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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 between model estimates showed reasonable consistency overall, although discrepancies were noted owing to different model structures. Distribution maps produced during the workshop and the associated script are available at the ICES SharePoint. Participants identified priorities for future research to be tackled during a subsequent workshop: combine outputs of different models in a single distribution map, include fish length in models, investigate environmental covariates and their use for predictions, investigate models’ abilities to reproduce known distributions and further consider the impact of vessel/gear effects.

This book provides a tutorial on how to use Shape-Constrained Generalized Additive Models (SC-GAMs) to build Species Distribution Models under the ecological niche theory framework (GAM-NICHE model), based on the development by Citores et al. (2020) Ecological Modelling 418: 108926. https://doi.org/10.1016/j.ecolmodel.2019.108926). SC-GAMs impose monotonicity and concavity constraints in the linear predictor of the Generalized Additive Models and avoid overfitting. SC-GAM is an effective alternative to fitting nonsymmetric parametric response curves, while retaining the unimodality constraint, required by ecological niche theory, for direct variables and limiting factors.

The JRC presented a brief review of the current STECF system in place to provide advice on Mediterranean fisheries management and data collection issues. JRC highlighted some structural risks and inefficiencies that currently exist. The review explored some examples of integrated actions that could reduce or mitigate such risks. Such actions as part of a long-term strategy would lead to a proactive advisory process as opposed to the current more reactive sequence of individual steps considered by STECF. STECF notes this initiative from the JRC and aims to revisit the topic in time for development of the next management plan stage, post 2025. On 21 February 2023, the Commission adopted the Fisheries and Ocean package consisting of four documents: the Communication on the functioning of the CFP, the Action Plan “Protecting and restoring marine ecosystems for sustainable and resilient fisheries”, the Energy transition initiative and the report on the functioning of the Common Market Organisation (CMO). The package brings together all different aspects of the EU’s policy on fisheries and the Ocean, looking at the future, and at how we can ensure that fisheries continue to grow in resilience and sustainability. With this package, the European Commission plans on launching a policy discussion with all institutions and stakeholders the EU’s policy on fisheries and the Ocean European Commission Published Refereed

The European Commission tendered the study “Marine Biodiversity Modelling” [RTD/2021/MV/10] to pursue the identification and characterization of a subset of candidate biodiversity models that could contribute to the implementation of the European Digital Twin of the Ocean (EU DTO). The EU DTO will be an operational infrastructure for digital ocean services that aims to support decision-making capabilities by authorities to implement EU policies like the Marine Strategy Framework Directive (MSFD) but also by citizens and businesses operating at sea. Specific objectives of the project were: Conduct a horizon scan to identify and map available modelling approaches used to hindcast, nowcast Develop a comprehensive catalogue to classify available modelling approaches according to their characteristics Propose a subset of the most meaningful models among major model typologies. Assess whether these models can be used in the implementation of the Digital Twin Ocean and can improve the decision-making capacity under the MFSD.

