Lemon sole

This stock is data limited and reference points have not been defined. There is no concern for fishing pressure but there is concern for biomass.Route 2 scoring has been applied to this rating due to the lack of data. The most recent assessment was published in 2025 by the International Council for the Exploration of the Sea (ICES). Lemon sole is mainly a valuable bycatch species in mixed fisheries and has low resilience to fishing pressure.The length-based indicator (LLBI) analysis suggests that fishing pressure is currently below the FMSY proxy. Landings in 2024 were 1180 tonnes, which is below the 2021-2023 average of 1696 tonnes. Although discard levels were high between 2011 and 2016, ranging from 1000 to 6000 tonnes, they have decreased significantly, falling from 668 tonnes in 2021 to 264 tonnes in 2024. As a result, there is currently no concern for fishing pressure.Stock size is monitored using a biomass index, with Itrigger used as a proxy for MSY Btrigger. Following a peak of 1.385 in 2016, the biomass index has steadily declined, falling below Itrigger (0.715) in 2023, and reaching 0.629 in 2024. This figure is also below the 2021-2023 average of 0.858, leading to a concern for biomass.Since 2024, lemon sole is no longer managed under a combined species Total Allowable Catch (TAC) with witch. The TAC for lemon sole only in 2026 is set at 1107 tonnes, a 24% reduction from the 2025 TAC of 1450 tonnes due to the continued decline in biomass.

There is some management of lemon sole in this region. Although largely a bycatch species, there is a novel species-specific TAC in place but the stock is in decline.Lemon sole is considered a valuable bycatch species in mixed fisheries, but there are currently no specific management objectives for this species in the region. The stock is managed under a Total Allowable Catch (TAC) system. Until 2024, lemon sole was grouped with witch flounder under a combined TAC due to the absence of targeted fishery for lemon sole (unlike witch, which is targeted in some areas). During this time, TACs often exceed scientific advice, but catches remained below advised levels.In 2024, the TACs for lemon sole and witch flounder were separated, allowing for better management of each species. The new TACs for lemon sole in 2024 and 2025 were set in line with scientific advice. However, evidence remains limited regarding whether catches are now aligned with species-specific limits. Currently, data is only available for 2024, with only 57.7% of the regional TAC for lemon landed. Although fishing pressure on the stock is below sustainable limits, there is concern for the declining biomass of lemon sole. As a result, the lemon sole TAC for 2026 has been set at 1107 tonnes – a 24% reduction from the 2025 TAC of 1450 tonnes. This adjustment reflects the downward trend in biomass. However, ICES has highlighted that data is limited and uncertainty around the stock status remains high.At present, a Minimum Conservation Reference Size (MCRS) for lemon sole is only in place for ICES areas 7d (and 7e), which is set at 25cm. Across the region, technical conservation measures (e.g. gear specifications) and landing obligations/exemptions may apply to this species.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 engagementLemon sole is included in the Southern North Sea and Eastern Channel mixed flatfish FMP and the Channel non-quota demersal FMP, both 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/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.Lemon sole are generally taken as bycatch in mixed fisheries by otter trawlers (62%), beam trawlers (33%), seine nets (3%), and gillnets (2%).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.

