5 Pressures and impacts on the environment

This chapter presents an assessment of the cumulative environmental effects on specific components of the Norwegian Sea ecosystem and on the particularly valuable areas, based on current knowledge. Cumulative effects assessment is a methodologically complex undertaking, and cannot yet be used to replace assessments of individual problems and species. In this case, pressures and their impacts on a selection of species and habitats were evaluated and used as a basis for an assessment of cumulative environmental effects. Assessments were made both for the current level of activity in different sectors and for scenarios constructed for future levels of activity. If activity patterns, and especially the location of activities, turn out to be different from those estimated in the assessments, the impacts during normal operations may also differ, and so may the probability and potential impacts of major or minor accidents. This was taken into account when the scientific basis was used during the preparation of the white paper. Fishing pressure on fish stocks is also included when the cumulative effects on individual species or species groups are assessed.

The expert group used a five-point scale (insignificant, minor, moderate, major, catastrophic) to indicate the level of impact in its discussion of cumulative environmental effects in the Norwegian Sea (see the description in Chapter 2.4). It is important to note that the scale is largely based on possible effects on the Norwegian Sea ecosystem as a whole. In most cases, the cumulative effects have been assessed at population level or for larger areas, rather than at individual level or more locally. This means that in cases where the category insignificant is used here, smaller-scale assessments (for example in connection with the regulation of specific activities) may indicate more serious impacts on individuals or on smaller areas. The expert group has attempted to assess cumulative effects up to 2025, based on the scenarios of future activity levels.

Greenhouse gases that have already been released to the atmosphere will result in climate change and ocean acidification. Because of the oceanographic and biological features of the Norwegian Sea, the impacts of ocean acidification are expected to become apparent particularly quickly here, and damage to ecosystems is expected as early as 2025.

There is considerable uncertainty as to how and how quickly the impacts of climate change will become apparent in the Norwegian Sea. However, warming of the Norwegian Sea is expected to lead to a northward and westward shift of the front zone between Atlantic and Arctic water. New species may expand their distribution northwards towards Norwegian waters. Southerly species along the Norwegian coast are expected to shift northwards along the coast towards Svalbard and the eastern part of the Barents Sea. Climate change and ocean acidification may reduce the resilience of ecosystems to other pressures. In future, the management regime must therefore be adapted to changes in ecosystems. This is discussed in more depth in Chapter 6.

5.1 Cumulative environmental effects

5.1.1 Cumulative environmental effects of normal activities

The Norwegian Sea is a large area, and large parts of the water masses and the deep seabed beyond the continental shelf are relatively unaffected by direct pressures from human activity. Like all marine areas, the Norwegian Sea is affected by long-range transboundary pollution, but no direct impacts on ecosystems have been demonstrated, although pollutants have been found in organisms at the highest trophic levels of food chains. Direct pressures from human activity are mainly concentrated in the continental shelf areas near the Norwegian coast. At present, the Norwegian Sea is one of the cleanest sea areas in the world, and the state of the environment here is generally good (see Chapter 3). However, several species and parts of the area show clear evidence of impacts, mainly from environmental pressures on the continental shelf.

The greatest cumulative effects in the Norwegian Sea today are on certain fish species, seabird species and seabed habitats. For various reasons such as natural fluctuations, climate change and high level of fishing pressure, certain fish stocks are not in a very healthy condition, and are therefore particularly vulnerable to even a small increase in human pressures. These include redfish ( Sebastes marinus and S. mentella) and coastal cod. Other species such as blue whiting and Greenland halibut are also considered to be vulnerable. The cumulative pressures on such stocks have been ranked as major on the five-point scale. However, management measures have been introduced at national and international level to improve the situation. The cumulative effects on certain seabed habitats such as corals, sponges and other vulnerable benthic fauna groups are also ranked as major in areas where bottom trawls are used. Seabirds are exposed to many complex environmental pressures, and the impacts may be direct (higher mortality, reduced fitness) or indirect (through food supplies or access to important habitats). Many of the seabird populations in the Norwegian Sea are declining and are therefore particularly vulnerable to an increase in cumulative effects. We know too little about the reasons for this decline, but poor food supplies are believed to be a critical factor. The cumulative effects on common guillemot, puffin, common eider, kittiwake and shag are ranked as moderate.

The human activity that currently puts most pressure on the Norwegian Sea during normal activities is the fisheries. Any fishery necessarily has some influence on the ecosystem where it takes place. The level of pressure depends on how much of a stock is harvested, how it is harvested, and the trophic level to which the stock belongs. If harvesting is not to have adverse impacts on ecosystems, it must be sustainable. Ideally, this means that only the surplus biological production is removed from the ecosystem each year. Permitted operational discharges from maritime transport make a relatively small contribution to the cumulative effects on the Norwegian Sea ecosystem, except for discharges of waste, which may have insignificant effects on marine mammals and the shoreline and up to moderate effects on seabirds, and discharges of oil, which are estimated to have insignificant effects on seabirds. Operational discharges from petroleum activities are generally so strictly regulated that they are only considered to have more local effects, which are ranked as insignificant for the Norwegian Sea ecosystem as a whole. However, there is still some uncertainty as regards the possible long-term effects of discharges of produced water from petroleum activities.

In addition to the above-mentioned pressures, which apply to the current situation, it is expected that by 2025, the impacts of gradual ocean acidification will begin to be apparent for corals and other benthic animals with calcareous skeletons. Ocean acidification may also result in changes in the species composition of phytoplankton, and thus have an impact on the food chains that include zooplankton, the benthic fauna, fish, seabirds and marine mammals, and on which all these species depend. Both the gradual process of climate change that is being observed and long-range transport of pollutants increase the level of uncertainty as regards the impacts that can be expected in 2025.

Particularly valuable areas

The coastal zone (including the Vestfjorden) and the Møre, Halten and Sklinna banks are the particularly valuable areas of the Norwegian Sea where cumulative environmental effects are currently considered to be greatest during normal activities. In the Jan Mayen/West Ice area and the arctic front zone, on the other hand, there is currently little activity (little maritime transport and fisheries activity, no petroleum activities), and little direct environmental pressure. These assessments are based on a situation with no petroleum activities in any of the valuable areas near the coast, but some activity along the edge of the continental shelf. The impacts of the current level of petroleum activity on the particularly valuable areas in the Norwegian Sea are assessed as insignificant. The impacts of operational discharges from maritime transport are also assessed as insignificant in the particularly valuable areas, except that discharges of waste have greater impacts, especially off the coast of Møre og Romsdal. Under normal circumstances, the fisheries and activities in the coastal zone put most pressure on the environment. There is considerable fisheries activity in several of the valuable areas, and species such as saithe, herring and cod are harvested. Bottom trawling operations may have an impact on the seabed. Seabirds may be taken as bycatches. There are many other pressures on the coastal zone that may affect particularly valuable areas (for example wind power production, aquaculture, runoff of pollutants and tourism), but their impacts have not been specifically assessed for each area.