The ICES Workshop on ICES reference points (WKREF1) was tasked to provide a thorough review of the ICES reference points system as a basis to re-evaluate the process for estimating, updating and communicating reference points in the context of the ICES advice. As part of the preparation leading to WKREF1 a large database of the most recent assessment outputs for 78 Category 1 stocks were collated in the form `FLStock` objects, which formed the basis for several components of the presented analyses.The first part of the meeting involved a detailed overview of the history and basis of the ICES references points system, which was aligned with the results of an empirical review of the procedures and choices made to derive ICES reference points for category 1 stocks. The ICES procedures were then contrasted with those used in the USA, Canada, New Zealand and across tuna Regional Fishery Management Organizations. A limitation in terms of transparency of the ICES procedures is a lack of complete documentation of the settings used for deriving reference points using, e.g., the EQSIM software. In comparison to other international standards, the main differences identified include the absence of a target biomass reference point and inconsistent estimates of the limit biomass reference point Blim, which is estimated to be below 10% of the unfished biomass (B0) for a high proportion of analysed stocks (around 50%). In addition, an important difference is that direct estimates of FMSY are used in ICES (which can be unreliable), whereas elsewhere FMSY is often replaced by more conservative biological proxies, such as Fspr% and FB%.The second part focused on the robustness evaluation of the current ICES reference point system. Work presented included examples that demonstrate differences in reference point estimates between standard ICES procedures (EQSIM) and full Management Strategy Evaluation (MSE) simulations, and a study that highlighted the considerable uncertainty in estimating Blim, with guidance on how to quantify uncertainty depending on length and contrast in the time-series. A large simulation experiment was conducted by applying a short-cut MSE approach to 68 Category 1 stocks, which revealed that the ICES MSY advice rule is the least robust of all tested generic approaches if assumptions about the typically highly uncertain stock recruitment relationship are violated. This led to poor performance of the ICES MSY advice rule associated with the lowest long-term yields, highest risks to fall below limit reference points and lowest probabilities of attaining biomass levels at MSY. Contributing factors to the poor performance were combinations of comparably high FMSY estimates and low Blim (trigger (lim > 10% B0), performance improved notably. Results from a backtest using hindcasting with forecasts of 1-5 years reinforced the need to re-estimate reference points regularly at benchmark assessments, and that short-term forecasts should not exceed a three-year time span to account for time-varying biological traits. Finally, presented work highlighted the advantages (in terms of high consistency and accuracy) of estimating the stock-recruitment relationship or reference points internally in the assessment model, which was illustrated for Stock Synthesis and SAM, and supported by a comprehensive simulation study.The key recommendations of WKREF1 were to: i) revise and simplify how Blim is derived. An absolute Blim should only be specified empirically in cases where there is sufficient contrast in the stock-recruit data to estimate a well-defined break-point. Alternatively, it is suggested that Blim should be determined as a plausible ratio of B0 based on biological principles and the life history of the stock (e.g. 10-25% B0 depending on the stocks characteristic; Section 7). ; ii) FP.05 should be calculated without Btrigger; iii) to use biological proxies (Fbrp) for deriving FMSY, and the resultant FMSY proxy must not exceed FP.05; iv) to report biomass target (Btrg) that corresponds to the FMSY proxy; and v) to set Btrigger as either a fraction of Btrg or multiplier of Blim. Specifications of setting reference points (e.g. Fbrp) or Btrigger should be informed through further simulation testing to be presented at WKREF2.

An ecosystem approach to fisheries management requires the consideration of commercial species as components of an ecosystem and the acknowledgement of the links between their productivity and the surrounding environment. To provide a knowledge base for such links, SEAwise consulted stakeholders throughout Europe and conducted a systematic review of the scientific literature.The systematic review resulted in 2050 articles from the literature search that were screened for their tile and abstract. 516 of them were retained for data extraction. The majority of studies were conducted in the Baltic Sea and the North Sea, followed by the Western Waters, and with only a few dozen papers in the Mediterranean Sea. Cod and herring were the most studied species, temperature and more generally climate and hydrodynamics indicators were the main drivers investigated, and reproduction was the main productivity-related process. The output of the systematic review is a database of scientific articles organised by regions, species, environmental drivers and productivity-associated processes and where outcomes, but also spatial and time scales, analytical methods etc. are described in a standardised fashion. This database will be analysed in the coming months and used in the downstream tasks of WP3.The most frequently driver identified by stakeholders across regions was climate change followed by species interactions, cod, pollution, commercial fish/shellfish and plankton. Climate change effects on stocks through temperature and salinity are relatively well covered in the literature as are effects of plankton and species interaction. Studies of the effects of pollution do not occur frequently and as a consequence require a dedicated effort is made in SEAwise to remedy this. Species reported frequently by the stakeholders included cod, seabass, sardine, sole, crabs, flatfish, Norway lobster, octopus, shrimps, herring, sprat, anchovy, hake, new species (species increasing in abundance as a result of climate change as well as invasive species of commercial interest) and sandeel. Among these, more than 10 papers were retrieved for cod, sardine, sole, herring, sprat, selected flatfish, anchovy, hake and sandeel. For the remaining species, a dedicated effort must be made in SEAwise if they are to be included in stock models.

