The state and trends of the Barents Sea ecosystem in 2019 - Summary

Photo: Thor S. Larsen, Norwegian Polar Institute

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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 high levels of demersal fish stocks, reduced fishing pressure and warm conditions.

Ecosystem state: The Barents Sea experienced warming with a record warm temperature condition in 2016. Since that the Barents Sea has become colder and the cooling continued in 2019. However, the air and water temperatures are still being typical of warm years.

The mesozooplankton and krill biomass was slightly higher than in recent years most likely due to low biomasses of planktivorous consumers. The total biomass of pelagic fish (capelin, polar cod, young herring and blue whiting) was at the lowest level in the last 20 years.

Most of the main demersal fish stocks (cod, haddock, Greenland halibut, Sebastes mentella, long rough dab, saithe) are in a healthy state and at a level at or above the long-term mean. The exception is S. norvegicus, which is still depleted. Diet composition, of cod has been relatively stable in recent years. Megabenthos biomass and abundance were at the long-term mean level. The stock of the northern shrimp is relatively stable in the last years. The snow crab population is still increasing and spreading over larger area.

The Barents Sea is important feeding area for habiting and visiting sea birds and marine mammals. In step with warming, birds follow the retreating sea ice and showed northern redistribution (centre of mass for auks, gulls and fulmar moved 150-300 km further north) in recent decade.

Number of individuals and species of marine mammals increased during last decades. The white-beaked dolphin was the most common species in 2019 during the ecosystem survey. The summer abundance of minke whales and humpback whales increased and were about 70,000 and 4,000, respectively.

Human pressure: The assessment for several commercial important stocks indicated that the stocks has been fished sustainably and has remained well above precautionary reference limits. The present (2016–2021) minke whale quota is considered precautious, conservative, and protective for the minke whale population in the Northeast Atlantic. The AIS tracking of vessel, 2012 to 2019, indicated decreased fisheries effort in the northern area, while an increase in passenger vessels to the Svalbard area.

Anthropogenic litter were observed at each fours (pelagic) and each second (bottom) stations during the ecosystem survey, and plastic dominated among all observations. Amount of plastic and other litters are relatively low in comparison to other sea areas.

Concentrations of most contaminants in fish and crustaceans in the Barents Sea are relatively low in comparison to other sea areas. Levels of the anthropogenic radionuclides Cs-137, Sr-90 and Pu-239,240 in seawater, sediments, fish and seaweed in the Barents Sea area are currently low. In recent decades, there has been a slow decrease in the levels of most anthropogenic radionuclides in the Barents Sea.

Expected changes in the coming years: Oceanic systems have a “longer memory” than atmospheric ones. According to the expert evaluation, the Atlantic water temperature is expected to decline slightly but remain typical of warm years.

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.

Most of the commercial fish stocks in the Barents Sea are at or above the long-term mean level. The exceptions are capelin, polar cod and gold redfish (Sebastes norvegicus). Concerning shellfish, the shrimp abundance has increased in 2018-2019 and is close to the highest observed. The abundance and distribution area of snow crab is also increasing, the stock of the red king crab is relatively stable in the last years.

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