In the recent decade, local fishers in the Jammer Bay, western Skagerrak, experienced declining landings of cod (Gadus morhua) and plaice (Pleuronectes platessa) and were unable to fish up their quotas making it difficult to earn a livelihood. To enable an Ecosystem Based approach to Management (EBM), we applied the Systems Approach Framework (SAF). The fishers' concerns and perceptions of the system were brought forward and integrated into the analysis. We examined whether the declined coastal landings were due to over-fishing, changes in adult cod and plaice distribution, climate change or discards. To address these issues, we integrated data from different, sources including international landings data for Skagerrak, fisheries survey data for the Greater North Sea, Danish landings data and hydrographic models of thermal seabed habitats for the Jammer Bay area, and Danish landings and discards data from the Skagerrak. Our results showed that declines in landings of cod and plaice in the Skagerrak appeared unrelated to quotas and effort. The fisheries survey data showed a regional shift in adult cod and plaice distribution from the southern and central North Sea areas to the northern North Sea areas. However, in the Jammer Bay area changes in where adult cod were caught were related to the distribution of suitable thermal habitats. No effects of changes in thermal seabed habitat were evident for adult plaice. The fisheries survey data showed that juveniles of both species occurred in high densities in the Jammer Bay area as compared to the remaining Skagerrak area and adjacent seas. Their occurrence coincided with the areas that were intensively fished, and high discards of juvenile cod and plaice were registered in the area during the period of the study. These results pointed to the need to implement protection measures for the juveniles of both species. The implementation of an Other Effective Area-based Conservation Measure (OECM) would allow spatio-temporal closures to protect the juveniles while maintaining sustainable fisheries. In this study, we demonstrate how multi-sourced empirical data can be mobilized to provide knowledge-based advice for OECM implementation.

The expansion of offshore wind farms (OWFs), driven by increasing global energy demands and marine spatial planning, is intensifying spatial conflicts and impacting fisheries. However, research on observed local and cumulative effects of OWFs on fisheries, especially regarding fishing effort reallocation, is limited. Retrospective analyses are crucial for informing science and policy. Denmark, a pioneer in large-scale OWFs, has over 15 operational farms totaling more than 2500 MW, with some early installations already decommissioned after 25 years. Analyses of the impacts and interactions between OWFs and various fishing fleets were conducted for four major Danish OWFs in the North Sea, Kattegat, and Western Baltic Sea from 2005 to 2023. This timeframe covers pre-, during-, and post-construction phases of the OWFs. Using available vessel monitoring system (VMS) and logbook data, we analyzed vessel-level fishing effort allocation, fishing efficiency, revenues and landings in relation to OWFs, fishing method, and benthic habitat fishing grounds, providing valuable insights into OWF-fisheries dynamics. This study identified major impacts of OWFs on Danish fisheries, as active fisheries within OWF sites generally ceased following construction. However, results indicate potential for reallocating fishing activities to surrounding areas offering similar opportunities. Most vessels are not exclusively dependent on OWF areas, as they typically have flexibility to switch between fisheries or gears and operate across wider areas due to their long range and polyvalent capabilities. Although minor gear-specific variations and localized concentrations in fishing effort were observed just outside OWF boundaries after their establishment, overall fishing patterns and efficiencies remained significantly consistent after OWF establishment – except for one OWF area. Fishing activity within and adjacent to OWFs showed in general similar gear composition, effort allocation, benthic habitat preferences, depth distributions, landings and economic efficiency, and species composition. Spatial fishing patterns associated with habitat also persisted and there was in general found continuity in fishing dynamics in surrounding areas following OWF establishment.

