King scallop

Stock Status Score: 0.75

There is concern for both biomass and fishing pressure of king scallop in Northern Ireland.

Annual surveys of the Northern Ireland king scallop fishery are conducted by the Agri-Food and Biosciences Institute (AFBI). The most recent assessment, published in 2026 and covering data up to 2025, does not include reference points for biomass or fishing pressure. As a result, the stock is assessed using route 2 (data‑limited) scoring. King scallop is considered to have high resilience to fishing pressure.

In 2024, 729 tonnes of king scallop were landed by UK‑registered vessels in ICES rectangles 37E3, 37E4, 38E4, 39E3 and 39E4 (excluding the Clyde fishery). This represents a notable increase from recent years, following a low of 393 tonnes in 2022. Although landings remain below the 2014 peak of 1,633 tonnes, the 2024 total exceeds the long‑term average of 603 tonnes (2000–2023). Also, there are currently no catch limits in place to ensure adherence to scientific advice. Consequently, landings frequently exceed recommended levels, ranging from 112% to 192% of advice between 2021 and 2024. Therefore, we consider there to be concern for fishing pressure.

Biomass trends can be inferred from both Landings per Unit Effort (LPUE) and survey‑derived stock indices. LPUE has declined since its peak in 2014 but has risen over the past three years. In 2024, LPUE reached 5.42, which is above the long‑term average of 3.89 (2000–2023). Biomass indices from the annual scallop survey are used to track biomass changes and account for year‑to‑year variability. These indices also form the basis of the landing advice. The advice is calculated using the ratio of the mean of the last two survey index values (Index A) to the mean of the three preceding values (Index B), multiplied by the recent three‑year average catch. A precautionary buffer was applied due to declining survey indices. The latest assessment reports Index A = 1.10 and Index B = 1.18, giving an A/B ratio of 0.94. As this ratio is below 1, it indicates a decline in biomass. Although more scallops are being caught with less effort, a ratio below 1 justifies some concern for biomass.

Based on the observed decline between the biomass indices, the landing advice for 2026 recommends that landings should not exceed 437 tonnes. This is a 25% reduction from the average landings between 2022 and 2024 (584 tonnes). The report also notes the reliance on accurate self‑reporting by commercial fishers and that the assessment does not include landings by Irish vessels operating on this stock.

Management of the Target Stock Score: 0.75

Alignment with Scientific Advice Score: 1

Monitoring, Control and Surveillance Score: 0.25

Management measures for king scallop in Northern Ireland appear to have a limited effect. There is no effort limit on this stock, and advised catch limits are not integrated into management, leaving the stock vulnerable to overexploitation. The fishery has a well‑developed and effective Monitoring, Control, and Surveillance (MCS) system with reliable enforcement and low levels of IUU activity.

Most king scallops taken from Northern Ireland waters are landed by NI vessels (around 70%), and most of the rest is from Scotland (15%) and the Isle of Man (9%). The Department for Agriculture, Environment and Rural Affairs (DAERA) manages fisheries in inshore Northern Ireland. There is no Fishery Management Plan, harvest strategy, or quota system for scallops in Northern Ireland. Although a stock assessment provides catch advice, this advice is not used to set catch limits or effort controls.

Management is instead based on gear restrictions, curfews, and minimum landing sizes (MLS) under the Conservation of Scallops Regulations (Northern Ireland) 2008. Key measures include:

• Minimum Landing Size (MLS) of 110 mm
• Night-time (2000–0600) and weekend fishing bans for all methods
• A maximum of 12 dredges per vessel
• Tow bars limited to 5.5 m

The MLS of 110mm protects juvenile scallops, which mature at around 80 mm, but may not fully safeguard the spawning stock as larger scallops contribute disproportionately to reproduction. Undersized scallops are discarded, and survival is assumed to be high.

Several areas within Northern Ireland’s inshore waters are closed to scallop dredging under the Scallop Enhancement Sites (Prohibited Methods of Fishing) Regulations (Northern Ireland) 2022 and the Inshore Fishing (Prohibition of Fishing and Fishing Methods) (Amendment) Regulations (Northern Ireland) 2003. Since 2022, four scallop enhancement sites have been closed to both dredging and diving (except for scientific work) to support stock recovery and reduce habitat impacts. Their effectiveness is not yet known, as enhancement and reseeding measures typically take years to show measurable results.

Management in the wider Irish Sea also influences this fishery. Under the Western Waters Effort Regime, vessels over 15 m are limited to 75 days of dredging between 1 April and 30 June 2026 in ICES Area 7. The Irish Sea seasonal closure (1 June–31 October) further prohibits scallop dredging. Landings of king scallop during this time come from the North coast which has no closed season.

