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The International Bottom Trawl Survey Working Group (IBTSWG) coordinate fishery-independent bottom trawl surveys in the ICES Area (Northeast Atlantic and North Sea) providing an important platform for the collection of additional data such as sampling larval sprat, stomach contents and fish parasites. These long-term monitoring surveys provide data for stock assessments and facilitate analyses of the distributions and relative abundance of fish. IBTSWG promotes the standardization of fishing gears and methods. This report summarizes national contributions in 2022–2023 and plans for the 2023–2024 surveys. In the North Sea, the surveys are performed in Quarter 1 and Q3. The Northeast Atlantic surveys are conducted mostly in Q1, Q3, and Q4 with a suite of 14 national surveys covering large areas of continental shelf extending from northern Scotland to the Gulf of Cádiz. The 2023-Q1 North Sea IBTS was impacted slightly by mechanical issues on one vessel, resulting in some of the Rectangles in the central North Sea being sampled with a single haul instead of the planned two. The 2022-Q3 North Sea IBTS was broadly complete, with the overall number of hauls comparable to previous years, though some Rectangles close to shore or with obstructions may not have had full coverage. The Northeast Atlantic surveys were mostly completed successfully, with the exception of the Scottish west coast groundfish survey in Q1 (cancelled due to vessel breakdown). There was incomplete survey coverage for some of the surveys, including the EVHOE survey (severe weather) and Portuguese groundfish survey (severe weather and mechanical problems). The Spanish surveys in the Gulf of Cádiz (cancelled in 2021) were undertaken in 2022. Recent updates to DATRAS, where the trawl survey data are stored, were summarised and data quality, including catch weights and species identification, was reviewed. IBTSWG met with members of various data users, including r

The Workshop on Raising Data using the RDBES and TAF (WKRDBES-Raise&TAF) met online (26–30 of September 2022) to evaluate the use of the Regional Database and Estimation System (RDBES) format to reproduce the 2022 InterCatch input and output, identifying a Transparent Assessment Framework (TAF) structure to organize the intermediate steps and to propose standardized output formats. The main outcomes of WKRDBES-Raise&TAF were: · RDBES provides sufficient support for current national estimation protocols. However, some minor issues were reported that hampered an exact reproduction of the estimates. Therefore, adaptations of the data model should not be excluded completely. · All the input to stock assessment that InterCatch currently provides, could be reproduced. The participants started from the current stock extracts that can be downloaded from InterCatch. · A workflow was proposed with a national TAF repository for each country, a stock estimation repository and a stock assessment repository. The intermediate output of those repositories will be stored in an ‘intermediate output database’ and depending on the user role, you will get access to the relevant stages in this workflow. · The following requirements for the standard output formats were defined: they cannot be more restrictive than the InterCatch input and output format; they should present measures of uncertainty and sample sizes (for national estimates) and should have a configurable domain definition (for national estimates). Despite those successful outcomes, the current plan for transition to an operational system was concluded to be too optimistic. WKRDBES-Raise&TAF therefore recommends to the Working Group on Governance of the Regional Database and Estimation System (WGRDBESGOV) to revise the roadmap and allow RDBES to be in a test phase also for 2023. WKRDBES-Raise&TAF felt the need to test the proposed workflow on a small scale and therefore recommends to the WGRDBESGOV to arrange a workshop where

