Beschreibung: Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional structure of communities. Here, we developed a comprehensive framework based on complementary multivariate statistical methodologies to simultaneously investigate the effects of environmental conditions on the spatial, temporal and functional dynamics of species assemblages. The framework is tested using survey data collected during more than 4000 fisheries hauls over the Baltic Sea between 2001 and 2016. The approach revealed the Baltic fish community to be structured into three sub-assemblages along a strong and temporally stable salinity gradient decreasing from West to the East. Additionally, we highlight a mismatch between species and functional richness associated with a lower functional redundancy in the Baltic Proper compared with other sub-areas, suggesting an ecosystem more susceptible to external pressures. Based on a large dataset of community data analysed in an innovative and comprehensive way, we could disentangle the effects of environmental changes on the structure of biotic communities-key information for the management and conservation of ecosystems.

Beschreibung: Identification of essential fish habitats (EFH), such as spawning habitats, is important for nature conservation, sustainable fisheries management and marine spatial planning. Two sympatric flounder (Platichthys flesus) ecotypes are present in the Baltic Sea, pelagic and demersal spawning flounder, both displaying ecological and physiological adaptations to the low-salinity environment of this young inland sea. In this study we have addressed three main research questions: 1) What environmental conditions characterize the spatial distribution and abundance of adult flounder during the spawning season? 2) What are the main factors defining the habitats of the two flounder ecotypes during the spawning season? 3) Where are the potential spawning areas of flounder? We modelled catch per unit of effort (CPUE) of flounder from gillnet surveys conducted over the southern and central Baltic Sea in the spring of 2014 and 2015 using generalized additive models. A general model included all the stations fished during the survey while two other models, one for the demersal and one for the pelagic spawning flounder, included only the stations where each flounder ecotype should dominate. The general model captured distinct ecotype-specific signals as it identified dual salinity and water depth responses. The model for the demersal spawning flounder revealed a negative relation with the abundance of round goby (Neogobius melanostomus) and a positive relation with Secchi depth and cod abundance. Vegetation and substrate did not play an important role in the choice of habitat for the demersal ecotype. The model for the pelagic spawning flounder showed a negative relation with temperature and bottom current and a positive relation with salinity. Spatial predictions of potential spawning areas of flounder showed a decrease in habitat availability for the pelagic spawning flounder over the last 20 years in the central part of the Baltic Sea, which may explain part of the observed changes in populations' biomass. We conclude that spatiotemporal modelling of habitat availability can improve our understanding of fish stock dynamics and may provide necessary biological knowledge for the development of marine spatial plans.

Beschreibung: Aim: The interdependencies between trophic interactions, environmental factors and anthropogenic forcing determine how species distributions change over time. Large changes in species distributions have occurred as a result of climate change. The objective of this study was to analyse how the spatial distribution of cod and flounder has changed in the Baltic Sea during the past four decades characterized by large hydrological changes. Location: Baltic Sea. Taxon: Cod (Gadus morhua) and flounder (Platichthys flesus). Methods: Catch per unit of effort (CPUE) data for adult and juvenile cod and for adult flounder were modelled using Delta-Generalized additive models including environmental and geographical variables between 1979 and 2016. From the annual CPUE predictions for each species, yearly distribution maps and depth distribution curves were obtained. Mean depth and the depth range were estimated to provide an indication on preferred depth and habitat occupancy. Results: Adult and juvenile cod showed a contraction in their distribution in the southern areas of the Baltic Sea. Flounder, instead, showed an expansion in its distribution with an increase in abundance in the northern areas. The depth distributions showed a progressive shift of the mean depth of occurrence towards shallower waters for adult cod and flounder and towards deeper waters for juvenile cod, as well as a contraction of the species depth ranges, evident mainly from the late 1980s. Main conclusions: Our study illustrates large changes in the spatial distribution of cod and flounder in the Baltic Sea. The changes in depth distribution occurred from the late 1980s are probably due to a combination of expanded areas of hypoxia in deep waters and an increase in predation risk in shallow waters. The net effect of these changes is an increased spatial overlap between life stages and species, which may amplify cod cannibalism and the interaction strength between cod and flounder