Bottom trawling affects seabed habitats, but its large-scale impacts remain poorly quantified. Assessment of trawling impacts is essential to support monitoring and achieving sustainability objectives under international conventions, sustainable development goals, and seafood certification programs. We present a Europe-wide quantitative assessment of bottom trawling impacts, accounting for regional seabed-community sensitivity drivers, across the Baltic, Atlantic, Mediterranean and Black Sea continental shelves. Using two risk-based indicators of seabed status-Relative Benthic Status determined as benthic community biomass relative to seabed fauna carrying capacity (RBStot) and RBSsen (biomass of the 10% most sensitive fauna relative to carrying capacity)-we found substantial regional and habitat differences. The Black, Baltic and Aegean-Levantine Seas showed low trawling intensity and high seabed status across habitats. In contrast, the Western Mediterranean, Ionian and Central Mediterranean and Adriatic Seas were the most severely impacted. Trawling affected the sensitive species biomass fraction more strongly than the total community biomass. RBStot was in good condition (here chosen as RBS > 75% for epifauna) for over 79% of habitat-ecoregion combinations. In contrast, RBSsen met this threshold in only 46% of these. A strong correlation emerged between the mean trawling intensity and RBStot and RBSsen, allowing the use of SAR to estimate ecosystem status. This relationship can support decisions on where, and by how much, SAR reductions are needed to achieve good environmental status in regions where no detailed assessment is available. Our approach provides a quantitative framework to balance fishery production with ecosystem sustainability, offering tools for environmental and fisheries management in Europe.

Small-scale fisheries (SSF) represent over three-quarters of all active vessels in the European fleet yet remain largely invisible in marine spatial planning due to the lack of spatial data. This data gap has contributed to the marginalisation of SSF in policy and governance, despite their ecological, economic, and socio-cultural significance. The recent revision of the EU Fisheries Control Regulation (CR 2023/2842), mandating vessel tracking for all fishing vessels-including those under 12 metres by 2029-offers a critical opportunity to integrate SSF into formal spatial and fisheries management processes. This paper synthesises insights from researchers across 24 institutions in Europe to assess the current state of SSF tracking, estimate existing coverage, and identify opportunities and challenges for implementing an EU-wide SSF tracking programme. We estimate that approximately 12% of the SSF fleet is currently tracked, primarily within net, trap, and dredge fisheries. While researchers broadly recognise the value of spatial data for improved spatial planning and ecosystem assessment, several challenges hinder implementation, including high implementation costs, limited institutional capacity, and fragmented or incompatible data infrastructures. We recommend: (i) the development of clear technical requirements and harmonised data protocols, (ii) leveraging tracking data to support participatory and adaptive management, and (iii) ensuring inclusive governance that reflects the socio-cultural dimensions of SSF. As EU Member States move toward full implementation of CR 2023/2842, early decisions will shape not only the technical architecture of tracking systems, but also the broader governance future of European SSF. A more equitable and integrated approach is essential-and achievable.

Spatial and temporal fishing effort (FE) estimates are crucial for informing scientific-based decisions in fisheries management, spatial planning, and conservation. Lower temporal resolution (longer intervals between vessel position registrations) reduces FE accuracy, thus calling for a balance between precision and feasibility for large-scale mapping, such as in European waters. Effective marine management is critically dependent on this kind of accurate, comprehensive, and appropriate data. New EU legislation mandates tracking all fishing vessels, including small-scale fisheries (SSF) (LOA <= 12 m), implying a reassessment of optimal polling intervals. While experts recommend high-frequency polling (1 poll/30 s) for SSF, large-scale fisheries (LSF) have been mapped with up to 2-h polling intervals. Here, our study evaluates how polling frequency affects fishing activity characterization and FE estimation across fleets. We found that low temporal resolution critically affects (1) FE by underestimation, (2) misclassification of fishing behaviour, (3) compliance challenges, (4) marine spatial planning conflicts, (5) seafloor impact assessment (6) inaccurate bycatch risk analysis, (7) geographic projection biases, and (8) CPUE-based abundance indices, affecting stock and mortality estimates. These results highlight a central problem: low-resolution tracking compromises the scientific and management of outputs. The promise of high-resolution tracking to improve accuracy, is affected by the trade-offs between cost and data processing capacity, and the burden on vessel operators. Thus, SSF and passive gears should be tracked with at least a 30-s polling frequency as a conservative approach. For LSF using active gears, further work is required to determine the optimal ping frequency, but overall, it should be on the scale of a few minutes, depending on the gear used. To address this, our work clearly supports a recommendation for future regulations to define minimum acceptable polling intervals, tailored by fleet segment, and that support mechanisms be implemented to ease adoption. These regulatory aspects should contemplate a close collaboration with the fishing industry to ensure practicality, compliance, and long-term success. Thus, our findings highlight the costs of low-resolution tracking, providing critical insights for decision-makers shaping future vessel monitoring policies.

