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The project ”Improving knowledge base for management of cod stocks in the Baltic Sea and in the Kattegat” focused on the key challenges for assessment and management of the Eastern and Western Baltic cod and cod in the Kattegat. The project was funded by European Maritime and Fisheries Fund and the Danish Fisheries Agency. The activities in the project involved providing new biological knowledge, advancing methods, and conducting data analyses and modelling.For the eastern Baltic cod, a new method for estimating age and growth based on otolith microchemistry was validated, which can in future replace the traditional age readings that are known to be problematic for the stock. A new approach for determining cod fecundity was also developed. This improves information of cod reproductive potential as well as alternative spawning stock biomass estimates from egg production methods, also applied in this project. The work of the present project as well as earlier related projects was synthesized to contribute to ICES benchmark in 2019 where analytical stock assessment for the eastern Baltic cod was re-established. Furthermore, the project demonstrated that future possible recovery of the eastern Baltic cod depends on ecosystem drivers affecting stock productivity, and communicates new challenges for management associated with ecosystem changes and the complexity of factors affecting cod.For the western Baltic cod, the project investigated ways to deal with stock mixing in survey data, and provided a currently optimal solution to this that is used in ICES stock assessment today. The impact of assumed historical recreational catch values on stock assessment was also investigated. The results demonstrated that it is beneficial for assessment quality to include recreational catch information in the assessment even when good quality data are available only for a few latest years. Impact of uncertainties in different data inputs (amount and age structure of discards and recreational catch, mean weight and maturity, stock mixing) on stock assessment and advice was also explored, based on the example of western Baltic cod. These analyses increased our understanding of the relative impacts of possible inaccuracies in different data inputs and their annual updates on stock assessment and associated management advice.For cod in the Kattegat, the project provided new genetic information on mixing of North Sea and Kattegat stocks that improves our understanding of spatio-temporal variations in stock mixing. These data on stock mixing are utilized in developing a stock assessment model within this project, which is a modification of the present SAM model. The stock assessment model was modified to take into account inflow of juvenile cod from the North Sea and estimate their return migration when the fish become mature. This facilitates evaluating status of different stock components.The project additionally provided new knowledge on the impacts of supporting fisheries management measures such as spawning closures and regulations of fisheries selectivity. We concluded that if spawning closures are applied, these should cover most of the stock distribution area during most of the spawning season, to avoid possible counterproductive effects. For western Baltic cod, understanding of recruitment processes was enhanced, for example, the recent stronger 2016 year-class was found to be likely related to high abundance of favourable food for larvae. Spawning closures do not appear to be among the dominant factors affecting year-class strength in Western Baltic cod.The project also investigated fisheries selectivity effects on reduction in abundance of larger Eastern Baltic cod in later decades. The results showed that fisheries likely contributed to this development in some years, however other factors must be more influential as the larger individuals disappeared simultaneously from fisheries and survey catches.

Fremskrivning af menneskelige aktiviteter og presfaktorer er et notat beståen af tre trin, der iterativt fremskriver EU's havstrategiindikatorer frem mod 2030. Det betyder, at rapporten er opbygget over tre trin, som inkluderer kobling af menneskelige aktiviteter og presfaktorer, derefter fremskrivning af menneskelige aktiviteter frem mod 2030 og slutteligt en fremskrivning af indikatorer frem mod 2030. Fremskrivningerne i notatet er så vidt muligt en kort kvantitativ fremskrivning. Hvor det ikke er muligt at fremskrive kvantitativt, er fremskrivningen kvalitativ. Når det er muligt, inddrages betydningen af klimaforandringer. Miljøministeriet har ikke ønsket, at effekten af planlagte nationale og internationale indsatser til forbedring af havmiljøet er inddraget, da Miljøministeriet selv ønsker at stå for denne del. Hvis det alligevel ikke kan undgås at tage højde for visse indsatser, fx indsatser, som allerede er implementeret (men ikke har haft effekt endnu), skal dette noteres for hver deskriptor.

