Report No. 37 to the Storting (2008-2009)

Integrated Management of the Marine Environment of the Norwegian Sea— Report No. 37 (2008 – 2009) to the Storting

To table of content

3 Ecosystems and the status of biological diversity and habitats in the Norwegian Sea

3.1 The ecosystems of the Norwegian Sea

Oceanographic conditions

The management plan area covers approximately 1.17 million km2, stretching from shallow bank areas on the continental shelf (50–300 metres) to deep-water areas down to 4 000 metres. The average depth of the Norwegian Sea is about 1 800 metres, and it is dominated by two deep-water basins, the Norwegian Basin and the Lofoten Basin, at depths of between 3 000 and 4 000 metres. It is separated from other sea areas further west by the Jan Mayen Ridge and Mohn’s Ridge, which run south and north-east from Jan Mayen.

Figure 3-1.EPS Map of the ocean currents flowing into and out of the Norwegian

Figure 3-1.EPS Map of the ocean currents flowing into and out of the Norwegian Sea

Source Institute of Marine Research/Norwegian Coastal Administration

Current patterns in the Norwegian Sea are largely determined by the seabed topography. The underwater ridge between Scotland and Iceland, which marks the southern boundary of the Norwegian Sea, is generally shallower than 500 metres. Warm, saline Atlantic water flows into the Norwegian Sea along two main paths, between the Faeroe Islands and Shetland, and between the Faeroe Islands and Iceland. The warm water flows northwards into the Barents Sea and the Arctic Ocean, but also spreads more widely into the Norwegian Sea. Cold, less saline water from the Iceland Sea flows into the southern part of the Norwegian Sea. In the south-western Norwegian Sea, the upper water layer is therefore relatively cold, whereas it is relatively warm in the rest of the Norwegian Sea.

Textbox 3.1 Definitions

Ecosystem: a dynamic complex of plant, animal and microorganism communities and their non-living environment interacting as a functional unit.

Kilde: Convention on Biological Diversity (CBD)

Biological diversity: ecosystem, species and intra-species genetic variability, and the ecological relationships between ecosystem components.

Kilde: Nature Management Act

Biological, geological and landscape diversity: includes all diversity that is not largely a result of human influence.

Kilde: Nature Management Act

Alien organism: an organism that does not belong to a species or population that occurs naturally in an area.

Kilde: Nature Management Act

Habitat type: a relatively homogenous environment, including all plant and animal life and environmental factors that operate there.

Kilde: Norwegian Biodiversity Information Centre

The climate of the Norwegian Sea is highly variable, both on a seasonal scale and from year to year. The large interannual variations are to a large extent explained by variations in the temperature of the inflowing Atlantic water, in the volume of cold Arctic water flowing in from the west, and in the heat loss from the sea to the atmosphere. Warm Atlantic water flowing into the Norwegian Sea loses a great deal of heat to the atmosphere, and this is of crucial importance for the mild climate of northwestern Europe. The inflow of warm Atlantic water also keeps the Norwegian Sea free of ice and results in high biological production.

Figure 3-2.EPS Interactions in the marine ecosystem of the Norwegian Sea

Figure 3-2.EPS Interactions in the marine ecosystem of the Norwegian Sea

Source Institute of Marine Research

Ecological conditions

The Norwegian Sea ecosystems, like all natural ecosystems, are constantly changing. This would be the case even without any influence from human activity. Biological production is high in the Norwegian Sea, and biomass is very high. Production is believed to be particularly high in the front zones between current systems. Ocean currents carry small organisms such as phytoplankton, zooplankton, eggs and larvae in and out of the Norwegian Sea.

Sunlight, carbon dioxide (CO2) and nutrients in the water masses provide energy and food for the growth of phytoplankton and seaweeds (primary production), and zooplankton species feed on phytoplankton. Both phytoplankton and to some extent seaweed and kelp also provide food for microorganisms and other grazing species in the food web. Zooplankton species, mainly copepods, amphipods and krill, are a key food source for many fish stocks and marine mammals in the Norwegian Sea. Copepods, including the dominant species Calanus finmarchicus, use the deep-water basins for overwintering and shelter from predators. They are found in surface waters for a short period in spring and summer, when they graze on phytoplankton and spawn, hatch and develop. During the brief, intense spring bloom, there is a huge quantity of planktonic algae in the surface layer. Plankton not only provides nutrition for species in the water column, but also for ecosystems on the seabed. Dead planktonic organisms and remains sink towards the bottom and provide food for organisms that feed on small particles. Plankton is the most important basis for the food chains of the Norwegian Sea.

Figure 3-3.EPS A school of herring, one of the key species in the Norwegian

Figure 3-3.EPS A school of herring, one of the key species in the Norwegian Sea

Source Photo: Erling Svensen

Most species in the Norwegian Sea feed on organisms at several levels in the food web. For example, saithe eat both plankton and other fish, and the largest krill species (planktonic crustaceans) feed on both phyto- and zooplankton. Whales and seals live on both zooplankton and fish, with variations between species. Certain species, for example Calanus finmarchicus and herring, are key species in the Norwegian Sea. Food chains, and probably the productivity of ecosystems, would change considerably if such species were to disappear. C. finmarchicus makes up a large proportion of the total animal biomass in the Norwegian Sea, and is an important element of food chains, for example as food for large fish stocks. Herring are prey for a wide range of species, from cod and saithe to whales and seabirds, and their roe and milt are also important food for fish, several seabird species and a variety of benthic animals and microorganisms.

While current knowledge of the ecosystems in the water masses of the Norwegian Sea is generally good, knowledge of ecosystems on the seabed is much poorer. In general, habitats vary with depth, the underwater landscape and other geological, physical and chemical conditions. The large deep-water basins contain level areas where there is a varied deep-water fauna but a limited biomass. Biological production is high in the shallow bank areas on the continental shelf.

