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The ICES Working Group on Ecosystem Assessment of Western European Shelf Seas (WGEA-WESS) aims to provide high quality science in support to holistic, adaptive, evidence-based man-agement in the Celtic seas, Bay of Biscay and Iberian coast regions. The group works towards developing integrated ecosystem assessments for both the (i) Celtic Seas and (ii) Bay of Biscay and Iberian Coast which are summarized in the Ecosystem Overviews (EOs) advice products that were recently updated. Integrated Trend Analysis (ITA) were performed for multiple sub-ecoregions and used to develop an understanding of ecosystem responses to pressures at varying spatial scales. Ecosystem models (primarily Ecopath with Ecosim; EwE) were developed and identified for fisheries and spatial management advice. The updated Celtic Seas EO represents a large step forward for EOs, with the inclusion of novel sections on climate change, foodweb and productivity, the first application of the new guidelines for building the conceptual diagram, inclusion of socio-economic indicators, and progress made toward complying with the Transparent Assessment Framework (TAF). We highlight ongoing issues relevant to the development and communication of EO conceptual diagrams. A common methodology using dynamic factor analysis (DFA) was used to perform ITA in a comparable way for seven subregions. This was supported by the design and compilation of the first standardized cross-regional dataset. A comparison of the main trends evidenced among subregions over the period 1993–2020 was conducted and will be published soon. A list of available and developing EWE models for the region was also generated. Here, we re-port on the advances in temporal and spatial ecosystem modelling, such as their capacity to model the impacts of sector activities (e.g. renewables and fisheries) and quantify foodweb indi-cators. We also reflect on model quality assessment with the key run of the Irish sea EwE model. The group highlighted the hurdles and gaps in current models in support of EBM, such as the choice of a relevant functional, spatial, and temporal scales and the impacts of model structure on our capacity to draw comparisons from models of different regions. The group aims to ad-dress these issues in coming years and identify routes for ecosystem model derived information into ICES advice. info:eu-repo/semantics/publishedVersion

Switching from the traditional 40- or 44-mm diamond mesh codends to 50-mm diamond mesh (D50) or 40-mm square mesh (S40) codends is known to improve the size selection for commercial species and reduce discarding in the Mediterranean demersal trawl fisheries. This change has been recommended in the General Fisheries Commission for the Mediterranean and European Commission regulations. However, ecosystem-based assessment of improved selectivity still remains a challenge, and that is the aim of this study. For this purpose, an Ecopath model was developed and used to initialize dynamic simulations in Ecosim. The simulations changed gear-specific fishing mortality rates to represent the shifting from traditional codend to alternative codends. Our results suggest that the use of D50 or S40 codends would have a positive impact on the ecosystem as a whole and on the stock status of several commercial and non-commercial groups. Mixed trophic impact analysis indicated that, for species, like red mullet, the S40 codend was significantly better than the D50 codend. This information can be useful to policymakers, particularly for the areas where red mullet is the main target species and could inform trawl mesh options in the eastern Mediterranean.

This work was undertaken as part of the research project titled: ‘Modelling the food web in the Irish Sea in the context of a depleted commercial fish community’, funded via the Marine Institutes Cullen Fellowship and hosted by the Scottish Association for Marine Science. Over the past century the commercial fish and shellfish stocks in the Irish Sea have changed dramatically, altering the way in which we utilise and manage different aspects of the ecosystem. As elsewhere in the North Atlantic, many of the Irish Sea stocks have historically been subject to high levels of fishing mortality leading to reduced spawning stock biomasses (SSB) and truncated age structures. Despite large reductions in fishing effort since 2003 there has been only slow recovery whist some fish stocks, such as whiting, do not appear to have improved. This project aims to use multi-species models to underpin the mechanisms behind the slow recovery of commercial fish stocks in the Irish Sea. This project was designed under the remit of the first ICES Integrated Benchmark Assessment, WKIrish. WKIrish is a multi-year process focussing on improving single-species stock assessments (principally cod, haddock, whiting, plaice, herring), incorporating a mixed fisheries model, and developing the integration of ecosystem aspects and working towards an integrated assessment and advice. Two multi-species models (LeMans; Ecopath with Ecosim), developed simultaneously, will be used to inform the development of an integrated ecosystem assessment and advice. This report describes the development of an Ecopath model of the Irish Sea, allowing the interested reader to understand the methodology and data used to construct the model. Importantly, the report is intended to provide transparency to the model construction process and highlight the limitations of the data and thus the caveats attached to model outputs.

[Extract from Executive Summary] This work was conducted under Work package 4 of the European Fisheries Funded program “Evidence Gathering in Support of Sustainable Scottish Inshore Fisheries”. The overall aim of the program was to work in partnership with Marine Scotland Fisheries Policy and with the Scottish Inshore Fisheries Groups to help develop inshore fisheries management. Specifically the program aims were to establish the location of fishing activities within inshore areas; to identify catch composition and associated fishery impacts; to define the environmental footprint and availability of stocks; to develop economic value within local fisheries and; to establish an information resource base to assist the development of inshore fisheries management provisions.

