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Havforskningsinstituttet gir råd for alle operasjoner til havs som involverer bruk av lydkilder, samt elektromagnetiske kilder som kan påvirke marine økosystemer. Dette inkluderer vitenskapelige undersøkelser, utbygging og sprenging i sjø, seismiske og elektromagnetiske undersøkelser i forbindelse med petroleumsvirksomhet og utbygging og drift av vindkraftanlegg til havs. Denne rapporten er en sammenstilling av tilgjengelig kunnskap omkring hvordan de overnevnte typer av undersjøisk støy påvirker livet i havet. Videre evalueres denne kunnskapen i lys av hvilke konsekvenser dokumenterte effekter kan gi på økosystemet. Denne rapporten er inndelt med et kapittel for hver av de overnevnte støykildene (seismikk, elektromagnetiske undersøkelser, undersjøiske sprenginger og vindkraft til havs), som igjen er inndelt i delkapitler med 1) kunnskapsgrunnlag, 2) konsekvensvurdering og 3) råd. Rapporten inneholder konkrete råd fra Havforskningsinstituttet for 2023 for de ulike typene av støy. I tillegg inneholder rapporten en oversikt over hvor det finnes sårbare koraller i norske farvann. Årsaken til at dette er med er grunnet at mange av operasjonene til havs lager støy også innebærer å plassere ulike måleinstrumenter på bunn, og de bør ikke plasseres i områder med korall-forekomster. Derfor er det relevant å også ha med informasjon om romlig fordeling av koraller her. Rapporten inneholder konkrete råd fra Havforskningsinstituttet for 2023 for de ulike typene av støy og elektromagnetisk stråling. Råd for seismikk og elektromagnetiske undersøkelser gis i form av rådgivningskart, som viser perioder og områder som bør unngås. Disse kartene inngår også i Oljedirektoratets meldesystem. Havforskningsinstituttets rådgivning for menneskeskapt støy i havet - Kunnskapsgrunnlag, vurderinger og råd for 2023

The Joint EIFAAC/ICES/GFCM Working group on eels (WGEEL) met by correspondence and video conference from September 7 – 10 September and 27 September – 4 October in 2021 to assess the state of the European eel and its fisheries, investigate the effects of contaminants on the reproductive capacity of the eel stock, discuss the findings of WKFEA, further identify issues specific to the Mediterranean region and report on any updates to the scientific basis of the advice, new and emerging threats or opportunities. For a better integration of the Mediterranean area, new members joined WGEEL, providing data and support as regional experts. This is considered an important step in a continuous process to identify and address Mediterranean-specific issues and harmonize the efforts of WGEEL and the recent ‘GFCM research Programme on European Eel’. The recruitment of European eel strongly declined from 1980 to 2011. The glass eel recruitment compared to that in 1960–1979 in the “North Sea” index area was 0.6% in 2021 (provisional) and 0.9 % in 2020 (final). In the “Elsewhere Europe” index series it was 5.4 % in 2021 (provisional) and 7.1% in 2020 (final), based on available dataseries. For the yellow eel dataseries, recruitment for 2020 was 16% (final) of the 1960–1979 level; the 2021data collection for yellow eel is ongoing. Time-series from 1980 to 2021 show that recruitment has stopped decreasing in 2011 but the trend thereafter is rather unclear.Preliminary analyses of 160 dataseries on yellow or silver eel abundance show the potential of the yellow and silver eels’ series to improve the stock assessment. A comprehensive framework of analyses of the yellow and silver stocks through these series will, however, require many iterations of data collection, analyses and further data needs.Mortality and biomass indicators have been reviewed and visualized, preparing for a future workshop on the evaluation of eel management plans (WKEMP). Spatial overviews and temporal trends show a lack of data for many regions and no evidence yet of a general improvement in stock status for regions with data. Overall silver eel escapement remains low and mortalities high. Doubts remain about the consistency of indicators across countries. The information provided on data and methods used for assessment are not available or sufficiently detailed to ensure transparency and reproducibility of estimates. These limitations and the incomplete reporting impair the use of these data to inform on the status of the stock at a larger scale.A review on the effects of contaminants (in a broader sense: spawner quality) on the reproductive capacity of eel highlighted this as an important, but a frequently lacking, aspect of stock assessment. Monitoring of silver eel quality should be considered as part of new or existing programmes.WGEEL supports the findings WKFEA and the suggested roadmap and agreed to implement the necessary steps towards achieving it. This implies further exploration and analyses of existing as well as the systematic collection of additional data. Implementation will require concerted data collection and assessment, which will require additional support.In summary, the working group has focused on exploring and analysing the data collected in the WGEEL database for their potential use in stock assessment. This included identifying gaps in the available data, defining data requirements for specific analyses in future and developing procedures for the analysis of these data. Furthermore, the group reviewed the effects of contamination on the reproductive potential of eels and renewed their recommendation to consider these in the assessment of effective spawning-stock biomass.