Some areas of the seabed have been surveyed in connection with planning and environmental impact assessment of petroleum activities. This has among other things resulted in the discovery of the Sula coral reef. Information from fishermen on bycatches of corals has also provided useful data for mapping of coral habitats. On the basis of information from all these sources, the Institute of Marine Research has carried out further surveys of selected coral reef complexes.

Coral reefs provide a habitat for many species, and support high biodiversity. At present, little is known about their role in ecosystems, but research is being carried out for example on their importance for fish. Corals also play a role in the CO2 balance in the sea since they deposit carbon as carbonate in their skeletons, but little is known about the importance of this process.

Relatively little is known about other seabed habitats in the Norwegian Sea below the depths to which sunlight penetrates, and about their role in larger-scale ecosystems. These include gorgonian forests, sponge communities, seamounts, mud volcanoes, cold seeps and black smokers. The Håkon Mosby mud volcano is an exception, and extensive studies have been carried out here. Surveys off the Lofoten and Vesterålen Islands under the MAREANO programme suggest that further work in the Norwegian Sea is likely to reveal other little-known habitats on the seabed. Little research has been done on the ecological importance of seabed habitats for life in the water column.

More is known about the ecological importance of seaweeds and kelp forests. These are found on suitable hard-bottom substrates in the coastal zone. Seaweed communities and kelp forests are highly productive areas, and are important nursery and feeding areas for fish and feeding areas for several seabird species.

3.2 Description of ecosystems and status of biological diversity and habitats

Our knowledge of the status of biological diversity and habitats in the Norwegian Sea is most complete for ecosystems in the water column and for fish, seabirds and marine mammals.

There appears to be a slowly declining trend in biomass, the largest proportion of which consists of plankton, in both Atlantic and coastal water in the Norwegian Sea. The most important fish stocks, such as Norwegian spring-spawning herring, blue whiting, Northeast Atlantic mackerel and Northeast Arctic saithe, are at satisfactory levels. On the other hand, stocks of deep-water species – redfish ( Sebastes marinus and S. mentella), Greenland halibut, tusk, ling and blue ling – have declined in recent years. There has also been a decline in the breeding populations of several seabird species that feed in the open sea. This decline has been most dramatic for Atlantic puffin and common guillemot, which feed on pelagic fish species, but a population decline has also been registered for northern fulmar, lesser black-backed gull (subspecies Larus fuscus fuscus) and black-legged kittiwake, which are surface feeders.

In the southern part of the management plan area, the kelp forests are in good condition, but in the northern part they have been severely depleted by overgrazing by sea urchins. However, re-establishment of Laminaria hyperborea has been registered as far north as Vega (Nordland) in the last few years. Both coral reefs in good condition and damaged reefs have been registered. The overall status of coral reefs in the Norwegian Sea is unknown. The same applies to other benthic biodiversity and habitats. The state of the Norwegian Sea environment is generally good.

3.2.1 Zooplankton – description and status

Most of the animal biomass in the Norwegian Sea consists of zooplankton, largely small crustaceans such as the copepod Calanus finmarchicus, pelagic amphipods and krill. Zooplankton, and especially adult C. finmarchicus, are a key food source for fish such as herring, blue whiting, mackerel and saithe. A number of marine mammals that occur in the Norwegian Sea also graze on zooplankton. Most species in the Norwegian Sea feed on organisms at several levels in food chains, and zooplankton are also food for other zooplankton species. For example, the largest krill species eat other zooplankton species as well as phytoplankton.

There appears to be a slowly declining trend in biomass in both Atlantic and coastal water in the Norwegian Sea. Better estimates of plankton biomass are needed.

3.2.2 Benthic habitat types – description and status

Corals form habitats such as coral reefs, coral rubble and gorgonian forests. The coldwater corals in the Norwegian Sea are generally found at depths of 200–500 metres. The reefs that have so far been found on the continental shelf in the Norwegian Sea (see Figure 3.4) include the largest known coldwater coral reefs. These are complex three-dimensional structures that provide suitable habitats for many sessile and free-swimming organisms. Coral reefs support high biodiversity, and the commonest fish species are tusk, ling and redfish. A great deal of work remains to be done on the role of coral reefs in the ecosystem and for the natural resource base.

It has previously been estimated that about 30–50 % of Norwegian coral reefs have been damaged or destroyed by bottom trawling. New discoveries provide a basis for revising this estimate. The protected Røst and Sula reefs are considered to be in very good condition, and the protected Iverryggen reef to be in good condition, but with damage to some parts of the area dating from before it was protected. The reefs in the Træna Deep are also in good condition. Knowledge about the role of gorgonian forests in the ecosystem and their distribution and status is even less complete than for coral reefs.

Sponges can occur in dense communities that are habitat-forming and may have similar ecological functions to those of gorgonian forests. There are known to be sponge communities in parts of the Barents and Norwegian Seas, but there is no detailed information on their distribution. However, sponge communities have been registered in the Tromsøflaket bank area and along the edge of the continental shelf in the Norwegian Sea. Redfish and a rich benthic fauna are often found in areas where there are sponge communities. Little work has been done on the ecological importance of sponge communities, but it is reasonable to assume that they are important for both fish and invertebrates. Sponges are among the groups of particular interest in connection with bioprospecting.

Figure 3-4.EPS Registered coral reefs in the Norwegian Sea

Figure 3-4.EPS Registered coral reefs in the Norwegian Sea

Source Institute of Marine Research

Seamounts are most often found on deep-sea ridges, but there are also isolated seamounts or groups of them on abyssal plains. In the Norwegian Sea, most seamounts are found along the continuation of the Mid-Atlantic Ridge from Jan Mayen and northwards. The fauna associated with seamounts in the Norwegian Sea has not been investigated. However, studies of seamounts in adjacent areas have revealed a rich benthic flora including sponges, bryozoans, tube worms, molluscs, echinoderms and bristle worms. The summits of the seamounts in the Norwegian Sea are at much greater depths (550–2 100 metres) than is usual in other sea areas.