If trends in climate change and ocean acidification continue as projected in the scenarios for 2025 and 2080, there will be major effects on all the particularly vulnerable areas and on the Norwegian Sea as a whole.

5.1.2 Impacts of acute pollution

There is a risk of accidents involving releases of oil, chemicals or radioactive substances in the Norwegian Sea. The consequences of accidents are additional to the impacts of normal activities. Because transport of chemicals is strictly regulated, the environmental risk associated with spills during this type of transport is expected to be generally low. Accidents involving radioactive contamination could result in considerable inputs of radioactive substances to the environment, and elevated concentrations in seawater, sediments and species at all trophic levels for several years after a spill. Modelling indicates that levels of radioactivity to which marine organisms are exposed are likely to be below the threshold values at which damage is expected. However, we know too little about the effects of radioactive contamination on the natural environment.

Petroleum activities and maritime transport in the Norwegian Sea represent a risk of accidents that could result in oil spills. Regular updating of the legislation for both industries means that operators must meet higher and higher standards. This reduces the probability of accidents (see Chapter 7.5). In general, the probability of a small spill is higher than that of a large spill. The potential consequences of different types of accidental events are closely linked with where they happen and their scale, the type of oil, the weather conditions, the time of year and how likely the spill is to affect vulnerable species and habitats. In addition, species and habitats that are known to be vulnerable to oil are generally found in larger numbers or at higher densities in coastal areas, and the distance to the shore is therefore another factor of importance in evaluating the potential consequences of a spill.

The environmental impacts of the current level of activity have been assessed by modelling major spills from blow-outs and shipwrecks in the Norwegian Sea. The results show the most serious potential consequences for seabirds and the shoreline, while potential consequences for earlier stages of fish life cycles and for the coastal seal species are assessed as less serious. It is less likely that a large proportion of a plankton population or of a benthic community will be affected by a spill, and the potential consequences are therefore not considered to be very important. The impacts of a major blow-out or a large oil spill from a ship may vary from insignificant to major, depending on whether vulnerable species and habitats are present and become contaminated. Generally speaking, the probability of major spills from petroleum operations is low.

In general, the probability that the shoreline or species and habitats near the coast will be affected is lower in the event of a blow-out from the oil and gas fields considered in this assessment than in the event of an oil spill from a ship near the coast, unless a blow-out affects large concentrations of seabirds foraging at sea. Thus, the probability of the most serious impacts on plankton (fish eggs and larvae), seabirds, marine mammals and the shoreline has been assessed as lower for the blow-outs modelled than for the spills from ships closer to the coast. If there is a major spill from a ship further from the coast in the Norwegian Sea, both the potential consequences and the probability of the most serious consequences are expected to be lower. However, a major spill from a ship or a petroleum installation in the open sea could spread more widely and affect a larger area. On the whole, the potential environmental consequences of a major oil spill from a ship or a blow-out in the 2025 scenario are assessed as similar to those at the current level of activity. The 2025 scenario assumes that several of the fields currently on stream have shut down, while several new gas fields and one new oil field are on stream. The scenario also includes exploration drilling in new areas. The closure of oil fields removes their contribution to the overall risk level. The development of oil fields and exploration drilling in new areas means that the environmental risk shifts to new areas. However, new gas fields do not involve the same risk of spills of oil as oil fields. A general increase in the volume of maritime transport in the Norwegian Sea is expected in the period up to 2025, mainly in the form of tanker traffic to and from Russia. As a result, there will be an increase in the probability of maritime transport accidents up to 2025 throughout the management plan area, and spills of crude oil, bunker fuel and petroleum products are expected to increase. The assessment did not include the effects of introducing stricter legislation or response measures. The growth in the volume of traffic is not necessarily expected to result in changes in the potential consequences of different types of accidents, but it is expected to result in an increase in the overall environmental risk associated with oil spills from maritime transport.

Particularly valuable areas

In today’s situation, a blow-out from petroleum operations in the Norwegian Sea could in the worst case have major impacts on the Vestfjorden and the coastal zone, which have been identified as particularly valuable and vulnerable areas. However, the probability of a blow-out is low. Modelling showed that oil from a blow-out on the Norne og Draugen fields would be most likely to reach the coast (probability of shoreline impact 10 and 16 % respectively). For other fields, the probability of oil reaching the shore is less than 5 %. On the basis of these figures, the probability of the most serious consequences is considered to be relatively low. In the event of similar spills from activities within or near particularly valuable and vulnerable areas, both the probability that such areas will be affected and the probability of more serious consequences are expected to be higher. The legislation governing the petroleum industry is risk-based and follows the principle that a higher risk requires greater efforts to reduce the probability of a spill occurring, which covers situations where there is a higher probability of more serious consequences. Reducing the consequences of spills by improving the oil spill response system can also reduce the level of environmental risk. Such measures are not included in the assessments described above. In the worst case, oil spills from ships, like the blow-outs that have been modelled, may have major impacts on the particularly valuable and vulnerable Vestfjorden and coastal zone. However, the probability of more serious consequences may be higher for near-shore spills of oil from ships than for blow-outs from the existing petroleum installations. The area around the Møre banks is most vulnerable to acute pollution from maritime transport in the Norwegian Sea, because of the large volume of traffic concentrated in this area. The risk of spills in or near the other particularly valuable and vulnerable areas is lower.

In the 2025 scenario, the Norne field has been closed down, and the potential consequences for the Vestfjorden are therefore less serious. The potential consequences for the other particularly valuable and vulnerable areas will depend on where new petroleum activities are started and whether new fields contain oil or gas. Gas fields do not present the risk of oil spills that oil fields do. For maritime transport, the potential consequences for the different areas are expected to about the same as in 2006, but the probability of oil spills is expected to rise with the projected rise in the volume of traffic, and this will result in a rise in the environmental risk associated with such incidents.