ASCOBANS, 2009. Conservation Plan for Harbour Porpoises in the North Sea as adopted at the 6th Meeting of the Parties to ASCOBANS, Bonn, Germany. 16 - 18 September 2009. Available at https://www.ascobans.org/sites/default/files/document/ASCOBANS_NorthSeaPlan_MOP6.pdf [Accessed on 06.07.2022].Calderan, S. and Leaper, R., 2019. Review of harbour porpoise bycatch in UK waters and recommendations for management. January 2019, WWF. Available at https://www.wwf.org.uk/sites/default/files/2019-04/Review_of_harbour_porpoise_in_UK_waters_2019.pdf [Accessed on 06.07.2022].Carlén, I., Nunny, L. and Simmonds, M. P. 2021. Out of Sight, Out of Mind: How Conservation Is Failing European Porpoises. Frontiers in Marine Science. Available at https://www.frontiersin.org/articles/10.3389/fmars.2021.617478/full [Accessed on 06.07.2021].Chadwick, H., Clear, N., Crosby, A., Hawtrey-Collier, A. and Williams, R. 2019 Annual Report. Marine Strandings in Cornwall and the Isles of Scilly. Available at https://www.cornwallwildlifetrust.org.uk/sites/default/files/2020-12/2019%20Summary%20Report%20-%20Marine%20Strandings%20in%20Cornwall%20and%20the%20Isles%20of%20Scilly.pdf [Accessed on 06.07.2022].Clean Catch UK. Joint Action To Reduce Wildlife Bycatch. Available at https://www.cleancatchuk.com/ [Accessed on 06.07.2022].Froese R. and Pauly D. (Editors), 2019. Microstomus kitt, Lemon sole. Available at: https://www.fishbase.de/Summary/SpeciesSummary.php?ID=1382&AT=lemon+sole [Accessed on 06.07.2022].ICES. 2021. Greater North Sea Sea Ecoregion – Ecosystem overview. In Report of the ICES Advisory Committee, 2021. ICES Advice 2021, Section 9.1, https://doi.org/10.17895/ices.advice.9434 [Accessed on 19.07.2022].ICES. 2022. Lemon sole (Microstomus kitt) in Subarea 4 and divisions 3.a and 7.d (North Sea, Skagerrak and Kattegat, eastern English Channel). In Report of the ICES Advisory Committee, 2022. ICES Advice 2022, lem.27.3a47d. https://doi.org/10.17895/ices.advice.19448039.ICES, 2018. ICES Advice: Bycatch of small cetaceans and other marine animals - review of national reports under Council Regulation (EC) No. 812/2004 and other information. Published 11 September 2018. Available at https://www.ices.dk/sites/pub/Publication%20Reports/Advice/2018/2018/byc.eu.pdf [Accessed on 06.07.2022].Leeney, R. H., Amies, R., Broderick, A.C., Witt, M. J., Loveridge, J., Doyle, J. and Godley, B. J. 2008. Spatio-temporal analysis of cetacean strandings and bycatch in a UK fisheries hotspot. Biodiversity and Conservation. 17, 2323. Available at https://link.springer.com/article/10.1007/s10531-008-9377-5#citeas [Accessed on 06.07.2022].Leeney, R. H., Witt, M. J., Broderick, A. C., Buchanan, J., Jarvis, D. S., Richardson, P. B. and Godley, B. J. 2011. Marine megavertebrates of Cornwall and the Isles of Scilly: relative abundance and distribution. Journal of the Marine Biological Association of the United Kingdom, 92(8), 1823-1833. Available at https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/marine-megavertebrates-of-cornwall-and-the-isles-of-scilly-relative-abundance-and-distribution/7981AA197C2320B6A9E2C01BD7A1F7B7 [Accessed on 06.07.2022].Moan, A., Skern-Mauritzen, M., Vølstad, J. H., Bjørge, A. 2020. Assessing the impact of fisheries-related mortality of harbour porpoise (Phocoena phocoena) caused by incidental bycatch in the dynamic Norwegian gillnet fisheries, ICES Journal of Marine Science, Volume 77, Issue 7-8, Pages 3039–3049. Available at https://doi.org/10.1093/icesjms/fsaa186 [Accessed on 06.07.2022].North Atlantic Marine Mammal Commission and the Norwegian Institute of Marine Research. 2019. Report of Joint IMR/NAMMCO International Workshop on the Status of Harbour Porpoises in the North Atlantic. Tromsø, Norway. Available at https://www.ascobans.org/sites/default/files/document/ascobans_ac25_inf.4.3a_joint-imr-nammco-ws-harbour-porpoise.pdf [Accessed on 06.07.2022].Omeyer, L. C. M., Doherty, P. D., Dolman, S., Enever, R., Reese, A., Tregenza, N., Williams, R. and Godley, B. J. 2020. Assessing the Effects of Banana Pingers as a Bycatch Mitigation Device for Harbour Porpoises (Phocoena phocoena). Frontiers in Marine Science. Available at https://www.frontiersin.org/articles/10.3389/fmars.2020.00285/full [Accessed on 06.07.2022].OSPAR, 2017. Intermediate Assessment 2017: Harbour Porpoise Bycatch. Available at https://oap.ospar.org/en/ospar-assessments/intermediate-assessment-2017/biodiversity-status/marine-mammals/harbour-porpoise-bycatch/ [Accessed on 06.07.2022].