Mud volcanoes: The largest mud volcano in the North Atlantic, Håkon Mosby, lies at a depth of 1 270 metres between Svalbard and the Norwegian coast. Mud and methane gas flow upwards from deeper layers in the volcano and are discharged, supporting an ecosystem containing an assemblage of species adapted to life with no sunlight (including microorganisms and a special group called the Pogonophora or bearded worms). Research is being carried out on the processes taking place in the mud volcano and how methane is metabolised in the ecosystem.

Cold seeps and black smokers are the two main types of vents on the seabed. Cold seeps are places where gases (hydrogen sulphide, methane or other gases) or hydrocarbon fluids are vented from the seabed at the same temperature as the surrounding water. Pockmarks are a type of cold seep found in many places in Norwegian waters, for example the Nyegga area of the Norwegian Sea (see Figure 3.5). In these areas, characteristic food chains may be formed in which bacteria support a wide range of more complex animals such as bearded worms, sea spiders, crustaceans, fish and feather stars.

The Earth’s crust consists of rigid tectonic plates, which move in relation to each other. Where they are moving apart, new crust is formed on the seabed, and this process has given rise to an oceanic volcanic ridge stretching northwestwards from Jan Mayen and between Svalbard and Greeland. Along this ridge, there is volcanic activity in the form of black smokers. Very hot water (400 °C) containing dissolved sulphur and iron and other metals gushes out from these structures. As with cold seeps, bacteria are the first stage in the food chains supported by black smokers. A number of new species and characteristic communities have been found around black smokers in other sea areas. At present, very little is known about these habitats in the Norwegian Sea.

Figure 3-5.EPS Registered seamounts (higher than 1 km) in the Norwegian
 Sea. The Håkon Mosby mud ­volcano and an area
 of cold seeps (Nyegga) are also shown

Figure 3-5.EPS Registered seamounts (higher than 1 km) in the Norwegian Sea. The Håkon Mosby mud ­volcano and an area of cold seeps (Nyegga) are also shown

Source Institute of Marine Research

Seaweed communities and kelp forests: Norway has the largest seaweed communities and kelp forests in Europe, and it is estimated that a total area of about 10 000 km2 along the Norwegian coast is covered by seaweed and kelp. This is about the same as the total area of cultivated land in Norway.

Laminaria hyperborea grows to a particularly large size to form dense kelp forests along the west coast of Norway. Kelp forests are highly productive ecosystems with a rich variety of epiphytic algae, fish and smaller animals. The kelp forests in the southern coastal parts of the Norwegian Sea are dense and productive, whereas those further north have been severely depleted by sea urchin grazing (see Figure 5.4). However, in the last few years re-establishment of L. hyperborea has been registered as far north as Vega. L. hyperborea grows on hard bottom and forms kelp forests from the low-tide level and down to a depth of about 20–25 metres, while individual plants can grow down to a depth of 40 metres in clear coastal waters. Kelp forests are an important habitat for coastal fish species, nursery areas for several fish species, and important feeding areas for seabirds. They are for example important for juvenile gadids (fish of the cod family) and wrasses, and as foraging areas for cormorants, shags and black guillemots during the breeding season.

Knotted wrack is the most important of the seaweed species, and the biomass along the Norwegian coast is estimated at 1.8 million tonnes. The largest stands are found in protected to moderately exposed areas along the coast, down to a depth of about two metres.

Laminaria hyperborea and knotted wrack are the only macroalgae that are used commercially in Norway. They are harvested almost entirely from inside the baseline. Knotted wrack is harvested along the coast from Frøya (Nord-Trøndelag) to the Vesterålen Islands and used in the production of seaweed meal and extract, and the harvest is just under 20 000 tonnes per year. L. hyperborea is harvested from Rogaland to Sør-Trøndelag, and alginate is extracted for use as a food additive and for other purposes. The Institute of Marine Research monitors trends in the status of kelp forests by sampling at fixed sites every year.

Figure 3-6.EPS Fish swimming above a kelp forest

Figure 3-6.EPS Fish swimming above a kelp forest

Source Institute of Marine Research

3.2.3 The most important fish stocks – description and status

TheNorwegian spring-spawning herring stock is migratory, and at certain times of year schools of herring can be found across large parts of the Norwegian Sea. They arrive at the spawning grounds in January/February and spawn on the coastal banks from Egersund (Rogaland) to the Vesterålen Islands between February and April. The main spawning grounds are off Møre og Romsdal and Nordland. Herring require a suitable substrate for spawning, since the fertilised eggs become attached to the substrate. After about three weeks, the eggs hatch and the herring larvae rise to the surface, where they drift northwards with the currents to the main nursery area in the Barents Sea.

The Norwegian spring-spawning herring stock is the largest herring stock in the world, and is the most important fish stock in the Norwegian Sea in both ecological and commercial terms. It provides food for other species at all levels of the food chain. Large quantities of energy are transferred from the open sea to coastal waters with herring roe and milt. Fishing of juvenile Norwegian spring-spawning herring in the Barents Sea is completely prohibited. Herring is also important as food for human consumption. It is rich in oil, and is exported to many different countries.

The total allowable catch (TAC) set for 2009 is more than 1.6 million tonnes, which is the same as the recommended TAC. Norway’s quota is just over 1 million tonnes.

