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Shellfish survey Vestlandet 2023 — Survey 2023005013
Get PDFKnowledge about the abundance, distribution and life-history of brown crab (Cancer pagurus) and Norway lobster (Nephrops norvegicus) along the Norwegian coast is limited due to a lack of fisheries-independent data. This coincides with a general monitoring gap of inshore areas in Western Norway (Vestlandet) where no regular fisheries survey takes place. The survey in October 2023 was a pilot study aiming to 1) collect data on the two important shellfish species in an area where commercial and recreational fishing takes place, 2) test a survey design as basis for potential future monitoring of these species on a more routine basis, including with a video sled, and 3) validate the representativeness of commercial data collected by reference fisheries on both species. In total, 74 stations were conducted: 41 with crab pots (6 pots in each link), 26 with Nephrops pots (12 in each link) and 7 with video sled. Stations were placed in a semi-randomized design in pre-selected areas based on bottom substrate, and in case of crab pots partially at or near stations of IMR’s fyke and gill net survey.Shellfish survey Vestlandet 2023 — Survey 2023005013publishedVersio
The copepod Acartia sp. is more sensitive to a rapid pressure drop associated with seismic airguns than Calanus sp.
Get PDFAirguns used in seismic surveys release high-pressure air, generating sound waves that may have adverse effects on marine life. However, knowledge of how seismic exposure impacts zooplankton is limited. One key characteristic of seismic signals that could potentially cause damage is a rapid pressure drop. In this study, the rapid pressure drop (~2 bar) was re-created in the laboratory using a pressure tube. To determine the range at which this drop occurs, the sound field around a seismic airgun array was modeled. The effects of this pressure drop on mortality and swimming behavior were tested in 2 common copepods, Acartia sp. and Calanus sp., both immediately and 5 h after treatment. Pressure-exposed Acartia sp. showed higher mortality rates (0 h: 5.6%; 5 h: 10%) compared to the controls, while mortality in Calanus sp. only increased after 5 h (3.3%). The swimming speed of pressure-exposed Acartia sp. (0 h: 0.49 mm s-1; 5 h: 0.52 mm s-1) was lower than in the control treatment, whereas the swimming speed in pressure-exposed Calanus sp. (2.64 mm s-1) only differed immediately after treatment. This study demonstrates that a rapid pressure drop can negatively affect zooplankton mortality and behavior at close range. The results also show that Acartia sp. is more sensitive to this pressure drop than Calanus sp., suggesting potential species-specific impacts from seismic exposure. Identifying the sound characteristics that can be harmful to zooplankton allows for a more accurate assessment of the most affected species and the range at which impacts can occur.publishedVersio
Genome-Wide Population Structure in a Marine Keystone Species, the European Flat Oyster (Ostrea edulis)
Get PDFOstrea edulis, the European flat oyster, was once a widespread economically and ecologically important marine species, but has suffered dramatic declines over the past two centuries. Consequently, there has been a surge in European restoration efforts, many of which focus on restocking as a conservation measure. In this study, we used whole-genome sequencing (WGS) data to investigate the population structure, demographic history, and patterns of local adaptation of O. edulis across its natural distribution with increased sampling densities at Scandinavian localities. Results revealed seven distinct genetic clusters, including previously undescribed complex population structure in Norway, and evidence for introgression between genetic clusters in Scandinavia. We detected large structural variants (SVs) on three pseudo-chromosomes. These megabase long regions were characterised by strong linkage disequilibrium and clear geographical differentiation, suggestive of chromosomal inversions potentially associated with local adaptation. The results indicated that genomic traces of past translocations of non-native O. edulis were still present in some individuals, but overall, we found limited evidence of major impacts of translocations on the scale of contemporary population structure. Our findings highlight the importance of considering population structure and signatures of selection in the design of effective conservation strategies to preserve and restore wild native European flat oyster populations, and we provide direct knowledge safeguarding sustainable mitigation actions in this important species.publishedVersio
Advice on fishing opportunities for northern shrimp (Pandalus borealis) in the Barents Sea (ICES subareas 1 and 2)
Get PDFThe Joint Russian-Norwegian Working Group on Arctic Fisheries (JRN-AFWG) advises that when the MSY approach is applied, catches of northern shrimp in the Barents Sea in 2025 should not exceed 150 000 tonnes.Advice on fishing opportunities for northern shrimp (Pandalus borealis) in the Barents Sea (ICES subareas 1 and 2)publishedVersio