5.1.3 Cumulative environmental effects on primary and secondary production (plankton)

None of the activities assessed has much impact on primary and secondary production in the Norwegian Sea, and the cumulative effects of the current level of activity are ranked as insignificant. Nor are the impacts of acute pollution expected to exceed this level. However, by 2025, more widespread damage at the level of primary and secondary production may occur as a result of ocean acidification, and this may have impacts at ecosystem level. The impacts of ocean acidification on primary and secondary production are assessed as moderate up to 2025 and major in the longer term.

5.1.4 Cumulative environmental effects on seabed habitats

Bottom trawling has major impacts on the benthic species and communities that are directly affected. The impacts at population level (in this case best considered as the Norwegian Sea as a whole) are more uncertain, and should be investigated further. The pressure on such areas varies, depending on how intensively they are trawled. Other physical disturbance of the seabed and discharges of drill cuttings from exploration and production drilling are considered to have more local impacts and only insignificant impacts on the Norwegian Sea as a whole. Operators are required to ensure that petroleum activities do not damage corals or other valuable benthic communities. Oil spills are not generally expected to have very serious impacts on benthic communities, but the potential consequences are likely to be higher in the event of a spill near the coast in shallow water, or if there is a possibility of direct contamination of the seabed (for example if a ship is grounded). Such consequences are expected to be local and will be less serious for the area as a whole. Accidents involving releases of radioactive material could have long-lasting impacts on benthic communities.

The expert group concluded that up to 2025, there could be major cumulative effects on some benthic species and habitats unless new measures are introduced to reduce the damage caused by bottom trawling, and the effects may be aggravated as ocean acidification increases. This applies particularly to corals and other organisms that have calcareous skeletons or are otherwise dependent on calcium. At present other physical disturbance of the seabed and discharges of drill cuttings from exploration and production drilling have more local effects, and this situation is expected to continue, provided that strict regulation to avoid damage is maintained.

Particularly vulnerable habitat types such as coral reefs, gorgonian forests and sponge communities

Corals form habitats such as coral reefs, coral rubble and gorgonian forests. Other animal groups such as sponges can also form dense stands and form habitats with similar ecological functions to coral habitats. Corals are fragile and extremely vulnerable to physical damage and sediment deposition. The oldest parts of known Norwegian coral reefs are more than 8 000 years old. Corals grow very slowly, and corals in the Norwegian Sea may stop growing altogether in the course of the present century as a result of ocean acidification. Because of their slow rate of growth, there is reason to believe that damage to these habitat types in the years ahead may in practice be irreversible. It has previously been estimated that about 30–50 % of Norwegian coral reefs have been damaged or destroyed by bottom trawling. This estimate should be updated now that new coral reefs, both intact and damaged, have been discovered. Even less is known about the status of gorgonian forests and sponge communities in Norwegian waters.

Source Photo: Erling Svensen

Sponges are also vulnerable to physical damage, bycatch and sediment deposition. Coral reefs, gorgonian forests and sponge communities are important for biological diversity and marine living resources. However, little is known about the exact role of these habitat types and species in ecosystems, and their distribution in the Norwegian Sea has not been properly mapped.

Source Photo: Institute of Marine Research/MAREANO programme

These habitat types are particularly vulnerable to fishing gear that may touch the seabed, such as bottom trawls and other towed gear, including Danish seines. Equipment such as sea anchors, sampling equipment including grabs, and equipment used to retrieve lost gill nets will also cause damage on contact with corals. Passive fishing gear such as gill nets and longlines can also cause damage if it is set above corals reefs or gorgonian forests. Nets and hooks easily become entangled in corals, and fishermen have indicated that they sometimes take considerable bycatches of corals. Retrieving lost gear can do more harm than good, so the solution may be to abandon the gear, which will then continue to catch fish («ghost fishing»).

Other activities can also damage or threaten these vulnerable habitat types, for example pipeline- and cable-laying using a vessel without a dynamic positioning system. Such processes and other activities involving physical disturbance of the seabed can also result in resuspension of sediments and sediment deposition on corals, sponges and other benthic animals.

Other examples of local activities that may damage vulnerable habitat types such as coral reefs are extraction of coral rubble, deposition of sediments and drill cuttings, collection of corals or other animals for bioprospecting, and detonations near the seabed in connection with military exercises. In addition, there are external pressures such as long-range transboundary pollution, climate change and ocean acidification (see Chapter 6). Because of the importance of coral reefs and gorgonian forests in the ecosystem and their vulnerability and current status, it is particularly important to take a precautionary approach to their management.

Source Photo: Institute of Marine Research

It is uncertain whether there are cold seeps and black smokers (including pockmarks) in the parts of the Norwegian Sea where trawling is permitted. The pockmarks in the Nyegga area, which are at a depth of 700–800 metres, may be at risk from trawling.

Kelp forests

The impact of kelp trawling on kelp forests is assessed as minor. The annual harvest is 150 000 tonnes, which is less than one per cent of the total biomass of Laminaria hyperborea along the Norwegian coast. Nevertheless, this harvest of a renewable resource may have local impacts, depending on the quantity harvested, the proportion of a stand harvested and the capacity of the kelp forests for recovery. Kelp trawling and storm damage generally leave considerable numbers of recruits in the undergrowth, so that the kelp forest recovers without problems. 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. For Norway as a whole, it is estimated that sea urchin grazing corresponds to an annual production of 20 million tonnes of kelp, which is about 130 times the harvest taken by trawling.

Source Institute of Marine Research

Kelp forests are important for biological diversity, for example as nursery areas for fish larvae and feeding areas for several species of seabirds. For certain seabirds, particularly shag and black guillemot, productive kelp forests near their breeding sites can be a key factor in breeding success. Climate change and a higher concentration of CO₂ in sea water may stimulate growth of Laminaria hyperborea and possibly in the long term boost the recovery of kelp forests that have been overgrazed by sea urchins. It is important to ensure that kelp resources, like other living marine resources, are managed sustainably, taking into consideration biological and habitat diversity and food supplies for fish stocks and seabirds.

