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The objective of WKFISHDISH2 was to develop a standardized and open-source way of routinely using trawl survey data to produce distribution maps which can be easily updated. To do so, workshop participants (i) reviewed models that can produce distribution maps from survey data in DATRAS and MEDITS formats, (ii) considered best practice guidance for data, and models, (iii) implemented best practice to produce distribution maps in a transparent manner, and (iv) populated an ICES repository with distribution maps and associated scripts. Nine models were reviewed, seven of which were considered appropriate to produce distribution maps using survey data. The two models excluded failed to estimate gear standardization factors. Best practice for data should consider the following: correct/remove erroneous observations, account for changes in haul duration/timing affecting catchability, use species-specific modelled areas, remove gears/surveys with no observations to reduce model converging time, and include appropriate explanatory variables. A step-by-step list to preprocess survey data was provided. Best practice for models should consider the following: account for skewed distribution of survey data by exploring different statistical error distributions, use open-source models able to reproduce distributions from simulated data, consider the complexity of the model required vs. the run-time (e.g. number of knots), avoid extrapolating the model to areas/depths where the species is not observed, and perform relevant model diagnostics/model selection. To compare distribution estimated by different models, the SPAtial EFficiency metric (SPAEF) was used together with centres of gravity, biomass hot spots (90 th percentile), and effective occupied areas. All seven models were able to produce satisfactory distribution maps for at least one species within the workshop time constraints, both with DATRAS data in the Atlantic and the MEDITS data in the Mediterranean. Comparisons be

The recent establishment of the “landing obligation” under the reformed EU Common Fishery Policy has the twofold objective of reducing the excessive practice of discarding unwanted catch at sea and encouraging more selective and sustainable fisheries. Within this context, the awareness of the spatial distribution of potential unwanted catches is important for devising management measures aimed to decrease discards. This study analyzed the distribution of Hot Spot density areas of demersal fish and crustaceans below the Minimum Conservation Reference Size (MCRS) in four different southern European seas: continental Portuguese coast, Catalan Sea, South of Sicily, Liguria and northern Tyrrhenian Seas using both bottom trawl survey data and information on the spatial distribution of commercial fisheries. Critical areas for discarding were identified as zones where the highest densities of individuals below MCRS were consistently recorded throughout a series of years. Results clearly showed a patchy distribution of undersized individuals in each investigated area, highlighting the overlap between high density patches of both discards and fishing effort. The present findings provide a relevant knowledge for supporting the application of spatial-based management actions, such as the designation of Fisheries Restricted Areas (FRAs), in order to minimize the by-catch of undersized specimens and improve the sustainability of demersal fisheries

Reducing the impact on vulnerable species through changes in fishing practices, such as the spatial or temporal avoidance of certain areas, is key to increase the ecological sustainability of fisheries. However, it is often hampered by the availability of sufficiently detailed data and robust indicators. Existing trawl surveys are a cost-effective data source to assess the vulnerability of fishing areas based on the quantities of vulnerable species caught. We developed a biological traits-based approach to the vulnerability of demersal assemblages using commercial trawl catch data. An expert-based approach identified a set of biological traits that are expected to condition the species’ response to trawling impact and are combined to produce the vulnerability index ranked into four levels (low, moderate, high, and very high vulnerability). The approach was tested in four southern European fishing grounds showing evidence of over-exploitation, through catches being dominated by species of relatively low vulnerability to fishing impacts. The general distribution of species’ biomass amongst vulnerability groups was highly homogenous across case studies, despite local differences in fishing fleet structure, target species and fishing depths. Within all areas the species with moderate vulnerability dominated and, in most instances, species of “very high” vulnerability were not recorded. Nevertheless, differences emerged when comparing the proportions of highly vulnerable species in the catches. Variability in vulnerability level of the catch was also observed at small spatial scales, which was principally explained by differences in habitat type and depth and, secondarily, by fishing effort. In fine mud in the shallower areas there was a higher presence of low vulnerable fauna. Furthermore, vulnerable organisms decreased in their presence in sandier substrates on the continental shelf. The spatial heterogeneity in assemblage vulnerability composition encourages the poten

Reducing the impact on vulnerable species through changes in fishing practices, such as the spatial or temporal avoidance of certain areas, is key to increase the ecological sustainability of fisheries. However, it is often hampered by the availability of sufficiently detailed data and robust indicators. Existing trawl surveys are a cost-effective data source to assess the vulnerability of fishing areas based on the quantities of vulnerable species caught. We developed a biological traits-based approach to the vulnerability of demersal assemblages using commercial trawl catch data. An expert-based approach identified a set of biological traits that are expected to condition the species’ response to trawling impact and are combined to produce the vulnerability index ranked into four levels (low, moderate, high, and very high vulnerability). The approach was tested in four southern European fishing grounds showing evidence of over-exploitation, through catches being dominated by species of relatively low vulnerability to fishing impacts. The general distribution of species’ biomass amongst vulnerability groups was highly homogenous across case studies, despite local differences in fishing fleet structure, target species and fishing depths. Within all areas the species with moderate vulnerability dominated and, in most instances, species of “very high” vulnerability were not recorded. Nevertheless, differences emerged when comparing the proportions of highly vulnerable species in the catches. Variability in vulnerability level of the catch was also observed at small spatial scales, which was principally explained by differences in habitat type and depth and, secondarily, by fishing effort. In fine mud in the shallower areas there was a higher presence of low vulnerable fauna. Furthermore, vulnerable organisms decreased in their presence in sandier substrates on the continental shelf. The spatial heterogeneity in assemblage vulnerability composition encourages the poten

