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

The third meeting of the Working Group on the Integrated Assessments of the Barents Sea (WGIBAR) was held in Murmansk on 22–25 February 2016. A report on the Barents Sea ecosystem state was prepared (Annex 5). Since the 1980s there has been a warming trend, reduced fishing pressure, and increased biomass of several mostly boreal spe-cies. The current situation is unprecedented. The main findings for 2015 are:• The atmosphere and ocean temperature was higher than the long-term mean (1951–2010) and higher than 2013 or 2014. The ice coverage was lower than normal and lower than 2013 or 2014. The seasonal ice maximum was observed in February, two months earlier than usual.• The mean biomass of mesozooplankton was somewhat higher than in 2014. Biomass was highest in the western Barents Sea (BS) in the area of inflowing Atlantic water, and was lower in the northeastern Barents Sea compared to 2013–2014.• The biomass of krill, mostly found in warmer water remained higher than the long-term mean and was higher than in 2014. Hyperiid amphipods (colder water), are at low levels.• The capelin biomass decreased to a low level. Causes of capelin decline are an increase in natural mortality (mainly due to high cod consumption), low growth, and relatively low recruitment.• Polar cod is at its lowest level since 25 years. There is no fishing on polar cod, but natural mortality appear to be very high. Increased consumption of cod has contributed to increase the natural mortality. In the last three years the recruitment of polar cod has been very poor, possibly due to changes in spawning habitat.• Cod stabilized at three million tonnes, well above the long-term mean (1946-). Haddock is declining slightly, but the stock size is at present about 1 mil-lion tonnes, twice the long-term mean (1950-).• Related to the retreating sea ice, new areas of sea are open for human activ-ity. A baseline mapping of benthic species vulnerable to trawling was pub-lished in 2015. This map should be of relevance to management of human activities.• The distribution area of the invasive snow crabs continued to increase, but the impact and development of this stock in future are unknown.• Due to the low levels of polar cod and capelin, cod and other piscivores have to compensate by feeding on other prey, which has potential large conse-quences for the foodweb.