Seabass

The sea bass stock in the northern and central Bay of Biscay is harvested sustainable and fully fished.Stock assessments are conducted by the International Council for the Exploration of the Sea (ICES). Following a benchmark in 2025, the latest assessment incorporates catch reallocation across connected ICES divisions and estuary-based recruitment data. These methodological updates have improved the accuracy of the assessment and reduced some uncertainties. However, recreational catches are only based on two years of data, and therefore continue to have a considerable level of uncertainty.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.From 1985 to 2002, F fluctuated around 0.18, remaining below FMSY (0.205). However, in 2003, F exceeded MSY, reaching a peak of 0.23 in 2005 before falling back below the threshold in 2008. Since then, total fishing pressure, across both commercial and recreational catches, has steadily declined from 0.2 in 2008 to an estimated 0.088 in 2024. Therefore, F is currently well below FMSY, indicating the stock is harvested sustainably. During the early 2000s, spawning stock biomass (SSB) hovered just above Blim (17,273 tonnes). After 2006, SSB began rising, surpassing MSY Btrigger (21,782 tonnes) from 2010 to 2014, before falling close to Blim again in 2017. In recent years, SSB has gradually increased, exceeding MSY Btrigger again in 2021 and is now estimated at 30,364 tonnes in 2025. Given that the proxy for BMSY is 30,495 tonnes, the 2025 SSB falls just below this level, so we consider the stock fully fished.Despite fishing pressure remaining below FMSY since 2008, SSB declined from 2011 to 2017. This suggests that stock dynamics are not only influence by fishing activity but also by variability in recruitment. Across the time series, annual recruitment has become increasingly variable. The highest recorded recruitment was in 2018, at approximately 179 million individuals. This figure dropped significantly to approximately 31 million in 2021. That said, the 2025 estimate (~89.9 million) exceeds the average for the previous three years (2022-2024), which stood at ~61.6 million.For 2026, ICES advises that under the EU multiannual plan (MAP) for Western Waters and adjacent waters, total catches (commercial and recreational) should be between 6423 and 7618 tonnes. This is a 187-190% increase from the 2025 advice, reflecting an updated assessment of stock status following the benchmark. It is important to note that a portion of this stock is harvested in neighbouring ICES divisions, which should be incorporated into broader management to avoid exceeding advice.

There are management measures in place, which are partly effective in managing the stock.Sea bass in the Bay of Biscay (ICES divisions 8a, 8b) is managed under the European Union’s multiannual management plan (MAP) for Western Waters. Although this stock is not subject to EU Total Allowable Catches (TACs) and quotas, it has been governed by the MAP since 2019. The plan applies to demersal stocks, including sea bass, and sets out conditions for determining fishing opportunities based on stock status and the current FMSY for the stock. It aims to ensure that stocks, particularly sea bass, are fished sustainably, and that management decisions reflect the best available scientific advice. ICES considers the FMSY range used in the MAP to be precautionary for sea bass in this region. Recreational fishing exerts a significant pressure on the stock, and since 2019, these catches, and a 5% post-release mortality rate, have been accounted for in ICES catch advice. Recreational removals are estimates based on observed data in 2010 and 2022, with 2024 recreational activity (kept and dead releases) estimated to have accounted for 26.9% of total removals.As sea bass is a non-TAC species, there is concern about potential displacement of fishing effort from other species with limiting quotas. Management measures are in place to mitigate risk and maintain stocks. A Minimum Landing Size (MLS) of 40cm was introduced for commercial catches in 2020, while recreational catches have been subject to a 42cm MLS since 2013. However, these offer only partial protection, as approximately 50% of females reach maturity at 42.14cm. This means a significant proportion of fish may be removed before the chance of reproducing, which can impact the long-term stock stability.In 2024, the French fleet accounted for 98.7% of sea bass landings in the Bay of Biscay, with the remaining 1.3% landed by Spanish vessels. The discard rate for France has gradually decreased, from 8.80% in 2021 to 7.06% in 2023. While Spanish discards are likely to occur, they are not fully quantified.In France, the dominant fishing party, several national management measures are in place to support the stock. These include a quota system for commercial sea bass fishing licenses (implemented in 2012), a voluntary closed season from February to mid-March for longline and handline fisheries in Brittany, and a recreational daily bag limit of two fish in 2025. Additionally, in January 2024, a one-month fishing ban was introduced in part of the Bay of Biscay for certain vessels and gear types, aiming to reduce cetacean bycatch. Although not designed for sea bass, the ban overlaps with their spawning period and may offer indirect benefits by reducing fishing pressure during their reproductive window. The closure is set to reoccur in January/February of 2025 and 2026.Despite these management measures, there are some limitations relating to data for recreational fisheries. Continued monitoring and research are essential to improve data quality and ensue effective management of the sea bass stock in this region.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.

