Scallop, Queen, scallops

Aequipecten opercularis

Method of production — Caught at sea
Capture method — Demersal otter trawl
Capture area — North East Atlantic (FAO 27)
Stock area — Isle of Man
Stock detail — Territorial waters (0-12nm)
Picture of Scallop, Queen, scallops

Sustainability rating four info

Sustainability overview

The most valuable fishery for queen scallops in the North-east Atlantic occurs in the Irish Sea and particularly around the Isle of Man. The stock is at unsustainable and very low levels. Scientists recommend a reduction in TAC and a precautionary approach which has subsequently been reduced to 992t. The inshore fishery is well-managed with a suite of management measures. However, this has not been sufficient to improve the stock status.

Management includes an annual TAC of a weekly catch limit of 4200 kg (Weeks 1-10) and 2800 kg (Weeks 11 onwards), weekly individual vessel quotas, minimum landing size of 55 mm, a season closure, trawling and dredging seasonal ban, a series of closed areas and temporal fishing restrictions.

A Pan-Irish Management Agreement is required to ensure that non-territorial stocks are managed sufficiently and do not reduce the stocks in territorial waters.

Monitoring occurs through Daily Catch Returns and VMS. Queen scallops are usually caught with otter trawls in the Isle of Man because they are keen swimmers and are easily caught in nets. Otter trawls are less damaging to the seabed than dredges, and bycatch is generally lower. This, coupled with management measures such as MPAs, area closures, and curfews to avoid catching brown crabs (which are more mobile overnight), means that there is a reduced risk to the ecosystem compared to dredging.


Queenies are a fast growing species with a maximum lifespan that rarely exceeds five years. Queen scallops are simultaneous hermaphrodites (i.e. an individual has both male and female reproductive organs) and become sexually mature at 1-2 years at approximately 40mm shell height. Although smaller than King scallops they can grow up to about 90mm. Queen scallops are broadcast spawners (i.e. they release eggs and sperms into the sea) and can spawn in both spring and summer. When one individual spawns, pheromones contained in the eggs and sperms released into the water column, signal to neighbouring scallops to release their own eggs and sperms ensuring synchronous spawning. Thus, in order for spawning (and subsequently recruitment) to successfully occur Queen scallops need to be present at relatively high densities. In low density populations there is a risk that the spawning stock may not be present at high enough densities to successfully reproduce (i.e. there are too few individuals around to come into contact for fertilisation), a phenomenon known as the Allee effect. They are usually found at depths down to about 100m on sand or gravel. It feeds on plankton and other organic material by filter feeding. They reach market size of 55mm (minimum landing size in Isle of Man; 40mm for rest of the Irish Sea) within 2-3 years depending on the available micro-algae feed from the water column.

Stock information

Criterion score: 1 info

Stock Area

Isle of Man

Stock information

The Isle of Man Queen Scallop stock is at very low levels. The estimated median population biomass in 2016 is 4678 t which is below the minimum biomass threshold, 2015 median population biomass (5327t) and the limit reference point (13,000t).

The territorial sea has had declines of total biomass by over 21,000t between 2010 and 2016 post-recruits biomass between 2010 and 2016. Recruit biomass declined sharply between 2009 and 2011 and has since been variable. These declines in biomass have meant that the fishery is heavily dependent on annual recruitment. When biomass decreases below the minimum threshold, recruitment may be impaired and fishing mortality should be reduced to allow stocks to increase. There is no scientific evidence that the stock can support increased TAC from 2015 levels (1240 t). Landings in the territorial sea were higher in 2016 (1240t) than in 2015 (1000t) despite these declines in biomass.

The stock status is also affected by the strength of the Allee effect (impacting the spawning potential), quality of habitats (impacting settlement) and the level of fishing mortality outside the territorial sea (impacting larval supply) and environmental factors (water temperature).

Larval dispersal studies show that there is limited connectivity between north east Celtic Sea, south Irish Sea, Cardigan Bay and Liverpool Bay with a high level of self-recruitment. No larval exchange occurs between the eastern Irish Sea and south but potentially between the south Irish Sea into the Celtic Sea and east-west exchange between the south Irish Sea and Cardigan Bay.

In the territorial waters, Queen scallop biomass is below the limit reference point. Within territorial waters, a precautionary strategy is in place (e.g. TACs, closed areas, season closures).


Criterion score: 0.25 info

The Inshore Queen Scallop fishery has been managed by Sea Fisheries (Queen Scallop Fishing) Byelaws since 2010. Manx waters have a robust and precautionary harvest strategy, however has not been successful at rebuilding or maintaining the stock.

The new statutory harvest controls in the IOM Territorial Sea (0-12nm) for the queen scallop fishery: Delayed queen scallop trawl fishery season until 1st July 2016 (instead of 1st June) (a closure between November and June each year (and a statutory closed season between 1st April and 31st May, no trawl fishery between November and April, and a very limited dredge fishery around October; Weekend and night-time curfews on queen scallop fishing; Prohibition of queen scallop dredges in the territorial sea (apart from one area in the 6-12nm from October); Maintenance of the cod-end mesh size for queen scallop trawls of 85mm and the MLS of 55mm; Territoral sea TACs of 992t; A vessel bag limit of 120 bags per week (4,200 kg) ; Four new temporary closed areas to queen scallop fishing (to increase spawning potential); Temporal and spatial closures; VMS tracking

A significant reduction in licences issued (from 135 to 48)

The (QMB) is an advisory body.

