Rationale: Increasing demand for fish and seafood means that the traceability of marine products is becoming ever more important for consumers, producers and regulators. Highly complex and globalised supply networks create challenges for verifying a stated catch region. Atlantic cod is one of the most commercially important species in the northeast Atlantic. Several regional fisheries supply cod into the trade network, of which some are at greater risk of overexploitation than others. Tools allowing retrospective testing of spatial origin would significantly assist sustainable harvesting of fish, reducing incentives for illegal fishing and fraud. Methods: Here, we investigate whether stable isotope ratios of carbon, nitrogen and sulphur can be used to retrospectively identify the catch region of Atlantic cod (Gadus morhua). We measured the isotopic composition of muscle tissue from 377 cod from 10 catch regions across the northeast Atlantic and then applied three different assignment methods to classify cod by region of most likely origin. The assignment method developed was subsequently tested using independently sourced, known-origin samples. Results: Individual cod could be traced back to their true origin with an average assignment accuracy of 70-79% and over 90% accuracy for certain regions. Assignment success rates comparable to those using genetic techniques were achieved when assigning among restricted and pre-selected regions. However, assignment accuracy to the fishery region estimated from independent samples across the whole geographic range of cod averaged similar to 25% overall, highlighting the need for careful application of isotope-based approaches. Conclusion: Stable isotope techniques can provide effective tools to test for origin in Atlantic cod, but not all catch regions are isotopically distinct. Stable isotopes could be combined with genetic techniques to result in higher assignment accuracy than could be achieved using either method independently. Assignment potential can be estimated from reference datasets, but estimates of realistic assignment accuracy require independently collected data.

Demersal fish stocks and seabird populations on the Faroe shelf have declined profoundly over the past half-century, and the relative role of exploitation and climate remains a key question. The dynamics of the subpolar gyre influences both the marine climate and several ecosystems in the northeastern Atlantic. Furthermore, a more than century old hypothesis suggests that production in marine ecosystems along the eastern margin of the Norwegian Sea is fueled by transport of nutrient- and zooplankton-rich subarctic waters from the Iceland Sea-Jan Mayen region. Recent research has, on the other hand, related the productivity of the Faroe shelf ecosystem to local processes. These contrasting perspectives are here combined, to explain the highly variable recruitment, and thus stock sizes, of Faroese cod (Gadus morhua) and guillemots (Uria aalge). We propose that good recruitment to demersal fish stocks and seabirds requires both high on-shelf biological production and high oceanic food content, proxied by large volumes of subarctic waters surrounding the Faroe shelf.

This report presents results from the NovasArc project that has collated data on the distribution of vulnerable marine ecosystems (VMEs) in Arctic and sub-Arctic waters. Eleven VMEs were identified ...

Marine ecosystem dynamics can vary on timescales ranging from months to centuries, but many observational data are limited to just a few decades. The bivalve Arctica islandica may live up to five centuries depositing annual growth increments in its shells which can serve as an indicator for ecosystem productivity. In the present study, 154 specimens of A. islandica were collected on the Faroe Shelf and standardised annual growth increments for 143 of them – 44 from coastal stations and 99 from shelf stations – were compared with climatic, oceanographic and biological variables. A. islandica growth from coastal and shelf stations was not correlated with basin-scale climate indices (the AMO index, the NAO index, the AO index or the subpolar gyre index) or, more locally, with windspeed or sea surface temperature on the Faroe Shelf. For the shelf stations there was a significant negative correlation between A. islandica growth and the volume transport of the Faroe Current flowing just north of Faroe Islands (r = -0.62). There was a weak nonsignificant positive correlation with an index of primary production on the Faroe Shelf (r = 0.31) and a strong negative correlation with a zooplankton biomass index in mid-summer (r = -0.76). There was also a strong positive correlation between A. islandica growth and the biomass of the bottom-feeding fish species Melanogrammus aeglefinus two years later (r = 0.62). These results seem to suggest that A. islandica growth may represent the amount of fresh phytoplankton that reaches the near-bottom water layers and could probably be regarded as a proxy for the strength of pelagic-benthic coupling that is modulated through phytoplankton-zooplankton interactions in the overlying water. Our results highlight the potential for A. islandica to serve as a long-term proxy for linking variability in pelagic ecosystem dynamics to demersal fish stocks.

