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183 pages, figures, 6 annexes, The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2021 together with time series covering all survey years, problems encountered, data quality checks and technological improvements as well as the planning for survey activities for 2022. In total, 19 surveys covering 25 functional units (FU’s) in the ICES area and 1 geographical sub- area (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis standardization and the use of recent technologies were reviewed. Due to the COVID-19 pandemic there were minimal disruptions to survey operations where one survey was not completed (GSA 17). A trial trawl Nephrops survey offshore Portugal was carried out on the new research vessel. Preliminary work on how to measure burrow system size was presented using high definition (HD) and standard definition (SD) image data. Further work on comparison of SD and HD indi- cates the change to HD system mounted with a different camera angle was not significantly different for two survey areas (FU 16 and FU 20-21). Automatic burrow detection based on deep learning methods continues to show promising re- sults where datasets from multiple institutes were used. The working group members have agreed to draft a roadmap for automatic system technology requirements with links to the Work- ing Group on Machine Learning in Marine Science (WGMLEARN) and current researchers. The working group is progressing plans for an international Nephrops Underwater television (UWTW) database to be established at the ICES Data Centre. End-users of UWTV datasets for epifauna reporting presented their work and showed the potential for adding value to the survey data, where many of the institutes are involved in providing data for similar research purposes

The Working Group on Improving use of Survey Data for Assessment and Advice (WGISDAA) provides a forum where survey practitioners, statisticians and stock assessment scientists can share expertise and knowledge to advance the science of fisheries surveys. The working group serves to bring together data collection and data users in a supportive and cooperative environment and to improve communication and coordination across survey groups in the ICES network. The working group developed a strategy for making decisions on survey design and implementation that maximises the benefits of long-term survey data and minimises the impacts of enforced changes to survey design and implementation. WGISDAA concluded that the increasing use of model-based indices is beneficial in dealing with change in data collection but requires an approach that integrates across data collection and data use to control overall uncertainty in indices. This is especially important in cases where multiple objectives are addressed by a single survey but also across different surveys. Existing practices for decision making are now documented and gaps in the strategy identified. Further workshops are being planned to develop the tools that quantify the trade-offs between different objectives and establish useful estimates of uncertainty for different survey designs / data collections.WGISDAA assisted The Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS), The International Bottom Trawl Survey Working Group (IBTSWG), The Working Group on Beam Trawl Surveys (WGBEAM) and The Working Group on Surveys on Ichthyoplankton in the North Sea and adjacent Seas (WGSINS) with survey design questions, most notable was the cooperation with WGMEGS on developing an improved spatial interpolation for the egg abundance data given the considerable changes in the in spawning distribution and the associated consequences to data consistency due to organisational difficulties in providing adequate survey coverage. A spatio-temporal annual generalized additive model (GAM) of egg distribution was developed which allowed for much more appropriate interpolation between samples and indicated that the total egg production and hence the standing stock biomass (SSB) was likely to be considerably smaller than previously thought. However, the temporal trend in production which matters most to the stock assessment was largely unaffected by the improved model except for the 2013 data point. Sensitivity analysis of the egg production calculation suggests that other factors in the index particularly temporal changes in fecundity or changes in catchability in the trawl survey are more likely causes of the current stock assessment difficulties. The group worked with stock assessors for North Sea cod, West of Scotland whiting and Celtic Sea gadoids. As for the mackerel assessment, cooperation was essential for resolving disparities in the information provided by different data sources. The group helped develop more appropriate combined indices that took account of changes in spatial distribution of the stock and the survey effort. For North Sea cod however, this still proved to be a poor explanation of the underlying dynamics and further investigation suggested that there has been increased mixing with an adjacent population of cod particularly at the older ages. A more appropriate method to deal with this failure of the closed population assumption is being developed.

