ALBERT

Description: The increasing CO2 concentration in the atmosphere caused by burning fossil fuels leads to increasing pCO2 and decreasing pH in the world ocean. These changes may have severe consequences for marine biota, especially in cold-water ecosystems due to higher solubility of CO2. However, studies on the response of mesozooplankton communities to elevated CO2 are still lacking. In order to test whether abundance and taxonomic composition change with pCO2, we have sampled nine mesocosms, which were deployed in Kongsfjorden, an Arctic fjord at Svalbard, and were adjusted to eight CO2 concentrations, initially ranging from 185 μatm to 1420 μatm. Vertical net hauls were taken weekly over about one month with an Apstein net (55 μm mesh size) in all mesocosms and the surrounding fjord. In addition, sediment trap samples, taken every second day in the mesocosms, were analysed to account for losses due to vertical migration and mortality. The taxonomic analysis revealed that meroplanktonic larvae (Cirripedia, Polychaeta, Bivalvia, Gastropoda and Decapoda) dominated in the mesocosms while copepods (Calanus spp., Oithona similis, Acartia longiremis and Microsetella norvegica) were found in lower abundances. In the fjord copepods prevailed for most of our study. With time, abundance and taxonomic composition developed similarly in all mesocosms and the pCO2 had no significant effect on the overall community structure. Also, we did not find significant relationships between the pCO2 level and the abundance of single taxa. Changes in heterogeneous communities are, however, difficult to detect, and the exposure to elevated pCO2 was relatively short. We therefore suggest that future mesocosm experiments should be run for longer periods.

Description: This report presents a review of the research knowledge and gaps on fish populations, fisheries and linked ecosystems in the Central Arctic Ocean (CAO). The CAO comprises the deep basins of the Arctic Ocean beyond the shelf break, which largely overlap with the High Seas of the Arctic Ocean, i.e. the marine areas outside the Exclusive Economic Zones (EEZs) of the Arctic coastal nations. The authors of the report are members of the European Fisheries Inventory in the Central Arctic Ocean (EFICA) Consortium. This study was funded by the European Commission as an EU contribution to the international cooperation within the Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean. The report contains desk-based research, using scientific research data bases as well as any available research performed by the EFICA Consortium partners and EU institutions or others. In Chapters 2-8 the authors review the literature and identify specific knowledge gaps. The gap analyses involve comparisons of actual knowledge with desired knowledge on the fish stocks of the CAO to be able to evaluate possibilities for future sustainable fisheries in the area. Chapter 1 is an introductory chapter, and Chapter 9 presents a holistic gap analysis based on Chapters 2-8 and recommendations for research priorities and the next steps. The critical gap analysis highlights that the knowledge gaps for the CAO are enormous and obstruct any quantitative analyses of its fish stocks. This agrees with the conclusions from the Fifth FiSCAO Report (FiSCAO 2018). While data for the physical environment in the CAO (oceanography, bottom topography and ice-cover dynamics) would be sufficient for fish stock modelling and assessment, there is a massive lack of biological and ecological data. The CAO is not a closed system and some aspects of the shelf seas are of high relevance for the CAO, notably connectivity of fish stocks and fish species moving north with climate warming. Scientific research and monitoring programs are established in the shelf seas, and new data are constantly being produced. Fish stock data are available from scientific projects and monitoring programs for some of the shelf seas (Barents Sea, Bering Sea, and to a lesser extent for the Beaufort Sea and the Chukchi Sea). Data exist also for the Russian shelf seas (Kara Sea, Laptev Sea, East Siberian Sea), but these data are not internationally available, while for the areas north of Canada/Greenland data are missing; they do not exist because of the severe ice conditions there. More data from all shelf seas may be hidden in reports that are not publicly accessible. We recommend to make current knowledge generally available by translating key publications and identification of valuable data reports. Research priorities comprise the collection and analysis of primary data in the CAO, and – to a limited extent – from adjacent waters through collaborations with other Signatories of the Agreement (e.g. on population genetics). Further research priorities include an evaluation of ecosystem vulnerability, social-ecological analyses, i.e. recognizing the close and often complex interactions between humans and nature, and recommendations for governance of the CAO. Fulfilling the 14 specific research priorities mentioned in Chapter 9 to “sufficient knowledge available” could enable the potential, future application of an Ecosystem Approach to Management for the CAO.

Description: As a result of global warming, the marine ecosystem around the North Pole, the Central Arctic Ocean (CAO), is in fast transition from a permanently to a seasonally ice-covered ocean. The sea-ice loss will enable summer access to the CAO for non-icebreaking ships, including fishery vessels, in the near future. However, the lack of knowledge on the CAO ecosystem impedes any assessment of the sustainability of potential future fisheries in the CAO. Taking a precautionary approach, nine countries and the EU established in 2021 the Agreement to Prevent Unregulated High Seas Fisheries in the Central Arctic Ocean, which a.o. includes mapping and monitoring of the CAO ecosystem before any commercial fishery is initiated. To reduce the existing lack of knowledge, the EFICA Consortium participated, together with ca. 250 on-board scientists, in sampling and data collection of ecosystem data during four legs of the international MOSAiC expedition in 2019-2020. This report describes the field work performed by the EFICA scientists using water-column acoustics, deep-sea video recording, and fish and eDNA sampling for targeting zooplankton and fish. Further ecosystem data (physical, chemical and biological) were collected by the EFICA scientists in collaboration with other scientists on-board. Together with this report, a metadata database containing lists of all collected samples and data that are relevant for future fishery assessment studies was delivered to the European Commission.