Landings by species and their associated fishing effort are crucial for stock assessment and estimating fishing mortality. While large scale fisheries (LSF) have historically received more attention, interest in standardized data from small scale fisheries (SSF) has increased significantly over the last decade. This study characterizes SSF and ongoing fishing activity data collection across 17 European countries, from the Baltic Sea to the Mediterranean, using 2019 as a reference year. The analysis reveals that 88% of commercial active fishing vessels are smaller than 15 m in total length and that such SSF (as considered in this study) accounts for over 83% of the total days at sea and 12% of the landed weight. However, fishing activity data collection for SSF is less comprehensive compared to LSF. Vessels larger than 10 m typically report their fishing activities in logbooks and sales notes, whereas for <10 m vessels, only 40% provide additional data sources to sales notes, namely with declarative forms. This results in significant data gaps and inaccuracies, especially regarding fishing effort, gears used, or fishing locations. This is especially true for vessels smaller than 10 m, likely as a product of having comparatively less ongoing requirements put in place, whereas vessels between 10 and 15 m also present fewer data reporting obligations (e.g. large part of this fleet is not covered by geo-localization data especially for the [10–12) m vessels) compared to vessels above 15 m (LSF). In the end, SSF fisheries have not only less data available than LSF, but their provided information is also consequently subject to more inconsistencies and inaccuracies. Therefore, a concerted effort will be needed to improve SSF data quality through coordinated, harmonized, and comparable data collection efforts across countries. Recommendations include enhancing data reporting requirements for smaller vessels, implementing supplementary technological solutions, and conducting cross-checks of census information with sampling data. Additionally, the development and use of geolocation devices and apps are recommended to enhance the accuracy and completeness of SSF fishing activity data collection.

Knowledge on the spatial and temporal distribution of the activities carried out in the marine environment is key to manage available space optimally. However, frequently, little or no information is available on the distribution of the largest users of the marine space, namely fishers. Tracking devices are being increasingly used to obtain highly resolved geospatial data of fishing activities, at intervals from seconds to minutes. However, to date no standardized method is used to process and analyse these data, making it difficult to replicate analysis. We develop a workflow to identify individual vessel trips and infer fishing activities from highly resolved geospatial data, which can be applied for large-scale fisheries, but also considers nuances encountered when working with small-scale fisheries. Recognizing the highly variable nature of activities conducted by different fleets, this workflow allows the user to choose a path that best aligns with the particularities in the fishery being analysed. A new method to identify anchoring sites for small-scale fisheries is also presented. The paper provides detailed code used in each step of the workflow both in R and Python language to widen the application of the workflow in the scientific and stakeholder communities and to encourage its improvement and refinement in the future.

We report the outcomes of a comprehensive study of the potential consequences of the implementation of the EU Maritime Spatial Planning Directive (MSPD) in Danish waters. The analyses are anchored in a framework developed in support of data-driven Ecosystem-Based Maritime Spatial Planning. The data for the models include not only human stressors but also information on the distribution of ecosystem components ranging from planktonic communities over benthic communities to fish, seabirds and marine mammals. We have established a baseline, based on state-of-the-art data sets, with respect to combined effects upon ecosystem components. Future scenarios for the developments in human stressors were estimated for 2030 and 2050 based on information on existing policies, strategies and plans and were compared to the baseline. In addition, we developed a scenario for implementation of the Marine Strategy Framework Directive (MSFD), i.e. working towards meeting the objectives of Good Environmental Status. Our results indicate that (1) combined human stressors will possibly increase in 2030 and 2050 compared to the baseline, (2) increased combined human stressors are likely to lead to a worsening of the environmental and ecological status sensu the Marine Strategy Framework Directive and the Water Framework Directive (WFD), and (3) the MSPD implementation process appears to conflict with the MSFD and WFD objectives. Accordingly, we are sceptical of claims of an untapped potential for Blue Growth in Danish marine waters.