The Working Group on Multispecies Assessment Methods (WGSAM) aims at enabling research on predator-prey interactions for developing advice on the ecosystem approach to fisheries management.This report details results related to WGSAM term of reference B: “Update of key-runs (standardized model runs updated with recent data) of multispecies and ecosystem models for different ICES regions”. Multispecies model key-runs are used in ICES advice processes, and WGSAM provides critical expert review of these key-runs to recommend appropriate use of results.Although key-run reviews have been conducted in the past, requests for reviews are increasing. Therefore, WGSAM first formalized a consistent set of review criteria to conduct key-run reviews. These are outlined in section 2 of this report and are posted online (https://iceseg.github.io/wg_WGSAM/ReviewCriteria.html). WGSAM then applied these review criteria to one key-run for the North Sea ecosystem. The review is detailed in section 3 of this report. As the review criteria were applied, WGSAM also noted any difficulties with the review process in order to further refine the review criteria and to make future key-run reviews more efficient and effective.WGSAM recommends the use of natural mortality estimates from the North Sea SMS key-run for use in single species stock assessment models of North Sea cod, haddock, herring, Norway pout, southern North Sea sandeel, northern North Sea sandeel, sprat, and whiting.

The Working Group on Multispecies Assessment Methods (WGSAM) aims to advance the operational use of knowledge on predator-prey interactions for advice on fisheries and ecosystem management. This report summarises the achievements of a 3-year cycle during which the group consolidated criteria to evaluate key-runs and more in general the skills assessment of multispecies models, released key-runs for the Baltic Sea, North Sea and Irish Sea all evaluated with those criteria, progressed in the areas of multiple models comparison, ensemble modelling and on the estimation of biological reference points in the context of multispecies interactions. The updated keyruns for the North Sea and the Baltic Sea provided the best available estimates of predation mortality for a number of key commercial stocks in these two ecoregions which have been already integrated into the stock assessments throughout benchmarks and inter-benchmarks. Analyses accumulate showing that ignoring strong trophic interactions may lead to bias in the perception of stocks status and in the calculation of reference points. Evaluations show advantages of using multi-model ensembles to capture the dynamics of the main stocks and the system overall. Results accumulated so far suggest that the benefits of ensemble modelling exist for both simple models, i.e. multispecies production models, as well as more complex ecosystem models. Various approaches are available to the practice of ensemble modelling, including a fully Bayesian ensemble framework suitable also for multi-model forecasts. The report includes also progresses with software developments to enhance accessibility of some complex routines, including ensemble modelling beyond “just a simple average approach” and computation of multispecies reference points, to a broader group of modellers and users. The group sees these developments as a great opportunity to work more towards cross-platform comparisons and further on multispecies skill assessment which will remain important themes for continuation of the work. To further progress the use of multispecies and ecosystem models, collection of ecosystem data remains highly relevant, with priority on stomach data and other information on processes affecting trophic interactions and trophodynamics of ecosystems (i.e., predator-prey overlap, temperature-dependent consumption, availability of other food).

This report describes the main findings from the EMFF project “Bæredygtig forvaltning af Kattegat-torsk; bedre viden om bestandskomponenter og migration” (J. nr. 33113-B-16-034) which was initiated to improve our understanding of stock mixing and migration in Atlantic cod in the Kattegat in order to improve the data for stock assessment and management. The stock assessment of the Kattegat cod has recently been challenged due to a large “unallocated mortality”, i.e. a large fraction of fish that disappears from the area, but cannot be explained by mortality due to fishing or natural causes. It has been hypothesized that migration between the Kattegat and the North Sea could explain some of the unallocated mortality. The major scientific questions we aimed at answering in the project were:1. Do cod from the North Sea and Kattegat mix within the Kattegat stock assessment and management area? If they do, then2. During which time of their life do North Sea cod enter the Kattegat?3. Are there any spatial patterns of mixing and are there indications of different magnitudes of mixing for different age classes?4. Do cod migrate between the Kattegat and North Sea? The project had three main components: Genetic analyses to identify population of origin of fish, chemical analyses to identify individual fish migration histories and finally integration of results with stock assessment and the development of future procedures for data collection and stock assessment in Kattegat cod. We used a unique combination of methodology that allowed us to both identify the population of origin, and hence mixing of populations, with high spatial and temporal resolution, and the migration trajectories of individual fish. Genetic data revealed that North Sea and local Kattegat/transition zone cod indeed co-occur (mix) within the Kattegat, and that there is a gradient in mixing proportion from high proportion of North Sea cod in the northern parts of the Kattegat to lower proportions in the south. We also found variation between ages and sizes of fish with higher proportions of North Sea fish among the younger/smaller fish. Chemical signatures in the cod otoliths also suggested that North Sea and Kattegat early juvenile stages have different environmental, and thus geographic, origins, and that the North Sea fish enter the Kattegat as larvae or juveniles and leave at approximately age 4, presumably for spawning. Collectively, the results indicate that North Sea cod enter the Kattegat as early life stages and migrate back to the North Sea when they reach sexual maturity. Analyses of spawning fish confirmed that spawning activity in the southern Kattegat is dominated by fish of local origin. Results from our study have improved our understanding of the complex interaction of different biological populations with the Kattegat stock assessment and management area. The project has thus contributed directly to improving the basis for sustainable management of cod in the Kattegat, in particular through the identification of future data collection and stock assessment strategies that are able to take migration into account. The project results have been communicated to the scientific community, including the ICES advisory working group, as well as stakeholders from industry and management at several occasions in Denmark and abroad.