The Joint EIFAAC/ICES/GFCM Working group on eels (WGEEL) met from September 6–9 and 12–20 September 2022 in Toombridge, Northern Ireland, to provide the scientific basis for the ICES advice on fishing opportunities and conservation aspects for the European eel and address requests from EIFAAC and GFCM.WGEEL assessed the state of the European eel and its fisheries, collated and analysed biometric data, reviewed and summarized available data on eel quality, further identified issues specific to the Mediterranean region, discussed the use of landings data for the assessment (following WKFEA) and reported on any updates to the scientific basis of the advice, new and emerging threats or opportunities.The recruitment of European eel declined markedly from 1980 to 2011. The glass eel recruitment compared to that in 1960–1979 in the “North Sea” index area was 0.5% in 2022 (provisional) and 0.6 % in 2021 (final). In the “Elsewhere Europe” index series it was 9.7 % in 2022 (provisional) and 5.5% in 2021 (final), based on available data series. For the yellow eel data series, recruitment for 2021 was 19% (final) of the 1960–1979 level; the 2022 data collection for yellow eel is ongoing. Time-series from 1980 to 2022 show that glass eel recruitment remains at a very low level.Analyses of data series on yellow or silver eel abundance (162 series analysed) and grouped biometric data were re-run this year and show the potential of the yellow and silver eels’ series to improve the stock assessment. A graphical analysis of the new biometric data integrated in the database, 1.2 million individual data and 4908 grouped data (combining length, weight and age data), was carried out to identify future analyses and information that might be missing. To identify the potential of Length-Based Models for stock assessment, a preliminary overview of the models, the input needed and of the assumptions was realised.A collation and integration of available data relating to eel quality – lipid content, parasites and virus, and contaminants - was carried out and examples of analyses and visualisation presented. A review of recent publications relating to eel quality was carried out. Recommendations for improving submission and harmonisation of relevant data, and using eel quality in the context of stock assessments are proposed.Available landings data was reviewed and scoped with potential methods for their use in the assessment of the European eel in preparation of a workshop foreseen in the WKFEA roadmap. Currently, landings data cannot be included in the assessment but follow up work for their use in a potential spatial assessment approach is recommended.In summary, besides updating recruitment time series, further progress was made in collating and analysing individual biometric data and eliciting there use in future assessment, particularly for a spatial assessment approach. Significant progress was made towards utilizing data on eel quality but its use in the assessment is currently data limited.

Controlled Source Electromagnetics (CSEM) technology has been used in the exploration for hydrocarbon reservoirs. It consists of an electric dipole source which is towed horizontally 30-50 m above the seabed or 10 m below the surface. As the electromagnetic (EM) signal propagates through the subsurface it may affect marine organisms that are electro- or magneto-sensitive. A device simulating these conditions (corresponding to three different exposure levels, low, strong, near field) was built to test the effect of EM on marine organisms in laboratory conditions.) Sandeel (Ammodytes tobianus) adults were filmed during a 15-minute near-field EM exposure but showed no significant changes in their behavior, nor any increased mortality. Haddock juveniles (Melanogrammus aeglefinus) were first exposed for 15 minutes to either one of the three EM levels then filmed and tested for magnetic orientation. None of the treatments caused mortality in fish. Juvenile haddock showed significant orientation according to the magnetic field but only after exposure to low and strong EM fields. They also showed a significantly reduced swimming speed following exposure to EM with intensities equivalent to distances of 100 (strong) and 1000 m (low) from the source with an average reduction in speed of 24%. Mean instantaneous swimming velocities of haddock decreased from 1.18 pixel/s (control) to 0.86 and 0.80 pixel/s after exposure to low and strong field levels respectively (GLM estimates), representing speed reductions of 27% and 32% after exposure to each respective level. Changes in swimming speed may affect dispersal of juveniles. However, it is unknown whether the decrease was a physiological or behavioural response. Therefore, it is not possible to make unequivocal conclusions about detrimental effects of CSEM at the population level.