1. Marine aquaculture relies on coastal habitats that will be affected by climate change. This review assesses current knowledge of the threats and opportunities of climate change for aquaculture in the UK and Ireland, focusing on the most commonly farmed species, blue mussels (Mytilus edulis) and Atlantic salmon (Salmo salar). 2. There is sparse evidence to indicate that climate change is affecting aquaculture in the UK and Ireland. Impacts to date have been difficult to discern from natural environmental variability, and the pace of technological development in aquaculture overshadows effects of climatic change. However, this review of broader aquaculture literature and the likely effects of climate change suggests that over the next century, climate change has the potential to directly impact the industry. 3. Impacts are related to the industry's dependence on the marine environment for suitable biophysical conditions. For instance, changes in the frequency and strength of storms pose a risk to infrastructure, such as salmon cages. Sea-level rise will shift shoreline morphology, reducing the areal extent of some habitats that are suitable for the industry. Changes in rainfall patterns will increase the turbidity and nutrient loading of rivers, potentially triggering harmful algal blooms and negatively affecting bivalve farming. In addition, ocean acidification may disrupt the early developmental stages of shellfish. 4. Some of the most damaging but least predictable effects of climate change relate to the emergence, translocation and virulence of diseases, parasites and pathogens, although parasites and diseases in finfish aquaculture may be controlled through intervention. The spread of nuisance and non-native species is also potentially damaging. 5. Rising temperatures may create the opportunity to rear warmer water species in theUKand Ireland. Market forces, rather than technical feasibility, are likely to determine whether existing farmed species are displaced by new ones.

agencies to maximise benefits from operational monitoring programmes (e.g. EuroGOOS, ECOOP GMES). As pressure upon national resources mount and growing awareness of environmental problems with a transboundary nature continues, for example at a catchment level in the Water Framework Directive and for a prospective European marine directive, the need for (international) collaborative regional initiatives have begun to be realised. As the first step towards establishing a wider regional initiative a European Marine Ecosystem Observatory (EMECO) has been established within the North Sea. To develop EMECO (www.cefas.co.uk/emeco) a bottom – up approach has been adopted based upon collaboration between agencies with statutory responsibilities for a range of environmental pressures from monitoring and assessment of nutrients and hazardous substances, wave monitoring to fish stock assessments. The monitoring programmes associated with such activities are by nature long-term and these programmes form key components of EMECO. However, there are a range of other programmes with either a relevant North Sea component (EU Ferry Box programme, International CPR programme, Smart-Buoy programme) or are part of wider initiatives (e.g. satellite remote sensing) that will also contribute to the observatory. It will also embrace initiatives to protect and conserve renewable and sustainable resources such as Marine Protected Areas and closed area for fisheries such as the Dutch Cod Box. The observatory will provide an opportunity to integrate research with monitoring and assessment programmes and to undertake reviews at a regional level to identify gaps in information and develop strategies to address shortcomings. Within the ecosystem approach, ICES is increasingly aware of the need to include ecosystem considerations in its fisheries assessment models in order to enhance their predictive properties. Moreover, ICES’ preparedness to carry out integrated assessments could be greatly enhanced by the scientific framework embedded in EMECO. This paper will describe the approach taken so far with EMECO, will explore the relationships and chances for collaboration with other initiatives (ECOOP GMES, EuroGOOS) and will examine how EMECO might contribute to ICES’ needs for environmental information in fisheries and ecosystem advice. Keywords: ecosystem observatory, monitoring, Ferry Box, Smart-Buoy, remote sensing

In 2004 an international consortium comprising England, Scotland, Netherlands, Germany, Denmark and Norway conducted an ichthyoplankton survey covering the whole of the North Sea in order to comprehensively survey cod and plaice spawning areas. At each station, ‘cod-like’ eggs were pre-sorted at sea from the plankton sample and preserved in ethanol for subsequent analysis using species-specific genetic probes. The remainder of the plankton sample was fixed in formalin and ichthyoplankton subsequently sorted and identified using traditional visual methods. The results showed stage I plaice spawning to be located in the traditional areas reported from the literature although with evidence of a more northward extension up the eastern edge of the Dogger Bank compared to data from the 1930s. The distribution of stage I cod eggs also conformed to historical patterns being most abundant around the southern and eastern edge of the Dogger Bank, in the German Bight, off the Moray Firth and to the east of the Shetland Isles. ‘Cod-like’ eggs were also found in southern Bight but this area was not as well sub-sampled for genetic analyses. Most of the ‘cod-like’ eggs on stations that were sub-sampled adequately in this region were shown to be whiting or other species. Data was also produced on the distribution of haddock eggs which were found over a wider region of the north-western North Sea than shown in historical maps. Whiting eggs were found south of the Dogger Bank and to the east of the Shetland Isles but were absent from the central North Sea. These results are discussed in relation to historical patterns of spawning and recent changes in the abundance of the North Sea plaice, cod and haddock stocks. Keywords: cod, plaice, spawning, ichthyoplankton, North Sea