This year the group changed its name to Working Group on Acoustic and Egg Surveys for small pelagic fish in NE Atlantic (WGACEGG). WGACEGG coordinates, assesses and quality controls acoustic and daily egg production (DEPM) surveys of several pelagic stocks in ICES areas 6-9. During three 2020 WGACEGG meetings, results of three DEPM surveys, three spring/summer acoustic surveys and all six autumn surveys were presented. Implications of the cancellation of three surveys (SAREVA and PELACUS (Spain)) and PELGAS (France) were also discussed, as were possible mitigations to minimize the effects on the relevant stock assessments. No concerns were raised about the surveys that took place. The results from the DEPM survey for sardine in 9a could not be provided until December, as COVID-19 had restricted laboratory access. WGACEGG also met with members of the Working Group on Southern Horse Mackerel, Anchovy, and Sardine (WGHANSA) to present the results from the 2020 Portuguese (PELAGO) acoustic survey in advance of the June assessment meeting. The working groups discussed the implications of PELAGO using a different vessel and of the earlier timing (compared to the timeseries) on the sardine and anchovy indices. The joint meeting also identified which surveys were at risk of being cancelled because of COVID-19 and discussed possible mitigations. Biomass estimates for both sardine and anchovy in division 9a were higher than observed in recent years as confirmed by both acoustic and DEPM surveys; DEPM derived Bay of Biscay anchovy spawning stock biomass was the highest on record although the number of recruits in the Bay of Biscay observed later in autumn did not reflect this increase. However, this was at least partly due to a northwards expansion into the English Channel where Bay of Biscay juveniles were found for the first time; sardine biomass in the Bay of Biscay from all available surveys suggested slightly lower values than the long-term average; in the English Channel sardine biomass was the second highest in the time-series; sprat biomass in the English Channel was similar to those observed in the last few years; herring biomass in the Celtic Sea had increased from 2019 but was still very low; Horse mackerel south and west of Ireland continued a three-year declining trend in biomass whereas boarfish biomass in the same area more than doubled. The group updated the grid map database and the joint analyses of the ecological drivers of pelagic species distributions within their ecosystems. Two ICES TIMES reports will be published soon; the acoustic report has been accepted and the DEPM report is currently under revision. WGACEGG participants also contributed to several peer reviewed publications in 2020 and more are under revision. WGACEGG and the Working Group on Acoustic Trawl Data Portal Governance (WGAcousticGov) agreed to continue the move towards using the ICES trawl acoustic database as the primary survey data repository. Progress on other collaborative activities was discussed, including with WGSPF (Small Pelagic Fish) and, specifically, a WGACEGG-led theme session for the 2022 SPF Symposium.

MSE testing of harvest control rules based on trends in biomass indices were analysed for generic anchovy-, sprat-, and sardine-like stocks, including several operating models. Consideration was given to coupling with different Uncertainty Cap (UC) levels and biomass safeguards, and the application of simple constant harvest rates.With regards to the coupling in time between assessment, advice, and management: results from WKDLSSLS1 were confirmed, indicating that the shorter the lag between observations, advice, and management, the bigger the catches and the smaller the risks, whereby in-year advice should always be preferred over the usual calendar (with an interim year) advice.Rules of type 1-over-2 outperform 2-over-3 (also called 1o2 and 2o3 respectively). When applied alone (without any Uncertainty cap or Biomass safeguard) for the sprat 7.de-like stock, it was shown that the 1o2 rule is capable or reducing risk faster than the 2o3 and reaching levels below 0.05 in the long term, while the latter does not. In addition, the simulations on anchovy and sardine-like stocks show that even after combining these rules with symmetric and asymmetric Uncertainty cap levels, rule 1o2 results in smaller risks for the same catch levels as the 2o3 rules, given a common Uncertainty cap level, which indicates that 1o2 outperforms 2o3 rules for these short-lived species.For all operating models, it was found that the 1o2 rule with symmetric UC(-0.8,0.8) implies faster reduction of risks than for any other tested UCs (particularly in the medium term), though at the expense of greater reductions of yield. For almost all Operating Models (OMs), the 1o2 rule with 20% cap was the least precautionary option. In general, inclusion of a biomass safeguard remarkably reduces risk in the medium and long terms by slightly reducing the relative yields for the stocks that have been historically over-exploited. A biomass safeguard based on Istat (geometricMean(Ihist)•e-1.645•sd(log(Ihist)) is proposed due to the greater robustness to the length of historical observations.Application of both an uncertainty cap and a biomass safeguard (Istat) to the 1o2 rule appears to perform better across all OMs and time-scales than either mechanism on its own. For short-lived stocks presumed to have been subject to an exploitation level before management at or above proxy FMSY levels the 1o2 rule with 80% symmetric uncertainty cap and with biomass safeguard (Istat) is the preferred option due to the faster reduction of risk levels in the first ten years (medium term). However, it should be noted that for stocks, which have likely been lightly exploited in the past, other rules may show a better balance between catches and risks. Hence, an earlier assessment of the past exploitation of the stock is very relevant to select the most suitable HCR for the management.Application of constant harvest rate rules can maintain constant risks, but are not able to move the stock towards precautionary levels when starting from high risk status, therefore, they require careful analysis of sustainable reference levels of harvest rates. Global comparisons suggest that when a careful tunning of a sustainable constant harvest rate is made by taking into account the stock life history and catchability and CV of the observation index, then such aconstant har-vest rate strategy will result in higher sustainable catches for the standard allowable levels of risks (0.05). However, if such a tuning is not achievable because of poor knowledge of the stock or of the observation properties, then the WK recommends for short-lived small pelagic fish stocks, the former trend rule 1o2 with a symmetric Uncertainty Cap constraint of 80% and with Biomass safeguard (Istat). However, due to the catch reduction properties it has, this trend rule should be considered a provisional HCR with the aim of achieving a better management system in about ten years or earlier. Longer application may lead to major losses of catches to the fishery in the long term.The work of WKDLSSLS is considered unfinished. Further research on the definition of optimal harvest control rules for data-limited short-lived stocks is ongoing. Therefore, the suggested either tuned constant harvest rate or the trend rule should be taken as an interim (provisional) proposal while guidelines are refined in 2021.