5.1.5 Cumulative environmental effects on fish stocks, including commercially harvested stocks

Harvesting a fish stock puts pressure on it, and under normal circumstances this will be the most important anthropogenic pressure. For example, the recommended TAC for Norwegian spring-spawning herring in 2009 is more than 1.6 million tonnes from an estimated spawning stock in excess of 12 million tonnes. The largest and most important fish stocks in the Norwegian Sea, such as Norwegian spring-spawning herring and saithe, are being harvested sustainably at present. Another large stock, that of blue whiting, is above the precautionary level, but has been heavily fished because there has been no international agreement on its management. An agreement is now in place, and the parties have agreed on steps to rebuild the blue whiting stock so that it can be harvested sustainably. Stocks of certain species, such as Greenland halibut, redfish ( Sebastes marinus and S. mentella), tusk and coastal cod, are in poorer condition, and the fisheries are considered to have major impacts on these species.

The main impacts of any major oil spills from the petroleum industry or ships are expected to be largely the result of damage to fish eggs and larvae. The scale of such impacts will depend on when and where a spill happens, fluctuations in fish stocks, and the properties of the oil. Damage to eggs and larvae can result in poorer recruitment from the year class affected. The most serious consequences are expected to be greatest in areas and at times of year when high concentrations of eggs and larvae are present. For a further discussion of the risks associated with acute pollution, see Chapter 5.6.

In the period up to 2025, the situation for fish stocks will probably change to some extent as a result of climate change and ocean acidification. There is some uncertainty about the possible long-term effects of discharges of produced water. In addition, the management regime will be important for the development of a number of fish stocks.

5.1.6 Cumulative environmental effects on seabirds

Although in most cases individual environmental pressures have insignificant or minor impacts on seabirds in the Norwegian Sea, the cumulative effects for the current situation (activity levels and external pressures) are classed as moderate. In the management plan area, pressures such as climate change and long-range transport of hazardous substances act together with regional and local pressures, including releases of pollutants from land, bycatches, poor food supplies and oil pollution (probably from illegal discharges from ships). Food supplies are the most important single factor, but it is uncertain to what extent poor food supplies are a result of large-scale changes (for example climate change) or the harvest taken by the fisheries. Many seabird populations in the Norwegian Sea are already declining, and are therefore particularly vulnerable to an increase in anthropogenic pressures. A combination of different pressures may have synergistic effects, so that the cumulative effect is greater than the sum of the separate impacts. Over time, this may result in a considerable reductions in numbers in many species, which under certain conditions may have negative impacts at colony or population level. The cumulative environmental effects on common guillemot, puffin, common eider, kittiwake and shag are assessed as moderate.

Any impacts of oil spills will be additional to the cumulative environmental effects considered here. In most cases, accidents are most likely to have minor or moderate impacts, but in the worst cases they may have major impacts on certain species.

It is generally assumed that the potential for serious environmental consequences is lower for small oil spills than for major spills. However, studies have shown that even small quantities of oil on the sea (from small illegal discharges and leaks from unspecified sources) can cause serious damage to seabirds, particularly if this results in repeated exposure. It has been suggested that more frequent exposure to small oil spills can have more serious effects on the long-term population stability of seabirds than infrequent major spills. A small oil spill that coincides in time and space with large numbers of seabirds can kill more birds than a major spill that does not. On the basis of current knowledge it is only possible to conclude that small oil spills may be an important pressure on seabirds, but it is not possible to quantify this at present.

The situation for individual seabird populations in 2025 is very uncertain, as are the possible effects of climate change, ocean acidification and changes in food supplies. It is therefore difficult to assess the cumulative environmental effects on seabirds in the 2025 scenario.

5.1.7 Cumulative environmental effects on marine mammals

At the current level of activity, the impacts of human activities and external pressures are assessed as moderate for minke whale and hooded seal, and minor for pelagic whale communities. However, the cumulative effects are assessed as major for porpoises in the Vestfjorden and for common seal generally. The impacts on minke whale, hooded seal and common seal are largely a result of deliberate harvesting, whereas porpoises are taken largely as a bycatch. The accident scenarios that have been assessed show that accidents involving oil spills may have from insignificant to moderate impacts on coastal seals, depending on whether or not a slick contaminates large numbers of animals.

In the period up to 2025 the situation for seals may deteriorate as a result of climate change, and as an indirect result of ocean acidification.

5.2 Pressures and impacts associated with the fisheries

The Norwegian fisheries, like any harvest from a renewable resource, are bound to have an effect on the stocks that are harvested. Fishing pressure is therefore not comparable with pressures such as pollution and the introduction of alien species. The challenge in fisheries management is to ensure that harvesting is carried out in a way that maintains fish stocks for the future and that minimises impacts on the seabed and on other species.

5.2.1 The fisheries in the Norwegian Sea

There are large stocks of Norwegian spring-spawning herring, blue whiting, mackerel and saithe in the Norwegian Sea, which provide the basis for the most important fisheries in this sea area. In addition, small quantities of the redfish Sebastes mentellaare harvested while feeding in the Norwegian Sea, and there are fisheries for tusk, ling, Greenland halibut, redfish and greater argentine along the continental slope. The Møre banks are intensively used as a fishing ground throughout the year. From January, fishing vessels follow the herring on their spawning migration towards spawning grounds on the Møre banks. Otherwise, herring, blue whiting and mackerel are fished in large parts of the Norwegian Sea, there is a year-round fishery for saithe all along the coast, greater argentine is trawled in certain areas, and there are other sporadic fisheries. The areas that are most intensively fished during the year are illustrated in Figure 5.5. With the exception of Northeast Arctic saithe, Norway shares all the commercially important fish stocks with other coastal states. Chapter 7.3 describes the fisheries management regime. Norway also harvests the minke whale stock, and much of the catch is taken within the management plan area.

Source Directorate of Fisheries

Within the time frame of the management plan, fisheries are the human activity that will probably have the greatest impact on the ecosystem. The harvest must be adjusted to ensure that the natural interplay between different components in the ecosystem is maintained. The pressure on the Norwegian Sea ecosystems depends on how much of a stock is harvested, how it is harvested, and the trophic level to which the stock belongs.

The effects of external factors such as variations in temperature and current patterns must also be taken into account in evaluating the pressure exerted by the fisheries. In some cases, external factors and natural fluctuations in fish stocks due to competition between species and variations in food supplies may be more important than anthropogenic pressures on the same stocks. Our knowledge of the impacts of fisheries varies from one species and area to another, and it is difficult to distinguish between human and other pressures. The fish stocks that are most important in commercial terms have been harvested and managed for many years, and a considerable body of knowledge has been obtained by research and in other ways, so that we know most about the impacts on these stocks. On the other hand, relatively little is known about the impacts of the fisheries on species that are not harvested commercially and on other parts of the ecosystem, see Chapter 9.