The state of marine systems subject to natural or anthropogenic impacts can be generally summarized by suites of ecological indicators carefully selected to avoid redundancy. Length-based indicators capture the status of fish community structure, fulfilling the Marine Strategy Framework Directive (MSFD) requirement for Descriptor 3 (status of commercial fish species). Although the MSFD recommends the development of regional indicators, a comparison among alternative length-based indicators is so far missing for the Mediterranean Sea. Using principal component analysis and dynamic factor analysis, we identified the most effective subset of length-based indicators, whether or not based on maximum length. Indicator trends and time series of fishing effort and environmental variables are also compared in order to highlight the individual and combined capability of indicators to track system changes across geographical sub-areas. Two indicators, typical length and mean maximum length, constitute the smallest set of non-redundant indicators, capturing together 87.45% of variability. Only in combination can these indicators disentangle changes in the fish community composition from modifications of size structure. Our study supports the inclusion of typical length among the regional MSFD Descriptor 3 indicators for the Mediterranean Sea. Finally, we show dissimilarity between the western and eastern-central Mediterranean, suggesting that there are sub-regional differences in stressors and community responses., Generalmente, el estado de los sistemas marinos sujetos a impactos naturales o antropogénicos puede ser resumido mediante un conjunto de indicadores ecológicos, cuidadosamente seleccionados para evitar la redundancia. Los indicadores basados en la talla reflejan el estado de la estructura de la comunidad de peces, cumpliendo el requisito de la Directiva Marco de la Estrategia Marina (MSFD) para el Descriptor 3 (estado de las especies de peces comerciales). Si bien MSFD recomienda el desarrollo de indicadores regionales, en el Mar Mediterráneo no se ha hecho hasta ahora una comparación entre los distintos indicadores disponibles basados en la talla. Mediante el análisis de componentes principales y el análisis de factores dinámicos, identificamos el subconjunto más eficaz de indicadores basados en la talla, estén o no basados en la talla máxima. Las tendencias de los indicadores y las series temporales del esfuerzo de pesca y las variables ambientales también son comparadas para resaltar la capacidad individual y combinada de los indicadores para detectar los cambios del sistema a través de las subáreas geográficas. Dos indicadores, Longitud Típica (TyL) y Longitud Máxima Media (MML), constituyen el conjunto más pequeño de indicadores no redundantes, captando juntos el 87.45% de variabilidad. Solo si se combinan, estos indicadores pueden discernir entre los cambios en la composición de la comunidad de peces y las modificaciones de la estructura de tallas. Nuestro estudio respalda la inclusión de TyL entre los indicadores regionales del descriptor 3 de MSFD para el mar Mediterráneo. Finalmente, mostramos diferencias entre el Mediterráneo occidental y el Mediterráneo centraloriental que sugieren diferencias subregionales en cuanto a factores impactantes y las respuestas de la comunidad.

The state of marine systems subject to natural or anthropogenic impacts can be generally summarized by suites of ecological indicators carefully selected to avoid redundancy. Length-based indicators capture the status of fish community structure, fulfilling the Marine Strategy Framework Directive (MSFD) requirement for Descriptor 3 (status of commercial fish species). Although the MSFD recommends the development of regional indicators, a comparison among alternative length-based indicators is so far missing for the Mediterranean Sea. Using principal component analysis and dynamic factor analysis, we identified the most effective subset of length-based indicators, whether or not based on maximum length. Indicator trends and time series of fishing effort and environmental variables are also compared in order to highlight the individual and combined capability of indicators to track system changes across geographical sub-areas. Two indicators, typical length and mean maximum length, constitute the smallest set of non-redundant indicators, capturing together 87.45% of variability. Only in combination can these indicators disentangle changes in the fish community composition from modifications of size structure. Our study supports the inclusion of typical length among the regional MSFD Descriptor 3 indicators for the Mediterranean Sea. Finally, we show dissimilarity between the western and eastern-central Mediterranean, suggesting that there are sub-regional differences in stressors and community responses., Generalmente, el estado de los sistemas marinos sujetos a impactos naturales o antropogénicos puede ser resumido mediante un conjunto de indicadores ecológicos, cuidadosamente seleccionados para evitar la redundancia. Los indicadores basados en la talla reflejan el estado de la estructura de la comunidad de peces, cumpliendo el requisito de la Directiva Marco de la Estrategia Marina (MSFD) para el Descriptor 3 (estado de las especies de peces comerciales). Si bien MSFD recomienda el desarrollo de indicadores regionales, en el Mar Mediterráneo no se ha hecho hasta ahora una comparación entre los distintos indicadores disponibles basados en la talla. Mediante el análisis de componentes principales y el análisis de factores dinámicos, identificamos el subconjunto más eficaz de indicadores basados en la talla, estén o no basados en la talla máxima. Las tendencias de los indicadores y las series temporales del esfuerzo de pesca y las variables ambientales también son comparadas para resaltar la capacidad individual y combinada de los indicadores para detectar los cambios del sistema a través de las subáreas geográficas. Dos indicadores, Longitud Típica (TyL) y Longitud Máxima Media (MML), constituyen el conjunto más pequeño de indicadores no redundantes, captando juntos el 87.45% de variabilidad. Solo si se combinan, estos indicadores pueden discernir entre los cambios en la composición de la comunidad de peces y las modificaciones de la estructura de tallas. Nuestro estudio respalda la inclusión de TyL entre los indicadores regionales del descriptor 3 de MSFD para el mar Mediterráneo. Finalmente, mostramos diferencias entre el Mediterráneo occidental y el Mediterráneo centraloriental que sugieren diferencias subregionales en cuanto a factores impactantes y las respuestas de la comunidad.

