Ecosystem overviews

Barents sea ecosystem overview

Our ecosystem overviews use risk-based methods to identify the main human pressures and explain how these affect key ecosystem components in each ICES ecoregion
​​​​​​​The Barents Sea is one of the shelf seas surrounding the Polar basin. It connects with the deeper Norwegian Sea to the west,
the Arctic Ocean to the north, and the Kara Sea to the east, and borders the Norwegian and Russian coasts to the south. The
500 m depth contour is used to delineate the continental slope to the west and the north. To the east the Novaya Zemlya
archipelago separates the Barents Sea and the Kara Sea. The Barents Sea covers an area of approximately 1.6 million km2. It has an average depth of ca. 230 m, and a maximum depth of about 500 m at the western end of Bear Island Trough. Its topography is characterized by troughs and basins, separated by shallow bank areas.

Key s​ignals
  • The last decade was the warmest on record, with the highest temperatures in 2007 and 2012. Spatial distribution of zooplankton and several fish species has extended northwards in the ice-free period o​ver the last decade. Although there has been a decrease in mesozooplankton biomass (2012 to 2014) and a declining trend in the proportion of large mesozooplankton, the biomass/productivity of plankton has remained relatively stable in recent years compared to the 1980s and 1990s. Capelin Mallotus villosus is the major grazer of zooplankton in the Barents Sea and its high biomass (> 3 million tonnes) over the last seven years has contributed to a high predation pressure on plankton. There is evidence of reduced growth in capelin.​
  • The decrease of mesozooplankton in Arctic waters of the Barents Sea has influenced the distribution and abundance of Arctic species such as the planktonic hyperiid Themisto libellula and polar cod, with a decrease in the biomass of T. libellula and a strong decline and recruitment failure of polar cod. Copepods and T. libellula are the most important prey of polar cod and decrease in their consumption by polar cod has been observed since 2010.
  • The North Atlantic Oscillation (NAO) and its variation affects the Barents Sea fundamentally. Part of this influence is through ice coverage. For example in 2014, north-westerly winds resulted in an increase in ice cover during summer (the widest summer ice cover for 20 years) as a result of the winter NAO index moving to a positive value and north-westerly winds prevailing over the Barents Sea. In contrast, ice cover in 2012 was the lowest ever recorded.
  • ​Fisheries landings have decreased since the peak of 1500 thousand tonnes in 2011. In 2014, catches of about 1300 thousand tonnes were reported from the stocks of capelin, cod (Gadus morhua), haddock (Melanogrammus aeglefinus), redfish (​Sebastes Spp.​)​, Greenland halibut (Reinhardtius hippoglossoides), and deep-water (northern) shrimp​ (Pandalus borealis). A fisheries management plan set the upper limits for landings in the reg​​ion.
  • The cod stock has extended towards the north further impacting the foodweb, e.g. through predation on polar cod. Between 1980 and 1999, the ratio of pelagic to demersal fish fluctuated greatly; currently the ratio is more stable. The change in trend is caused by the increased biomass of haddock and cod. Currently the biomass of the main demersal stocks is about equal to the biomass of pelagic stocks. As the cod stock has increased, the condition (blubber thickness) of the two other main fish predators in the Barents Sea (minke whales Balaenoptera acutorostrata ​and harp seals Pagophilus groenlandicus) has declined.
  • Snow crabs Chionoecetes opilio, an invasive species, are increasing in abundance and expanding westwards. Red king crabs, another invasive species, are also established in the ecoregion.


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Barents sea ecosystem overview

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