Overall, these measures restrict fishing activity to some extent, particularly through closed areas, curfews, and offshore seasonal closures. However, there are no responsive effort controls or catch limits linked to stock status. Although scientific assessments provide catch advice, this is not implemented in management. As a result, current measures do not fully integrate scientific recommendations and leave the stock vulnerable to overexploitation.

This fishery is also part of the UK King Scallop Fishery Improvement Project (FIP), a six-year initiative launched in March 2025. The project aims to elevate king scallop fisheries to a level which meets the certification standards set by the Marine Stewardship Council (MSC).

Monitoring, control and surveillance of UK fisheries are delivered through licensing, vessel tracking, statutory reporting, observer coverage, inspections and other monitoring systems. All commercial fishing vessels must hold a valid UK fishing licence to operate in UK waters, although exemptions may apply to some unpowered vessels under 10 metres. Depending on the area, target species and activity, additional permits or authorisations may also be required.

Vessel tracking requirements vary by vessel size, area and administration through Vessel Monitoring Systems (VMS) and, where applicable, inshore VMS (iVMS).

• Vessels 12 m and over must report their position every two hours via VMS.

• Vessels under 12 m report their position continuously where iVMS applies, or may operate full VMS where required by licence conditions or when fishing offshore.

Reporting of fishing activity, catches, landings, discards and port movements is mandatory, with logbooks supporting traceability:

• Vessels 12 m and over submit electronic logbooks under Council Regulation 1224/2009.

• Vessels 10–12 m (and under 10 m Producer Organisation vessels) use paper logbooks, updated daily and submitted within 48 hours of landing.

• Non-PO vessels under 10 m are generally exempt unless required by licence conditions.

UK vessels must also carry fishery observers when directed, providing independent verification of activity and catch. Remote Electronic Monitoring (REM), using cameras, sensors and positional data, is being increasingly deployed to improve data quality and support enforcement. Its rollout is supported by the Fisheries Act 2020 and the Joint Fisheries Statement. In Scotland, REM has been mandatory for scallop dredge vessels since June 2024 and pelagic vessels since March 2026.

Together, these measures help prevent illegal, unreported and unregulated (IUU) fishing through vessel licensing, catch documentation, positional monitoring, statutory reporting and compliance checks. Enforcement action may include financial penalties, prosecution, licence suspension or other sanctions. The UK has committed to reducing IUU fishing and maintains a blacklist of vessels involved in such activities. This rating reflects full compliance with UK monitoring, control and surveillance requirements.

The Marine Conservation Society views Remote Electronic Monitoring (REM) with cameras is one of the most cost-effective tools for providing reliable fisheries data and aiding informed management decisions. Fully monitored fisheries enhance collaboration, data accuracy, stock recovery, and reduce impacts on marine wildlife and habitats. However, the full potential of REM may only be achieved when it tracks fishing location and documents catch and bycatch, particularly where vulnerable species and habitats are at risk.

The Fisheries Act (2020) requires the development of Fisheries Management Plans (FMPs) (replacing EU Multi-Annual Plans) in the UK. 43 FMPs have been proposed and are at various stages of development and implementation, these should all be published by the end of 2028. FMPs have the potential to be very important tools for managing UK fisheries, although data limitations may delay them for some stocks. It is also essential the UK governments define and adopt a standardised approach or model across the four nations to a universally defined FMP design, to ensure the consistence, quality and coherence of all the proposal FMPs. 

The Marine Conservation Society is keen to see publicly available Fishery Management Plans for all commercially exploited stocks, especially where stocks are depleted, that include: 

• An overview of the fishery including current stock status, spatial coverage, current fishing methods and impacts 

• Targets for fishing pressure and biomass, and additional management when those targets are not being met, based on the best scientific evidence 

• Timeframes for stock recovery 

• Improved data collection, transparency, and accountability, supported by technologies such as Remote Electronic Monitoring (REM) 

• Consideration of wider environmental impacts of the fishery, including habitat impacts and minimising bycatch 

• Stakeholder engagement 

A Northern Ireland non-quota shellfish FMP has been proposed, coordinated by DAERA that incorporates this stock. At the time of writing, it is too soon to know whether proposed management measures will be effective in managing the stock. For more information about this FMP and expected progress and timelines, see [https://www.gov.uk/government/collections/fisheries-management-plans#published-fmps]. 