The workshop on the production of swept-area estimates for all hauls in DATRAS for biodiver-sity assessments (WKSAE-DATRAS) considered three groups of surveys for which data are sub-mitted to the Database of Trawl Surveys (DATRAS): various Beam Trawl Surveys, the Northeast Atlantic International Bottom Trawl Survey (Northeast Atlantic IBTS), and the North Sea Inter-national Bottom Trawl Survey (North Sea IBTS). All countries contributing to the above-mentioned surveys were represented by at least one par-ticipant during the workshop, apart from the Netherlands and Norway. The main objectives of the workshop were to establish tow-by-tow swept-area estimates for time-series as far back in time as possible, compare different approaches for the estimates of missing observations, and harmonize the resulting dataseries for biodiversity assessments. For all of the surveys considered, problems with data quality were detected. This included the Beam Trawl Surveys but was most pronounced for the North Sea IBTS. Outliers and potential erroneous data were listed for reporting back to the respective national institutes. In particular, missing observations or algorithms affected wing spread-based swept-area, which is needed in several applications. This workshop compared the Marine Scotland Science-MSS/OSPAR approach, which includes a data quality check for the information needed for the calculation of swept-area, and the DATRAS approach, which depends solely on correctly reported data from the national institutes. Larger data gaps were identified, in particular for several years of the North Sea IBTS. For those surveys, it is proposed that the best possible way forward at this moment is to use estimates based on the MSS/OSPAR approach. However, if dubious records (i.e. extreme outliers) were identified by the MSS/OSPAR and no other information was available, values (e.g. speed over ground or the depth at which a change from short to long sweeps should have happened) were taken from the manual. However, expe-rience has shown that the survey manuals are not followed in all instances, and so persistent country-specific and survey-specific deviations may occur. The national institutes are encouraged to check, correct, and fill in missing survey data through re-submissions to DATRAS. It is recommended that DATRAS data quality control on data sub-mission is extended for the information needed for the calculation of swept-area (e.g. distance, depth, door spread, and wing spread) and that this is done in close cooperation between the ICES Data Centre and the respective ICES survey working groups, WGBEAM (Working Group on Beam Trawl Surveys) and IBTSWG (International Bottom Trawl Survey Working Group). info:eu-repo/semantics/publishedVersion

The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2020 together with time series covering all survey years, problems encountered, data quality checks and technological improvements as well as the planning for survey activities for 2021.In total, 19 surveys covering 25 functional units (FU’s) in the ICES area and 1 geographical subarea (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis standardization and the use of most recent technology were reviewed. Due to the COVID-19 pandemic there were disruptions across several functional units to: survey operations (FU 30, GSA 17, FU 10, FU 13 – Jura, FU 34, FU 28-29); data processing (FU 23-24) and survey coverage (FU 9).Further results from field studies on behaviour aspects of burrow emergence using bottom cages monitored by an automated camera system and on short-range migration using acoustic tracking and remote operated vehicle (ROV) surveys in marine protected areas have become available and are summarised in this report.Geostatistical investigations to reduce uncertainty estimates showed comparable results to historical trends for one survey area in the North Sea. Other preliminary work to redefine survey area using best available datasets was also discussed. Reference sets compilation and count evaluations using still image annotations and Lin’s concordance correlation coefficient (CCC) quality control were presented. Automatic burrow detection based on deep learning methods applied to a test dataset with annotated burrow counts from a HD camera system from two projects showed promising results. The working group members were encouraged to provide more material with annotated burrow counts for further development of machine learning tools.An underwater television (UWTV) survey manual has been accepted for publication in the ICES Techniques in Marine Environmental Sciences (TIMES) series. The working group is currently developing plans for a Nephrops UWTW database to be established at the ICES data centre.

114 pages, figures, tables, 5 annexes, The Working Group on NephropsSurveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the na-tional contributions on the results of the surveys conducted in 2020 together with time series covering all survey years, problems encountered, data quality checks and technological improve-ments as well as the planning for survey activities for 2021. [...]