In 2014, the Queen Management Board (QMB) began to react to stock declines by reducing the TAC from the 5,000t in 2013/14 season to 1,000t. Scientific advice has advised implementing a precautionary approach by limiting harvesting to 20 -25 % of the estimated median biomass (at 935-1170 t). The TAC has recently been adopted this advice at 992 tonnes (in the 2017 fishing season). TACs are divided into approximately an 80:20 split between otter trawlers and dredgers, respectively.

The QMB have been extending a network of closed areas around the Isle of Man territorial waters since the 2014-15 fishing season with licence conditions enforced using Vessel Satellite Monitoring Systems (VMS).

Monitoring, amidst stock declines has become more stringent: each vessel must carry a GPS logger that is submitted to DEFA on a weekly basis with reporting requirements for catch and fishing effort. A mid-season break has been implemented, to allow managers to assess and provide advice on catch and stock data. Additionally, Bangor University collect data on size-at-age, sexual maturity and spawning events on a monthly basis.

DEFA and government enforcement vessel assess closed areas in association with the fishing industry. Between 2016 and 2017 scientific monitoring has assessed seabed habitat types, scallop density and age and size distributions to determine suitable scallop habitat and key conservation features. Monitoring also assesses scallop growth rates and recruitment.

Whilst the IOM territorial sea has implemented harvest controls in response to stock status declines (though TACs, closed areas, a Minimum Legal Size (MLS)), the biological stock area outside the IOM territorial sea has not implemented such measures to limit effort.

Since management measures have been increasingly implemented into the fishery to consider downward trends in abundance. Additionally, further management is being implemented to allow queen scallop fisheries to rebuild e.g. closed areas to promote spawning.

Capture Information

Criterion score: 0.5 info

Queen scallops are active swimmers and when disturbed by tickler chains on otter trawl, quickly swim upwards and are captured in the fishing net. Otter trawls are used in the summer season when higher temperatures cause this swimming behaviour while skid dredges being used are used in the winter months.

Bycatch and discarding is monitored and managed by the IOM Government and the Manx Fish Producers Organisation. Bycatch is generally considered as low (<10%) in the Manx Queen scallop trawl fishery, but has increased in recent surveys. Bycatch significantly varied between fishing ground and time of year, but generally includes: fish (e.g. dab, cod, whiting, gurnards, monkfish), cephalopods (e.g. squid), elasmobranchs (e.g. smoothounds, blonde ray, thornback ray, spotted ray, cuckoo ray, small-spotted catsharks, nursehounds) and invertebrates (e.g. Dead man’s fingers, oyster, sea squirts, star fish, whelk, sea urchin, crabs). However, many invertebrates are unidentifiable or not retained in the surveys.

Otter trawls catch exhibit higher levels of finfish bycatch but are more environmentally friendly to habitats compared to dredges.

The introduction of the new Landings Obligation regulations require some bycatch (e.g. whiting) to be landed. Therefore, local Manx Fisheries Producers Organisation (MFPO) have trailed gear modifications on commercial vessels in summer 2016.

Recent surveys have observed general increases in discard rates of undersized queen scallops but discard mortality from otter trawling is nearly a third of that observed in skid dredges.

Mobile fishing gears cause the greatest levels of disturbance to marine benthic communities, either by direct (removal, burial or crushing), indirect (increase susceptibility to predation) or change biogeochemical properties of the environment. However, otter trawls are comparatively much less destructive than dredges.

An area in excess of 85% of the territorial sea is not trawled for queen scallops with the mean footprint of the fishery, relatively stable at around 12% of the territorial sea. The Queenie Conservation Zone, is a designated dredge box with a TAC for the dredge fishery.

Conservation zones in Manx waters promote spawning potential and trawling is prevented from occurring in vulnerable marine habitats. Since June 2016, around 3% of Manx waters are protected as MPAs, with additional seasonal or temporary protected areas.

Habitats and species of conservation concern (some of which are covered by UK BAP, EU Habitats Directive and OSPAR) have identified around the Isle of Man e.g. maerl beds, modiolus beds, sabellaria spinulosa and edwardsia timida. S. spinulosa (the tube-building polychaete worm) are particularly vulnerable because they are located within areas of high queen scallop densities. There is no statutory protection for S. spinulosa reefs in the UK. In territorial waters, protection is provided, however, the efficacy of protection outside territorial waters is unknown.

Future Fisheries, the Isle of Man’s Fisheries Strategy, highlights the importance of ecosystem management, and emphasises the significant role of Marine Protected Areas in protecting the marine environment and supporting sustainable fisheries.

Most queen scallops are caught with otter trawls and there are protective measures throughout the Isle of Man to protect vulnerable habitats, and most substrate is predominantly sand or fine gravel.


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