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].

Most lemon sole landings are from otter trawling, but this gear type is likely to cause some damage to the seabed. Bycatch is moderate and may include vulnerable species.In 2024, 74% of the landings of lemon sole in this region were taken by otter trawl, with a smaller proportion (21%) by beam trawl. Of a total catch of 1444 tonnes, 264 tonnes were discarded (18.3%).Lemon sole is primarily caught as bycatch in plaice and mixed demersal fisheries, where minimum mesh sizes for otter trawls can range from 80 to 100mm. Given that lemon sole typically matures between 20-30cm, this mesh size may pose a risk of juvenile removal. However, discard levels of individuals below minimum size (BMS) have remained consistently low across the region. Since 2021, ICES subarea 4, and divisions 3a and 7d have reported average annual BMS discards of less than 0.5 tonnes.Demersal otter trawls have the potential to take relatively high quantities of bycatch. In the Northeast Atlantic there are reported catches of demersal elasmobranchs and endangered, threatened and protected (ETP) species (e.g. sharks, rays and marine mammals). Bycatch data is limited in many UK and EU fisheries as they are generally not well monitored.Demersal trawls have contact with the seabed resulting in penetration and abrasion of habitat features. The impact of trawling on the seabed depends on the location and scale in which trawling occurs. For example, areas that are used to natural disturbance through tides and waves, are less sensitive to habitat impacts. Areas not used to mobile towed gears are typically more sensitive to trawling. Lemon sole often inhabits sandy or gravely substrate, with gravel habitats more vulnerable to trawling activity. Trawl gears are also known to have some of the greatest impacts on Vulnerable Marine Ecosystems (VMEs).In the North Sea area, impacts from bottom trawling are variable. Fishing grounds vary, but the habitat is generally mud and sand, which are less vulnerable to trawling than features such as reefs and seagrass. Data from 2024 indicates an estimated 70% of the 0-200m zone, and 27% of the 200-800m zone, has been at least partially trawled. Average fishing mortality in the areas has reduced since the late 1990s for pelagic, demersal, and shellfish stocks. However, fishing in the North Sea in general has reduced the number of large fish in the ecosystem (mostly cod, saithe, ling, sturgeon, and some elasmobranchs). There are concerns about the impact of North Sea trawling on sea pens.There are Marine Protected Areas (MPAs) in this area, some of which are designated to protect seabed features from damaging activities. This 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 or effort), 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 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).To improve monitoring and reporting of fishing activity, MCS would like to see remote electronic monitoring (REM) with cameras implemented, used and enforced.