The International Bottom Trawl Survey Working Group (IBTSWG) coordinates fishery-independent multispecies bottom-trawl surveys within the ICES area. These long-term monitoring surveys provide data for stock assessments and facilitate examination of changes in fish distribution and abundance. The group also promotes the standardization of fishing gears and methods and survey coordination. This report summarizes the national contributions in 2020–2021 and plans for the 2021–2022 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 ranges from North of Scotland to the Gulf of Cádiz. Despite the COVID-measures and bad weather, most surveys were able to complete the majority of the planned hauls. The Portuguese survey (PT-GFS-Q4) was cancelled in 2020 due to issues associated with the new vessel and a COVID-outbreak. A COVID-related delay in submitting the cruise application form for the French CGFS20 survey resulted in no authorisation to trawl in UK waters and only 70% of the core stations were completed. Issues with the UK permits, were also experienced in the North Sea surveys, only being resolved at the last moment, expected to be a returning issue. Therefore, IBTSWG addressed the permit issue in further detail in order to better evaluate the impact and propose possible solutions.All surveys, except for the Spanish GCGF-Q1 21 which is cancelled due to a vessel refit, are planned to take place according to the manuals in the next year.The SCOROC Q3 20 survey recorded second highest recruitment of zero group haddock on the Rockall Bank since the start of the new survey series in 2011. The North Sea Q1 21 survey recorded good recruitment of haddock as well, and high recruitment of mackerel, while overall herring recruitment seemed low except for three exceptionally large catches in the Skagerrak/Kattegat bringing the index above average. Both North Sea surveys reported large amounts of target species outside their index areas, which may warrant a revision of the species-specific areas on which the standard abundance indices are calculated.IBTSWG will continue a number of collaborative activities later this year. The Workshop on the Further Development of the New IBTS Gear (WKFDN) will focus on updating results of gear trails with the potential new gears. The Workshop on the production of swept area estimates for all hauls in DATRAS for biodiversity assessments (WKSAE) will continue work on the Northeastern Atlantic Flexfile available via DATRAS, for which country specific algorithms are used to fill data gaps relevant for the calculation of the swept area. This and the already available North Sea Flexfile can be used to produces swept area indices. IBTSWG also met with members of the assessment groups, Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK) and Working Group on Elasmobranch Fishes (WGEF), to improve communication on for example circumstances affecting the execution of the surveys but also changes in survey design potentially impacting the indices.

The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improvements as well as the planned for survey activities for 2020. The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improve- ments as well as the planned for survey activities for 2020. In total, 19 surveys covering 25 func- tional units (FU’s) in the ICES area and 1 geographical subarea (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis, standardiza- tion and the use of most recent technology were reviewed. A new survey summary template by FU/GSA has been developed and adopted for future re- ports, which shall allow the data end users to extract the most relevant information on the survey results in a more easy way. Necessary actions and reviewer comments were addressed on the draft version of the Series of ICES Survey Protocols (SISP). Similarly, the working group reviewed the specifications for a Nephrops underwater TV database to be established at the ICES data centre and agreed on fur- ther action on this issue. First results from field studies on behaviour aspects of burrow emergence using bottom cages monitored by an automated camera system and on short-range migration using acoustic tracking are now available. Comparison of standard definition (SD) and high definition (HD) indicates the change to HD system mounted with a different camera angle may affect the detection rate and may thus require a revision of bias correction factors. New image reviewing software allows an easier way of an- notation of burrows than previous mosaicking methods, which has further advantages for inter- preting the results from different counters and for providing quality assured material for deep learning methods. The WG members agreed to collect information on burrow diameter size us- ing HD images and burrow annotation or mosaicking software because a change in the burrow size distribution may indicate recruitment events and the size of the burrow has an effect on bias correction factors in general. Automatic burrow detection based on deep learning methods applied to a test data set with an- notated burrow counts from a HD camera system showed promising results. The WG members were encouraged to provide more material with annotated burrow counts for further develop- ment of machine learning tools.

