Working Group on the Integrated Assessments of the Barents Sea (WGIBAR)

The Working Group on the Integrated Assessments of the Barents Sea (WGIBAR) conducts and develops integrated ecosystem assessments for the Barents Sea.In this report the group updated and extended historical time-series used for the integrated as-sessments. New spatial time-series for mesoplankton and 0-group fish were added to the existing time-series. Trend analysis was performed and the application of ecosystem models to assess-ment of the Barents Sea ecosystem was discussed. The annual report “The state and trends of the Barents Sea ecosystem” was updated. This provides information on the status and changes in the Barents Sea ecosystems for the Joint Russian-Norwegian Fisheries Commission, the Joint Russian-Norwegian Environmental Commission, the Norwegian Ministry of Climate and Envi-ronment.The group discussed the current state and changes of the Barents Sea ecosystem and concluded that:• The Barents Sea has become colder since 2015–2016, and the cooling continued from 2018 to 2019. However, the air and water temperatures are still typical of warm years. Mesozooplankton biomass in the Barents Sea in autumn 2019 was approximately the same as in recent years, and krill biomass has shown an in-creasing trend in recent decades. Temperatures in 2020-21 are expected to de-cline slightly but will remain relatively high; the plankton are anticipated to therefore provide good feeding conditions for planktivorous consumers.• In 2019, total biomass of pelagic fish in the Barents Sea was estimated to be at the lowest level in the last 20 years. The main demersal fish stocks in the Barents Sea are in a healthy state and at a level at or above the long-term mean. Diet composition of cod has been relatively stable in recent years. The stock of north-ern shrimp is relatively stable in the last years. The snow crab population is still spreading, and its abundance is increasing in the Barents Sea.• The white-beaked dolphin was the most common species of marine mammal in 2019 during the ecosystem survey. Summer abundance of minke whales and humpback whales in the Barents Sea has increased recently.• The main stocks are fished sustainably, without violations of fisheries regula-tions. Concentrations of most contaminants in fish and crustaceans in the Bar-ents Sea are relatively low in comparison to other sea areas. The amount of plas-tic and other litter in the sea is also relatively low. Levels of the anthropogenic radionuclides Cs-137, Sr-90 and Pu-239,240 in seawater, sediments, fish and sea-weed are currently low.The WGIBAR provides background ecosystem information on stock development of relevance to assessment expert groups. This report also identifies vulnerable and valuable areas in the Bar-ents Sea.