Parasitic salmon lice cause great economic losses in the aquaculture of Atlantic salmon and rainbow trout. It also has a significant impact on wild populations of salmonids, particularly sea trout in areas with aquaculture activity. Several pharmaceuticals have been used for treatment of salmon lice infestations, but over time the lice have developed resistance to these treatments, and there is a growing concern regarding the environmental impact of chemical and pharmaceutical treatments on non-target organisms. Consequently, there has been a strong incentive to find alternative methods for de-lousing. The use of cleaner fish, which pick lice from the skin of infested salmonids, has become an important tool to fight lice. Lumpfish and several species of wrasses are used as cleaner fish. There are extensive fisheries for wrasses in the UK, along the Swedish west coast and in Norway. In addition, there is aquaculture of ballan wrasse and lumpfish in Norway, and lumpfish in the UK and Iceland. The fisheries and use of cleaner fish have evolved relatively fast, whereas scientific data collection, as well as the development of a regulatory framework, has lagged behind. Challenges linked to poor welfare, transmission of diseases and changes in the genetic structure of local populations as a result of translocations have raised questions regarding the sustainability of the current cleaner fish practice. Both ballan wrasse and lumpfish are relatively new as farmed species, and as new species in aquaculture, there are knowledge gaps that must be filled. Research on different aspects for each of the two species has recently increased to address problems and prepare the fish for a life as cleaner fish in sea cages. There is also an increase in research that aims to increase survival and welfare of cleaner fish. There is still a way to go, but information from farmers who have good results show that it should be possible to achieve improvement. A wide range of research projects and studies have been initiated in Scandinavia and the UK over the last decade. In order to facilitate a more rapid spread and implementation of good management solutions that are based on knowledge of the species, it is therefore important that scientists and regulating authorities in different institutions and countries have a common knowledge-base and are collaborating efficiently. This report presents the state-of-knowledge on the biology of cleaner fish, the challenges regarding environmental impacts of fishing, translocation and how management have dealt with the fisheries in the Nordic countries. The development and challenges related to the use and welfare of cleaner fish in captivity are presented and discussed. Based on our shared expert knowledge, we hopefully provide management recommendations on how the fisheries and use of cleaner fish can become more sustainable. A sustainable fishery should allow the target species to replenish and have no long-term or permanent negative changes on ecosystem diversity, function, or productivity. A sustainable practice should minimize the harm and death of cleaner fish, as well as escapement and the associated risks; including transfer of new diseases to new species and areas, and irreversible genetic changes in the wild populations that reduce fitness or adaptability. The report also identifies data gaps that may be filled with future, hopefully collaborative, research or monitoring activities. Although there is an active collaboration between Swedish and Norwegian cleaner fish researchers there is still a considerable potential for improvement through exchange of knowledge and experiences between scientist and managers in Norway, Sweden and the UK, as well as with those in other countries with developing or emerging fisheries for wrasses, like Denmark.

Salmon lice cause economic losses in salmonid aquaculture. The use of cleaner fish has become an important tool to fight lice. Lumpfish and several species of wrasses are used. There are extensive fisheries for wrasses, and aquaculture of ballan wrasse and lumpfish. Fisheries and use have evolved fast, but the development of a regulatory framework has lagged behind. Challenges linked to poor welfare, diseases and changes in the genetic structure have raised questions on the sustainability of the current practice, and The Norwegian Food Safety Authorities stated that if the welfare is not improved and the effect of cleaner fish better documented, the use can be reduced or terminated. This will have implications for the Swedish and potential future Danish fishery. This report presents the state-of-knowledge on biology, fisheries and how management have dealt with the fisheries and use.