The Workshop on Realigning of the Ecosystem Observation Steering Group (WKREO) reviewed the critical task and information requirements of data collectors and data users that contribute to the development of ICES fisheries and ecosystem advice. The information requirements were mapped on to the existing expert group structure to identify gaps, bottlenecks and network communication characteristics. There was a high degree of consensus across the WKREO working group participants regarding the necessary tasks, but no clear understanding of which current expert groups are responsible for a number of these tasks. Additionally, this lack of clear structure has led to gaps in collaborative analysis and communication, so the group also considered ways to formalise effective communication flow going forward. WKREO discussed a variety of options that ultimately led to consensus of group responsibilities and information flow that are outlined in a set of new standard ToRs for different groups. Our proposal should facilitate improvements in the quality of fisheries advice and improve ecosystem science compared to the current network architecture. The WKREO proposal took a regional approach to data collection and analysis to better match the regional advisory processes compared to the existing methodological-focused data collection, resulting in a realignment of expert groups. Network indicators suggest realignment is qualitatively and quantitatively advantageous, particularly benefiting the ecosystem approach and progressing ICES science. It better supports the development of new science and regional monitoring products through effective sharing of skills and resources, while also providing an important link to regional data collection groups that hold the key to making decisions on future monitoring at the international level. The issues impacting the flow of data into advice are near universal around the world. Although the organisation and group names may differ, the principles and challenges of what we describe are the same. Countries developing or thinking of (re-)organising workflows could learn a lot about what works and what does not from the ICES experience. The group specifically identified the following benefits of the new structure: • Fisheries independent data and information are reviewed on a regional level, resulting in an improved understanding of the regional processes. • Fisheries independent data are used appropriately, and collections are understood by data users; • Combining fisheries independent data may lead to a better understanding of ecosystem processes; • Could more effectively incorporates fisheries independent surveys (e.g. national surveys) that currently are not used / not available to ICES; • Improved alignment of fisheries independent data with fish stock assessment groups and integrated ecosystem assessment groups; • Improved insight of regional changes and patterns by examination across surveys and across data types. • Improved survey planning and improved efficiency by evaluation of the survey; • Generation of cross-regional developments, knowledge, expertise as Fisheries Independent Regional Monitoring Groups co-develop linked by approach through IEASG activities; • Opportunity to incorporate (expertise on) non-fisheries monitoring (e.g. phytoplankton, zooplankton, benthos, mammal, birds, etc.) to enhance survey value; • Theme-specific workshops initiated by the survey coordination groups improve expertise across regions.• Improved cross-network understanding of information flow and clarity of responsibility through common structure from “data to advice”. • Appropriate division of labour with regards to skills and resources.

The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improvements as well as the planned for survey activities for 2020. The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improve- ments as well as the planned for survey activities for 2020. In total, 19 surveys covering 25 func- tional units (FU’s) in the ICES area and 1 geographical subarea (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis, standardiza- tion and the use of most recent technology were reviewed. A new survey summary template by FU/GSA has been developed and adopted for future re- ports, which shall allow the data end users to extract the most relevant information on the survey results in a more easy way. Necessary actions and reviewer comments were addressed on the draft version of the Series of ICES Survey Protocols (SISP). Similarly, the working group reviewed the specifications for a Nephrops underwater TV database to be established at the ICES data centre and agreed on fur- ther action on this issue. First results from field studies on behaviour aspects of burrow emergence using bottom cages monitored by an automated camera system and on short-range migration using acoustic tracking are now available. Comparison of standard definition (SD) and high definition (HD) indicates the change to HD system mounted with a different camera angle may affect the detection rate and may thus require a revision of bias correction factors. New image reviewing software allows an easier way of an- notation of burrows than previous mosaicking methods, which has further advantages for inter- preting the results from different counters and for providing quality assured material for deep learning methods. The WG members agreed to collect information on burrow diameter size us- ing HD images and burrow annotation or mosaicking software because a change in the burrow size distribution may indicate recruitment events and the size of the burrow has an effect on bias correction factors in general. Automatic burrow detection based on deep learning methods applied to a test data set with an- notated burrow counts from a HD camera system showed promising results. The WG members were encouraged to provide more material with annotated burrow counts for further develop- ment of machine learning tools.