Over a third of sea bass in areas 8a and b in the Bay of Biscay is caught using nets, which cause limited damage to the seabed. However, this gear can have high levels of bycatch, including marine mammals, marine reptiles, seabirds, and ETP fish species.In 2024, sea bass was primarily caught using lines (35%), nets (27%), and bottom trawling (16%). The French fleet dominated landings, accounting for 98.7% of total catch, with Spanish vessels contributing the remaining 1.3%. An estimated 864 tonnes were also removed through recreational fishing, making up 26.9% of total removals.While nets cause minimal damage to the seabed, particularly when suspended in the water column, they are still responsible for high levels of bycatch, including endangered, threatened, and protected (ETP) species. Monitoring of bycatch across EU fisheries remains limited, but in the Bay of Biscay, observer programmes and fisher reports indicate that trammel and set gillnets are heavily responsible for bycatch of ETP fish (rays, basking sharks, and bluntnose six-gilled sharks), marine reptiles (loggerhead and leatherback turtles), marine mammals (harbour porpoise, common and bottlenose dolphins), and seabirds (Balearic and Cory’s shearwaters, Northern gannets, European shags, and common guillemots). Seabirds in the Bay of Biscay and Iberian Coast ecoregion are particularly vulnerable to fishing activity. In 2023, trammel nets were estimated to have caught 425 Balearic shearwaters, while set gillnets caught 1687 Northern gannets. This coincides with ongoing population declines of these species, especially along the western Iberian and Portuguese coasts. The Iberian form of the common guillemot has already been lost in Galicia and Portugal, attributed in part to fishing bycatch. Although bird scarers have proven effective in reducing seabird bycatch, their use in the sea bass fishery is currently unknown, and no specific seabird bycatch mitigation measures are in place.Marine mammals are similarly affected. In 2023, trammel nets were estimated to have caught 377 harbour porpoises off the Iberian coast, raising sustainability concerns for local populations. Bycatch of common dolphins is also concerning, with 1834 individuals bycaught in set gillnets in 2023. Gillnets and trammel nets in the Bay of Biscay and Iberian coast ecoregion are estimated to be responsible for 70% of common dolphin bycatch across all NE Atlantic ecoregions. Standings data and drift modelling suggest that 11,330 common dolphins died in 2023 from being bycaught in French waters of the Bay of Biscay and Western Channel - exceeding the Potential Biological Removal (PBR) threshold of 4927 individuals per year. Bottlenose dolphins are also impacted by net fisheries, with 315 caught in set gillnets during 2023.The concern for cetaceans led the European Commission to request that France, Spain, and Sweden take stronger action under the Habitats Directive and Common Fisheries Policy to reduce unsustainable bycatch of cetaceans. To study, protect, and reduce accidental capture of cetaceans, both France and Spain have national legislation in place:France:A government action plan to improve bycatch monitoring (observers and electronic monitoring), build knowledge, and develop mitigation strategies.A national action plan for cetacean protection, aiming to reduce anthropogenic pressures from fishing, noise pollution, and coastal pollution.Order MERM2033160A (2020), requiring pelagic trawlers in the Bay of Biscay to use acoustic deterrent devices (pingers).Spain:A national plan with steps to reduce fisheries bycatch.Order APA/1200/2020, which mandates acoustic deterrents (pingers), movement rules, mandatory landing of accidental cetacean bycatch, and establishes a commitment to improving knowledge of cetacean populations.Pingers, when used correctly, have shown up to 85% effectiveness in reducing common dolphin bycatch. However, further action is recommended by the ICES Workshop on mitigation measures to reduce bycatch of short-beaked common dolphins in the Bay of Biscay (WKEMBYC2), including the modification and potential extension of temporal closures of high risk fisheries. When these closures coincide with peak fishing activity, there is a trade-off between the fishery and mitigate measures, with uncertainties surrounding the promise of financial compensation. Ongoing monitoring and data collection will be critical in assessing the effectiveness of mitigation measures and for establishing long-term effective protection against cetacean bycatch.Sea bass is also part of a mixed fishery in the Bay of Biscay, where under current fishing patterns, it is not possible to meet all single stock catch advice. Pollack, primarily caught by nets (52%) and lines (39%), is currently the most limiting species. As such, the sea bass net fishery may amplify the exploitation risks for pollack in the region. While Blim for sea bass is projected to be achievable by 2026, Bpa is not, indicating continued sustainability concerns.Additional risks in the net fishery comes from gear loss, as nylon gillnets when lost at sea can continue fishing through ‘ghost fishing’ until they become tangled and sink or are removed. As all gear types require financial investment, there is incentive to maintain and retrieve lost nets and prevent ghost fishing.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.

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