Project manager Jesper H. Andersen This report contains, as said in the title, the supplementary material to the synthesis report from the ECOMAR project (2018- 2020). The supplementary material consists of three parts: 1) Annex A, being the data sets and layers dealing with human pressures and activities, 2) Annex B, being the data set related to ecosystem components and analogue data sets, and 3) Annex C, being additional data used for the mapping of potentially cumulative effects in Danish marine waters as well as maps of results mentioned, but not show in the synthesis report. For each data set, a specific reference to the data authoring organization as well as contact information for the Data Author. THE VELUX FOUNDATIONS

The WKFlatNSCS benchmark was convened to evaluate the appropriateness of data and methods to determine stock status for four sole stocks; North Sea (Sol.27.4), eastern English Channel (Sol.27.7d), Bristol Channel, Celtic Sea (Sol.27.7fg) and southwest of Ireland (Sol.27.7h–k); and one turbot stock, Skagerrak and Kattegat (tur.27.3a).For sole in the North Sea a new index of stock abundance was derived, combining data from Belgium, Germany and The Netherlands (two survey series using different vessels). An updated category 1 assessment was agreed, continuing to use the Aarts and Poos model previously employed. Reference points were calculated using Eqsim and the forecast settings agreed.For sole in the eastern English Channel, the main objective of the benchmark was to resolve an issue with the plus group in the French landings and commercial landings per unit of effort data. The catch data were revised several times between the data evaluation workshop and the benchmark meeting, and at the benchmark meeting, it became clear that there were issues that could not be addressed at that time concerning:1. whether the methodology used to estimate ages for length classes where no samples for ageing had been taken was appropriate; and,2. whether the calculations of effort being used to raise the sampled discards was being calculated appropriately and consistently between the sampled fleet and the total fleet.As a result it was not possible to evaluate whether the catch-at-age data were appropriate for the assessment, or to evaluate the performance of an assessment. A further process following the benchmark meeting will be set up to complete this work.For Sole in Bristol Channel, Celtic Sea, maturity assumptions and average stock weights-at-age were revised. An updated category 1 assessment was developed, reducing the reliance on commercial tuning series, and moving to a statistical catch-at-age model (SAM). Reference points were calculated using Eqsim and the forecast settings agreed.For Sole in the southwest of Ireland, no appropriate method for evaluating the stock status and trends was found, due to the sampling only covering a small part of the total fishery, which is not considered to be representative of the whole area. The Workshop agreed to use category 5 to provide advice for this stock.For Turbot in Skagerrak and Kattegat, a synthesis of work on stock boundaries within Division 3a was presented, indicating that turbot in this area may be part of two stocks, the North Sea and Baltic Sea. A combined index from five surveys (BTS, BITS, IBTS and two Danish national surveys) was used as a tuning index for a SPiCT biomass dynamics model to determine stock status.The Workshop identified the need for future work:• to provide a basis for catch advice for sole in 7d this year;• to collect more sample data from 7h and to identify whether sole in 7h are connected to those in 7e or 7fg by genetics and movement for a future benchmark;• to investigate whether the management boundaries for turbot in 3a are appropriate based on current understanding of stock boundaries for a future benchmark.