The state of marine systems subject to natural or anthropogenic impacts can be generally summarized by suites of ecological indicators carefully selected to avoid redundancy. Length-based indicators capture the status of fish community structure, fulfilling the Marine Strategy Framework Directive (MSFD) requirement for Descriptor 3 (status of commercial fish species). Although the MSFD recommends the development of regional indicators, a comparison among alternative length-based indicators is so far missing for the Mediterranean Sea. Using principal component analysis and dynamic factor analysis, we identified the most effective subset of length-based indicators, whether or not based on maximum length. Indicator trends and time series of fishing effort and environmental variables are also compared in order to highlight the individual and combined capability of indicators to track system changes across geographical sub-areas. Two indicators, typical length and mean maximum length, constitute the smallest set of non-redundant indicators, capturing together 87.45% of variability. Only in combination can these indicators disentangle changes in the fish community composition from modifications of size structure. Our study supports the inclusion of typical length among the regional MSFD Descriptor 3 indicators for the Mediterranean Sea. Finally, we show dissimilarity between the western and eastern-central Mediterranean, suggesting that there are sub-regional differences in stressors and community responses., Generalmente, el estado de los sistemas marinos sujetos a impactos naturales o antropogénicos puede ser resumido mediante un conjunto de indicadores ecológicos, cuidadosamente seleccionados para evitar la redundancia. Los indicadores basados en la talla reflejan el estado de la estructura de la comunidad de peces, cumpliendo el requisito de la Directiva Marco de la Estrategia Marina (MSFD) para el Descriptor 3 (estado de las especies de peces comerciales). Si bien MSFD recomienda el desarrollo de indicadores regionales, en el Mar Mediterráneo no se ha hecho hasta ahora una comparación entre los distintos indicadores disponibles basados en la talla. Mediante el análisis de componentes principales y el análisis de factores dinámicos, identificamos el subconjunto más eficaz de indicadores basados en la talla, estén o no basados en la talla máxima. Las tendencias de los indicadores y las series temporales del esfuerzo de pesca y las variables ambientales también son comparadas para resaltar la capacidad individual y combinada de los indicadores para detectar los cambios del sistema a través de las subáreas geográficas. Dos indicadores, Longitud Típica (TyL) y Longitud Máxima Media (MML), constituyen el conjunto más pequeño de indicadores no redundantes, captando juntos el 87.45% de variabilidad. Solo si se combinan, estos indicadores pueden discernir entre los cambios en la composición de la comunidad de peces y las modificaciones de la estructura de tallas. Nuestro estudio respalda la inclusión de TyL entre los indicadores regionales del descriptor 3 de MSFD para el mar Mediterráneo. Finalmente, mostramos diferencias entre el Mediterráneo occidental y el Mediterráneo centraloriental que sugieren diferencias subregionales en cuanto a factores impactantes y las respuestas de la comunidad.

Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. This reportis from STECF Expert Working Group19-10: 2019stock assessments ofdemersal stocks in the western Mediterranean Seafrom the meeting in Arona Italy from 9thto 15rdSeptember 2019. A total of 19 fish stocks were evaluated. The EWG reports age based assessments and short term forecasts for 15 of the 19 stocks. Catch advice for the other four stocks was based on ICES category 3 evaluations of biomass indices. The content of the report gives the STECF terms of reference, the basis of the evaluationsand advice, summaries of state of stock and advised based on either the MSY approach for assessed stocks or the precautionary approachfor category 3 based advice. Thereport contains the full stock assessment reports for the 15 assessments, one full category3 evaluation and briefre-evaluations and validations of the 2018 results for the final three stocks for which two year’sadvice was given in 2018.The report also contains the STECF observations and conclusions on the assessment report. These conclusionscome from the STECF Plenary meeting November 2019