5.2.2 Impacts on commercially exploited stocks

The main pressure exerted by the fisheries is the deliberate harvesting of commercial stocks, which results in changes in stock sizes and in the size and age structure of stocks. Very selective fishing of specific year classes can also result in changes in genetic make-up. Evolutionary impacts are further described below.

The stocks of Norwegian spring-spawning herring, Northeast Arctic saithe, Northeast Arctic cod and Northeast Arctic haddock are being harvested sustainably and are in good condition. The impacts of the fisheries are considered to be moderate for these species. The blue whiting and mackerel stocks are both above the precautionary level, but have been heavily fished, and the expert group has assessed the impacts of harvesting as major for these species. Stocks of other species such as Greenland halibut, the redfish Sebastes marinus and S. mentella, tusk and coastal cod are not in good condition (see the descriptions of each stock in Chapter 3.2), and the expert group has ranked the impacts of the fisheries as major for these species.

The Norwegian spring-spawning herring stock was severely depleted at the end of the 1960s, resulting in total collapse. After a long recovery period, the spawning stock had rebuilt to more than 12 million tonnes in 2009, about the same level as in the 1950s. The collapse of the stock also resulted in major changes in its feeding and wintering patterns. Today, the herring follow very similar patterns to those in the period preceding the collapse. The more recent management regime has been greatly influenced by the earlier collapse of the stock. An important element of the international regime for management of Norwegian spring-spawning herring is the complete protection of juvenile herring in the Barents Sea.

Saithe north of 62°N: Low fishing pressure over the last 10 years has had a positive effect on recruitment and stock development.

Blue whiting: A coastal state agreement between Norway, the EU, Iceland and the Faeroe Islands has only been in place for this stock since 2007. Over the past 10 years, catches have therefore been above the level recommended by the International Council for the Exploration of the Sea (ICES), and the expert group therefore assessed the impacts of the fisheries on the blue whiting stock as major. The stock is now mainly jointly managed by the coastal states listed above, while the North East Atlantic Fisheries Commission (NEAFC) manages a more limited area of its distribution. Recruitment has been poorer since 2005, and a reduction in the spawning stock is expected. The coastal states have therefore decided on a two-year phased reduction in fishing mortality (for 2009 and 2010) to ensure that that the stock is managed within safe biological limits.

Mackerel: The Northeast Atlantic mackerel stock has been highly selectively fished for more than 30 years. As a result, the age and size structure of the stock has changed dramatically from the 1970s to the present. In broad outline, there has been a change from a stock in which all age groups from one to 12 years are present and there is a substantial proportion of large, older fish, to one with only three to four age groups, strongly dominated by younger year classes (2–5 years). Estimates of the spawning stock are uncertain because far more mackerel is caught than is reported to ICES. Illegal landings, discards and slippage of whole catches or parts of catches add to the uncertainty. Statistical calculations by ICES indicate that unaccounted catches account for at least another 60 % over and above reported catches. It is important to obtain better information on the problem of slippage of mackerel catches, and on the basis of research to implement practical measures and legislation to minimise unintended mortality from fishing with pelagic trawls and purse seines.

Ling, tusk and blue ling: These species are fished across large areas of the North Atlantic. No estimates of stock sizes are available. Calculations based on catch per unit effort suggest that their stocks have declined in the past 40 years, but figures for the fishing grounds in the Norwegian Sea are so uncertain that it is impossible to determine how great the decline has been. ICES has recommended that catches of tusk and ling should be limited to 5 000 tonnes and 6 000 tonnes respectively in the Norwegian Sea and Barents Sea. In 2007, catches of both species were over 10 000 tonnes. ICES recommends that there should be no directed fishery for blue ling, and that spawning areas should be closed and technical measures introduced to reduce bycatches in mixed fisheries.

Greenland halibut: there is a limited coastal fishery and the species is also taken as a bycatch in trawl fisheries. In 2002 and 2003, catches were reduced to the level recommended by ICES, but in the period 2004–2007 they rose again to far more than the recommended level. The state of the stock is uncertain, and the expert group assessed the impacts on Greenland halibut as major. ICES stresses that further measures should be taken to reduce catches.

Redfish (Sebastes marinus): Results of research cruises and catches in trawl fisheries show a substantial reduction in abundance, and suggest that the stock is at a record-low level. Weak year classes are expected to persist for many years. Because the spawning stock and recruitment are continuing to decline, ICES recommends stricter restrictions. The measures currently in force are inadequate. ICES has reiterated its advice that there should be no directed fishery, that area closures should be maintained and that there should be stricter bycatch limits for trawl fisheries. Strict protection of juvenile fish is important to ensure recruitment and to rebuild the stock.

Redfish (Sebastes mentella): Before 2005, recruitment failure had been a problem for this stock for 15 years . Recruitment improved in the period 2005–2007, which was partly ascribed to protection of juvenile age groups in the shrimp fisheries. To safeguard the stock in the years ahead, it is essential to protect the mature component of the stock, so that stable recruitment is ensured for many years ahead. Important measures to rebuild the stock are to control the fishery in the Norwegian Sea and limit bycatches of redfish in the shrimp fishery. ICES recommends that there should be no directed trawl fishery for Sebastes mentella in the Barents and Norwegian Seas. Area closures should be maintained and bycatch limits should be as low as possible until a significant increase in the spawning-stock biomass and number of juveniles has been verified.

Greater argentine: This species is found across much of the Northeast Atlantic, and with the exception of greater argentine around Iceland, is considered to belong to a single stock. However, the stock structure is unclear, and ICES recommends genetic studies so that this can be evaluated further. There is very little information on stock development and age and length distribution, and it has not been possible to make reliable estimates of stock size in recent years. Given the lack of stock estimates and analyses, the Institute of Marine Research has recommended that the quota should be set at the level that appears to have been sustainable over the last 20 years, i.e. 10 000 tonnes. However, more information is needed to improve assessments of fishing pressure on the stock.

Fisheries also have impacts on other fish stocks that are taken as bycatches. However, in many cases bycatches have to be permitted so that quotas can be utilised. To ensure that such bycatches are included in figures for the total harvest from a particular stock, a certain proportion is set aside to allow for bycatches when the TAC is shared between different vessel groups. The authorities are also making considerable efforts to reduce bycatches through requirements to use selective gear or sorting grids and by opening and closing fishing grounds as appropriate.