Beschreibung: The ICES Workshop on ICES reference points (WKREF2) was tasked review the WKREF1 report and based on the outcome develop updated guidelines for the ICES reference points system and recommendations for ACOM consideration. The WKREF1 report has suggested 5 key recom- mendations to simplify and harmonise the ICES reference points framework representing a ma- jor change to the current guidelines. At WKREF2, we detailed discussions and four key concerns were raised about the proposed approach. The first related to the simplification of rules to define Blim. Around two thirds of category 1 stocks would end up as WKREF1 “Blim Type 2” where Blim would be set as a fraction of B0. The Allee effect or “depensation” maybe more important than previously thought and should be furthered explored for ICES stocks since it has important consequences for Blim. A number of challenges and issues around defining Blim using the current guidelines were documented. Some suggestions on improvement criteria were discussed including using classifiers to define spas- modic stocks and using change point algorithms to address non-stationary productivity regimes. However, further work is need to make these approaches operational and there was no consen- sus that the WKREF1 Blim types should replace the current guidelines. WKREF1 recommended that the FMSY proxy should be based on a biological proxies and should be less than the deterministic FMSY. It was pointed out that the stochastic FMSY estimated in EqSim for example, is lower than the deterministic FMSY and that the current guidelines ensure that the FMSY should not pose a more than 5% risk to Blim. A large amount of work described in WD 1 was carried out to develop an MSE framework to consistency and robustness test a candidate refer- ence point system for North East Atlantic stocks. However, WKREF2 recommended that further work needs to be carried out to condition and test the simulation framework before the conclu- sions could be adopted by ICES and incorporated into the guidelines. A number of considerations for defining MSY related reference points were discussed including using model validation and prediction skill to ensure that ICES provide robust and credible ad- vice. There is evidence that density dependence (DD) is important in the majority of ICES stocks (68% in recruitment and 54% in growth). The correct prediction of the shape and strength of density-dependence in productivity is key to predicting future stock development and providing the best possible long-term fisheries management advice. A suggested approach to use surplus production models (SPMs) to account for DD in FMSY was suggested and discussed but there was no consensus on whether that approach was appropriate. There was consensus that the FECO approach as a means of adapting target fishing mortality to medium-term changes in productiv- ity should be included in the guidelines subject to a benchmark and ACOM approval. While WKREF1 and 2 focused mainly on Category 1 stocks ToR c) called for a “simplified and harmonised set of guidelines for estimating MSY and precautionary reference points applicable in the advice framework across various ICES stock categories.” Ideally the ICES assessment cat- egories should provide equivalent risk across all stocks. This issue was discussed but no recom- mendations emerged. There was no consensus a revised reference point framework was proposed at WKREF2. How- ever, it was agreed that it should be presented here for further discussion at ACOM and other fora. The key feature of the suggested approach is that the stock status evaluation is treated in- dependent of the Advice Rule (AR). The main feature of the system is that the biomass trigger is not linked to a stock status evaluation, it is linked to the expected biomass when fishing at the target fishing mortality, in contrast to the current ICES approach. It also entailed that FMSY would also become an upper limit of fishing mortality and that the advised fishing mortality would be set at or lower than that level. WKREF2 did not discuss what to do in situations where SSB〈 Blim or alternative forms of HCR for the advice rule. Building community understanding and con- sensus around simplified and harmonised guidelines has yet to be achieved. A further workshop WKREF3 will be required to achieve that aim. The report includes 6 recommendations for ACOM consideration.

Beschreibung: ICES

Beschreibung: The main objective of the workshop was to review the recommendations of WKREF1 and con- sider how these might feed into a new reference points framework and guidelines for ICES. There were a number of presentations on the wider issues of best practice for reference points, the Allee effect, density dependence and the WKIRISH approach. The starting point was to try and develop a set of simplified and harmonised guidelines based on the WKREF1 report rather than evolving the current guidelines to include the WKREF1 conclusions. A key aspect of the meeting was to allow for discussions in order to build a shared understanding of the strengths and weakness of the current framework and of the new framework emerging from WKREF1.

