Seabass

Stock Status Score: 0

The seabass stock in this region is harvested sustainably and fully fished.

Stock assessments are conducted by the International Council for the Exploration of the Sea (ICES). A benchmark assessment in 2025 introduced revised reference points, improving the accuracy of the stock assessment and reducing some uncertainties. Although recreational catches remain uncertain because they are estimated from surveys and make up a substantial proportion of total removals, the benchmark found that stock status relative to the reference points was robust across a range of recreational catch scenarios.

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) and precautionary reference point (Bpa) to ensure reproductive output is maintained. Because BMSY is not defined, the Good Fish Guide applies its own definition of 1.4 x MSY Btrigger.

Since 1985, F has steadily increased, eventually exceeding FMSY (0.17) between 2011 and 2015, with a peak of 0.22 in 2013. This was followed by a sharp decline after emergency measures were implemented, bringing F back below FMSY, where it fluctuated between 0.08 and 0.12. In 2025, F is estimated at 0.116, which is below FMSY, and therefore indicates that the stock is currently harvested sustainably.

Between 1985 and 2010, spawning stock biomass (SSB) varied between 22,000 and 34,000 tonnes. However, a decline begun in 2010, with SSB falling below MSY Btrigger (19,339 tonnes) in 2015 and then below Blim (15,666 tonnes) from 2016 to 2018. After this period of low biomass, the stock began to recover, exceeding MSY Btrigger in 2021. The current estimate for 2026 is 26,630 tonnes, which is between MSY Btrigger and the BMSY proxy (27,075 tonnes). Therefore, the stock is considered to be fully fished.

Fishing pressure is not the only factor influencing bass stock status, recruitment variability is also a driver. Throughout the time series, annual recruitment has fluctuated significantly. Over the past 15 years, the highest recorded recruitment occurred in 2014, reaching approximately 116 million individuals, while the lowest occurred in 2025, at 19 million. For 2026, this has increased again to almost 70 million individuals.

For 2027, ICES advises that when the maximum sustainable yield approach is applied, total removals (both commercial and recreational) should not exceed 5,576 tonnes. This is a 7.6% increase from the 2026 advice. It is important to note that some catches within this region are attributable to the neighbouring Bay of Biscay stock, meaning that management decisions in 4b-c, 7a, and 7d-h, can also affect the population in 8a-b. While migration has been accounted for in the new assessment, uncertainties remain regarding stock structure and connectivity among populations.

Management of the Target Stock Score: 0.25

Alignment with Scientific Advice Score: 0.5

Monitoring, Control and Surveillance Score: 0.5

There are multiple management measures in place for seabass in this region. However, the evidence indicates that the effectiveness of some, such as the closed season, could be improved. There is no formal TAC for seabass due to the large proportion of recreational catches, meaning that total removals often exceed scientific advice. There are also concerns regarding bycatch controls in some fisheries, particularly those using gillnets and trawls. As a result, MCS is considered adequate overall, although some gaps remain that could be addressed to improve compliance and ensure management measures are fully effective.

After spawning stock biomass (SSB) began declining in 2010, emergency management measures were introduced in 2015, followed by the adoption of a precautionary management plan by one of the relevant authorities. These interventions appear to have successfully reduced fishing pressure, with fishing mortality (F) falling below FMSY in 2016 and remaining below this threshold since. As a result, the stock has recovered, with SSB increasing above MSY Btrigger.

Seabass management remains challenging given that fish move between neighbouring assessment areas. ICES notes that part of the catch from the neighbouring Bay of Biscay stock is taken within divisions 4.b-c and 7.a, d-h. This overlap needs to be considered when setting management measures to ensure that catches remain within sustainable limits for both stocks.

UK seabass management aims to balance fishing opportunities with conservation needs while reflecting agreements between the UK and EU. Unlike many commercially important species, seabass is not managed through a Total Allowable Catch (TAC) and is therefore not subject to the landing obligation. Instead, management relies on a combination of licensing requirements, gear restrictions, catch limits, and seasonal closures.

For 2026, commercial fishers must hold an authorisation to catch, retain, tranship, or land seabass. Targeted fishing is only permitted using hooks and lines. While fixed gillnets and demersal trawls and seines may retain bass as bycatch under specific conditions and catch limits. Bass caught using unauthorised gears, including pelagic trawls, ring nets, and drift nets, must be discarded.

Additional management measures include:

• A Minimum Conservation Reference Size (MCRS) of 42 cm.
• A seasonal closure from 1 February to 31 March, intended to protect bass during the main spawning period.
• Annual catch limits of:
  • 8 tonnes for hook-and-line vessels.
  • 5.4 tonnes of bycatch for fixed-net vessels.
  • 10 tonnes of unavoidable bycatch for demersal trawls and seines, with bass comprising no more than 20% of the total catch weight per trip.
• A requirement to immediately return all bass caught during the February to March closure period.
• Recreational 3-bag limit per fisher.
• Spatial and effort controls implemented by IFCAs and the Welsh Government, including closed areas and restrictions on shore-based nets.

Although the closed season aims to protect spawning aggregations, there is growing evidence that the timing of seabass spawning has shifted, likely in response to changing environmental conditions. This raises questions about whether the current February to March closure still provides optimal protection, or whether a different timing may be more effective for protecting spawning aggregations.

Monitoring, enforcement, and the ability to adapt management measures remain essential to maintaining stock recovery. While the measures introduced since 2015 have reduced fishing mortality, they have also led to higher levels of discarding. In 2025, an estimated 629 tonnes of bass, equivalent to 29.3% of commercial catches, were discarded. Discards occur when fish are undersized, exceed authorised catch limits, or are caught using unauthorised gears. Juvenile bass make up a significant proportion of these discards, highlighting the importance of Bass Nursery Areas (BNAs), which provide protection through seasonal and area-based fishing restrictions.