Evolutionary impacts

Heavy fishing pressure can result in sexual maturation at an earlier age and smaller size. This in turn may have an impact on egg production (number and quality) by a particular spawning stock. The possibility of such evolutionary changes in fish stocks indicates that it is preferable, in accordance with the precautionary principle, to keep mortality of juvenile fish low and delay harvesting until fish reached sexual maturity.

The herring and mackerel fisheries in the Norwegian Sea largely take sexually mature fish. It is therefore not expected that fishing exerts much selective pressure towards earlier sexual maturation in these species. In the case of blue whiting, immature fish have been somewhat more heavily exploited because of the lack of an international agreement, so that a certain selective pressure towards earlier sexual maturation could theoretically be expected in this species. Immature fish of demersal species such as cod, Greenland halibut and redfish have been relatively heavily exploited over the past 30–40 years. Selective pressure towards earlier sexual maturation and subsequent evolutionary impacts of fishing are therefore most likely to be found in this species group.

Loss of fishing gear

Every year, fishing gear is lost and sinks to the seabed or is washed ashore. Since 1980, the Norwegian Directorate of Fisheries has run an annual programme to retrieve gear that has been reported as lost and other lost gear that for various reasons has not been reported. Norway is leading the way in this area, and the Directorate has shared its expertise with other fishing nations that wish to address the problem of retrieving lost and abandoned gear.

Fishing gear can continue to catch fish long after it has been lost or abandoned (this is known as «ghost fishing»). This is a problem because it results in unregistered harvesting of fish stocks. Whales, seals and seabirds can also be killed if they become entangled in such gear. The scale of this problem has not been specifically investigated in the Norwegian Sea. Norwegian regulations now include a requirement to report the loss of gill nets.

Illegal, unreported and unregulated fishing (IUU fishing)

It is important that all fisheries in international waters (for example the fisheries for herring, mackerel, blue whiting and Sebastesmentella in the «Banana Hole») are managed, controlled and inspected in accordance with international agreements to avoid illegal, unreported and unregulated fishing. The fisheries in international waters in the Northeast Atlantic are regulated by the NEAFC, where Norway is an important member. To reduce the uncertainty of catch estimates, it is essential that all catches are registered. In the Norwegian Sea, there are particular problems related to illegal and unreported fishing for mackerel. This is further discussed in the section on the impacts of the fisheries on the mackerel stock.

5.2.3 Impacts on other components of the ecosystem

Plankton

Since there is very little directed fishing for plankton in the Norwegian Sea, the fisheries will only have indirect impacts on plankton. Zooplankton is an important part of the diet of herring, mackerel and blue whiting, which are the major pelagic fish stocks in the Norwegian Sea. If harvesting reduces the size of these stocks, it will also reduce the amount of plankton they eat. This in turn will make a larger proportion of the total zooplankton production available to other plankton-eating species, such as mesopelagic fish (small plankton-eating species that live at depths of 200–1000 metres), cephalopods, seabird, whales and other zooplankton species.

If a directed fishery for plankton is started up in the period up to 2025, various problems could arise. For example, fish eggs and larvae could be taken as a bycatch. This problem would have to be solved before a large-scale plankton fishery could be developed. Since there is no large-scale harvesting of plankton in the Norwegian Sea today, we know little about the possible consequences of a directed fishery on plankton production.

Seabirds

The impacts of fisheries on seabirds may be both direct and indirect, since they may change the food supplies available. It is difficult to document and quantify these impacts. Breeding failure, changes in feeding habits, higher adult mortality and mass mortality events are all indications that seabird populations are facing problems. The expert group assessed the impacts of harvesting of fish stocks on seabirds stocks to be moderate for common guillemot, puffin, common eider, shag and kittiwake. The best documented examples of negative interactions between fisheries and seabirds in Norwegian waters are related to the collapse of the Norwegian spring-spawning herring stock at the end of the 1960s and the Barents Sea capelin in the mid-1908s. When the herring stock collapsed, the drift of herring larvae northwards along the Norwegian coast in summer more or less ceased. The breeding success of puffins on the Røst archipelago is closely linked with year-class strength and the timing of larval drift in herring. The collapse in the herring stock resulted in prolonged breeding failure for the Røst puffin population, which dropped by more than half in less than 10 years. In the first 20 years after the herring stock collapsed, the puffins had only three successful breeding seasons. However, the puffin population on Røst has shown a positive trend in the last five years.

There is little documentation of unintentional bycatches of seabirds in fishing gear in the management plan area. It is therefore difficult to predict the impacts of bycatches on seabird populations. Gill netting mainly affects coastal and pelagic diving species, while surface-feeding species are mainly affected by longlining. Even relatively small bycatches can be a threat to red-listed species such as common guillemot, lesser black-backed gull (subspecies Larus fuscus fuscus), Slavonian grebe, yellow-billed diver, Steller’s eider and velvet scoter. The Norwegian Institute for Nature Research has recently completed an overview of current knowledge, and concluded that there is only fragmentary information about the scale and impacts of bycatches of seabirds in Norwegian waters. A seminar on bycatches held by the Directorate for Nature Management spring 2008 concluded that data on the scale of bycatches of seabirds in the Norwegian fisheries must be collected and used to estimate the impacts on seabird populations. This work is being started up in 2009. Fishing effort, catches and all bycatches, including seabirds, are therefore being registered on a daily basis by a reference fleet of gill net vessels that cover the entire coastline and a second reference fleet of seagoing fishing vessels, and reported to the Institute of Marine Research. The data collected will be scaled up to provide an estimate of total bycatches during fishing operations.

Lost gill nets, longlines and other gear can also be a threat to seabirds, but there have been few studies of such «secondary» bycatches. Several species, particularly cormorants, shags and gannets, which use remains of fishing gear as nesting material, risk becoming entangled and dying. Collection of dead seabirds from the shoreline often reveals auks, gannets and cormorants that are entangled in remains of fishing nets. These birds may well have been taken as a bycatch during fishing and then discarded.