Report of the JOINT EIFAAC/ICES/GFCM Working group on eels (WGEEL)
No full textThe Joint EIFAAC/ICES/GFCM Working group on eels (WGEEL) met in a split meeting from 09-13 September (online) and 23 September–01 October 2024 (hybrid meeting) in Tirana, Albania to provide the scientific basis for the ICES advice on fishing opportunities and conservation aspects for the European eel and further address requests from EIFAAC and GFCM, if brought to the attention of the group. WGEEL assessed the state of the European eel and its fisheries (Section 2), collated biometric data, reviewed the implementation of the Workshop on the Future of Eel Advice (WKFEA) roadmap, identified issues for the future benchmark process, reported on any updates to the scientific basis of the advice, new and emerging threats or opportunities. After high levels in the late 1970s, the recruitment declined dramatically in the 1980s and remains low. Compared to 1960–1979, the recruitment in the “North Sea” index series was 1.1% in 2024 (provisional) and 0.5% in 2023 (updated). In the “Elsewhere Europe” index series, it was 7.2% in 2024 (provisional) and 7.4% in 2023 (updated). For the yellow eel data series, recruitment in 2023 was 11.4%. The time-series from 1980 to 2024 show that glass eel recruitment remains at a very low level. The trend of reported commercial landings shows a long-term continuing decline, from a level of around 10 000 t in the 1960s and remained above 2 000 t (glass eel + yellow eel + silver eel) in the past decade. The commercial glass eel fishery in 2024 was 56.1 and 54 t in 2023. Spain was the only country allowing a recreational catch of glass eel in 2023, with landings estimated at 1.3 t, but banned recreational fisheries in 2024. Reported landings from yellow and silver eel commercial fisheries (Y, S, YS) add up to 2 366 t in 2022 and 2 027 t in 2023 (provisional data). Reported recreational landings for yellow and silver eel combined was 551 t for 2022 (15 coun-tries reporting) and 84 t for 2023 (10 countries reporting). Contents of the country reports were reviewed to update the scientific basis of the advice, in-cluding any new or emerging threats or opportunities (Section 3). Current threats to the eel pop-ulation were briefly described within the following categories: hydropower, screening and pas-sage, eel health parameters, climate change and invasive aquatic species. A dedicated section also highlighted the need to consider the risks associated with a prospective closure of the eel lifecycle in captivity (i.e. artificial reproduction). Ongoing eel or eel-related projects were also described in this section. In 2021, the Workshop on the Future of Eel Advice (WKFEA) defined milestones toward an im-proved eel assessment targeting a full benchmark process in 2027. The progress towards the im-plementation of the roadmap established by WKFEA was evaluated and updated accordingly. Issues to be addressed during the future benchmark were defined and described in Section 4. Other tasks carried out during the meeting (Section 5) consisted in: clarifying the process for the integration the WGEEL database into the ICES Data Screening Utility (DATSU), establishing a questionnaire for the next datacall in preparation for the benchmark, and preparing for the tech-nical evaluation of EU Member States’ Progress Reports (WKEMP).publishedVersio
Skreitokt 2024 - Kartlegging av gytebestanden av skrei i 2024
Get PDFSkreitoktet 2024 ble i hovedsak gjennomført i henhold til plan, og i henhold til metodikk etablert for tidsserien. Mindre avvik er notert med tanke på tidspunkt for gjennomføring, og tilfang av enkeltfiskobservasjoner. Toktnr: 2024002004Skreitokt 2024 - Kartlegging av gytebestanden av skrei i 2024publishedVersio
Predator biomass affects west–east shifts in Barents Sea capelin (Mallotus villosus) spawning ground use
Get PDFSpawning locations of migratory fish influence the environmental and oceanographic fate of eggs and larvae. However, we have an incomplete understanding of how and why realized spawning locations vary. We quantified the yearly variation in spawning location for Barents Sea capelin (Mallotus villosus) within the recognized spawning areas along the coast of northern Norway and Murman. Furthermore, we tested whether water temperature, sea ice cover, predation and capelin fisheries are associated with spawning locations. Estimated spatial variation in spawning longitude used data from Soviet-Russian ichthyoplankton surveys from 1959 to 1993 and a bootstrap procedure. The mean spawning area along the coast was then calculated by combining larvae observations with backtracking a larvae drift model from potential spawning areas. We fitted a generalized additive model (GAM) to assess the effects of environmental conditions on these drift-corrected spawning longitudes. Capelin's mean yearly spawning location varied substantially across the study period. An increase in immature cod biomass, a major predator of capelin, during the spawning migration period in winter and early spring corresponds to more eastward capelin spawning. The eastward shift in mean spawning longitude seems to reach an eastern limit at high immature cod biomass. Sea temperature, sea ice cover and capelin fisheries were not associated with mean capelin spawning longitude. We show that the realized spawning areas for capelin are related to cod biomass, potentially through cod predation depleting and/or acting as a migration barrier for mature capelin.publishedVersio