Fisheries using bottom trawls are the most widespread source of anthropogenic physical disturbance to seafloor habitats. To mitigate such disturbances, the development of fisheries-, conservation-, and ecosystem-based management strategies requires the assessment of the impact of bottom trawling on the state of benthic biota. We explore a quantitative and mechanistic framework to assess trawling impact. Pressure and impact indicators that provide a continuous pressure-response curve are estimated at a spatial resolution of 1 x 1 min latitude and longitude (similar to 2km(2)) using three methods: L1 estimates the proportion of the community with a life span exceeding the time interval between trawling events; L2 estimates the decrease in median longevity in response to trawling; and population dynamic (PD) estimates the decrease in biomass in response to trawling and the recovery time. Although impact scores are correlated, PD has the best performance over a broad range of trawling intensities. Using the framework in a trawling impact assessment of ten metiers in the North Sea shows that muddy habitats are impacted the most and coarse habitats are impacted the least. Otter trawling for crustaceans has the highest impact, followed by otter trawling for demersal fish and beam trawling for flatfish and flyshooting. Beam trawling for brown shrimps, otter trawling for industrial fish, and dredging for molluscs have the lowest impact. Trawling is highly aggregated in core fishing grounds where the status of the seafloor is low but the catch per unit of effort (CPUE) per unit of impact is high, in contrast to peripheral grounds, where CPUE per unit of impact is low.

This study applied the Systems Approach Framework (SAF) to address the issue of declining Atlantic cod fishery in coastal areas. Interviews of 58 fishers from 26 harbours and meetings with national fisheries organisations and managers revealed the perception of an offshore movement of coastal cod. Numerical modelling based on fishing survey data did not substantiate these perceptions in the data-poor coastal waters. However, Data Storage Tag (DST) information combined with bottom sea water temperature data from the spatio-temporal hydrodynamic Baltic Sea Ice-Ocean Model showed changes in potential cod habitat distribution in the Skagerrak-Kattegat and western Baltic from 1979 to 2016. Subsequently, cod habitats were defined in three categories: (i) potentially suitable (T ≤ 12 °C); (ii) episodic (12 < T ≤ 16 °C); and (iii) unsuitable (T > 16 °C). The environmental changes were linked to the socio-economic component of cod fishery. Cod catches (weight and monetary value) were retrieved using logbook information and data from the Vessel Monitoring System (VMS, 2005–2016) and the Automatic Identification System (AIS, 2006-2016). General additive modelling significantly showed the largest proportion of catches took place in the potentially suitable habitat whereas catches were lower in the episodic habitat and rare in the unsuitable habitat. The results of this first large-scale SAF application are highly valuable for adapting existing fisheries management by: (i) providing information on habitat shrinkage for Maximum Sustainable Yield (MSY) based stock assessments; (ii) adding a spatio-temporal dimension for coastal productivity relative to the vessel-based Individual Transferable Quota (ITQ) system; and (iii) providing a predictive scenario simulation tool for sustainable management under changing environmental conditions.

The member states of the European Union use multi-metric macrobenthos indicators to monitor the ecological status of their marine waters in relation to the Water Framework and Marine Strategy Framework Directives. The indicators translate the general descriptors of ecological quality in the directives into a single value of ecological status by combining indices of species diversity, species sensitivity and density. Studies and inter-calibration exercises have shown that the indicators respond to chemical pollution and organic enrichment, but little is known about their response to bottom trawling. We use linear mixed effects models to analyze how bottom trawling intensity affects the indicators used in the Danish (Danish Quality Index, DKI) and Swedish (Benthic Quality Index, BQI) environmental monitoring programs in the Kattegat, the sea area between Sweden and Denmark. Using year and station as random variables and trawling intensity, habitat type, salinity and depth as fixed variables we find a significant negative relationship between the BQI indicator and bottom trawling, while the DKI is related significantly to salinity, but not to trawling intensity. Among the indicator components, the species diversity and sensitivity indices used in the DKI are not significantly linked to trawling, and trawling only affects the BQI when species sensitivities are derived from rarefied samples. Because the number of species recorded per sample (species density) is limited by the number of individuals per sample (density), we expect species density and density to be positively correlated. This correlation was confirmed by a simulation model and by statistical analysis of the bottom samples in which log species density was highly significantly related to log density (r = 0.75, df = 144, p < 0.001). Without accounting for the effect of density on species density, indicators based on species density will be affected by temporal and spatial variations in density linked e.g. to variable recruitment success. When this variation is accounted for by random year and station effects we find log trawling intensity to explain more of the variation in log density than in the indicators currently used to monitor Good Ecological and Environmental Status in the Kattegat. Disregarding random effects and the relationship between density and species density, the impacts of bottom trawling are likely to be lost in the translation of ecological quality into macrobenthos indicators.