Marine mammals

The fisheries may also have indirect impacts on marine mammals, since these animals prey on fish and therefore compete with people for the same resources. However, we have only limited information on the which fish species the various marine mammals eat, and how much. Bycatches of marine mammals can be a problem. A particularly large bycatch of porpoises is taken in gill nets in the Vestfjorden. Data from 2006 indicate that the local bycatch is so large that the porpoise population in the Vestfjorden is only maintained by immigration from neighbouring areas. The expert group assessed the impact of this bycatch as major for the porpoise population in the Vestfjorden. The impacts effects on minke whale, hooded seal and harp seal stocks are largely related to harvesting, and are ranked as moderate. There is nothing to suggest that the current harvest of minke whales is a threat to the North Atlantic minke whale stocks. There is little data on hooded seals, but a decline in pup production has been observed in the Norwegian Sea. ICES has concluded that if the harvest is continued, there is a risk that the stock will not be able to recover, and that it may in the worst case decline further, even if the decline was not caused by hunting. ICES has therefore recommended that no harvest of hooded seal should be permitted in the West Ice from 2007 onwards. For common seal, the impacts of hunting and bycatches are assessed as major.

5.3 Pressures and impacts associated with the oil and gas industry and other energy production

5.3.1 Petroleum activities in the Norwegian Sea

Since the first areas in the Norwegian Sea were opened for petroleum activities in 1979, about 160 exploration wells have been drilled, and currently 12 fields are on stream. As of September 2009, a further two fields are under development: Skarv and Morvin. At present, petroleum activities are largely concentrated in the area between 62°N and 68°N and east of 2°E, mainly on the Halten bank. A scenario for 2025 has been analysed, featuring three new field centres for gas production, a new oil field off the coast of Møre og Romsdal, including transport ashore, and a new pipeline to Kollsnes for gas export. The scenario also includes exploration drilling in the area between Jan Mayen and Iceland. Iceland has already announced its first oil and gas licensing round for areas bordering on the Norwegian continental shelf around Jan Mayen, and the country is planning to award exploration licences in autumn 2009. The scenario for 2025 also assumes that four oil fields that are currently on stream will have closed down. There will be a decline in oil production in the management plan area up to 2025, while gas production will increase markedly up to 2020, and then decline somewhat. Total production in 2025 is expected to be about the same as today, but with a shift towards a larger proportion of gas. The basis for value creation in the petroleum industry is described in more detail in Chapter 4.1.

In general, the petroleum industry can have negative impacts on the environment through operational discharges of chemicals, oil and other naturally occurring substances, including radioactive substances released to the sea, emissions to air of nitrogen oxides, volatile organic compounds and carbon dioxide (NO_x, VOCs and CO₂), and also in other ways, such as physical disturbance of the seabed and effects of seismic surveys on fish and marine mammals. The Norwegian petroleum industry is therefore strictly regulated in order to avoid or minimise damage. The impacts of acute discharges to sea are discussed in section 5.6 below. It is not possible to identify direct impacts on the Norwegian Sea specifically from emissions to air from petroleum activities, and this issue is therefore not discussed further. Chapter 6 deals with the impacts of total emissions of greenhouse gases on climate change and ocean acidification.

Oil and gas fields differ, and often different technical solutions are required to reduce discharges on different fields. Technology and operating conditions are continually being developed and improved, but existing and new installations often require different technical solutions. For example, lack of space or other features may make it impossible to install new and improved technology on an existing installation. Thus, solutions must be evaluated on a case-to-case basis.

5.3.2 Impacts of operational discharges to sea

Today, allowed operational discharges to sea consist mainly of produced water, drill cuttings and small quantities of chemical additives and cement from drilling operations.

Source Norwegian Petroleum Directorate

Zero-discharge targets for releases of environmentally hazardous substances to the sea from petroleum activities were first set out in a white paper on an environmental policy for sustainable development (Report No. 58 (1996–1997) to the Storting). Since then, the authorities and the industry have been cooperating on refining the targets and developing measures to meet them. The petroleum industry has invested heavily in technology for reducing discharges to sea, and the measures implemented so far have resulted in substantial reductions. Stricter requirements for discharges, that include the requirement of zero discharges of produced water, have been introduced in the Barents Sea.

The Norwegian Pollution Control Authority, the Norwegian Petroleum Directorate and the Norwegian Radiation Protection Authority published a report in December 2008 evaluating the environmental and social costs and benefits of zero discharges. They concluded that a socioeconomic cost-benefit analysis should be conducted for each new development that will include overall environmental assessments of measures to prevent discharges of produced water and/or drill cuttings and drilling mud.

The quantities of environmentally hazardous chemical additives used and discharged on the Norwegian continental shelf are declining, in accordance with the zero-discharge target for such substances. In 2007, 90 % of the discharges of chemical additives on the Norwegian shelf were green-category substances (substances that have no significant environmental impacts) according to the system used by the Norwegian Pollution Control Authority. Discharges of red-category or black-category substances were reduced from 4 160 tonnes in 1997 to approximately 24 tonnes in 2007, a reduction of over 99 %. Today the petroleum industry is only responsible for less than 3 % of total discharges to the sea of environmentally hazardous substances on the authorities’ priority list. The efforts to meet the zero-discharge targets are described in more detail in the white paper on the Government’s environmental policy and the state of the environment in Norway (Report No. 26 (2006–2007) to the Storting).

The total volume of produced water discharged on the Norwegian continental shelf in 2007 was approximately 162 million m, 13.6 million m of which was discharged to the Norwegian Sea. As fields age, the total volume of produced water discharged to the Norwegian Sea will increase to approximately 28.5 million m up to 2014. Later, as oil fields are shut down, the total volume of produced water discharged will be substantially reduced, and is expected to be 7 million m in 2025. Discharges are strictly regulated and the produced water must be thoroughly treated before discharge. Produced water is usually discharged relatively high up in the water column and the most toxic water-soluble fractions are rapidly diluted by seawater. The acute impacts of operational discharges of produced water and drill cuttings are assessed as insignificant since they will generally be local and short-term and will not have effects at population level. There is more uncertainty about the long-term effects. No impacts at population level have so far been demonstrated by research and monitoring, but further studies are being conducted.

Source Norwegian Petroleum Directorate

Produced water contains naturally occurring, low-level radioactivity from rock formations. The quantities depend on the type of formation and vary from field to field. It is difficult to assess the direct impacts on the environment of discharges of such substances with water. Background levels only appear to be exceeded in the vicinity of discharges. However, there is a need for more knowledge about the concentrations of these radionuclides in the Norwegian Sea (in seawater, sediments and living organisms) and of the effect level for the marine environment.