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. The Scientific, Technical and Economic Committee for Fisheries held its 64th plenary as a virtual meeting from 6 to 10 July 2020.

The Workshop on Data Limited Stocks of Short-Lived Species aimed to provide guidelines on the estimation of MSY proxy reference points for category 3–4 short-lived species and to evaluate the management procedures currently in use and their appropriateness for short-lived species by means of Long-Term Management Strategy Evaluations (LT-MSE).In relation to assessment methods for short-lived data-limited stocks and estimation of biological and MSY proxy reference points, the WK focused on the application of SPICT (Pedersen and Berg, 2017). The WK was updated on recent improvements of SPiCT and the harvest control rules (HCRs) used to manage stocks after WKLIFE VII and VIII by including either the MSYfractile or MSY-PA rules. For the optimal SPiCT advice rule, users should refer to the update ICES guidelines. Work on fitting SPICT to case studies was made before and during the workshop: Assessments to Anchovy in 9.a South resulted in a satisfactory fitting of SPICT, whilst fitsto Anchovy in 9.a West and to Sprat 7.de were still unsatisfactory. In addition, there were some presentations on applications of SPiCT to several Cephalopod populations. Length-based indicators of stock status were discarded as generally they are not suitable for short-lived species where recruitment induces major interannual changes in the length distribution of catches. Aprovisional application of a two-stage assessment was presented for Sprat in 7de, but results were still provisional.In relation to the evaluation of management procedures for these stocks, MSE testing of harvest control rules based on trends of biomass indices were analysed for anchovy-, sprat-, and sardinelike stocks including several operating models. All simulations showed that the shorter the lag between observations, advice and management, the bigger the catches and the smaller the risk.This implies that In-year advice should always be preferred over the normal calendar (with an interim) year advice for these stocks. Major drivers of risks are by order of relevance: historical exploitation level (and trajectory), and the harvest control rule (HCR) with its selected Uncertainty Cap (UCap). This emphasizes the relevance of trying an initial assessment of the relative status of the stock regarding optimal exploitation to judge if a precautionary buffer is required to start management. Further work on the assessment of past exploitation level is required.Regarding the trend-based harvest control rules (HCRs): In general, 1-over-2 outperforms 2- over-3 rule (ICES default rule) because for quite similar catches the former implies lower risks. For symmetrical application of the interannual uncertainty cap, best performance (least risks for minimum reduction of catches) occurs using the 1-over-2 rule with a symmetrical 80% uncertaintycap. The riskiest performance results were from applying a 20% uncertainty cap, both for 1-over-2 and 2-over-3, and the performance worsens with time. For asymmetrical Uncertainty Caps, tested for rules with a maximum interannual upward revision of 20%, results showed optimal performance when allowing reductions of 60% or greater percentages from the previousadvices for in-year advice, and of 70% or greater for normal (calendar) advice. While the 1-over-2 rule with asymmetric uncertainty cap is the most precautionary, it implies a continued large reduction of catches. The 1-over-2 rule with no uncertainty cap gives the highest catches at all times. Intermediate rules in terms of balance between catches and risks are: 1-over-2 (with symmetrical80%Ucap) and 1-over-2 with biomass safeguard (using either Imin, the minimum past observed abundance index, or Itrigger, 1.4*Imin). Rule 1-over-2 with symmetrical 80% Uncertainty cap might be preferred as a good compromise between moderate risks and catches though it can lead to major reduction of catches in the long term.Given the trade-off between competing rules, it seems that selection of a rule should better be made in consultancy with managers and stake holders according to their objectives for each fishery.Further research will be needed on the definition of proxies for BRPs and of the optimal harvest control rules (including the SPiCT advice rules) for the management of these SLDLS, covering further testing of biomass safeguards and of asymmetric uncertainty caps or the use of constant or variant harvest rate strategies instead of the trend-based rules.