Adult anglerfish conduct annual migrations between spawning areas and feeding areas; for Faroese waters this migration has so far not been described. Therefore, anglerfish migration and distribution in Faroese waters was investigated by mark-recapture studies, including data storage tags, as well as data from scientific trawl surveys, commercial trawlers and gillnetters. The fish distribution was compared to hydrographical conditions such as sea surface- and bottom temperature. A clear seasonal offshore-onshore migration was observed. Anglerfish occupied shallower waters (<200 m) during summer and deeper waters, especially on the western side of the Faroe shelf, during winter. This seasonal movement was most evident for sexually mature fish longer than 70 cm indicating spawning in deep waters during winter. Further, during winter anglerfish experienced cold water, which indicated that they were distributed close to the main interface of cold water masses surrounding the shelf. The fish were mostly located in warm water (6.5–11°C) and seldom occurred in colder waters than 4°C. Anglerfish appeared generally inactive, only around 5% of the total data storage tag recordings showed more than 5 m vertical movement between two subsequent hourly recordings. This vertical activity varied seasonally by being higher during winter than summer and diurnally by being higher during night time than day time, indicating that sunrise and day length played an important role in vertical movements.

Recruitment to the Faroe Plateau cod ( Gadus morhua ) stock (62°N, 6.8°W) is highly variable between years, and availability of suitable prey during the early life stages may determine the year class strength. Here we first investigate interannual variability in recruitment (1983–2017) of cod based on survey data and data from stock assessments. Positive relationships between the spawning stock biomass and larval abundance and between juvenile abundance and recruitment at year 1 were detected. However, the relationship between larval abundance and juvenile abundance was not statistically significant, indicating variable survival during the larval/early juvenile stages. We then investigated if food availability at the larval and early juvenile stages could explain the variability in recruitment using an 8-year long time series of larval and juvenile gut content. Feeding at the early larval stage, present during the pre-bloom, was relatively stable between years. However, large interannual variability in feeding at the early juvenile stage was detected. When juvenile survival and mean length were high, juveniles clearly had less food in their guts. This contradiction is suggested to be due to intense grazing pressure on the zooplankton at high juvenile abundances. However, years with high larval survival coincided with years when the phytoplankton spring bloom was early and intense, suggesting that production of suitable prey during the larval stages determines larval growth and survival and that this production is dependent on the phytoplankton spring bloom characteristics.

Marine fisheries are often allocated to stocks that reflect pragmatic considerations and may not represent the species' spatial population structure, increasing the risk of mismanagement and unsustainable harvesting. Here we compile mark-recapture data collected across the North Atlantic to gain insight into the spatial population structure of Greenland halibut (Reinhardtius hippoglossoides), an issue that has been unresolved for decades. The dataset contains 168130 fish tagged from 1952 to 2021, with 5466 (3.3%) recaptured individuals. Our results indicate that fish tagged at <50 cm body length migrate at higher rates, suggesting that mark-recapture studies on adult individuals underestimate population-level migration rates. We find evidence for migrations across management units in the North Atlantic indicating two regional offshore populations: one in the Northeast Atlantic, where the West Nordic and Northeast Arctic stocks, currently managed separately, likely belong to a single population that spans from the Kara Sea to Southeast Greenland; and one in the Northwest Atlantic where migration was observed between the Newfoundland and Labrador stock and the Northwest Arctic stock in Davis Strait and Baffin Bay. Our findings indicate complex population structure with implications for international and domestic fisheries management of this long-lived species.

Marine biota are redistributing at a rapid pace in response to climate change and shifting seascapes. While changes in fish populations and community structure threaten the sustainability of fisheries, our capacity to adapt by tracking and projecting marine species remains a challenge due to data discontinuities in biological observations, lack of data availability, and mismatch between data and real species distributions. To assess the extent of this challenge, we review the global status and accessibility of ongoing scientific bottom trawl surveys. In total, we gathered metadata for 283,925 samples from 95 surveys conducted regularly from 2001 to 2019. We identified that 59% of the metadata collected are not publicly available, highlighting that the availability of data is the most important challenge to assess species redistributions under global climate change. Given that the primary purpose of surveys is to provide independent data to inform stock assessment of commercially important populations, we further highlight that single surveys do not cover the full range of the main commercial demersal fish species. An average of 18 surveys is needed to cover at least 50% of species ranges, demonstrating the importance of combining multiple surveys to evaluate species range shifts. We assess the potential for combining surveys to track transboundary species redistributions and show that differences in sampling schemes and inconsistency in sampling can be overcome with spatio‐temporal modeling to follow species density redistributions. In light of our global assessment, we establish a framework for improving the management and conservation of transboundary and migrating marine demersal species. We provide directions to improve data availability and encourage countries to share survey data, to assess species vulnerabilities, and to support management adaptation in a time of climate‐driven ocean changes.