Large-scale, climate-induced synchrony in the productivity of fish populations is becoming more pronounced in the world's oceans. As synchrony increases, a population's ‘portfolio’ of responses can be diminished, in turn reducing its resilience to strong perturbation. Here we argue that the costs and benefits of trait synchronization, such as the expression of growth rate, are context dependent. Contrary to prevailing views, synchrony among individuals could actually be beneficial for populations if growth synchrony increases during favourable conditions, and then declines under poor conditions when a broader portfolio of responses could be useful. Importantly, growth synchrony among individuals within populations has seldom been measured, despite well-documented evidence of synchrony across populations. Here, we used century-scale time series of annual otolith growth to test for changes in growth synchronization among individuals within multiple populations of a marine keystone species (Atlantic cod, Gadus morhua). On the basis of 74,662 annual growth increments recorded in 13,749 otoliths, we detected a rising conformity in long-term growth rates within five northeast Atlantic cod populations in response to both favorable growth conditions and a large-scale, multidecadal mode of climate variability similar to the East Atlantic Pattern. The within-population synchrony was distinct from the across-population synchrony commonly reported for large-scale environmental drivers. Climate-linked, among-individual growth synchrony was also identified in other Northeast Atlantic pelagic, deep-sea and bivalve species. We hypothesize that growth synchrony in good years and growth asynchrony in poorer years reflects adaptive trait optimisation and bet hedging, respectively, that could confer an unexpected, but pervasive and stabilizing, impact on marine population productivity in response to large-scale environmental change.

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examina-tion of changes in fish distribution and relative abundance. The group also promotes the stand-ardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG.

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent bottom trawl surveys in the ICES area in the Northeast Atlantic and the North Sea. These long-term monitoring surveys provide data for stock assessments and facilitate examination of changes in fish distribution and relative abundance. The group also promotes the standardization of fishing gears and methods as well as survey coordination. This report summarizes the national contributions in 2021–2022 and plans for the 2022–2023 surveys coordinated by IBTSWG. In the North Sea, the surveys are performed in quarters (Q) Q1 and Q3, while in the Northeast Atlantic the surveys are conducted in Q1, Q3, and Q4 with a suite of 14 national surveys covering a large area of continental shelf that extends from the north of Scotland to the Gulf of Cádiz. North Sea surveys in 2022-Q1 were affected severely by mechanical and COVID-related issues, as well as the number of storms experienced during the survey period. Some of the ICES rectangles in the survey area could not be sampled and a larger number of the rectangles were only sampled with a single tow. North Sea surveys in 2021-Q3 were broadly complete, with the wider area surveyed and comparable number of hauls. However, some rectangles close to shore or with obstructions may not have had full coverage. Most of the surveys in the Northeast Atlantic were completed successfully. However, the two Spanish groundfish surveys in the Gulf of Cádiz could not be undertaken in 2021. Vessel-related problems also affected the Spanish survey of the Cantabrian Sea, although this survey was completed using two vessels over a more protracted survey window. The IBTSWG welcomed the return of the Portuguese groundfish survey (Q4) after a two-year absence, with the survey being undertaken by the new research vessel, the “Mario Ruivo”. IBTSWG discussed the roadmap for the new survey trawl, following on from the Workshop o

The ICES Working Group on Mixed Fisheries Methodology (WGMIXFISH-METHODS) met to progress work on the improvement and development of the mixed fisheries advice. In this report the group provides a summary of the work completed in 2022. The work addressed included improving workflows for the advice process, presenting methodological advances, developing new ecoregions and responding to issues encountered during WGMIXFISH-ADVICE 2022. Additionally, plans for a second scoping workshop were discussed and the contribution of WGMIXFISH to mixed fisheries information in the Fisheries Overviews was reviewed. A key methodological advance used data on quota exchanges between countries to update the Min mixed fisheries scenario to address concerns over choking behaviour in fleets that generally do not entirely consume their initial quota allocation. This update is predicated on the assumption that when TAC changes become restrictive, the usual quota exchanges will become less likely. An Irish Sea model has been in development for several years and a mature version was presented. A formal review process has been initiated to evaluate this model with a timescale consistent with incorporating this ecoregion into the formal mixed fisheries advice process for 2022. To help improve the understanding of the main outputs from the mixed fisheries model a new design for the headline “advice” plot was approved at this meeting. This new design presents the results from each mixed fisheries scenario for a particular stock. This should enable stakeholders to draw easier comparisons between the different scenarios presented for their stock of interest. Future work ahead of next year’s meeting will focus on finalising the plans initiated at this meeting for a second scoping workshop and refining the contribution of WGMIXFISH to mixed fisheries information presented in the Fisheries Overviews.

