The ecoregion remains relatively clean, with low pollution levels. The contaminating compounds in the ecoregion originate from three sources: coastal sources, sources from outside the ecoregion, and from the local oil and gas industry.
The pollutants likely to be having the greatest effects on the biota are persistent organic pollutants (POPs) and heavy metals; the major sources of these are found outside the ecoregion. In general, the levels of most POPs are declining in the Arctic, indicating reduced primary emissions.
Both toothed and baleen whale are highly migratory species, and therefore accumulate contaminants along their migratory routes. Toothed whales in general are particularly prone to the accumulation of high levels of not only POPs, but also heavy metals, due to their high trophic level and generally low capacity for metabolization of pollutants. Killer whales (Orcinus orca) are considered particularly vulnerable, and seal-eating individuals in the eastern part of the Norwegian Sea have been shown to have levels of POPs and mercury above thresholds for health effects. In hooded seals, levels of POPs have been shown to be below known threshold levels for effects on reproductive capacity and the immune system, but above levels for effects on thyroid hormone levels, which may affect growth. High levels of POPs have been found in pilot whales (Globicephala melas) and white sided dolphins (Lagenorhynchus acutus) around the Faroe Islands, and in pilot whales, threshold levels for liver damage are exceeded for mercury, this is likely to be similar in the Norwegian Sea. The effects on pollutants on seabirds have not been studied sufficiently in the Norwegian Sea ecoregion. Studies just outside the ecoregion, however, indicate that POP concentrations may present health issues in glaucous gull (Larus hyperboreus) in Svalbard, and adverse population effects in common eider (Somateria mollissima) on Store Grindøya when combined with other stressors. Pollution levels in the major pelagic fish stocks in the Norwegian Sea are fairly low.
The release of pollutants in produced water from petroleum activities (oil releases to the sea, phenols, PAHs, radioactive compounds, etc.) are fairly stable over time; in some cases, their release is slowly rising and the organic acid content is declining. Haddock (Melanogramus aeglefinus) caught northwest of Kristiansund and at the Halten Bank have been found to have levels of DNA adducts, a measure of exposure to PAHs, similar to those seen in the North Sea. A recent review in the North Sea concluded that fish and mussels caged close to offshore produced water discharges show mild acute effects, and petrogenic bile metabolites in caged fish show exposure 10 km from produced water discharges.
Concentration of contaminants in coastal areas are related to local human activities. Increased activities in the aquaculture sector have caused increased emissions of copper along the coast of western Norway but it is unclear whether this is spread to the open parts of the Norwegian Sea. Input of contaminants from river run-offs to coastal areas is negligible.