Figure 3-7.EPS On 17 November 2005, the research vessel Johan Hjort registered
 a school of herring off Andenes in the Vesterålen Islands
 that was 5 500 metres long and estimated at 230 000

Figure 3-7.EPS On 17 November 2005, the research vessel Johan Hjort registered a school of herring off Andenes in the Vesterålen Islands that was 5 500 metres long and estimated at 230 000 tonnes

Source Institute of Marine Research

Theblue whiting is a small pelagic gadid, generally found in schools in the mesopelagic zone. It is one of the most numerous fish species in this zone of the Northeast Atlantic. The main spawning area for the Atlantic stock is west of the British Isles, outside the management plan area, but some blue whiting also spawn in the Norwegian Sea, along the edge of the continental shelf northwards towards the Tromsøflaket bank area. The stock is in relatively good condition, but the fishing mortality is too high after several years of catches above the level recommended by the International Council for the Exploration of the Sea (ICES). Recruitment to the stock has been weak since 2005.

Thesaithe is another gadid. It is both pelagic and demersal, and is found at depths of 0–300 metres. The saithe stock north of 62°N is in good condition. Saithe spawn on the coastal banks from the North Sea to the Lofoten Islands in winter, with a peak in February. The most important spawning grounds in Norwegian waters are near the Lofoten Islands, Halten bank, the Møre banks and the Tampen and Viking banks in the North Sea. Eggs and larvae drift northwards with the currents, and young saithe congregate in the coastal zone from Western Norway to the south-eastern part of the Barents Sea. The saithe is the most important predatory fish in the Norwegian Sea. It is often found at high density in areas where the current patterns result in concentration of prey species. Large saithe are believed to be an important predator on herring both along the coast and far out to sea. Low fishing pressure over the last 10 years has had a positive effect on recruitment and stock development. The reproductive capacity of the stock is good, and it is being harvested sustainably. Since herring are an important prey species for saithe, the good condition of the herring stock is presumably contributing to the satisfactory development of the saithe stock.

Themackerel is a fast-swimming, pelagic, schooling species that can undertake long migrations. Mackerel do not spawn in the Norwegian Sea, and development from larvae to juveniles therefore takes place outside the management plan area, but the Norwegian Sea is an important feeding area for the species in summer and autumn. Its feeding distribution in the Norwegian Sea has been expanding in recent years, and the species has been observed north of 75oN. The mackerel stock reached a minimum in 2003, but is now increasing again. The spawning stock has risen from 1.7 million tonnes in 2002 to 2.5 million tonnes in 2007. It is now above the precautionary level, and the stock is classified as having full reproductive capacity. However, ICES considers that the stock is being harvested at increased risk. There is considerable uncertainty about the stock level because of illegal landings, discards and slippage of whole catches or parts of catches. The North Sea component of the mackerel stock is still depleted and needs protection. Mackerel is one of the fattiest fish in this area, and is rich in omega-3 fatty acids.

Northeast Arctic cod and Northeast Arctic haddock are mainly found in the Barents Sea. However, these stocks spawn on and along the edge of the continental shelf in the Norwegian Sea, and eggs and larvae drift northwards along the coast. Their roe and milt, together with herring larvae, are therefore an important part of the diet of other species. Cod has always been one of Norway’s most important export products, and Norwegian stockfish produced from cod is used as an ingredient in cooking all over the world.

The redfish Sebastes marinus is a long-lived, slow-growing species that lives at depths of 100–500 metres on the continental shelf from the North Sea to the Barents Sea, along the coast and in some areas in the fjords. Its spawning grounds are on and along the edge of the continental shelf from Shetland north to Andøya (Nordland), and the most important areas are Storegga (the edge of the continental shelf off Møre og Romsdal), the Halten Bank and off the Vesterålen Islands. Recruitment to the stock has been poor since the early 1990s, and it is now at a historical low, due to the increasingly weak year classes over the last 10 years. This situation is expected to persist for many years, and the S. marinus stock is classified as vulnerable.

S. mentella is also a long-lived, slow-growing species of redfish, which is found at depths of 400–600 metres along the continental slope northwards from Shetland, around Svalbard and in the Barents Sea. The stock also undertakes feeding migrations into the Norwegian Sea at depths of 300–450 metres. The spawning grounds stretch along the edge of the continental shelf from Shetland to the Tromsøflaket bank area. ICES has not defined reference points for the stock, but investigations suggest that the immature component is at a historical low. S. mentellais classified as vulnerable.

The Greenland halibut is a large Arctic flatfish that lives in cold waters. Northeast Arctic Greenland halibut spawn mainly in autumn and winter at depths of 500–800 metres from the Vesterålen Islands and northwards to Bjørnøya and Spitsbergen. Adult fish are found along the edge of the continental shelf from UK waters to Franz Josef Land and in the deeper parts of the Barents Sea. The Greenland halibut is a very valuable commercial species. The stock has been growing slowly in recent years, but is still low. ICES has recommended maintaining a TAC of less than 13 000 tonnes in 2009.

Greater argentine are found in both the Western and the Eastern Atlantic. In the Eastern Atlantic, they occur from the British Isles to Svalbard, in deeper parts of the North Sea, and west to Iceland and the east coast of Greenland. In these areas, they are most commonly found at depths of 200–600 metres. In spring, greater argentine concentrate along the continental slope and in deeper areas of the continental shelf, while at other times of year they are more widely distributed.

Ling and blue ling are two gadids that live above hard or sandy bottom in warm, relatively deep areas of the continental shelf, on the bank areas and in the fjords in the management plan area. They also range from Biscay to Iceland, the Skagerrak and Kattegat and the southwestern Barents Sea. Ling is found mainly at depths of 300–400 metres, but can range between 60 and 1000 metres. Blue ling is found at slightly greater depths. The main spawning grounds are in the North Sea, Storegga, near the Faeroe Islands and on the banks west of the British Isles and southwest of Iceland. ICES bases its advice on registered landings of each country’s catches. In the case of blue ling in the area covered by the management plan, ICES has pointed out that trends in catches indicate that the stocks are seriously depleted. The species is therefore considered to be vulnerable.