Denne udredning beskriver situationen i den danske fiskeri-, akvakultur- og fiskeindustrisektor i et historisk perspektiv, hvor udviklingen over det seneste årti analyseres. Endvidere identificeres sektorens styrker, svagheder, muligheder og trusler. Udredningen udgør en del af det faglige grundlag for udarbejdelsen af det nye danske program for den Europæiske Hav- og Fiskerifond for 2021-2027. Der fokuseres på erhvervsmuligheder og rammevilkår for sektorerne, men også biologiske, miljømæssige, økonomiske, sociale og regionale aspekter inddrages (IFRO). Inden for programmets første prioritet vurderes det, at forvaltningen med individuelt omsættelige kvoter og fartøjskvoteandele har givet og fremover forventes at give et stabilt grundlag for dansk fiskeri, hvor fangstkapacitet og ressourcegrundlag er afstemt. Brexit og en mulig udelukkelse fra fiskeri i britisk farvand udgør sammen med den dårlige tilstand af torskebestandene i Østersøen de væsentligste udfordringer. Der er udfordringer i fiskeriet i forhold til landingsforpligtelsen, hvor alle fisk under mindste referencestørrelse af kvoterede arter skal landes og afskrives på kvoten. I relation til landingsforpligtelsen er der desuden betydelige udfordringer i forhold til problematikken med choke species, hvor fiskeriet skal ophøre, når den første kvote er opfisket, og fiskeriet efter denne art forventes at ”kvæle” (choke) fiskeriet efter andre arter. For kystfiskeriet fastlægger en ny politisk aftale rammerne indtil 2022. Implementering af landingsforpligtelsen fortsætter, såvel som fiskeriet fortsat påvirkes af den dårlige miljøtilstand i flere danske havområder (IFRO). Inden for programmets prioritet 2 muliggør stigende global efterspørgsel efter fisk en mulighed for vækst, og overgangen til en ny regulering baseret på udledning af næringsstoffer kan understøtte en positiv udvikling i akvakulturerhvervet. Tilførsel af ekstra kvælstof samt en teknologiudvikling med en højere grad af recirkulering og vandrensning giver vækstmuligheder i dambrug. Dette er dog ikke tilfældet i havbrug, hvor der er indført et stop for nye tilladelser. Der forventes fortsat vækst inden for skaldyrsopdræt til konsum. Der ses også muligheder i at anvende tang og muslinger som et marint virkemiddel til reduktion af næringsstoffer i det marine miljø. Udviklingsmuligheder inkluderer endvidere et fortsat fokus på recirkuleringsteknologi, økologisk opdræt og ASC-certificering. Endelig har både opdrætsfisk og vildtfangede fisk et lavt CO2-aftryk per kilo i sammenligning med okse- og svinekød, hvorfor certificering af fisk som klimavenlig kan forbedre afsætningsmuligheder og give prispræmier (IFRO). Fiskeindustri og -engroshandel opererer på et verdensmarked, hvor konkurrence med lavtlønslande har ført til udflytning. Dette er de senere år dog imødegået af automatisering, såvel som dansk fiskeengroshandel er i fremgang. Sektoren er afhængig af frihandel og vil påvirkes af begrænsninger i handlen, f.eks. handelskrigen mellem USA og Kina, Ruslandssanktioner og Brexit, men omvendt også af EU’s indgåelse af bilaterale handelsaftaler. Udviklingsmuligheder inkluderer et fortsat fokus på produkter af høj kvalitet og høj værdi, et fortsat fokus på certificering af bæredygtighed og miljø og forøgelse af råvaregrundlaget fra den voksende akvakultursektor i Asien (IFRO). Inden for programmets prioritet 3 ses det, at fiskeri og fiskeindustri er af størst betydning i Nord- og Vestjylland, havbrug er lokaliseret i de indre farvande og dambrug spredt ud over Jylland. I de fiskeriafhængige områder understøtter tilskudsordningen FLAG lokalt drevne tiltag mod etablering og udvikling af små virksomheder, erhvervssamarbejde, innovation og diversificering af den marine økonomi. Udviklingsmuligheder i områderne inkluderer blå økonomi og aktiviteter inden for de marine sektorer. Der er også udviklingsmuligheder inden for blå bioøkonomi med muslinge- og tangopdræt samt udnyttelse af invasive arter, stillehavsøsters, sortmundet kutling, søstjerner og strandkrabber (IFRO). Inden for programmets prioritet 4 er der fokus på en integreret havforvaltning. Hvor forvaltningen tidligere foregik separat for hver sektor, er der de senere år blevet arbejdet på at integrere forvaltningen. Udgangspunktet er havstrategidirektivet og udarbejdelsen af havplaner, hvor udvikling af de enkelte marine sektorer kan ske i et positivt samspil med de øvrige sektorer. Dette kræver både nye data og ny viden om havmiljøet (IFRO).