Beschreibung: Published

Beschreibung: Non Refereed

Beschreibung: 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. Within a management strategy evaluation harvest control rules were tuned and robustness tested for the anchovy and sardine stocks in the Adriatic Sea. This investigation was done in support of GFCM and a continuation of the preliminary report (EWG 21-adhoc-02). For the sardine stock no meaningful MSE could be conducted. For the anchovy stock two HCRs were identified to be achieving the management targets and being robust

Beschreibung: European Commission

Beschreibung: Published

Beschreibung: Non Refereed

Beschreibung: 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. Within a management strategy evaluation harvest control rules were tuned and robustness tested for the anchovy and sardine stocks in the Adriatic Sea. This investigation was done in support of GFCM and a continuation of the preliminary report (EWG 21-adhoc-02). For the sardine stock no meaningful MSE could be conducted. For the anchovy stock two HCRs were identified to be achieving the management targets and being robust.

Beschreibung: European Commission

Beschreibung: Published

Beschreibung: Non Refereed

Beschreibung: 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. Within a management strategy evaluation harvest control rules were tuned and robustness tested for the anchovy and sardine stocks in the Adriatic Sea. This investigation was done in support of GFCM and a continuation of the preliminary report (EWG 21-adhoc-02). For the sardine stock no meaningful MSE could be conducted. For the anchovy stock two HCRs were identified to be achieving the management targets and being robust.

Beschreibung: Published

Beschreibung: Non Refereed

Beschreibung: 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 report documents the outcomes of STECF Expert Working Group 22-16: 2022 stock assessments of demersal stocks in the Adtiat ic, Ionian and Aegean Seas from the meeting held in Rome from 17th to 23th October 2022. A total of 16 fish stocks were considered and 15 were fully evaluated. The EWG reports age based assessments, target Fs, with short term forecasts for 9 stocks of the remaining 6 stocks, four of these do not have short term forecasts as he assessments are not suitable, and one is given ICES category 3 advice. The content of the report gives the STECF terms of reference; the basis of the evaluations; assessments, summaries of state of stock and advised catch or F based on either the MSY approach for assessed stocks and category 3 based advice for those without assessments. The report contains the full stock assessment reports for the 14 assessments, the exploration of assessments and category 3 evaluations for the remaining stock. The report also contains the STECF observations and conclusions on the assessment report. These conclusions come from the STECF Plenary meeting November 2022.

Beschreibung: European Union

Beschreibung: Published

Beschreibung: Refereed

Beschreibung: 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 report is from STECF Expert Working Group 21-15: 2021 stock assessments of demersal stocks in Adriatic, Ionian and Aegean Seas from the meeting held remotely from 18th to 22th October 2021. A total of 9 fish stocks were evaluated. One stock had prior advice from 2020 for 2021 and 2022, and this is reiterated here. Index advice for 2022 and 2023 is provide for one other stock. The EWG reports age based assessments and short term forecasts for 5 of the remaining 7 stocks and surplus production assessments for two stocks. The content of the report gives the STECF terms of reference, the basis of the evaluations and advice, summaries of state of stock and advised based on either the MSY approach for assessed stocks or the precautionary approach for category 3 based advice. The report contains the full stock assessment reports for the 7 assessments, the exploration of assessments and category 3 evaluations for the remaining five stocks. The report also contains the STECF observations and conclusions on the assessment report. These conclusions come from the STECF Plenary meeting November 2021.

Beschreibung: European Union

Beschreibung: Published

Beschreibung: Refereed

Beschreibung: 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 report documents the outcomes of STECF Expert Working Group 22-09: 2022 stock assessments of demersal stocks in the western Mediterranean Sea from the meeting held remotely from 5th to 11th September 2022. A total of 20 fish stocks considered and 18 were fully evaluated. Two stocks had prior advice from 2021 with catch advice for 2022 and 2023, and this is reiterated here. The EWG reports age based assessments, target Fs, with short term forecasts for 15 of the remaining 18 stocks, of these 15, 12 were also analysed for biomass reference points. Catch advice for three stocks was based on ICES category three evaluations of biomass indices. The content of the report gives the STECF terms of reference; the basis of the evaluations; assessments, reference point calculations; summaries of state of stock and advised catch or F based on either the MSY approach for assessed stocks and category 3 based advice for those without assessments. The report contains the full stock assessment reports for the 15 assessments, the exploration of assessments and category 3 evaluations for the remaining three stocks. The report also contains the STECF observations and conclusions on the assessment report. These conclusions come from the STECF Plenary meeting November 2022.

Beschreibung: European Union

Beschreibung: Published

Beschreibung: Refereed