The state and trends of the Barents Sea ecosystem in 2020 - Summary

Photo: Trine Lise Sviggum Helgerud, NPI.

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Since the 1980s, the Barents Sea has gone from a situation with high fishing pressure, cold conditions and low demersal fish stock levels, to the current situation with relatively high demersal fish stock sizes, reduced fishing pressure and warm conditions. The current situation is unprecedented, and the Barents Sea appears to be changing rapidly. The main points for 2020 are:

The state and trends of the Barents Sea ecosystem in 2020

Ecosystem state: BS has experienced a warming trend since 1990s, while becoming colder after 2015–2016. Temperatures in 2020 are still being typical of warm years. Temperatures in 2021-2022 are expected to decline slightly but will remain relatively high.

The spatial distribution of mesozooplankton biomass across the Barents Sea displayed a typical pattern with high levels in southwestern and northern regions, and relatively low levels in central areas. Compared to the preceding 5-year averages, mesozooplankton biomass in 2020 was lower in the western, central, and eastern Barents Sea and slightly higher south and east of Svalbard. Krill indices of biomass and abundance have shown increasing trends over recent decades.

The 2020-year classes of capelin, redfish and polar cod were strong, while those of cod, haddock and herring seem to be weak. In 2020, the total biomass of pelagic fish increased due to strong recruitment of 1-year old capelin and polar cod. Most of the main demersal fish stocks (cod, haddock, Greenland halibut, beaked redfish, long rough dab, saithe) in the BS are in a healthy state and at a level at or above the long-term mean. The exception is the golden redfish stock, which is still depleted. Cod food consumption in 2020 was close to the level of 2019. Capelin is still the most important food item for cod. Importance of euphausiids, hyperiids, polar cod and snow crab has increased in cod diet, while importance of haddock, shrimp and herring has decreased. The stock of the northern shrimp is relatively stable.

The snow crab population is still spreading, and its abundance is increasing in the Barents Sea. Aggregations of the red king crab have been shifted eastward and north-eastward. The distribution of megabenthos shows relative stable large-scale patterns, a fall in biomass in 2020 can be the result of the fall in temperature during 2013-2014.

The white-beaked dolphin was the most frequently observed species of marine mammals in 2020 during the ecosystem survey. The abundance of minke whales and humpback whales in the BS are increasing, and they generally overlap with capelin distribution.

Human pressure: Concentrations of most contaminants in fish and crustaceans in the Barents Sea are relatively low in comparison to other sea areas and the levels are either stable or decreasing.

The contaminant load in polar bears from Svalbard is dominated by fat-soluble organic pollutants, their degradation products (metabolites) and perfluorinated compounds, while levels of new commercial chemicals are low. Levels of radioactive pollution in the Barents Sea are low and generally decreasing.

The levels in fish and seafood is far below the maximum permitted level for radioactive cesium in food. Amount of plastics and other litter in 2020 was close to what has been found earlier.

Expected changes: According to the expert evaluation based on the analysis of the internal structure of the long-term variations in hydrometeorological parameters, over the next two years (2021–2022), temperatures are expected to decline slightly but will remain relatively high.

Due to high temperatures and low sea-ice extent in recent years, the ice coverage of the Barents Sea is expected to remain below normal. The proportion of first-year ice and young ice will continue to increase and species that are associated with sea ice for most of their life cycle are at risk of extinction or being greatly reduced. Earlier ice melting, later freeze-up and a more transparent ice cover will further reduce the relative contribution of ice algae to total primary production. Krill biomass will most likely continue to increase due to larger contribution from M. norvegica.

The planktivores fish stocks such as capelin and polar cod will most likely increase in 2021 due to strong 2019-2020-year classes. The abundance of herring is expected to decrease from 2020 to 2021 as the relatively strong year class has now left the Barents Sea. The haddock stock is expected to decrease. For cod and Greenland halibut, a slight decrease in total abundance.

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