King scallop

King scallops from the North Sea appear to be declining in abundance but are not subject to overfishing. Therefore, there is concern for biomass but not for fishing pressure.Since 2017, Cefas has conducted annual stock assessment for king scallops in ICES Divisions 27.7.e, 27.7.d, 27.7.f, and 27.4.b. Specific assessment areas were selected within these based on regional differences in scallop growth and fishery exploitation rates. This rating focuses on the southern part of the North Sea (4.b.S), along the Yorkshire and Durham coast. Between 2017 and 2023, international landings, primarily by UK vessels, average around 1,700 tonnes per year.Scoring for this stock is based on assessments published in 2025, using data up to 2023/2024. Due to the absence of a biomass reference pointed needed to estimate Maximum Sustainable Yield (MSY), there is some uncertainty in the assessment. As a result, Route 2 scoring has been applied, with king scallops considered to have a high resilience to fishing pressure.Harvestable biomass (the weight of scallops above the minimum landing size and within areas open to dredging) has fluctuated between 5,400 and 9,000 tonnes from 2018 to 2024. A gradual decline has been observed in recent years – from 8,911 tonnes in 2022 to 6,739 tonnes in 2024. Without reference points, it remains unclear whether this represents an unhealthy stock level. However, as this latest figure (6,739 tonnes) is below the average from 2021 to 2023 (7,418 tonnes), there is concern for biomass.Fishing pressure is assessed using the harvest rate (HR), defined as the proportion of harvestable biomass removed by fishing in the 12 months following each stock survey. Cefas estimates that a harvest rate of 23.0% corresponds to MSY, which would maintain the stock at 35% unfished levels. In 2023, the estimated HR was 11.48% – the lowest since 2018 – indicating no concern for fishing pressure as it remains well below the MSY threshold.Nonetheless, there remains some uncertainties with this assessment. Biomass surveys use both dredging and underwater video systems to account for areas where dredging is not possible (e.g., conservation zones or unsuitable habitats). Additional scallop stocks are known to exist outside of survey areas, but it remains unclear how these unfished areas interact with fish stock, and specifically, whether larval exchange occurs or if dredged areas are self-sustaining.

Few appropriate management measures are in place to control scallop fishing in the central North Sea. There are currently no catch limits or controls on the fishery, and biomass is declining.Stock assessments for king scallops off the Yorkshire and Durham coast only began in 2018. While data quality has improved since then, some uncertainties still remain, which may limit the effectiveness of evidence-based management measures. It is also possible that inshore and offshore scallop stocks are connected, potentially through larval exchange, which suggests a more coordinated approach is needed across management areas.Scallop beds in the North Sea (central south) extend from within the 6 nautical mile limit out into offshore UK water. This rating focuses on the offshore dredge fishery for king scallops within the UK fishery limits.In offshore English waters, the main regulatory framework for scallop dredging is the Scallop Fishing (England) Order 2012, which applies beyond 6nm. Key measures include:UK scallop licence required for vessels over 10m.Maximum of 16 dredges permitted (0-12nm)Minimum Conservation Reference Size (MCRS): 100mmBycatch limit: 10% of total catch under shellfish permitGear specifications and restrictionsEffort limit under the Western waters regime: vessels 15m and above are restricted to 70 days at sea in ICES area 7 between January 1 and March 31.The 100mm MCRS helps to protect juvenile scallops, which typically mature around 80mm. However, it may not fully protect long-term stock stability, as reproductive output is proportional to size, with larger individuals contributing more.Importantly, there is no Total Allowable Catch (TAC) for scallops, meaning no binding catch limits are in place to prevent overfishing. Additionally, the offshore fishery lacks a formal harvest strategy, as fishing effort is not directly linked to stock size, and catch remains unregulated. While current fishing pressure is below the MSY proxy, biomass is declining, and there is still no agreed reference point against which to assess stock status. Due to the likely connectivity between scallop populations, high fishing pressure in neighbouring areas may still negatively impact the North Sea stock.Marine Protected Areas (MPAs) in this region include the Southern North Sea MPA and the Holderness Offshore Marine Conservation Zone (MCZ). However, neither currently prohibits bottom-towed fishing gear. Only the Holderness Offshore MCZ is designated for benthic features, while the Southern North Sea MPA is focused on harbour porpoise conservation. As a result, existing MPAs provide limited benefit to scallop habitats or stocks.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).Management compliance in the EU and UK has been inconsistent, with ongoing challenges in enforcing some regulations.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. As of January 2024, the EU is introducing a Remote Electronic Monitoring (REM) mandate for EU vessels, including CCTV cameras on vessels 18m or more that pose a potential risk of non-compliance, within the next 4 years. Across the UK, different approaches to REM are being taken and legislation is expected to be in place across all 4 countries within the next few years.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 impactsTargets for fishing pressure and biomass, and additional management when those targets are not being met, based on the best scientific evidenceTimeframes for stock recoveryImproved 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 bycatchStakeholder engagementKing scallop is included in the King scallop FMP, coordinated by Defra. 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/publications/joint-fisheries-statement-jfs/list-of-fisheries-management-plans].

Scallop dredging can be very damaging to seabed habitats and species. There is yet to be restrictions on where dredging can occur, so vulnerable habitats and species may be at risk.According to MMO landings data in this region of the North Sea, dredging accounts for approximately 92.8% of king scallop landings. This method remains dominant due to its efficiency, but poses 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 the net. Dredges are attached to tow bars dragged along the seabed, with up to 2 dredges per bar. The number of dredges used is limited by vessel engine power and regional legislation.On average, scallop dredging penetrates the seabed by up to 6cm, and can reduce species abundance and richness by 8-12% per pass. Recovery times vary depending on the species and habitat, ranging from months to years. More dynamic environments, such as sandy or wave-exposed areas, support faster-growing species that recover more quickly. In contrast, sheltered habitats like gravel beds or inshore zones, often host slow-growing, long-lived species such as maerl, horse mussels, seagrass, and sea fans, which are more vulnerable to damage and slower to recover.The seabed in this area is primarily composed of sand, mud, and mixed sediments, but also supports highly diverse and vulnerable habitats such as mussel beds and rocky reefs – some of which are within designated Marine Protected Areas (MPAs). One MPA within the region is the Holderness Offshore Marine Conservation Zone (MCZ), which has been designated to protect vulnerable seabed ecosystems, glacial tunnel valleys, and ocean quahogs – an Endangered, Threatened, or Protected (ETP) species.Scallop dredging in these sensitive habitats can cause long-lasting ecological damage, with recovery potentially taking decades. The Holderness Offshore MCZ is included in the proposed North Sea Marine Protected Areas Fishing Gear Byelaw 2024. This byelaw would prohibit scallop dredging within the MCZ, but until it is implemented, vulnerable benthic features and species remain exposed to potential damage.Bycatch is another key concern. Since 2019, scallop dredgers have been required to land all quota species under the EU Landing Obligation, with the exception of skates and rays. For non-quota species, bycatch must not exceed 5% of total retained catch. Common bycatch species include queen scallop, brown crab, and spider crab. While bycatch levels are not currently thought to threaten theses populations, it is not fully recorded, and some organisms remain on the seabed after the dredge passes, of which can experience high mortality from incurred damage. This raises concerns about unmeasured impacts on vulnerable species and habitats.Discarding, often due to minimum size restrictions, also occurs. While post-release survival is believed to be relatively high, no quantitative assessments of discard rates or survival have been conducted.

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