A new approach for estimating the fishing mortality benchmark Fmsy (fishing pressure that corresponds to maximum sustainable yield) is proposed. The approach includes density-dependent factors. The analysis considers 53 data-rich fish stocks in the Northeast Atlantic. The new Fmsy values are estimated from an ensemble of data sources: (i) applying traditional surplus production models on time-series of historic stock sizes, fishing mortalities, and catches from the current annual assessments; (ii) dynamic pool model (e.g. age-structured models) estimation for stocks where data on density-dependent growth, maturity, and mortality are available; (iii) extracts from multispecies and ecosystem literature for stocks where well-tested estimates are available; (iv) the “Great Experiment” where fishing pressure on the demersal stocks in the Northeast Atlantic slowly increased for half a century; and (v) linking Fmsy to life history parameters. The new Fmsy values are substantially higher (average equal to 0.38 year−1) than the current Fmsy values (average equal to 0.26 year−1) estimated in stock assessments and used by management, similar to the fishing pressure in the 1960s, and about 30% lower than the fishing pressure in 1970–2000.

In the deep waters of the Nordic Seas and adjacent areas, several benthic habitats such as cold-water coral reefs, coral gardens, and deep-sea sponge aggregations have been classified as vulnerable marine ecosystems (VMEs), due to their uniqueness, limited spatial extent, physical fragility, and slow recovery rate. In the last decade observations carried out by habitat mapping programmes in Norway, Iceland, and more recently in the Faroe Islands have substantially increased knowledge on the distribution of VMEs in the Nordic Seas. Nevertheless, large areas have not been explored due to the cost and logistics of obtaining observations in the deep-sea. Species distribution models can be used to predict the distribution of VMEs and their indicator species. Here we present the predicted distribution of 44 VME indicator taxa including 20 sponges, 17 cold-water corals, and 7 seapens in the Nordic Seas based on data compiled and models developed by the NovasArc project (2016-2018). Models for 44 VME indicator species were developed using the maximum entropy algorithm MaxEnt, using an extensive database compiled from habitat mapping surveys, by-catch data from bottom fish surveys, and records from reports and peer reviewed publications. Modeled distributions showed good agreement with observations. Niche overlap measures were used to identify seven groups and four subgroups of VME indicator taxa that co-occur. These were consistent with the species composition of known biotopes in the study area. A VME Index that combine the predictions for all VME indicator species was computed to identify particularly valuable and vulnerable ecosystems that should be targets of further exploration and conservation efforts. Such areas were identified at shelf break and slope off Iceland, the Faroe Islands, and central Norway, and the continental shelf off southern Greenland. The predicted distribution of VMEs in Arctic and sub-Arctic waters allows for the evaluation of interactions with fisheries and other anthropogenic activities and provides an important input for managers.

The availability of suitable prey during the early life of fish may determine recruitment to the adult population. Since larval and juvenile feeding can be highly selective, their preferences for certain prey species and sizes should be considered when estimating the availability of prey. In this study, diet composition (and prey preferences) of 4984 (1366) Faroe Plateau cod ( Gadus morhua ) larvae and juveniles between 3 and 63 mm sampled on the central Faroe shelf (62°N, 6.8°W) over an 8-year period was investigated. Cod preyed on successively larger food items as they grew. Yolk-sac larvae consumed phytoplankton, copepod eggs and nauplii before the yolk sac was exhausted. Copepod eggs followed by calanoid nauplii were the predominant and preferred food items in the early larval stage. In the late larval stage these were replaced by small to medium sized (0.6–1.2 mm) copepod species mainly Pseudocalanus sp., Acartia sp. and early stage Calanus finmarchicus , of which the two former species appeared most preferred. Temora longicornis was highly abundant in juvenile cod, but the preference for this species was neutral. Positive selection and high abundance of late stage (≥ 1.5 mm) C. finmarchicus was observed in early juveniles, but C. finmarchicus was replaced by decapod larvae in late juveniles. Other abundant prey species such as Oithona sp. and barnacle larvae occurred in varying numbers in the guts, but were generally not positively selected at any stage. Late larval and early juvenile cod appeared to suffer from unfavourable feeding conditions as they fed on smaller prey than what they prefer potentially indicating bottle necks in the feeding at these development stages.

