Dover sole

Sole biomass in the North Sea is in a good state and fishing pressure is within sustainable limits.Stock assessments are carried out annually by the International Council for Exploration of the Sea (ICES). The most recent assessment was published in 2024.The stock assessment defines reference points for fishing pressure (F) and biomass (B). For fishing pressure, there is a target to keep F at or below Maximum Sustainable Yield (MSY). For biomass, there is no target. However, there is a trigger point (MSY BTrigger). Below this level, F should be reduced to allow the stock to increase. Because BMSY is not defined, the Good Fish Guide applies its own definition of 1.4 x MSY BTrigger.In 2023, spawning stock biomass (SSB) is 55,955 tonnes. This is a decline from a recent peak in 2021, but it remains above MSY Btrigger (52,532 tonnes). In 2025, it is predicted to increase further to 61,320 tonnes. However, recruitment in the last 5 years has been relatively low.Fishing pressure (F) has decreased in recent years from 0.33 in 2011 to 0.079 in 2023. This is below FMSY.ICES advises that when the MSY approach is applied, catches in 2025 should be no more than 10,196 tonnes. This is an increase of 177% from the previous years advice due to the upward revision of stock status after the recent benchmark. The SSB for the stock was previously estimated around Blim and SSB is now above MSY Btrigger.

There is no management plan in place for North Sea Dover sole, but some measures are in place which are largely effective. Discarding is high for this stock.The sole fishery in the North Sea is managed by Total Allowable Catch (TAC) and technical measures. TAC has been set in line with scientific advice in recent years and catches have been in line with the TAC. Since 2022, the TAC has followed the MSY approach, rather than having an upper and lower limit. In 2025, advice has increase substantially, however, TAC uptake has been less than 100% in recent years and it is thought that catch will remain below advice.Sole in the North Sea has been under the landing obligation since 2016, and Norway and UK national legislation regarding discards. Catch monitoring programs estimate that discarding in 2023 amounted to 8.22% of the total catch (includes below minimum size landings (BMS)).Technical measures in place for this fishery are:Minimum mesh sizes and minimum conservation reference size (MCRS) of 24cm.Mesh size regulations for towed trawl gears require that vessels fishing North of 55°N (or 56°N east of 5°E, since January 2000) should have a minimum mesh size of 100 mm, while to the south of this limit, where the majority of the sole fishery takes place, an 80 mm mesh is allowed. In the fishery with fixed gears a minimum mesh size of 100 mm is required.A closed area has been in operation since 1989 (the plaice box) - this applies to vessels using towed gears, but vessels smaller than 300 HP are exempt.In the plaice box, and in the 12 nautical mile zone, the maximum aggregated beam length is 9m.Between 2014 and 2018 the use of pulse trawls in the main fishery operating in the North Sea increased and fewer vessels were operating with traditional beam trawls. The pulse gear allows fishing of softer grounds and as a result the spatial distribution of the main fisheries has changed to the southern part of the Division 4.c. As a consequence, a larger proportion of the sole catch is now taken in this area. Following the EU decision in February 2019 to revise the technical measures regulations, the pulse gear was prohibited from 1st July 2021. It is expected that the fleets will revert to the traditional gears and fishing grounds.A number of Marine Stewardship Council certifications are available for North Sea sole.The EU and UK both have fishery management measures, which can include catch limits, population targets, and gear restrictions. However, compliance in the EU and UK has been inconsistent, with ongoing challenges in implementing some regulations. The goal of reaching Maximum Sustainable Yield (MSY) by 2020 was missed, with less than half of UK TACs in 2024 following ICES advice. In 2024, the EU and UK reaffirmed their commitment to sustainable fisheries by aligning management with scientific advice to gradually approach MSY. However, no new target date has been set for achieving MSY across all fisheries. The Landing Obligation (LO), an EU law retained by the UK post-Brexit, requires all quota fish to be landed, even if unwanted (over-quota or below minimum size). It aims to encourage more selective fishing methods, reduce bycatch, and improve catch reporting. However, compliance is poor, and accurate discard levels are hard to quantify with current monitoring programmes. The UK is in the process of replacing the LO with country-specific Catching Policies.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 engagementA Southern North Sea and Eastern Channel mixed flatfish FMP has been proposed, coordinated by Defra that covers the English waters within ICES divisions 4b, 4c and 7d. The FMP covers the following flatfish species (quota and non-quota): sole, dab, plaice, flounder, halibut, lemon sole, witch, turbot, brill. It is too soon to know whether the 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.

Gill net fisheries can be very selective with regards to targeted fish species. However, they can encounter bycatch of vulnerable species including porpoise, sharks and seabirds.Dover sole in the North Sea are taken by beam trawlers (93%), gillnets and trammel nets (3%), bottom trawls (3%) and other gear types (1%).Gillnets and fixed nets can be very size selective, but can bycatch species such as sharks, cetaceans and other marine mammals. Reports indicate that there is concern regarding the bycatch of cetaceans, particularly harbour porpoise, by gillnets. The IUCN lists harbour porpoise as being of least concern globally, but vulnerable in Europe. They are also classified as a priority species under the UK Post-2010 Biodiversity Framework and are protected under the European Union (EU) Habitats Directive and Habitats Regulations as transposed into UK law, under which there are explicit bycatch requirements. To comply with the Habitats Directive, the UK has recently designated five Special Areas for Conservation for harbour porpoises, however, there is currently no management in place for these.One of the areas of most concern is off the South West of England, where areas of higher gillnet fishing effort coincide with areas of larger harbour porpoise populations. While cetacean bycatch has been a long-term problem around Cornwall, the occurrence of stranded cetaceans has increased over the last two decades. In 2019, 24% of stranded cetaceans exhibited features consistent with bycatch or entanglement in fishing gear, a further 19% were assessed as being possible bycatch, and 52% had an unknown cause of death. However, this stock does not cover the Western English Channel, and harbour porpoise bycatch is not considered to be a problem in the North Sea where the majority of catches of lemon sole take place.Because of gillnets' durability (they are made of nylon), if lost, they can continue to fish for several weeks before becoming tangled and bundled up, a phenomenon known as 'ghost fishing'. However, static nets, as with all gear, represent an investment by fishermen, and therefore there are incentives to avoid losing or damaging gear.There are MPAs designated to protect seabed features from damaging activities in this region. The fishery overlaps with parts of these MPAs, but the proportion of the catch coming from these areas is expected to be relatively low in relation to the unit of assessment (i.e. less than 20% of the catch) and so these impacts have not been assessed within the scale of this rating. Given the important role that MPAs have in recovering the health and function of our seas, MCS encourages the supply chain to identify if their specific sources are being caught from within MPAs. If sources are suspected of coming from within designated and managed MPAs, MCS advises businesses to: establish if the fishing activity is operating legally inside a designated and managed MPA; and to request evidence from the fishery or managing authority to demonstrate that the activity is not damaging to protected features or a threat to the conservation objectives of the site[s].

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