The Working Group on Widely Distributed Stocks (WGWIDE) reports on the status and considerations for management of Northeast-Atlantic mackerel, blue whiting, Western and North Sea horse mackerel, Northeast-Atlantic boarfish, Norwegian spring-spawning herring, striped red mullet (Subareas 6, 8 and Divisions 7.a-c, e-k and 9.a), and red gurnard (Subareas 3, 4, 5, 6, 7, and 8) stocks. Northeast-Atlantic (NEA) Mackerel. This species is widely distributed throughout the ICES area and currently supports one of the most valuable European fisheries. Mackerel is fished by a variety of fleets from many countries (ranging from open boats using handlines on the Iberian coasts to large freezer trawlers and Refrigerated Sea Water (RSW) vessels in the Northern Area). The assessment methodology was modified during the 2019 inter-benchmark process. The 2019 WGWIDE assessment was an update of the benchmarked assessment incorporating a new year for the catch information, for all surveys (egg survey, IESSNS survey and recruitment index) and for the RFID tagging recapture. After a strong increase from the late 2000s to 2014, the SSB has been declining since 2015, but remains at high levels (well above MSY Btrigger), The estimated fishing mortality has been steadily declining since the mid-2000s, and is now estimated to be close to FMSY. This decrease of the fishing mortality, while the stock has been sustaining high catches (consistently in excess to ICES advice) is explained by a succession of good recruitments, indicating a current high productivity for this stock. Blue Whiting. This pelagic gadoid is widely distributed in the eastern part of the North Atlantic. The assessment this year followed the Stock Annex based the conclusions from the Inter-Benchmark Protocol of Blue Whiting (IBPBLW 2016). The method for calculating mean weight at age for the preliminary (2019) was however changed, such that the observed values were used. Previously, a three year average was used. Most of the annual catches are taken in the first halfyear, which makes it possible to use preliminary catches for 2019 in the assessment. This is done to reduce the effect of potential biases from the single survey used for this assessment. The SSB of the stock is large but declining since 2018. F has been reduced in recent years, but is still above FMSY. Recruitments in 2017–2019 are estimated to be low, following a period of high recruitments. Western Horse Mackerel. This species is widely distributed throughout the Northeast Atlantic: it spawns in the Bay of Biscay, and in UK and Irish waters; after spawning, parts of the stock migrate northwards into the Norwegian Sea and the North Sea. The stock is assessed using the Stock Synthesis integrated assessment model. The 2019 assessment is an update of the benchmark assessment with the inclusion of the 2018 data. According to the assessment results, the 20154-2018 recruitment estimates are the highest observed since 2008 (and higher than the geometric mean estimated over the years 1983–2018). Fishing mortality since 2012 has been decreasing overall, dropping to low values in 2015–2018 due to lower catches and a reduced proportion of fraction of the adult population in the exploited stock; it is however currently above FMSY. SSB in 2017 was estimated as the lowest in the time-series, below the limit reference point and is just above in 2018. The updated assessment shows the same trend as the previous ones, but rescales the absolute level of SSB and F over the most recent decade and, although this years’ revision is smaller, this indicates that there is still considerable uncertainty associated with it. An interbenchmark workshop occurred prior to the 2019 assessment working group: the workshop revised the biomass reference points from 911587t to 1168272t for MSYBtrigger and 0.108 to 0.074 for FMSY, hence the significant drop in adviceNorth Sea Horse Mackerel. After being benchmarked in January 2017, the CGFS and NS-IBTS survey indices were modelled with a zero-inflated model to produce a combined index. The observed trend in the last decade suggests that the stock is still at a low level in comparison with values earlier in the time-series. In 2017, the survey index showed a declining trend, and the stock remained at a low level in 2018. The result of the Length-Based Methods to estimate proxy MSY reference points for North Sea Horse Mackerel indicated that in 2018 fishing mortality was slightly above FMSY. Northeast Atlantic Boarfish. This is a small, pelagic, planktivorous, shoaling species, found at depths of 0 to 600 m. The species is widely distributed from Norway to Senegal. The directed fishery for boarfish in the NEA is a relatively new one with large catches during the early 2000s when the fishery was unregulated. Catches have reduced significantly since 2012 to the current level. Annual catch advice is provided using the data limited category 3 approach based on output from an exploratory Bayesian surplus production assessment model. The assessment model utilises catch data, an acoustic survey estimate of stock size and indices from a number of bottom-trawl surveys. The current assessment indicates that biomass peaked in 2012 at twice the historic mean before a rapid decline until 2014. Since this time the biomass level has been relatively stable. Norwegian Spring Spawning Herring. This is one of the largest herring stocks in the world. It is highly migratory and distributed throughout large parts of the NE Atlantic. This stock was benchmarked in 2016 (WKPELA). The assessment model introduced in the benchmark (XSAM), incorporates uncertainty in the input data, and has been used to provide advice after the benchmark. The SSB on 1 January 2019 is estimated by XSAM to be above Bpa (3.184 million t). The stock is declining and there is an upward revision of SSB for later years in this year’s assessment. The revision is, however, within the confidence limits of the model. Fishing mortality in 2018 is estimated to be below the management plan F that