An ecosystem-based management of human activities in the Barents Sea, as described in the management plan, requires an ongoing assessment of the ecosystem. Important issues are pollution, safe seafood, acute pollution and biodiversity.
Massive fisheries, increasing maritime transport and exploration, and oil and gas production represent a danger to the environment. We also face increased fishing activities and tourism in the Arctic. This means new and highly demanding challenges, especially to provide reliable environmental forecasts to support search and rescue operations.
The ecological quality of an ecosystem includes biological, physical and chemical factors, including the result of human-made influence. The biological and physical elements in ecosystems affect each other directly and indirectly. This requires a holistic ecosystem-based management, significantly different from a sector-based management.
In order to understand the ecosystem, it is especially important to identify key species, the driving forces in the processes, and to understand the relationships between these species and the other parts of the ecosystem.
The Barents Sea is restricted to the west of the Norwegian Sea and the east of Novaya Zemlya. The sea is situated on the continental shelf between 70 ° N and 82 ° N, from the Norwegian coast in the south to the border on the Arctic Ocean in the north. The area is approximately 1.6 million km2. The average depth is about 230 meters and varies from large areas with about 100 meters to the deep grooves of approximately 400 meters.
The ecosystem is affected by the polar front, where cold arctic water masses meet warm Atlantic and costal water currents. This current system in the Barents Sea is influenced by the sea bed, where deep grooves and banks form barriers to the water masses.
Monitoring an area the size of the Barents Sea and the waters off Lofoten is a demanding task. It requires functional "surveillance platforms” like satellites, aircraft, ships, small boats, automated stations to collect data, and time-limited projects (platforms) usually linked to specific issues.
Successful management of our marine ecosystems demands a "toolbox" of approaches and models, providing insight from different ecosystem perspectives and levels. Even with a well-stocked toolbox adapted to our seas, we cannot monitor all elements at all time.
Ecosystem functionality can be described by the transport of biomass through the food chain, from primary producers in the form of phytoplankton in the bottom of the chain, to top predators such as marine mammals, seabirds, and humans.
The bottom fauna constitutes a major biomass. The amount of biomass traded in this system is unknown, although in the past few years major efforts have been made to describe this part of the ecosystem.
A clear increase of temperature in the Barents Sea has been observed over a long period of time. This affects the ice. In 2007 the ice cover was generally much thinner than the long-term average. The ice cover in November was the lowest since 1951. Last year’s observations show that the temperature has dropped and that the ice cover now is thicker than the two preceding years.
The largest portion of total primary production during the year, according to the models, occurs in the warm, south-western parts of the Barents Sea. Biomass is transported further into the Barents Sea via grazing zooplankton and further up the food chain.
Despite the fact that half of the produced phytoplankton ends up on the seabed, we have no evidence yet linking the primary production to benthic animals and benthic community.
In 2008, there was relatively low inflow of Atlantic water in spring, especially in February-March and May-June. Less phytoplankton is indicated, but whether this has contributed to the observed reduction in the zooplankton biomass in 2008, is hard to tell.
An almost inverse relationship between capelin and zooplankton is observed. The variation in zooplankton biomass is reflected in variations in the capelin population.
It has been a period of massive overfishing of cod, but this unregulated, unreported and illegal fishing is now significantly reduced. Cod population estimates are now at the maximum level of indices since 1995 and 1998.
Measurements of sea birds in 2008 confirmed previous signals of a significant nesting failure of many seabird colonies along the coast from Lofoten to Finnmark. Several seabird populations in this area have been in decline for some time. This may indicate lack of food in parts of the ecosystem. This issue is examined further in this report. Lack of food may in turn affect shellfish, fish and marine mammals. Colonies of seabirds are often linked to pelagic fish and zooplankton. Changes in nesting populations and youth production may indicate changes in the biomass in areas close to the various colonies.
The distribution of marine mammals appear to be linked to specific prey: Humpback, minke and fin whales are associated with spawning mature capelin and polar cod, while the white beaked dolfin is associated with younger capelin and blue whiting.
New knowledge about the relationship between cod, herring and capelin helps us customize the management in relation to
• the overall effect that temperature fluctuations have on biological diversity
• the importance of the quantitative relationships between key species
• the impact of fisheries
The Barents Sea is an important growth and harvest areas for Norwegian seafood and long transported pollution may be harmful. However, the present level of pollution is well below the limits that are set.