The Workshop on the management strategy evaluation of the reference point, Fcap, for Sprat in Division 3.a and Subarea 4 (WKSpratMSE) was held in ICES headquarters in Copenhagen 11-12 December 2018, and continued to work by correspondence through February 2019. The aim of the workshop was to estimate an appropriate Fcap for sprat in Division 3.a and Subarea 4 (Skagerrak, Kattegat, and North Sea) and sprat in divisions 7.d and 7.e (English Channel). This was done in response to the outcomes of the Benchmark Workshop on Sprat (WKSPRAT 2018). Two external reviewers participated and reviewed the analytical work and conclusions of the workshop. See full participant list in Annex 1. Sprat in the English Channel (Divisions 7de) is a category 3 stock and is assessed based on the acoustic survey carried out in area 7.e. Previously, the “2-over-3” rule had been used to provide catch advice, but evaluations during the last WKSPRAT benchmark suggested that such rule is not appropriate for short, highly productive species. The workshop therefore compared through simulations the performances of a “1-over-2” rule (with and without an uncertainty cap) and of different fixed harvest rates. The simulations suggested that a 1-over-2 rule for short-lived highly productive species might cause the stock to fall below safe levels and eventually to collapse because the rule is not reactive enough to limit the catches when there is a recruitment failure. When removing the uncertainty cap, performances improve, but the risk still remains above safe limits. The use of a fixed harvest rate seems to prevent risk and maximize catch, depending on the proportion used. Simulations suggest that a 20% harvest rate is considered appropriate to maintain the stock at safe biomass levels and to produce relatively high yield. One external reviewer suggested that these rules continue to be explored at the relevant upcoming Workshop for Data-limited Short-lived Stocks (WKDLSSLS). Sprat in Skagerrak, Kattegat, and the North Sea (Division 3a, Subarea 4) is a category 1 stock and follows the ICES MSY approach where the advised yearly catches correspond to the estimated stock biomass in excess of the MSY Bescapement, but constrained so that the fishing mortality is no higher than a limit F (Fcap). A “full” closed loop management strategy evaluation (MSE) was carried out to test for a range of F’s and find an appropriate Fcap value that showed a less than 5% probability of SSB < Bescapement. The value of Fcap was conditioned on using Bpa as MSY Bescapement. A “short-cut” MSE featuring an assessment emulator was implemented to compare the two approaches. The stock and fleet dynamics were conditioned on the most recent assessment from WKSPRAT2018. Performance statistics between the “full” and “short-cut” MSEs were similar, suggesting that short-cut MSEs should continue to be explored, as they have the advantage of being unaffected by assessment numeric convergence. According to these analyses, Fcap of 0.69 is precautionary.