was used to give advice for 2018. A new management plan was implemented for the 2019 advisory year. Striped Red Mullet in North Sea, Bay of Biscay, Southern Celtic Seas, Atlantic Iberian Waters. This stock has been considered by WGWIDE since 2016. It is a category 5 stock without information on abundance or exploitation in relation to proxy reference points and indicators, and the evaluation is based on commercial landings. A time series of biological sampling of catches is being developed, and it may be possible to produce an analytical assessment in the near future, The advice for this stock, following the ICES precautionary approach, was given in 2017 for 2018, 2019 and 2020. Northeast-Atlantic Red Gurnard. This stock was first considered by WGWIDE in 2016, and this represents the second time the group has advised upon it. This is a category 6 stock, with large uncertainties in landings data due to poor resolution at the species level. Landings have fluctuated without trend since 2006, and discards remain significant –over 90% of catch in some cases. There remains no indication of where fishing mortality is relative to proxies and no stock indicators, and the evaluation is based on commercial landings, given the caveat that they will be incomplete. Advice for this stock is provided on the basis of the ICES precautionary approach for 2020 and 2021.

This projected was originally applied for in 2016 under the program Fiskeri, natur og miljø EHFF. The project was granted from 01-04-2016 to 05-08-2018, and extended to 31-12-2018 (in an application from 14-12-2017).The scope of the project was to improve the biological advice on soles in Skagerrak, Kattegat, the Belts and Western Baltic. Sole is a small but very valuable fish important to fisheries. Therefore, the stock assessment on sole is important for the commercial fisheries. In the autumn of 2015, a benchmark for the sole stock in the Danish waters was carried out improving the precision of biomass estimates and estimates of fisheries pressure. Based on this revised assessment, it also became clear that knowledge on spawning areas and areas for juvenile sole is sparse and may introduce a potential error in the assessment. Furthermore, regional differences in growth rates and mortality are not well-known. In order to minimize these potential errors, this project was set up to include analyses of extended surveys, new initiatives to collaborate directly with the fishermen as well as include results of using new fishing gear technology. The intention was to improve not only stock assessment but also improve the basis for the fisheries management.The report presented in this document is a direct outcome of the project documenting the achieved goals. The results are to be included in the on-going ICES working group on sole (WGBFAS) and be used in the forthcoming benchmark process.

The Working Group on Multispecies Assessment Methods (WGSAM) works on the development of multispecies and ecosystem models that have potential or actual application for supporting advice on management of fish stocks and fisheries and assessing the implications of multispecies interactions. This report describes key-runs (standardized model runs updated with recent data) of multispecies and ecosystem models for the Baltic and Irish Sea. Model key-runs are used in ICES advice processes, and WGSAM provides critical expert review of these key-runs to recommend appropriate use of results. WGSAM first formalized a consistent set of review criteria to conduct key-run reviews (https://ices-eg.github.io/wg_WGSAM/ReviewCriteria.html), as these are increasingly requested. . WGSAM then applied these review criteria to three potential key-runs: two for the Baltic Sea ecosystem and one for the Irish Sea ecosystem. Any difficulties with the review process were noted to further refine the review criteria and to make future key-run reviews more efficient and effective.WGSAM notes that streamlining processes for updating data would facilitate future key-runs. From 2020, WGSAM will require draft key-run results and documentation 2–4 weeks before the meeting to allow more thorough review prior to the meeting. This will increase available meeting time for model comparisons, ensemble modelling, and coming to agreement on recommendations. For the Baltic Sea, multispecies model key-runs estimate predation mortality to provide timeseries of natural mortality (M) for use in single species stock assessments for herring and sprat. The review of key-runs from an SMS model (used in the previous 2012 key-run) and a newly developed Gadget model demonstrated that both models provided consistent time-series of M for herring and sprat when using the same assumptions regarding residual natural mortality, despite different representations of cod population dynamics. WGSAM recommends the use of natural mortality estimates from the Baltic SMS key-run for use in single species stock assessment models of Baltic herring and sprat. Due to issues of stability in the historical period the Gadget model was not selected as a key-run. WGSAM notes that the results of the SMS key-run depend on the outcome of the ICES Eastern Baltic cod assessment. Any bias in this assessment directly influences the predation mortality estimates. Uncertainty estimates for M from SMS should not be used as these assume that the cod population abundance is known without error. For the Irish Sea, an an Ecopath with Ecosim (EwE) model was reviewedto suggest methods by which some of the outputs could be used to provide an indicator to help inform the choice of Ftarget within the pre-defined Fmsy ranges. This allows for the incorporation of ecosystem information when setting Ftarget for individual stocks, while remaining within the existing precautionary fisheries management framework and reference point ranges used by ICES. An EwE model key-run was accepted as a basis for generating the indicator(s) but directly use of modelled Fmsy values in other models or for management was not recommended.

