Brill

Stock Status Score: 0

Brill in this region is considered underfished and harvested sustainably.

Stock assessments are carried out by the International Council for Exploration of the Sea (ICES). This rating is based on the assessment published in 2026.

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.

The relative exploitable biomass (B/BMSY) of this stock has declined in recent years but has remained above MSY Btrigger (0.5) since the start of the time series. In 2026, relative exploitable biomass is 1.49. Therefore, the stock is considered under fished.

Relative fishing pressure (F/FMSY) has declined after a peak in 2001 but has remained below FMSY (1) throughout the time series. In 2025, relative fishing pressure was estimated at 0.32, and therefore the stock is harvested sustainably.

ICES advises that when the MSY approach is applied, catches in 2027 should be no more than 3,254 tonnes. This is an increase of 5.4% from the previous year, which reflects an increase in the estimated biomass.

Management of the Target Stock Score: 0.25

Alignment with Scientific Advice Score: 0.25

Monitoring, Control and Surveillance Score: 0.25

Few management measures in the North Sea and English Channel are specifically designed for brill. Nevertheless, the stock is currently abundant and appears to be harvested sustainably. Although a species-specific TAC was only introduced in 2024, catch limits have been set in line with scientific advice and have effectively controlled fishing mortality. The fishery has a well‑developed and effective Monitoring, Control, and Surveillance (MCS) system with reliable enforcement and low levels of IUU activity.

As a predominantly bycatch species, North Sea brill is managed largely through measures designed for mixed demersal fisheries. The stock falls within the EU North Sea Multiannual Plan (MAP) and is taken primarily by trawl fisheries targeting sole and plaice, with smaller catches from trammel and gillnet fisheries. Consequently, fishing mortality is controlled mainly through technical measures applied to these fisheries, including gear selectivity requirements, cod-end mesh size regulations, and restrictions on beam length. In UK waters, minimum mesh size requirements apply to bottom trawls and nets operating in the North Sea and English Channel.

An 80 mm mesh size is commonly used in the North Sea sole fishery and is effective at retaining marketable sole, but it is also likely to capture immature brill. In UK waters of the English Channel (ICES Divisions 7d and 7e), a minimum conservation reference size (MCRS) of 30cm is in place. However, there is no MCRS in the North Sea. This increases the risk of recruitment overfishing, as immature fish may be removed before contributing to spawning biomass and reproductive output. Dutch Producer Organisations have applied a voluntary minimum market size for brill. However, this was reduced from 32 cm to 25 cm between 2017 and 2026. Although increasing mesh sizes would likely reduce catches of juvenile brill and improve stock resilience, such measures would also reduce catches of marketable sole.

Additional protection is offered by the Plaice Box in the North Sea - 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. Although established to protect juvenile plaice, the closure could provide some indirect benefits for brill.

Brill falls under the Landing Obligation (LO), which aims to improve catch reporting, reduce unwanted catches and encourage more selective fishing practices. As a result, brill caught in North Sea otter trawl and net fisheries, and in beam trawl fisheries in the English Channel, must generally be landed. However, survivability exemptions apply to some beam trawl fisheries in Scottish and EU waters of the North Sea, allowing certain catches to be returned to the sea. Despite the LO, average discard rates between 2023 and 2025 were estimated at around 5.1% of total catches.

Historically, brill and turbot were managed under a combined TAC covering ICES Subarea 4 and UK waters of Division 2a. This management did not align with ICES stock areas, limiting effective control of species-specific exploitation rates and potentially encouraging high-grading and overexploitation of the higher-value brill stock. Since 2024, a specific TAC for brill has been implemented, improving species-specific management. Brill TACs have been set below ICES advice since 2024, as they account for third-country catches (approximately 0.55% of removals). Catches in 2024 were below both the TAC and advised catch level. Catches also remained below advised levels under the previous combined TAC system.

Despite these measures, brill remains largely managed within a mixed-fishery context. ICES notes that, under current fishing patterns, it is not possible to simultaneously achieve all single stock catch advice within the North Sea demersal fishery, primarily due to the zero-catch advice on cod making it a choke species. However, interactions between brill and cod are considered limited, as fisheries catching brill generally record negligible cod landings.

Monitoring, control and surveillance of UK fisheries are delivered through licensing, vessel tracking, statutory reporting, observer coverage, inspections and other monitoring systems. All commercial fishing vessels must hold a valid UK fishing licence to operate in UK waters, although exemptions may apply to some unpowered vessels under 10 metres. Depending on the area, target species and activity, additional permits or authorisations may also be required.

Vessel tracking requirements vary by vessel size, area and administration through Vessel Monitoring Systems (VMS) and, where applicable, inshore VMS (iVMS).

• Vessels 12 m and over must report their position every two hours via VMS.
• Vessels under 12 m report their position continuously where iVMS applies, or may operate full VMS where required by licence conditions or when fishing offshore.

Reporting of fishing activity, catches, landings, discards and port movements is mandatory, with logbooks supporting traceability:

• Vessels 12 m and over submit electronic logbooks under Council Regulation 1224/2009.
• Vessels 10–12 m (and under 10 m Producer Organisation vessels) use paper logbooks, updated daily and submitted within 48 hours of landing.
• Non-PO vessels under 10 m are generally exempt unless required by licence conditions.

UK vessels must also carry fishery observers when directed, providing independent verification of activity and catch. Remote Electronic Monitoring (REM), using cameras, sensors and positional data, is being increasingly deployed to improve data quality and support enforcement. Its rollout is supported by the Fisheries Act 2020 and the Joint Fisheries Statement.

