Plaice

The stock of plaice in the North Sea and Skagerrak is considered underfished but remains harvested at sustainable levels.Stock assessments for plaice in the North Sea and Skagerrak are carried out by the International Council for the Exploration of the Sea (ICES). 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.Following a decline from 2014 to 2019, spawning stock biomass (SSB) has been increasing in recent years and in 2025, SSB is estimated at over 1,230,000 tonnes. This is over double the MSY Btrigger (544,290 tonnes) and also exceeds the BMSY proxy of 762,006 tonnes. This indicates the stock is currently underfished. Fishing mortality has greatly reduced since the 1990s, falling from 0.44 in 1997 to below FMSY (0.123) for the first time in 2008 at 0.110. Fishing mortality briefly exceeded FMSY again from 2016 to 2018, but has since reduced to its lowest at 0.040 in 2024. As this is below FMSY, the stock is considered to be harvested sustainably.ICES advises that when the MSY approach is applied, catches in 2026 should be no more than 164,129 tonnes. This is a decrease of 7.3% from advice for 2025, mainly due to the reduction in the FMSY reference point from 0.152 to 0.123.

There is no management plan for North Sea plaice, and discard rates remain high. However, some measures are in place and have successfully recovered the stock.Plaice in the North Sea and Skagerrak is managed under a Total Allowable Catch (TAC) system, aligned with ICES’ Maximum Sustainable Yield (MSY) approach since 2017. For both subarea 4 (North Sea) and subarea 20 (Skagerrak), TACs have consistently been set below scientific catch advice. These limits also account for expected migration between stocks in the North Sea, Skagerrak, and the eastern English Channel (Area 7d). Actual catch levels have also remained below advice and have declined in recent years. This is partly due to a reduction in the number of vessels targeting plaice, resulting in low TAC uptake.A recovery plan initiated in 2007 successfully reduced fishing pressure on North Sea plaice to sustainable levels, leading to a significant increase in stock size. However, discard rates remain high – rising from 40% in 2014 to 63% in 2023, with an estimated 56% in 2024. Discards include fish below the Minimum Conservation Reference Size (MCRS), currently set at 27 cm in UK waters. This measure aims to protect juvenile plaice from being caught before reproducing, which could otherwise reduce overall stock biomass.Although assessments assume zero survival of discarded fish, plaice is frequently exempt from the Landing Obligation (LO) under survival exemptions in many fisheries. Additional conservation efforts in UK waters include gear mesh size regulations:Otter Trawls:ICES Area 4b: 100mm mesh cod-end.ICES Area 4c: 80mm mesh cod-end.Beam Trawls:South of 55˚N: 80mm mesh cod-end.55˚N to 56˚N: 100mm mesh cod-end.North of 56˚N: 120mm mesh cod-end.Further technical measures include the Plaice Box - a closed area established in 1989. It restricts vessels using towed gear with engine power over 300 horsepower and enforces a maximum aggregated beam length of 9m. This 9m limit is also in place within the UK’s 12 nautical mile zone.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, which incorporates part of 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/publications/southern-north-sea-and-eastern-channel-mixed-flatfish-fisheries-management-plan-fmp

Beam trawls have significant impacts on the seabed, including damage to benthic communities and vulnerable marine habitats. They can also have high bycatch, potentially of vulnerable species, including North Sea cod.Landings of plaice in this region are caught by beam trawl (35%), otter trawl (49%), and other gear types (16%). The majority of discarded plaice occur from beam trawls (71%). This is due to flatfish beam fisheries often using a minimum mesh size of 80mm, which selects for sole at their minimum conservation size - 24cm. However, this results in high discard rates for plaice, whose minimum landing size is larger - 27 cm.Beam trawls have the potential to take relatively high quantities of bycatch, including those of conservation concern. In the Greater North Sea ecoregion, bycatch from beam trawls can include marine mammals, seabirds, fish, elasmobranchs, and endangered, threatened and protected (ETP) species. Bycatch data for UK and EU fisheries is often limited due to insufficient monitoring. However, some North Sea trawl fisheries are Marine Stewardship Council (MSC)-certified and do record bycatch. These records, especially where certified and uncertified fleets overlap, can help indicate expected bycatch species. Certified fleets have reported bycatch of vulnerable North Sea cod, with the southern substock below safe biological and reproductive thresholds. In 2023, there was also a marked increase in bycatch of Spurdog - an ETP species. However, stock assessments for Spurdog indicate that fishing pressure is currently below safe limits, and the stock size is above MSY Btrigger. With North Sea cod now under zero catch advice, incidental capture in flatfish fisheries may be contributing to population decline or hindering recovery. To mitigate this, some areas have implemented measures such as the UK North Sea Cod Avoidance Plan. This includes a minimum 120mm mesh size requirement in the Scottish North Sea, seasonal closures to protect spawning stocks, and mandatory relocation from areas where high cod concentrations are observed.Beyond bycatch concerns, beam trawling—particularly with chain-mat gear—can significantly impact benthic communities. Demersal trawls make direct contact with the seabed, causing penetration and abrasion of habitat features. The extent of seabed impact depends on gear type, sediment composition, and the area's natural resilience. For instance, regions that are used to tidal and wave disturbances are less sensitive, whereas areas untrawled areas may be more vulnerable. Beam trawls typically penetrate the seabed between 1cm and 8cm, with heavier gear causing greater disruption than otter trawls.In the Greater North Sea ecoregion, impacts from bottom trawling are variable. Most fishing grounds consist of mud and sand, which are less susceptible to damage than habitats like reefs and seagrass beds. In 2022, it was estimated that 66% of the ecoregion shallower than 800m had been trawled—70% of this from depths of 0–200m and 27% from 200–800m. Areas with the highest fishing pressure include Skagerrak, Kattegat, and parts of the central North Sea.There are Marine Protected Areas (MPAs) in this area, some of which are designated to protect seabed features from damaging activities. While this fishery overlaps with some MPAs, the catch from these zones is estimated to be less than 20% of the total effort, and therefore is not assessed within this current rating. Given the critical role MPAs play in recovering marine health and supporting ecosystem function, the Marine Conservation Society urges supply chain actors to verify whether their sources originate from within MPAs. If so, businesses should confirm that fishing operations are legally conducted and request evidence from the fishery or managing authority to ensure activities do not harm protected features or compromise conservation objectives.To improve monitoring and reporting of fishing activity, The Marine Conservation Society would like to see remote electronic monitoring (REM) with cameras implemented, used and enforced.