Tusk is a demersal gadid species, which prefers rocky bottom on the continental shelf and continental slope at depths of 100–1 000 metres. It ranges from Ireland to Iceland and Greenland, and is also found in the Skagerrak, the western part of the Barents Sea and in the fjords. There are known spawning grounds off the coast of south and central Norway and south and south-west of the Faeroe Islands and Iceland. Tusk is caught together with ling in longlining and as a bycatch. The status of the stock is unknown.

Norwegian coastal cod is of marginal importance in the Norwegian Sea. There are several stocks distributed from Stad at about 62°N to the border with Russia, but about 75 % of the overall stock is found north of 67°N, and therefore outside the management plan area. Coastal cod are found from the kelp zone down to about 500 metres. They spawn in the inner parts of most fjords, in tributary fjord arms of the larger fjord systems, but also further out in the same areas as Northeast Arctic cod.

Atlantic salmon is of no commercial value in the Norwegian Sea, since salmon fishing in the open sea is not permitted. However, this is the most important nursery area for salmon. There are indications that salmon are taken as a bycatch in pelagic trawling in the Norwegian Sea, but there have been few studies of this. Salmon is managed through the North Atlantic Salmon Conservation Organization (NASCO).

Cephalopods are predators that feed on crustaceans, molluscs and fish. Twenty species have been registered in Norwegian waters. The most important species in the Norwegian Sea are the European flying squid ( Todarodes sagittatus) and the boreoatlantic gonate squid ( Gonatus fabricii). Flying squid used to be fished commercially in the Norwegian Sea. The gonate squid is an important prey species for most marine mammals in the area and for many fish species. Juvenile squid that live near the surface are also important for some seabird species. Our knowledge of squid in the open sea, particularly in deep water, is limited.

There are several shrimp stocks and a separate capelin stock in the bank areas around Jan Mayen (and in Icelandic and Greenland waters).

3.2.4 The most important seabird populations – description and status

The Norwegian Sea is important for some of the largest seabird populations in the Northeast Atlantic, several of which are considered to be very valuable at both the national and the international level. Seabirds are wholly or partly dependent on the sea for food. The most typical seabirds (fulmars, gannets, cormorants, auks and many gulls and terns) spend most of the time at sea and forage entirely at sea. A number of seabirds are slow-maturing, and have low reproductive rates but long life spans. As predators, they are at the top of food chains, and their long life makes them vulnerable to hazardous substances. Slow sexual maturation and a low reproductive rate make them vulnerable to changes in food supplies. Thus, the state of seabird populations can be a good indicator of the state of the marine environment.

Figure 3-8.EPS Puffin carrying herring

Figure 3-8.EPS Puffin carrying herring

Source Photo: Tomas Aarvak

The Norwegian Sea serves several ecological functions for North Atlantic seabirds. It is a wintering and passage area for many species, while others spend much of the year in the area. The northern parts are feeding grounds for populations that breed further north and east. About 1.6 million seabirds use the area during the breeding season (this does not include the seabird colonies on the Røst archipelago). The most important breeding colonies are on Jan Mayen and Runde island (Møre og Romsdal). In addition, roughly one million seabirds breed on Røst, including about 866 000 puffins. Birds from the colonies on Røst forage in parts of the Norwegian Sea and the Vestfjorden throughout the year. There are also many smaller seabird colonies along the coast of Norway. The most numerous species that breed on the mainland are puffin, common eider and herring gull. Fulmar, Brünnich’s guillemot and little auk are the commonest species on Jan Mayen.

There are large seasonal variations in the distribution of seabirds in the Norwegian Sea. Divers, grebes, cormorants, marine diving ducks (common eider, king eider, long-tailed duck) and gulls dominate in winter along the mainland coast. The distribution of pelagic species in winter is probably highly dynamic and dependent on the distribution of their prey. In spring, birds migrating back to breeding areas and wintering populations are the dominant elements. Many species return to their breeding sites early in spring. In summer, most seabirds present in the area are either breeding populations or sexually immature birds and other non-breeders.

Figure 3-9.EPS Seabird colonies in the Norwegian Sea

Figure 3-9.EPS Seabird colonies in the Norwegian Sea

Source Directorate for Nature Management

Pelagic species (including most auks, kittiwakes and fulmars) may forage at great distances from their breeding colonies, whereas coastal species have a more limited radius of action and are dependent on finding food closer to their breeding sites. During autumn, the seabird populations move southwestwards in the Norwegian Sea. At the end of the breeding season, still flightless chicks of common guillemot, Brünnich’s guillemot and razorbill are accompanied by one of the parents (usually the male) as they swim away from the colonies and out to the open sea. Auks moult at sea in early autumn, with particularly large concentrations off Røst and Runde. During the moult, they are flightless and extremely vulnerable to all forms of human disturbance. Most ducks and geese moult before migrating southwards.

Common guillemot: Numbers at most breeding colonies have dropped by 90 % since the early 1980s. The breeding population on Runde reached a record low in 2005. In contrast, the population on the Sklinna archipelago has risen, probably because of immigration from other areas. The mainland population is considered to be critically endangered. If the present negative trend continues, it is probably only a matter of time before the species ceases to breed at many sites.

Puffin: The population of this species has also shown a dramatic decline over the past 20–30 years. Most birds belonging to the Norwegian population breed in colonies from Røst and northwards. The breeding population on Røst has declined to only 27 % of the 1979 level (corresponding to a drop of more than one million pairs of puffins), but this is still one of the largest colonies in Europe. The breeding population on the Sklinna archipelago has declined by 60 % since 1980 due to breeding failure because of food shortages. The species is classified as vulnerable.

Thefulmar population on Røst has declined by 15 % per year for the past 10 years, and the population on Runde has declined by more than 10 %.