Together, these measures help prevent illegal, unreported and unregulated (IUU) fishing through vessel licensing, catch documentation, positional monitoring, statutory reporting and compliance checks. Enforcement action may include financial penalties, prosecution, licence suspension or other sanctions. The UK has committed to reducing IUU fishing and maintains a blacklist of vessels involved in such activities. This rating reflects full compliance with UK monitoring, control and surveillance requirements.

Similar monitoring, control and surveillance requirements apply to EU vessels under the EU Fisheries Control Regulation, including vessel tracking, electronic catch reporting, landing declarations, inspections and traceability requirements. The revised Regulation entered into force in January 2024 and introduces a phased requirement for REM with onboard cameras on EU vessels over 18 m identified as high risk for Landing Obligation non-compliance, alongside wider increases in digital reporting and traceability. Implementation and enforcement are undertaken by individual Member States, so observer coverage, inspection activity, enforcement effort and REM deployment can vary between countries and fisheries.

The Marine Conservation Society views Remote Electronic Monitoring (REM) with cameras as 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. 

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 impacts 

• Targets for fishing pressure and biomass, and additional management when those targets are not being met, based on the best scientific evidence 

• Timeframes for stock recovery 

• Improved 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 bycatch 

• Stakeholder engagement 

A Southern North Sea and Eastern Channel mixed flatfish FMP has been proposed, coordinated by Defra that incorporates 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/collections/fisheries-management-plans#published-fmps]. 

Capture Method Score: 0.75

Habitat Impacts: 0.75

Bycatch Impacts: 0.25

Vulnerable and ETP Species: 0.5

Ecosystems and Trophic Webs: 0.25

Beam trawls have significant impacts on the seabed, including damage to benthic communities and vulnerable marine habitats. As brill is primarily a bycatch species in flatfish fisheries, its contribution to bycatch impacts on depleted species, such as North Sea cod, is likely to be limited, though not negligible. There is also bycatch of ETP species, including prohibited blue skate, which could possibly be hindering recovery of the species. While the relatively low level of brill removals is unlikely to affect food-web dynamics, beam trawling may contribute additional pressure to an ecosystem already altered by fishing and climate change.

Landings of brill in the North Sea and English Channel are from beam trawls (50.3%), otter trawls (34.7%), trammel and gillnets (11.3%), and other gear types (3.7%). In 2025, a discard rate of 5.1% was recorded, an increase from 2024 (3.1%).

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 and Celtic Seas ecoregions, 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 Greater North Sea and 61% of the Celtic Seas seabed shallower than 800m was trawled.

There are several Marine Protected Areas (MPAs) within the North Sea and English Channel that are designated to protect sensitive benthic habitats and species that may be vulnerable to bottom-towed fishing gears. While some sites, such as Dogger Bank, Wight-Barfleur Reef, and South Dorset Marine Conservation Zone (MCZ), already have restrictions on bottom-towed gears, protection remains incomplete across the MPA network, with several sites only recently considered through the MMO's Stage 3 byelaw process. As such, some designated features may remain exposed to disturbance from bottom trawling, potentially limiting habitat recovery and the achievement of conservation objectives. 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.

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 are often limited due to insufficient monitoring. However, some North Sea demersal trawl fisheries, which target flatfish species, are Marine Stewardship Council (MSC)-certified and record bycatch. This can provide an indication of the species likely to be encountered where certified and uncertified fleets overlap. Certified fleets have reported bycatch of North Sea cod, of which the southern substock is currently under zero-catch advice due to biomass being below safe biological limits. As brill is primarily a bycatch species within flatfish fisheries rather than a target species, its direct contribution to cod bycatch and any associated impacts on stock recovery are likely to be limited. Measures to reduce cod bycatch are also in place in parts of the Scottish North Sea, including the UK North Sea Cod Avoidance Plan, which incorporates larger mesh sizes, seasonal closures and move-on requirements.

In terms of endangered, threatened and protected (ETP) species, the certified fleet reported a marked increase in blue skate and spurdog bycatch in 2024. However, the risks associated with these species differ. Blue skate, as part of the common skate complex, remains protected in UK and EU waters, with fishing, retention, transhipment and landing prohibited, and is managed under a zero-catch approach. The recent increase in blue skate bycatch suggests that the demersal fishery could possibly hinder the recovery of the species. By contrast, spurdog biomass has recovered above MSY Btrigger and current fishing mortality is considered sustainable, indicating that incidental catches in the North Sea demersal fishery are unlikely to be contributing to population decline.

Brill occupies a mid- to upper-trophic-level position in the marine food web, feeding primarily on crustaceans and small fish while also serving as prey for marine mammals and larger predatory fish. The North Sea and English Channel ecosystems have undergone substantial change in recent decades due to climate change and fishing pressure. In the North Sea, rising sea temperatures have altered trophic pathways through declines in zooplankton abundance, while reductions in key forage species such as sandeels have affected energy transfer through the food web. While in the English Channel, many higher-trophic-level species, including gadoids and elasmobranchs, have declined, while lower-trophic-level invertebrates have become increasingly prominent in landings. The loss of top predators can trigger cascading effects on ecosystem structure and functioning.

Compared with the major flatfish fisheries targeting sole and plaice, catches of brill are relatively low, suggesting the fishery is unlikely to exert a substantial influence on ecosystem dynamics. However, brill is commonly caught using trawls, which can cause seabed disturbance and generate multi-species bycatch. Consequently, habitat alteration and incidental catches may continue to exert pressure on an ecosystem that has already been substantially modified.