environment, Food and Agriculture (DEFA) have suggested that more management is required to sustain the stock. A significant increasing number of vessels over six years have been of serious concern for the fishery. Therefore, the Isle of Man has cut the king scallop fishing licences by nearly half from 156 to about 88. Due to the increased concerns for the King Scallop fishery in recent seasons, DEFA have appointed a Joint Scallop Management Board. The board will be formed of fishermen and scientists and will manage both queen and king scallops. The Isle of Man has implemented good habitat management however, until recently, too many dredgers have been fishing.


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: 1 info

Stock Area

Isle of Man

Stock information

In recent seasons, the number of vessels and effort has increased in the fishery, concurrent with declining landings-per-unit-effort (LPUE), prompting concerns within the fishing industry. Landings have increased steadily over this time and effort levels are considered to be too high to sustainably maintain the fishery. The Isle of Man’s Department for Environment, Food and Agriculture believe that the fishery is fished at an unsustainable level. There are currently no reference points, however, there is increased concern for stock biomass and fishing mortality.


Criterion score: 0.25 info

There has been an increase in the number of vessels applying pressure to this fishery over the past six years, causing serious concern for the stock. Most recently, to account for increases in effort, the number of vessels eligible to fish in the 0-3 NM area has been cut by 59 percent (from 89 to 37). Therefore, the Department of Environment, Food and Agriculture (DEFA) have appointed a Joint Scallop Management Board to manage both queen and king scallops.

Management measures include a 110 mm minimum landing size; VMS; a 1,400kg a day limit; a king scallop season (between 1st November and 31st May); a Future Fisheries strategy; licences; a curfew (no fishing permitted between 6pm and 6am); dredge restrictions (5 aside in 0-3nm) and five new inshore conservation zones around the coastline (where commercial dredge and trawl fishing will be prohibited). Outside these zones, dredge and trawl fishing can continue between 0-3 NM but with additional access restrictions (which depend on past effort and landings). The marine zoning plan mandates further management of mobile-gear fishing effort, with access restrictions based on vessels’ track-records.

VMS and fishing effort data from E-logbooks are used monitor and map fishing effort around the Isle of Man. The DEFA ensure and monitor compliance with fishing regulations in the fishery which is deemed effective.

Capture Information

Criterion score: 0.5 info

King scallops are fished using Newhaven dredges which have teeth to rake out and capture king scallops out of the seabed, into a chain mesh bag. Over 75% of the megafauna encountered by scallop dredges remains on the seafloor and is often not recorded. Isle of Man king scallop bycatch mainly comprises queen scallop, common starfish, cuckoo skate, sea urchin and curled octopus. Other main bycatch are brown crabs. They are particularly vulnerable to capture because the teeth (found on king scallop dredgers) dig out crabs which buried in the sediment. To prevent their capture, Manx dredgers have curfews at night (when edible crabs are most active).

The Isle of Man has marine habitats includes many biogenic habitats such as horse mussel beds and maerl reefs which are very important for processes such as nutrient cycling and provide complex habitats for juveniles. These habitats can be extremely vulnerable to bottom-towed fishing gears. Generally, the more intensely these habitats are fished, the greater declines in species richness, diversity and abundance.


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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

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