Certain sub-populations of lesser black-backed gull (subspecies Larus fuscus fuscus) have shown a positive trend in the last 10 years, but the overall population is still only 25 % of the pre-1980 level. This may be related to food shortages and the collapse of the herring stock in the 1980s. Another possible explanation is high levels of hazardous substances in wintering areas in East Africa.

There has been a decline in the kittiwake population along the coast throughout the management plan area. The most dramatic decline is on Runde, where numbers have dropped by 75 % since 1980. The species is classified as vulnerable.

Most coastal diving species have shown a different trend. The cormorant population declined in the period 1985–87, but has since risen sharply at most colonies along the coast. The shag population has also shown a positive trend in the past 10 years after a dramatic decline in the mid-1980s. The trend for the breeding population of common eider has varied from one area to another.

3.2.5 The most important marine mammal species – description and status

Blue whales, fin whales, humpback whales and minke whales all pass through the management plan area on migration between breeding areas in warmer waters (where they spend the winter months), and summer feeding grounds near the arctic front and the marginal ice zone. They use the Norwegian Sea mainly as a feeding area. Sperm whales and northern bottlenose whales feed along the continental slope, while species such as porpoises and killer whales are common in waters nearer the coast. There are also several important areas for the coastal seals ( grey seal and common seal) along the Norwegian coast, while ice-covered waters north of Jan Mayen are an important habitat for hooded and harp seals.

The following species are currently harvested in the Norwegian Sea: minke whale, harp seal, common seal and grey seal. The Norwegian minke whale quota for 2009 is 885 animals, 135 of which are to be from the central Atlantic stock in the Norwegian Sea. Harp seals are harvested in the West Ice, and the quota for 2009 is 40 000 animals. Hooded seals were also harvested until 2006, but since then hunting of this species has been prohibited because of uncertainty about stock status. Coastal seal populations in Norway are relatively small compared with those in neighbouring countries. Hunting of both grey and common seals is permitted, and the quotas for 2009 are 1 040 and 860 animals respectively.

3.3 Particularly valuable and vulnerable areas

Within the management plan area, certain areas have been identified as being particularly valuable in terms of the environment and natural resources. A particularly valuable area is a geographically defined area that provides ecological goods and services of particular value, assessed on the basis of the proportion of a population or habitat it contains at international, national or regional level, and taking into account capacity for recovery, population status and Red List classification. Areas were selected using predefined criteria. The main criteria were that the area concerned was important for biodiversity or for biological production. In addition, a number of secondary criteria were evaluated, including some that were not purely biological (for example economic, social and cultural importance, and scientific value).

The vulnerability of valuable areas to various environmental pressures has also been assessed on the basis of the species and habitats that occur naturally in each area and their productivity. The vulnerability of a habitat or species to different environmental pressures varies, and has been assessed on the basis of the likely impacts of different pressures on species or habitat development and survival. There may also be temporal and spatial variations in vulnerability (see box 3.2).

Textbox 3.2 Vulnerability

Vulnerability can be defined as a measure of how liable a species or habitat is to be negatively affected by external, often anthropogenic pressures.

An assessment of the vulnerability of an area is generally based on which species and habitats occur naturally in the area and their productivity. Factors such as seasonal variations, distribution patterns, age/stage of the life cycle, behaviour and biological characteristics are used to determine the vulnerability of a particular species. Vulnerability to environmental pressures is assessed on the basis of the likely impacts of different pressures on the development and survival of a species or population. Some species are particularly vulnerable at times of the year when most of the population is concentrated in a limited area (for example fish during spawning and seabirds during the breeding season). The vulnerability of habitats depends on factors such as the substrate type (for example sand or rock), whether it contains sessile or motile species, and whether the habitat type is rare. Certain areas dominated by long-lived, habitat-forming species such as corals and sponges may be particularly vulnerable to certain environmental pressures because habitat formation is a very slow process. Areas where biological production is high may be particularly vulnerable at certain times of year (for example when eggs and larvae (the early stages of fish) are present). Vulnerability can be measured at individual, population, community and ecosystem level. For management purposes, impacts at population, community and ecosystem level are most important.

Eleven particularly valuable areas have been identified in the Norwegian Sea. These areas meet at least one of the two main criteria for selection, i.e. importance for biodiversity and importance for biological production. Some areas were also selected on the basis of secondary criteria (e.g. high concentrations of individuals/species, distinctiveness, undisturbed areas, or economic importance). The selected areas are of very different kinds, but their common features are that they are important for more than one species, generally meet more than one of the selection criteria and have already been recognised as valuable. It is not possible to delimit the particularly valuable and vulnerable areas precisely, but Figure 3.10 indicates their approximate extent.

Figure 3-10.EPS Particularly valuable and vulnerable areas in the Norwegian

Figure 3-10.EPS Particularly valuable and vulnerable areas in the Norwegian Sea

Source Directorate for Nature Management/Institute of Marine Research

The areas selected and their vulnerability to specific environmental pressures are further described below. The discussion of vulnerability focuses on potential direct pressures, regardless of the actual level of activity in the Norwegian Sea today. Vulnerability to specific pressures will vary from one valuable area to another, since they are defined as valuable on the basis of the presence of different species and habitats. All eleven areas are to some extent vulnerable to the accumulation of pollutants, the introduction of alien species, climate change, ocean acidification and the combined impacts of all human pressures.

3.3.1 The coastal zone

The coastal zone includes a wide range of areas where oceanographic conditions vary widely. The southernmost section (Stad (62°N) to Runde island), the coast of Sør- and Nord-Trøndelag (including the Froan, Vikna and Sklinna archipelagos), the southern part of Nordland (including islands and skerries in Sømna and Vega municipalities), the Remman archipelago and the Vestfjorden are considered to be particularly valuable.