There are also concerns about how effectively some of the current bycatch provisions operate in practice. For fixed-net fisheries, there is potential for bass to be effectively targeted while being recorded as bycatch. For demersal trawls and seines, the requirement that bass must not exceed 20% of the catch by weight could create an incentive to retain additional catches of other species in order to remain within the permitted proportion. This has the potential to increase catches of non-TAC species, including species of conservation concern.

Despite the stock's recovery, questions remain over whether overall removals are fully aligned with scientific advice. ICES expresses seabass advice as total removals, including commercial catches, recreational catches, and release mortality. Although fishing mortality has remained below FMSY in recent years, estimated total removals exceeded the ICES-advised level in every year in the last five years. In 2025, ICES advised that total removals should not exceed 2,620 tonnes. Estimated commercial catches were 2,146 tonnes and estimated recreational removals were 2,362 tonnes, resulting in total removals of 4,508 tonnes, around 72% above the advised level. However, recreational removals are estimated using a model based on a 2012 survey and adjusted to account for subsequent management measures, rather than being derived from annual surveys and monitoring. As a result, there remains considerable uncertainty around recreational catches and removals.

Further improvements in data collection would strengthen seabass management. Recreational removals remain poorly quantified, and there is uncertainty around discard levels. Better monitoring of both commercial and recreational fisheries, alongside improvements in gear selectivity, alongside spatial and temporal management, would help reduce catches of undersized fish. Continued illegal targeting of seabass also remains a risk to stock recovery and should continue to be a priority for enforcement.

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.

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 Bass FMP has been proposed, coordinated by Defra and the Welsh Government 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

Bycatch Impacts: 0.25

Vulnerable and ETP Species: 0.75

Ecosystems and Trophic Webs: 0.5

Gillnets have minimal impacts on benthic habitats because they cause little disturbance to the seabed. However, their non-selective nature can result in relatively high levels of bycatch, including ETP species such as harbour porpoise. In some areas, current harbour porpoise bycatch rates are considered unsustainable and are hindering population recovery. While current levels of seabass removal are unlikely to have a significant effect on food-web dynamics, the bycatch associated with net fisheries has the potential to affect ecosystem function and alter trophic structure.

In 2025, lines accounted for the largest proportion of commercial seabass landings (39%), followed by bottom trawls (29%), fixed and drift nets (16%), other gears (9%), and Danish seines (7%). While line fisheries can actively target seabass, catches taken by other gears are largely incidental as seabass cannot legally be targeted using trawls, nets, and seines.

Fixed nets, consisting of one or more vertical panels of netting suspended between a float line and a weighted ground line, generally have minimal impacts on benthic habitats because they cause little disturbance to the seabed. However, their non-selective nature means they can be associated with relatively high levels of bycatch. Seabass is caught as a bycatch species in net fisheries, as management measures prohibit the targeted fishing of seabass with this gear type. Consequently, the direct contribution of seabass to the bycatch of other non-target species is considered limited, but not negligible.

Fixed-net fisheries are associated with the bycatch of a range of species, including marine mammals, seabirds, fish, elasmobranchs, and endangered, threatened, or protected (ETP) species. Globally, gillnet fisheries are recognised as posing one of the greatest bycatch threats to cetaceans, particularly small coastal species. Within the Greater North Sea ecoregion, harbour porpoises are the species most commonly affected, with annual bycatch estimated at around 389 individuals. In the Celtic Seas ecoregion, harbour porpoise bycatch is also considered to be occurring at unsustainable levels. Harbour porpoises are listed by OSPAR as threatened and/or declining in both regions and are protected under UK and EU legislation, which includes requirements to minimise bycatch. Other species known to be caught in fixed nets include grey seals, harbour seals, guillemots, and several elasmobranch species, including the common skate complex. While seabass is only a bycatch species in fixed-net fisheries, there is evidence that these gears can have significant impacts on ETP species, including unsustainable bycatch rates of harbour porpoise.

Acoustic Deterrent Devices (ADDs), such as pingers, have been shown to reduce harbour porpoise bycatch in gillnet fisheries, but their use remains inconsistent and their effectiveness is uncertain. Seabird bycatch is also a concern, particularly in inshore waters. While bird-scaring devices have demonstrated some success in reducing seabird interactions, there are currently no species-specific mitigation measures documented for the fishery, and the uptake of bird deterrents is largely unknown.

Several Marine Protected Areas (MPAs) within UK waters overlap with this fishery and have been designated to protect sensitive habitats and vulnerable species. Static-net fishing remains permitted in most offshore MPAs, although all fishing activity is prohibited within the three Highly Protected Marine Areas (HPMAs). Additional restrictions on static-net fisheries may also apply in inshore waters through local Inshore Fisheries and Conservation Authority (IFCA) byelaws.

Nylon nets, if lost, 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.

Seabass are mesopredators, feeding primarily on small fish, crustaceans, cephalopods, and other benthic invertebrates. Historic fishing pressure has reduced populations of comparable predatory fish species in UK waters (e.g. gadoids), and climate-driven changes in species distributions and ecosystem functioning may have affected food-web resilience in some areas. However, despite recent increases in both commercial landings and recreational removals, it is unlikely that current levels of exploitation in this fishery are having a significant impact on ecosystem function across the broad geographic scale covered by this assessment.

However, the relatively high bycatch rates associated with this gear type, including the incidental capture of ETP species, have the potential to place additional pressure on ecosystems that are already subject to multiple environmental and anthropogenic stressors. This is of particular concern in areas where cetacean bycatch is occurring at levels capable of affecting population stability. Declines in species such as harbour porpoise could result in changes in trophic webs and ecosystem functioning.