The benchmark workshop on sprat (WKSPRAT) was held in ICES headquarters in Copenhagen from 5–9 November 2018. The benchmark process started in June 2017 with a 3 day data compilation meeting, also held at ICES. Three stocks were benchmarked: North Sea sprat, 3.a sprat and the Channel sprat. During the benchmark process, several arguments were put forward on the connection between the North Sea stock and the 3.a stock in Kattegat-Skagerrak. It was therefore agreed to merge the two stocks and assess them as one stock assessment unit. Sprat in area 4 and 3a During the 2018 benchmark, enough evidence were presented to merge the sprat stocks in the Skagerrak-Kattegak and in the North Sea. The catch data and the indices of abundance from 3.a were included in the data from area 4. Three surveys are carried out in the area (IBTS in Q1 and Q3 and HERAS survey) and were all used as tuning indices in the model. The IBTS indices were standardized using a delta-GAM approach: the inclusion of 3.a data increased the internal consistency between all age classes for all indices. The SMS model, previously used to assess the North Sea component, was used to assess the new combined stock. The model year is resolved into 4 seasons, where season 1 corresponds to quarter 3 of the calender year. The term ‘season’ is hence used here to identify the model year, while the term ‘quarter’ refers to the calendar year. The final model formulation includes a power function for the age 0 catchability of IBTS Q1, a constant maturity ogive and the inclusion of the very few catches reported for season 4 (Q2) into season 1 (Q3) of the following year. The new stock assessment shows a considerable improvement in the retrospective pattern, as well a better fitting to some ages of the IBTS surveys and catches (as indicated by survey and catch CVs). The stock reference points were revised following ICES standard guidelines. Blim was estimated as the breakpoint of the segmented stock recruitment relationship and Bpa was derived from Blim. Short-term forecast settings were updated. The Management Strategy Evaluation (MSE) settings for the estimation of the Fcap were presented and discussed. Several scenarios were proposed to be tested and results will be evaluated during an ad-hoc MSE workshop that will take place on 11–12 December 2018. Sprat in area 7d,e Not enough evidences were available to change the boundaries of the English Channel stock. The stock is a category 3, and the data available are still scarce. An acoustic survey (PELTIC) is carried out in the English part of area 7.e since 2013. In 2017, the survey has been extended to include also the French part of 7.e and in 2018 the Eastern Channel was surveyed as well. Also, an IBTS index in Q1 is available for the Eastern Channel from 2007 onwards. The time series from the PELTIC survey has been used since 2017 to provide advice. At the benchmark, the updated time series was presented: the method used to produce the acoustic index was revised compared to previous years and it was changed to StoX (StoX, 2015). Concerns were raised because of the uncertainty in the stock distribution, and the fact that the acoustic survey covers only the Western part of the English Channel. No analytical assessment seems to work so far: both a seasonal and non-seasonal SPiCt were attempted during the benchmark workshop, but the short time series in the acoustic index and the lack of any contrast in the data still does not allow the model to converge. The group agreed to provide a seasonal advice based on an empirical method, i.e. to use both indices for trends, but only the acoustic survey for provision of advice. Two advice rules were proposed: the 1 over 2 rule, and a fixed F rule. Both options will be tested in an MSE framework and presented during the ad-hoc MSE workshop that will take place on 11–12 December 2018.

The a4a approach to Management Strategies Evaluation ( MSE ) is to develop a set of common methods and procedures to build a minimal standard MSE algorithm. This has the most common elements of both uncertainty and management options. Such a tool set should allow for the development of MSE simulations for many fisheries in an operational time frame. Between the 30th of January and the 3rd of February, in Ispra, Italy, the JRC organized a workshop on development of MSE algorithms with R/FLR/a4a. The workshop was a mix of hands-on coding and discussion/implementation of concepts associated with MSEs. The participants used the most recent version of the a4a MSE code, modularized the most important processes and developed their own version of several processes so that the MSE could model and test alternative management procedures to the one initially coded., JRC.D.2-Water and Marine Resources

To efficiently manage and maintain fish stock abundance and age structure, it is necessary to understand variability in its spatial distribution. The main objective of this study was to describe the demographic structure of the Bay of Biscay anchovy during the main spawning period based on adult samples from 15 daily egg production method surveys. The proportion of age-1 individuals was modelled using generalized additive models with a binomial distribution and a logit link in relation to geographical and environmental covariates. The possibility of obtaining different models depending on the average age-1 proportion (low or high) was also explored. In general, age-1 individuals were found in shallow waters close to the coast, especially associated with the Gironde and Adour river plumes, whereas older individuals were prevalent on the shelf break and in oceanic waters. However, in years with a high age-1 proportion the younger individuals were also dominant in oceanic waters. These results could be used for management purposes, such as defining protected areas for particular age groups. Con el fin de gestionar eficientemente la abundancia y la estructura espacial de un stock es necesario entender su distribución espacial. El objetivo principal de este trabajo es describir la estructura demográfica de la anchoa del golfo de Bizkaia durante el periodo de desove a partir de las muestras de adultos recogidas en 15 campañas del método de producción diaria de huevos. La proporción de individuos de edad 1 se modeló en función de variables geográficas y ambientales por medio de un modelo aditivo generalizado con distribución binomial y función enlace logit. Además se estudió la posibilidad de obtener diferentes modelos dependiendo de si la proporción de edad 1 promedio es baja o alta. En general, los individuos de edad 1 se encontraron en aguas poco profundas cerca de la costa, especialmente en las plumas de los ríos Garona y Adur, mientras que los individuos de mayor edad prevalecieron en el cantil y en aguas oceánicas. Sin embargo, los años con una alta proporción de edad 1, los individuos jóvenes fueron también predominantes en aguas oceánicas. Estos resultados podrían utilizarse para fines relacionados con la gestión, tales como la definición de áreas protegidas para determinados grupos de edad.