Coastal areas with islands and skerries support a rich bird life, and there are large numbers of breeding and overwintering seabirds along the whole coastline. Coastal species of seabirds are dependent on shallow-water areas where they can find food, whereas pelagic species forage further out to sea and use considerably larger areas. The section of the coastal zone Stad to Runde, the coast of Sør- and Nord-Trøndelag (including the Froan, Vikna and Sklinna archipelagos), and the southern part of Nordland (including islands and skerries in Sømna and Vega municipalities) are considered to be particularly valuable for seabirds. Runde island supports one of the most important seabird colonies in the southern half of Norway, with large numbers of auks, including common guillemots, a species classified as critically endangered. The lesser black-backed gull (subspecies Larus fuscus fuscus) also breeds all along the coastal zone, with the most important breeding populations in Sør- and Nord-Trøndelag and the southern part of Nordland. Although some sub-populations have increased in numbers, the subspecies as a whole has shown a dramatic decline and has almost disappeared from Norway. The Froan archipelago is a key feeding area for seabirds both in the breeding season and at other times of year, and there are several large cormorant colonies.

Marine mammals such as the grey seal, common seal, common porpoise and killer whale occur all along the coastal zone. The coastal seals are stationary, particularly during the breeding season and the moult, and congregate at specific localities during these periods. Whelping and moulting areas are critical and vulnerable habitats for these species. The Froan archipelago is considered to be a particularly valuable whelping area for grey seals. Grey seals are only gregarious during the whelping and moulting seasons, whereas common seals live in colonies throughout the year. Porpoises live in small groups and are also relatively stationary. The distribution of killer whales, on the other hand, varies through the year. In winter they are found mainly in coastal waters, while in summer they are more widely distributed in the Norwegian Sea and Barents Sea. One component of the killer whale population in the Norwegian Sea follows the same migration pattern as Norwegian spring-spawning herring. In years when herring overwinter in the Vestfjorden (including the fjord arm Tysfjorden), killer whales therefore congregate in the same areas.

Kelp forests are an important habitat for many marine organisms in the coastal zone. There are rich stands of Laminaria hyperborea in the southern part of the management plan area, but further north the kelp forests have been severely depleted by sea urchin grazing.

The Vestfjorden, between the Lofoten Islands and mainland Norway, has historically been one of the main spawning areas for Northeast Arctic cod. For most of the period 1970–2000, the Vestfjorden, including the fjord arms Ofotfjorden and Tysfjorden, was also the main overwintering area for Norwegian spring-spawning herring. Although its importance has declined in recent years, the Vestfjorden is potentially a very important area for major fish stocks. It is also particularly important for seabirds, especially those from the seabird colonies on Røst. The area is further described in the management plan for the Barents Sea–Lofoten area.

Species and habitats in the coastal zone are vulnerable to oil pollution, discharges of waste, bycatches, and expansion of recreational activities, and if several such pressures are acting together, they become even more vulnerable. There are large numbers of seabirds in the coastal zone throughout the year. The southernmost section (Stad (62°N) to Runde island), the Froan and Vikna archipelagos, the southern part of Nordland and the Vestfjorden are for example important for coastal diving species and auks all year round (as foraging, overwintering, breeding and moulting areas). Seabirds are such a varied group that vulnerability is often assessed for ecological groups with similar behaviour in terms of habitat use, foraging and food choices. Vulnerability to environmental pressures such as oil spills, overfishing and waste varies from one ecological group to another. Vulnerability to oil, for instance, is often specified for particular ecological groups and certain times of year. Species that forage by diving from the surface are considered to be vulnerable to oil spills throughout the year. This applies particularly to auks such as guillemots and puffins, divers, cormorants and marine ducks (pelagic and coastal diving species). The vulnerability of other ecological groups is considered to be higher at specific times of year (surface-feeding species). Seabirds may also be vulnerable to near-shore wind farms.

3.3.2 The Møre, Halten and Sklinna banks

The continental shelf provides a productive environment with high biodiversity. It is relatively narrow off the coast of Møre og Romsdal, but widens considerably off Nord- and Sør-Trøndelag and Nordland. The continental shelf includes front zones, areas with strong currents and retention areas. Various species use it for spawning, feeding, as a nursery area or for overwintering, and drift trajectories for fish eggs and larvae pass through it. Three shallow bank areas on the continental shelf are considered to be particularly valuable: the Møre, Halten and Sklinna banks.

Norwegian coastal water and Atlantic water dominate the water masses in this area. The main current of Atlantic water follows the edge of the continental slope northwards, while the coastal water forms a wedge on top of and on the coastal side of the denser Atlantic water. Further north, the distinction between the two water masses becomes less clear. The Norwegian coastal current is an important transport route, carrying fish eggs and larvae from the spawning areas northwards to nursery areas along the coast and in the Barents Sea. There are large concentrations of fish larvae on the bank areas in spring, as the coastal water has a longer residence time in these areas. The Møre, Halten and Sklinna banks are all important spawning and nursery areas for Norwegian spring-spawning herring and saithe. The Halten and Sklinna banks are also highly productive retention areas for drifting fish eggs and larvae.

The bank areas also support a rich bird life as a result of the large stocks of pelagic fish species such as herring. Seabirds generally eat a variety of fish, but some of them are more specialised and dependent on particular fish species. There may be wide variations in food preferences through the year, between years and between regions. Auks, petrels, cormorants and gannets spend most of the time at sea and forage entirely at sea.

In spring, and particularly in the second quarter of the year, fish eggs and larvae of the most important Northeast Atlantic stocks are concentrated in the bank areas. At individual level, fish eggs and larvae are vulnerable to oil in the water column. Herring spawn on the seabed and are dependent on a suitable substrate. The herring spawning grounds on the Møre, Halten and Sklinna banks are vulnerable to physical disturbance, for example caused by bottom gear, anchor chains, fixed installations, dumping of rock or discharges of drill cuttings. Seismic surveys will also affect fish during spawning and spawning migration.