Capture Method Score: 0.75

Habitat Impacts: 0.75

Bycatch Impacts: 0.5

Vulnerable and ETP Species: 0.25

Ecosystems and Trophic Webs: 0.5

King scallops are predominantly caught using dredges that physically penetrate and disturb the seabed. Given the potential for unquantified mortality and limited available evidence, the fishery may also affect non-target species, potentially at local population levels. Although dredging previously overlapped with vulnerable habitats and ETP species, ongoing impacts are unlikely as these areas are now closed to mobile bottom‑towed gear. Scallop dredging may also act as an additional stressor on already altered ecosystems and food webs in the region.

Dredges dominate the king scallop fishery because they are highly efficient, but they also pose significant environmental risks, particularly to sensitive seabed habitats. A standard king scallop dredge (Newhaven dredge) consists of a heavy steel frame and chainmail net, with a toothed bar that flips scallops into a net. Dredges are attached to tow bars dragged along the seabed, with up to two dredges per bar. The number of dredges used is limited by vessel engine power and regional legislation.

As they move, dredges penetrate the substrate by around six centimetres and can reduce benthic species abundance and richness by 8–12% with each pass. In dynamic sandy or wave‑exposed environments, benthic communities tend to recover more quickly. However, in more sheltered or structurally complex habitats such as gravel beds, maerl, and seagrass, recovery is slow and damage can persist for decades. Any long‑lived, slow‑growing species are particularly vulnerable, and dredging in such areas has historically caused long‑lasting ecological change.

Sediments around the Northern Irish coastline are predominantly sand and mud, but the region also contains highly diverse and sensitive benthic communities, including patchy Modiolus (horse mussel) beds and one of the densest ocean quahog populations in the UK. Both habitats have previously overlapped with scallop dredging, prompting significant concern and subsequent management action.

Strangford Lough, once an important scallop ground, was closed to all mobile bottom‑towed gear in 2003 to protect its horse mussel reefs, with only diving now permitted. The Outer Belfast Lough Marine Conservation Zone (MCZ) was later designated to safeguard ocean quahog, a long‑lived species on OSPAR’s List of Threatened and/or Declining Species & Habitats. Despite this designation, environmental conditions for ocean quahog have remained unfavourable since 2015, with assessments up to 2025 showing no improvement. Mobile demersal gear was banned from the site in 2023, though anchoring continues to pose a risk. At the same time, eight additional MPAs and four scallop enhancement sites were closed to demersal mobile gears. These measures reflect a broader shift toward protecting the most vulnerable habitats from further disturbance. Although the king scallop fishery is considered unlikely to currently be causing population‑level declines in vulnerable or ETP species, recovery of long‑lived benthic communities following dredging can take considerable time.

Bycatch is another important consideration in the scallop dredge fishery. Under the EU Landing Obligation, all quota species except skates and rays must be landed, and non‑quota bycatch must remain below 5% of retained catch. In practice, bycatch in king scallop dredges around the British Isles ranges from roughly 15–53% of total catch biomass, with queen scallop, brown crab, and spider crab among the most frequently caught species. However, bycatch monitoring and reporting remains limited, and a large proportion of bycaught organisms (around 75%) are unaccounted for because they are damaged and left on the seabed, where mortality can be high. Discarding also occurs due to size limits or market preferences, and although post‑release survival is thought to be relatively good for undamaged scallops, there are no quantitative assessments to confirm this. As a result, the true scale of fishing mortality remains uncertain, particularly for organisms left damaged on the seabed, and it is therefore possible that this fishery is impacting other species in dredged areas at a population level that is not captured by current bycatch surveys.

King scallops are low trophic level suspension feeders that consume filtered plankton. They are preyed upon by a range of species throughout their life cycle, including fish, crustaceans, cephalopods and elasmobranchs.

The Celtic Seas ecosystem has undergone substantial change over the past century, driven primarily by fishing and, more recently, climate change. Intensive fishing during the mid to late 20th century depleted many commercial fish stocks, including cod, whiting, sole, plaice and herring, as well as large elasmobranchs such as the once-abundant common skate complex. These declines altered trophic interactions and were associated with reductions in some seabird populations through changes in prey availability. While some stocks have recovered, others remain depleted.

More recently, climate-driven changes in oceanographic conditions have altered plankton communities, shifted species distributions and increased the prevalence of warm-water species. Although scallop dredging is not a primary driver of ecosystem change in the Celtic Sea, it removes a prey species from the system and is associated with bycatch mortality, sediment disturbance and smothering. These pressures may add to existing ecosystem stressors and contribute to broader ecological change over time.