The Workshop on stock identification of West of Scotland cod (WK6aCodID) convened to recommend the most plausible scenario of population structure for stock assessment and fishery management advice. The review considered geographic variation and movements of cod lifestages inferred from genetic analyses, scientific surveys, fishery data, tagging, and otolith microchemistry and shape. Based on the review, several population structure scenarios were hypothesized (including the scenario assumed in the current advisory unit), and the plausibility of each scenario was evaluated. Practical implications of the most plausible scenario, including the derivation of a catch time-series, were considered to form recommendations for benchmark stock assessment workshops. The workshop considered three hypotheses - hypothesis 1: closed homogenous population; hypothesis 2: a metapopulation with overlapping subpopulations (but not necessarily with areas within Division 6.a) (Clyde, Dogger inshore, Dogger offshore) and hypothesis 3: multiple overlapping subpopulations related to Dogger stocks (between Division 4.a and Division 6.a) and a separate subpopulation of Clyde. While hypothesis 3 provides the strongest scientific evidence, treating the Clyde as a separate population is problematic with respect to reconstructing historical catches and undertaking assessments. Over the last two decades of local management with the Clyde cod closure, incorporating minimal catches into subpopulations is unlikely to impact assessments at the present time. Given the current weak state of Clyde cod, hypotheses 2 and 3 would be practically indistinguishable in terms of assessment outcome and the workshop considers hypothesis 2 amenable to stock assessment in the short- to medium-term, while investigations continue into the assessment of the Clyde cod and the improvement of data availability. Given linkages of the inshore and offshore subpopulations to cod in Division 4.a, i

The ICES Working Group on Mixed Fisheries Advice (WGMIXFISH-ADVICE) met remotely to produce mixed fisheries forecasts for the Bay of Biscay, Celtic Sea, Iberian Waters and North Sea. Mixed fisheries advice highlights the potential implications of single-stock (total allowable catch and effort) management on the catches of multiple stocks caught together in mixed fisheries. It takes into account past fishing patterns and catchability of the different fleets, and the TAC advice produced by the single-stock advice groups, to provide quantitative forecast of over- and under-exploitation of the different stocks given mixed fishery interactions. The mixed fisheries forecasts were produced using the “FCube” (Fleet and Fishery Forecasts) methodology for the Celtic Sea, and on the “FLBEIA” (Fisheries Library Bio-Economic ImpaPrct Assessment) methodology for the Bay of Biscay, Iberian Waters and North Sea. The Bay of Biscay mixed fisheries projections consider the single-species advice of 14 demersal stocks (ank.27.78abd, hke.27.3a46-8abd, hom.27.2a4a5b6a7a-ce-k8, mac.27.nea, meg.27.7bk8abd, mon.27.78abd, nep.fu.2324, pol.27.89a, sdv.27.nea, sol.27.8ab, whb.27.1-91214 and whg.27.89a. Based on current fishing patterns and single-stock catch advice, the most limiting stock for Bay of Biscay demersal fisheries is pollack, whose quota is first reached for 15 of 22 defined fleets. The least limiting stock is black-bellied anglerfish (11 of 22 fleets). The Celtic Sea mixed fisheries projections consider the single-species advice for 12 demersal stocks (cod.27.7e–k, had.27.7b–k, whg.27.7bce–k, nep.fu.16, 17, 19, 20–21, 22, and outside FUs, sol.27.7fg, mon.27.78abd, and meg.27.7b k8abd). Based on mixed-fisheries considerations and single-stock catch advice, cod is the most limiting stock for Celtic Sea demersal fisheries. This is due to the zero-catch advice for cod and because almost all fisheries operating with demersal gears catch cod. The Iberian waters