3.3.3 The Sula reef and the Iverryggen reef

There are large coral reef complexes on the continental shelf off Central Norway. The Sula reef and the Iverryggen reef are considered to be particularly valuable.

The Sula reef is a major Lophelia reef complex, and supports fish species including redfish, ling, tusk and saithe. Another important reef complex, the Iverryggen reef, lies on the continental shelf on the north-east slope of the Halten Bank. Both of these areas have been proposed for inclusion in Norway’s national marine protection plan, and they are protected against bottom trawling.

The coral reefs on the continental shelf off Central Norway are large, spatially complex biological structures, which makes them suitable habitats for many sessile and free-swimming organisms. Coral reefs support high species diversity and high fish densities, and the most common fish species are tusk, ling and redfish.

Coral reefs are vulnerable to physical disturbance of the seabed.

3.3.4 The edge of the continental shelf

The edge of the continental shelf is the transitional area between the relatively shallow continental shelf and bank areas and the deep-water areas of the Norwegian Sea, and runs all the way from Stad to northwestern Svalbard. The area supports high biological production and diversity, large concentrations of many fish and seabird species, and many coral reefs. It is therefore considered to be particularly valuable.

There is vigorous mixing of the water masses in convergence belts in the front zone between the Norwegian coastal water and the Atlantic water, and this results in enhanced biological production and large quantities of zooplankton and pelagic schooling fish species. Seabirds utilise the high biological production, and the edge of the continental shelf is an important feeding area, particularly for auks and pelagic species such as fulmar and gannet. The large concentrations of zooplankton also make the area an important feeding ground for baleen whales, and it is particularly important for fin whales in the south and for blue whales west and north of Svalbard. Moreover, there are important spawning grounds for deep-water species such as redfish ( Sebastes marinus and S. mentella), Greenland halibut and greater argentine in various areas.

The strong currents along the edge of the continental shelf provide highly suitable conditions for sponge communities and coral reefs. The Røst reef is a coral reef complex on the edge of the continental shelf 110 km west of Røst in the Lofoten Islands. This is the largest known cold-water coral reef, and is therefore particularly valuable. The area was further described in the management plan for the Barents Sea–Lofoten area.

The edge of the continental shelf is a large area with many different species and habitats, which vary in their vulnerability to different environmental pressures. For example, some fish stocks are vulnerable to excessive harvesting, benthic communities to physical disturbance, seabirds to oil pollution (all year round) and bycatches, and Greenland halibut and redfish to oil when eggs and larvae are present.

3.3.5 The arctic front

The arctic front is the zone where warm Atlantic water meets cold, less saline Arctic water. The eastern extent of the front is variable in the southern Norwegian Sea and more stationary further north. Front zones are valuable both because they are limited areas with a high concentration of biological production and because they support high biodiversity. Nutrients are released in or transported to the upper water layers, where they support high primary production (phytoplankton production). This results in high production of zooplankton such as krill and copepods, which in turn are food for other organisms higher up the food chain, including fish, seabirds and marine mammals.

High biological production makes this an important feeding area for several whale species, including blue whale, fin whale, minke whale and northern bottlenose whale. Further north, the marginal ice zone stretching further northwards to the Fram Strait north-west of Svalbard is also important for the same species, and also for species that are more permanently associated with ice-covered waters, such as the bowhead whale.

Seabirds and marine mammals are vulnerable to oil spills and substances that are liable to bioaccumulate. Different species may vary in their vulnerability at different times of year (see further details on seabird vulnerability in section 3.2).

3.3.6 Areas near Jan Mayen and the West Ice

Jan Mayen lies in a front zone where the north-flowing North Atlantic Current meets a branch of the south-flowing East Greenland Current. These waters support high production and large numbers of zooplankton, fish, seabirds and marine mammals. Jan Mayen is exceptionally important for seabirds, with 300 000 breeding pairs and several colonies. The most numerous species are fulmar, little auk, Brünnich’s guillemot and kittiwake. Jan Mayen and its waters out to the territorial limit are considered to be of high conservation value, and a protection plan is being drawn up.

The West Ice, the area of drift ice that forms each winter north of Jan Mayen, is a whelping area for harp seal and hooded seal. It is of crucial importance for the populations of these seal species because it is the only part of the Norwegian Sea where large stable areas of ice form in winter. The West Ice is vulnerable to climate change, and the area of winter ice has been shrinking in recent years. Outside the breeding season and the moult, both harp seal and hooded seal make long feeding migrations to Svalbard, along the edge of the continental shelf in the Norwegian Sea, and to East Greenland. A marked decline has been observed in the number of hooded seal pups born, and the species is therefore considered to be vulnerable.

Several whale species, including the bowhead whale, narwhal and beluga whale, are associated with the marginal ice zone all year round in the northern Norwegian Sea, and feed on the rich zooplankton and fish resources.

Harp seals and hooded seals are vulnerable to oil spills, particularly during the breeding season. The areas near Jan Mayen and the West Ice are important breeding, moulting and feeding areas for seabirds (especially in the period April-December). Different species may vary in their vulnerability at different times of year (see further details on seabird vulnerability in section 3.2)

3.4 The underwater cultural heritage

The underwater cultural heritage includes all traces of human activity that are now in or under water, for example remains from shipwrecks, and other traces of human activity in and near the sea. Adverse impacts on the cultural heritage are usually irreversible, so that any damage results in a permanent loss of value. The impacts of environmental pressures on the cultural heritage depend on the type and scale of pressure, and on the type of cultural heritage affected, its state of preservation and the nature of the surrounding environment. The Norwegian cultural heritage authorities have only very limited information on the underwater cultural heritage of the Norwegian Sea. This has not been systematically surveyed and registered in the same way as the cultural heritage on land.

To front page