Sandeel in the North Sea is a priced commercial species and an ecological key species acting as prey for numerous predators from birds, through fish, to sea mammals. Sandeel is in particular important to the Danish fishery and fishmeal industry. However, large fluctuations in stock size and a complicated system of sub areas, where several have been deemed data poor by ICES, have been a challenge for the dependent industry. The main aim of the present project was to provide a scientific basis for making a re-evaluation of the models and management regime used by ICES to provide advice for sandeel in the North Sea. This required (i) reviewing the literature to identify holes in our basic knowledge, (ii) investigating transport of sandeel larvae between fishing grounds and differences in population dynamics and productivity to guide decisions regarding management areas, (iii) developing a new survey index from the existing sandeel dredge survey, and (iv) make an effort to improve existing stock assessment models where possible. Approximately half way through the project period, the ICES benchmark for sandeel took place. Here, all new results from the project was presented and used to facilitate a number of changes and improvements of the models and management regime.After the benchmark the project carried on to further underpin some of the decision made during the benchmark meeting. These included conducting otolith analyses and population genetics, revealing novel insight, and the factual area divisions decided at the benchmark meeting was specifically evaluated using larval drift simulations. Studies of environmental drivers of sandeel recruitment and productivity were also finalized during the second half of the project. The results revealed that the productivity of forage fish in the North Sea in general (sandeel included) has declined over time, explaining why the high fishing mortalities experienced during the 1990s cannot be maintained today. Correlative links were found between environmental variability and sandeel recruitment, suggesting that recruitment forecasting is potentially possible. This work has therefore been presented before the members of the ICES WKS2D working group. This group is now planning to test an operational forecasting model in the coming years. Lastly, the process of evaluating a range of management strategies was initiated to support the ongoing process of developing a long-term management plan. The MSE work is still ongoing and the continuousness of this work has been ensured by a new project initiated in 2017.

The ICES Workshop for management strategy evaluation for Norway Pout (WKNPOUT) took place 26–28 February 2018 at ICES Headquarter chaired by Andrés Uriarte, Spain, with the assistance of ICES Secretariat. 12 participants, both scientific experts and stakeholders, from Denmark and Norway, attended the meeting. The group addressed the special request from the European Union and Norway to advise on the long-term management strategies of Norway Pout in ICES Subarea 4 (North Sea) and ICES Division 3.a (Skagerrak-Kattegat). The proposed management strategy is based on the ICES escapement strategy with the aim of achieving a high probability of having the minimum SSB required to produce MSY (Blim) surviving to the following year. ICES was requested to evaluate: 1. Whether a management strategy is precautionary if the TAC is constrained with a lower bound in the range of 20 000 tonnes to 40 000 tonnes and an upper bound in the range of 150 000 tonnes to 250 000 tonnes, or another range suggested by ICES. 2. Whether such a strategy would be precautionary if the TAC constraints referred to in paragraph 1 are overridden by a constraint on the maximum value of fishing mortality (Fcap), and whether the application of the Fcap would allow a precautionary strategy with a higher minimum TAC than if the Fcap was not applied. 3. Whether a provision to override the minimum value of the TAC when the stock is forecast to be below some threshold value would allow a precautionary strategy with a higher minimum TAC than if the escape-clause was not included, and whether such a provision would provide any additional benefit to the inclusion of an Fcap as referred to in paragraph 2. The alternative management procedures were tested in the framework of a management strategy evaluation (MSE) set up according to the assessment model SESAM adopted for Norway pout in the 2016 benchmark. One thousand simulations (replicates) were projected over 20 years for each of the different harvest control rules. Each replicate begins in the 2018 TAC year which starts in quarter 4 of calendar year 2017. Each replicate randomly draws a true state of the system (starting population, age and quarterly fishing patterns and series of past recruitments) from the joint distribution estimated by the last stock assessment. This is taken as the approach