Integrated ecological-economic fisheries models evaluation, review and challenges for implementation Nielsen, J. R., Thunberg, E., Holland, D. S., Schmidt, J. O., Fulton, E. A., Bastardie, F., Punt, A. E., Allen, I., Bartelings, H., Bertignac, M., Bethke, E., Bossier, S., Buckworth, R., Carpenter, G., Christensen, A., Christensen, V., Da Rocha, J. M., Deng, R., Dichmont, C. M., Döring, R., Esteban, A., Fernandes, J. A., Frost, H., García, D., Gasche, L., Gascuel, D., Gourguet, S., Groeneveld, R. A., Guillén, J., Guyader, O., Hamon, K., Hoff, A., Horbowy, J., Hutton, T., Lehuta, S., Little, L. R., Lleonart, J., Macher, C., Mackinson, S., Mahevas, S., Marchal, P., Mato-Amboage, R., Mapstone, B., Maynou, F., Merzéréaud, M., Palacz, A., Pascoe, S., Paulrud, A., Plaganyi, E., Prellezo, R., van Putten, E. I., Quaas, M. F., RavnJonsen, L., Sanchez, S., Simons, S., Thébaud, O., Tomczak, M. T., Ulrich, C., van Dijk, D., Vermard, Y., Voss, R. & Waldo, S. 2018 In : Fish and Fisheries. 19, 1, p. 1-29 Publication: Research peer-review › Journal article – Annual report year: 2018

Mapping trawling pressure on the benthic habitats is needed as background to support an ecosystem approach to fisheries management. The extent and intensity of bottom trawling on the European continental shelf (0–1000 m) was analysed from logbook statistics and vessel monitoring system data for 2010–2012 at a grid cell resolution of 1 × 1 min longitude and latitude. Trawling intensity profiles with seabed impact at the surface and subsurface level are presented for 14 management areas in the North-east Atlantic, Baltic Sea and Mediterranean Sea. The footprint of the management areas ranged between 53–99% and 6–94% for the depth zone from 0 to 200 m (Shallow) and from 201 to 1000 m (Deep), respectively. The footprint was estimated as the total area of all grid cells that were trawled fully or partially. Excluding the untrawled proportions reduced the footprint estimates to 28–85% and 2–77%. Largest footprints per unit landings were observed off Portugal and in the Mediterranean Sea. Mean trawling intensity ranged between 0.5 and 8.5 times per year, but was less in the Deep zone with a maximum intensity of 6.4. Highest intensities were recorded in the Skagerrak-Kattegat, Iberian Portuguese area, Tyrrhenian Sea and Adriatic Sea. Bottom trawling was highly aggregated. For the Shallow zone the seabed area where 90% of the effort occurred comprised between 17% and 63% (median 36%) of the management area. Footprints were high over a broad range of soft sediment habitats. Using the longevity distribution of the untrawled infaunal community, the seabed integrity was estimated as the proportion of the biomass of benthic taxa where the trawling interval at the subsurface level exceeds their life span. Seabed integrity was low (<0.1) in large parts of the European continental shelfs, although smaller pockets of seabed with higher integrity values occur. The methods developed here integrate official fishing effort statistics and industry-based gear information to provide high-resolution pressure maps and indicators, which greatly improve the basis for assessing and managing benthic pressure from bottom trawling. Further they provide quantitative estimates of trawling impact on a continuous scale by which managers can steer.