Icelandic stocks: The Ministry of Industries and Innovation in Iceland decided considering the Covid-19 outbreak that Iceland would be without ICES advice for the 2020/2021 fishing year for stocks that are con-sidered local to Iceland. For NWWG these stocks are cod (cod.27.5a), haddock (had.27.5a), saithe (pok.27.5a), Icelandic summer spawning herring (her.27.5a) and Icelandic slope beaked redfish (reb.27.5a14). The assessments for these stocks were therefore not discussed at the NWWG 2020 meeting in April. Only tables (landings, survey indices and results of the assessment) were up-dated. Capelin in the Iceland-East Greenland-Jan Mayen area: In November 2018 ICES advised that the initial (preliminary) quota in 2019/20 should be 0 tonnes. In October 2019, the Icelandic Marine Research Institute (MRI) advised an intermediate TAC of 0 tonnes based on an acoustic survey in September and based on winter surveys in Jan-uary–February 2020 this advice was not changed. All advice was based on the HCR from ICES WKICE (2015). There were no capelin fisheries or landings in the fishing season 2019/2020. Offshore West Greenland Cod: The West Greenland offshore stock component is comprised of the NAFO subdivisions 1A-E in West Greenland. The East Greenland stock component is comprised of the area NAFO subdivi-sion 1F in South Greenland and ICES Subarea 14 in East Greenland. Some mixing occurs between the two stocks in West Greenland which at present is considered to act as a nursing area for juveniles of the East Greenland stock component. An annual TAC of 5000 tonnes was set in 2015-2018 and the average catches have been 3000–4000 tonnes per year. TAC in 2019 was set at 2000 tons, 900 tons was fished. Cod ages 6-8 years dominates the catches. Both the German Groundfish survey and Greenland Shrimp and Fish survey indices show that the biomass and abundance increased in the period 2010–2015 due primarily to the 2009 YC and in part the 2010 YC. In the period 2016-2018, the German survey did not cover the area, and in 2019 only covered the southern part (NAFO 1E). The Greenland survey showed a reduction in biomass in 2016, due to a decrease in the 2009 and 2010 yearclasses at age 6 and 7 yrs which where historically high at age 5 and 6 yrs in 2015. The decrease has been attributed as an effect of fishing and migration inshore and eastward. The abundance of older cod (age >7 yrs), how-ever, increased since 2017 compared to previous years where older cod where almost absent indicating that not all cod has migrated out of the area and/or they returned from the inshore area. The Greenland survey show a massive increase in biomass and abundance in 2019, but is caused by two very large hauls. The dominating yearclass is the 2015 YC, which was also domi-nating the German survey in 2019 in NAFO 1E...

Vulnerable Marine Ecosystems (VMEs) may be regarded as habitats characterized by habitat forming species sensitive to anthropogenic activities. A habitat is a recognizable space which can be distinguished by its abiotic characteristics and associated biological assemblage, operating on particular spatial and temporal scales (ICES, 2005b).

The lack of information on the distribution of VMEs in the deep sea is hampering the development and application of measures to protect these habitats from anthropogenic impacts (Weaver et al. 2011). Given the wide distribution of deep-sea habitats, and the expense and complexity of documenting these habitats (e.g. using video or photographs), Environmental Niche Models (ENMs) are increasingly recognised as an effective way to obtain knowledge on the likely distribution of VMEs and other deep-sea ecosystems (Vierod et al. 2014). Indeed, several studies have used ENMs to predict the distribution of VME indicator species (e.g. Davies and Guinotte, 2011; Yesson et al. 2012; Rengstorf et al. 2013; Ross and Howell, 2013), and the use of these models has been recommended as part of the process for designing management plans to protect VMEs from fishing impacts (Ardron et al. 2014; Vierod et al. 2014). The models developed in this study represent a first attempt to model the distribution of all important VMEs in the Arctic and sub-Arctic region of the Northeast Atlantic.