best reflecting the uncertainties in the SESAM assessment. An alternative reducing the uncertainty in the initial stock numbers, recruitment and exploitation pattern at the median estimate from the last assessment was also tested. The simulations were conditioned by a maximum realized level of fishing mortality the fishery can exert (assumed at 0.89; Fhistorical), which means that the full TAC will not be taken if the required F exceeds this value. First the group tested whether the current ICES procedure for providing TAC advice for Norway Pout, based on an escapement strategy (the default method), was precautionary. Results showed that it is not precautionary (as tested with unconstrained levels of fishing mortality), because the probability of SSB falling below Blim is higher than 5%. This is probably linked to cases of very high TAC and F when very high recruitments occur, in association with observation errors in the assessment. This called for modifying the default escapement strategy either by setting an upper F (Fcap) or including conditions on TACmin/ TACmax as explored here. Concerning Request 1: The group tested HCR escapement strategies (as the default method) bounded by a combination of TACmin (at either 20, 30 or 40 kt) and TACmax (at 150 and 200 kt). Results show that these HCR were precautionary for TACmin at 20 kt for the two TACmax levels and for a TACmin at 30 kt when bounded by a TACmax of 150 kt. They gave median and mean TACs (around 100–130 kt depending upon the rule) and realized catches around 110–115 kt, with TACs set at TACmin or at TACmax around 20–24% and 36–46% of the cases respectively. In these cases, Fhistorical was reached in 9–16% of the years, which makes the results sensitive to the assumption that the fishery will not exceed catches requiring F above Fhistorical. Other combinations based on higher values of TACmin or TACmax led to unprecautionary outcomes. Concerning Request 2: The same combinations of TACmin and TACmax as for request 1 were explored with Fcap at either 0.3 or 0.4. Results showed that the inclusion of a Fcap increases the range of TACmin and TACmax combinations that are precautionary, reaching for Fcap up to a TACmin at 30 kt and a TACmax of 200 kt. On average, TACs become considerably lower when Fcap is applied (ranging between 72 and 97 kt depending upon the combinations) and realized catches did not exceed 92 kt. In general, TAC increases with increasing Fcap. The gain in average TAC by increasing TACmin or TACmax is minimal, but the TAC constraints affect the probability of falling below Blim. For these bounded rules, the probability of setting TAC at TACmin is very similar to the probability for HCRs without an Fcap, but the probability of reaching TACmax is considerably lower due to the application of the Fcap. The absolute changes in TAC between years are smaller with Fcap constraints as well, (in the order of 40 000 t) partly because of the lower TAC in general. Applying Fcap makes the HCR more robust to violations of the assumption of an Fhistorical, as the probability of reaching Fhistorical becomes significantly lower than for the HCR without an Fcap. The sensitivity of the performance of tested HCR to the alternative fittings of the stock recruitment relationship is minor, as shown for examples of rules with Fcap. Concerning request 3, due to time limitation and little interest from stakeholders to override the TACmin, the group did not fully cover this request, but an exercise was made to find out if the TACmin of 40 000 t might become precautionary under an alternative configuration of the escapement policy. An escapement strategy with a TACmin at 40 000 tonnes aiming at an escapement Biomass at 65 000 t instead of the current Blim (39 450 t) would become precautionary with combinations of Fcap in the range 0.3 to 0.4 and TACmax in the range 150 to 200 kt. TACmin would be set in around 48% of the years, which gives a median TAC slightly above TACmin. Mean TAC for the three HCR is in the same order of size as for Request 2. The Special request also asked ICES to evaluate whether the results of the MSE would be significantly changed if the TAC year were defined as 1 November to 31 October rather than a calendar year. The latter TAC year is applied to the EU Member States fishing in EU waters, while Norway uses the calendar year (January–December). Furthermore, ICES advice is produced based on a forecast from 1 October to 30 September, and ICES uses such forecast to advice management for the period 1 November- 31 October. The MSE adopted to answer the request follows the same practice. The WK has not compared the results of the MSE for the TAC year defined as 1 November to 31 October with those for a calendar year, as the latter would require a time shift in the assessment and forecast. The report includes some considerations on the current practice for advice and the TAC year.