85 pages, figures, tables, 5 annexes, The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improve-ments as well as the planned for survey activities for 2020. In total, 19 surveys covering 25 func-tional units (FU’s) in the ICES area and 1 geographical subarea (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis, standardiza-tion and the use of most recent technology were reviewed. A new survey summary template by FU/GSA has been developed and adopted for future re-ports, which shall allow the data end users to extract the most relevant information on the survey results in a more easy way. Necessary actions and reviewer comments were addressed on the draft version of the Series of ICES Survey Protocols (SISP). Similarly, the working group reviewed the specifications for a Nephrops underwater TV database to be established at the ICES data centre and agreed on fur-ther action on this issue. First results from field studies on behaviour aspects of burrow emergence using bottom cages monitored by an automated camera system and on short-range migration using acoustic tracking are now available. Comparison of standard definition (SD) and high definition (HD) indicates the change to HD system mounted with a different camera angle may affect the detection rate and may thus require a revision of bias correction factors. New image reviewing software allows an easier way of an-notation of burrows than previous mosaicking methods, which has further advantages for inter-preting the results from different counters and for providing quality assured material for deep learning methods. The WG members agreed to collect information on burrow diameter size us-ing HD images and burrow annotation or mosaicking software because a change in the burrow size distribution may indicate recruitment events and the size of the burrow has an effect on bias correction factors in general. Automatic burrow detection based on deep learning methods applied to a test data set with an-notated burrow counts from a HD camera system showed promising results. The WG members were encouraged to provide more material with annotated burrow counts for further develop-ment of machine learning tools

The Workshop on methods to develop a swept-area based effort index (WKSABI) was held at ICES HQ, Copenhagen, on 8–9 January 2019 under the co-chairmanship of Kai Wieland, Den-mark, and Henrik Degel, Denmark. The workshop was attended by 12 participants representing seven different countries.The objectives of the workshop were to adopt and agree on swept-area based effort indices for trawl surveys available in DATRAS and define and describe MFSD indicators using these swept-area based indices. Surveys considered where the North Sea International Bottom Trawl Survey, the Northeast Atlantic International Bottom Trawl Surveys and the Baltic International Trawl Survey. MFSD indicators considered were Marine Litter and the Large Fish Indicator (LFI).In total, eight presentations were given addressing the Terms of References of the workshop. Based on the initial presentations on data availability, quality check and swept-area based results for the different surveys and MFSD indicators, caveats were described, and methodological strat-egies to overcome existing data issues were defined.Swept-area based survey indices require tow-by-tow information of towed distance and door or wing spread from all survey participants. For several reasons, this information is not always available and missing values have to be estimated. The level of data availability for this purpose differed considerably between the surveys. Despite the use of standardized survey trawl, gear geometry between countries or within countries between years can vary substantially and it was therefore concluded that algorithms for estimating missing values should be as specific as pos-sible for a given survey, vessel, country, and year combination. This is important in order to minimize bias and variability when including the imputed values for the calculation of swept-area. After these requirements are met and datasets have been completed, further analysis on the potential of swept-area based indices for abundance and its use in stock assessment can be un-dertaken. Since door spread has been much more often observed than wing spread and is usually measured with a low variability than wing spread, swept are based on door spread is preferred if indices rather than absolute estimates are required.The calculation of the MFSD indicators Marine litter and LFI require the availability of swept-area and this is then usually based on wing spread. Since direct observations of wing spread area missing for the majority of surveys and years, generic models across years and vessels have been used for estimating the missing values. This may be appropriate when trends rather than partic-ular year effects are needed. Although estimates of MFSD indicators suffer of the problems men-tioned above, missing checks of data quality on marine litter submissions or the application of ‘global’ length-weight relationships for species for which no specific observations are available in the calculation of e.g. LFI may be more important here.