Joint Norwegian-Russian monitoring of 0-group fish on autumn surveys in the Barents Sea, 1965-2023
Get PDFA joint Norwegian-Russian survey of 0-group fish (here defined as fish hatched earlier in the same calendar year) in the Barents Sea was started in September 1965 with the motivation to provide initial information on year class strength of commercially important fish stocks (ICES 1965, Eriksen and Prozorkevich 2011). The survey initially used echosounders to record 0-group fish combined with trawl sampling to identify the composition of the acoustic backscatter (Dragesund and Olsen 1965). The joint 0-group survey was continued the following years with participation also by the United Kingdom from 1966 to 1976. Intercalibration of the echosounders was done before the start of the survey to improve comparability of results obtained by different research vessels (Dragesund 1970, Dragesund et al. 2008).Joint Norwegian-Russian monitoring of 0-group fish on autumn surveys in the Barents Sea, 1965-2023publishedVersio
Consequences of acute and long-term excessive iodine intake: A literature review focusing on seaweed as a potential dietary iodine source
Get PDFMacroalgae, also called seaweed, are becoming more widespread as food in Western diets. Seaweed can accumulate iodine, an essential nutrient for humans. However, some species of seaweed may contain very high amounts of iodine, and therefore, iodine has been identified as one of the major hazards in the seaweed food chain. Macroalgae may be consumed regularly, though many consumers report eating macroalgae only occasionally. The aim of this paper is to explore possible health consequences of excessive iodine intake according to long-term (chronic) or occasional (acute) excessive exposure to iodine, relating to a regular (chronic) or occasional (acute) seaweed intake, respectively. Furthermore, through a modeling exercise, we add different amounts of seaweed to the diet in a population group to explore the possible safe amounts that can be added without exceeding excessive iodine intakes and risking detrimental health effects. Chronic excessive iodine intakes were associated with several negative health outcomes at variable doses in various studies. For acute excessive iodine exposure, negative health effects seemed to be associated with higher iodine exposures. However, the research on this topic was limited. The chronic and acute iodine exposures needed to result in negative health outcomes may easily be ingested by macroalgae consumption. Adding seaweed to the diet must be done thoughtfully to avoid the risk of exceeding thresholds for excessive iodine intake.publishedVersio
Long-term annual trawl data show shifts in cephalopod community in the western Barents sea during 18 years
Get PDFClimate change is threatening marine ecosystems on a global scale but particularly so in the Arctic. As a result of warming, species are shifting their distributions, altering marine communities and predator-prey interactions. This is known as the Atlantification of the Arctic. Warming may favor short-lived, opportunistic species such as cephalopods, marine mollusks that previously have been hypothesized to be winners in an ocean of change. To detect temporal regional trends in biodiversity, long-term annual surveys in hotspots of climate change are an unparalleled source of data. Here, we use 18 years of annual bottom trawl data (2005–2022) to analyse cephalopods in the western Barents Sea. More specifically, our research goals are to assess temporal trends in cephalopod fauna composition, abundance and biomass, and to relate these trends to climate change in the western Barents Sea. Main changes in cephalopod diversity and distribution occurred in mid-2000s and early 2010s, which corresponds with a period of warming in the Arctic since the late 1990s/early 2000s. Repeated increased occurrence of the boreal-subtropical cephalopods was recorded from 2005–2013 to 2014–2022. Moreover, the abundance of cephalopods in the area (in general and for most taxa) increased from 2005–2013 to 2014–2022. These observations suggest that the cephalopod community of the Barents Sea is subjected to Atlantification since the 2005–2013 period. This corresponds with previously reported evidence of the Atlantification in fishes and benthic invertebrates in the Barents Sea and benthic invertebrates. ‘Typical’ Arctic cephalopod species such as Bathypolypus spp., Gonatus fabricii and Rossia spp., however, are still much more abundant in the western Barents Sea compared to the deep-sea and the boreal-subtropical species. We also found indirect indications for body-size reduction in Bathypolypus spp. from 2005–2013 to 2014–2022. Overall, the temporal trends in the Barents Sea cephalopod fauna provide evidence for changing marine communities in the Arctic.publishedVersio