Drilling of exploration and production wells produces waste in the form of drill cuttings and drilling mud. Discharges of drill cuttings may result in sediment deposition on the seabed close to the point of discharge. In general, discharges of drill cuttings are permitted if water-based drilling mud has been used, but if oil-based muds are used, drill cuttings and drilling mud must be reinjected or taken ashore for treatment. The impacts of discharges of drill cuttings from drilling with water-based mud are mainly local. Vulnerable organisms such as corals and sponges can be smothered by sediment. Studies of sponges have concluded that the impacts of discharges of drill cuttings and other petroleum activities are greatest within a radius of 50–100 m from the drilling site, and that certain chemicals may have impacts on larvae and recolonisation in certain species within a radius of 300–500 m. Discharges are not permitted in areas where surveys have revealed the presence of particularly valuable and vulnerable benthic communities or habitats, such as corals.

5.3.3 Impacts of other activities

Other pressures on the environment include physical disturbance of the seabed, seismic surveys, introduction of alien species attached to hulls (rigs and production ships), decommissioning of facilities and discharges of waste or litter. However, our knowledge of their impacts varies.

Physical disturbance of the seabed: this is largely due to mechanical work such as pipelaying (including burying and armouring), construction of installations and use of anchors. Benthic communities and corals are affected by physical disturbance, but the impacts are limited and local. Conducting adequate surveys and adapting petroleum operations to take this into account should ensure that corals and other valuable benthic communities are not damaged by petroleum activities.

Seismic surveys: these are conducted to assess the potential for petroleum deposits, and are an important aid to good decision-making in both the exploration and the production phases. Geological surveys of the seabed involve the use of sound pulses. These are discharged by air cannons, creating air pressure. It is the noise generated by this activity in the form of sound waves or disturbance of particles in the water that can have a negative impact on the marine environment. The impacts of seismic surveys on fish eggs and larvae are confined to the area in the vicinity of the air cannon. The impacts at population level are considered to be insignificant, and the level of uncertainty is low. For adult fish, the impacts of seismic activities are considered to be limited to within a few metres of the air cannon.

Alien species: in the impact assessment for the oil and gas industry and other energy production, only the hulls of installations and rigs were considered as routes of introduction for alien species. The risk of alien species being introduced through these vectors is considered to be very low (introduction by ballast water was considered in the impact assessment for maritime transport), and the impacts of the introduction of alien species are not discussed further here.

Waste/litter: the petroleum industry has sound procedures for waste management and for the environmentally acceptable disposal of waste. The risk of litter in the sea and resulting impacts on marine life is therefore considered to be very low.

5.3.4 Impacts of offshore wind power

There is currently no offshore wind power production on the Norwegian continental shelf. At the international level the only experience available is from production in shallow waters in coastal areas. This means that there is considerable uncertainty about the possible impacts if offshore wind production is established. Wind turbines do not themselves produce emissions to air, and it is considered unlikely that there will be any operational discharges to the sea. Thus any releases of pollutants to air or the sea will be during construction work and maintenance operations. Environmental pressures will in general be associated with infrastructure (cables, anchors, etc.), the possibility of collisions and barrier effects for seabirds, the aesthetic (visual) impact and noise. During the construction phase, vessel operations, use of explosives and physical disturbance will produce noise, while during the operational phase wind turbines will be a permanent source of noise.

Any environmental impacts of the establishment and operation of offshore wind farms are expected to be restricted to species and habitats in the vicinity of the installations, and any damage is expected to be at the individual level. However, there is some uncertainty about the impacts of offshore wind farms on seabirds. We do not know enough about the risk of collisions for local and migrating birds or about barrier effects. We also have limited knowledge about the impact of noise from wind turbines on the behaviour of fish and marine mammals.

5.4 Pressures and impacts associated with maritime transport

5.4.1 Maritime transport in the Norwegian Sea

Ship traffic in the Norwegian Sea consists mainly of fishing vessels, followed by cargo vessels, bulk carriers, tankers and gas tankers, and offshore supply vessels. In internal waters and in the Vestfjorden the main form of traffic is passenger transport (conventional and high-speed ferries and the Hurtigruten fleet), followed by cargo vessels and fishing vessels larger than 24 metres. Transport of iron ore from Narvik also accounts for a considerable proportion of ship traffic in the Vestfjorden. The different traffic routes are described in more detail in Chapter 4.1. Traffic density is highest along the Norwegian coast from Røst at the southern end of the Lofoten Islands to Stad at 62°N, and much lower in the rest of the Norwegian Sea. Maritime transport of oil and gas, particularly gas, is likely to increase considerably up to 2025. However, this will depend on future developments in the petroleum industry in northwestern Russia and on the Russian and Norwegian sides of the border in the Barents Sea, as well as on the choice of transport. Apart from this, only small changes in traffic density seem likely to occur during the period up to 2025. The Government is seeking to ensure that a larger volume of goods transport is switched from road to sea, and this would increase the volume of traffic, but on the other hand maritime transport is a more secure and environmentally friendly alternative for shipping goods than road transport.

Maritime transport can put pressure on the environment through operational discharges to water and air, illegal discharges, the introduction of alien species via ballast water or attached to hulls, and noise. According to the impact assessment for the maritime transport sector operational discharges to the Norwegian Sea are small. No significant impacts from operational discharges of oil, sewage or organotin compounds have been found, and operational discharges to air from maritime transport or fisheries activities have not in themselves been found to have direct impacts. However, maritime transport involves a risk of collisions, which can result in acute oil or chemical pollution (see section 5.6). Norway is playing an active role in the efforts, particularly in the IMO, to make maritime transport a safer, more environmentally friendly form of transport (see Chapter 7.5).

5.4.2 Impacts of discharges to the sea

Shipping puts pressure on the environment on a day-to-day basis through ordinary operational discharges. However, operational discharges of oil and oil residue from ships in the management plan area are considered to be small. Discharges of oil, sewage and organotin compounds from anti-fouling systems have not been found to result in impacts of any magnitude in the management plan area, and the impacts are assessed as insignificant for the area as a whole. Much of the extensive littering of the coastal and sea areas comes from ships and fishing vessels, and the impacts are assessed as moderate for the most seriously affected species, such as the kittiwake.

Discharges of sludge and oily bilge water from machinery spaces, discharges of oil and oily mixtures from the cargo area (slops) and oil residue (sludge) are regulated internationally by MARPOL (International Convention for the Prevention of Pollution from Ships). The convention permits a certain level of discharges of oily bilge water and oily mixtures from tank washings. Tank washings are the largest legal source of oil discharges today (oily mixtures from washings 840 tonnes/year, oily bilge water 0.470 tonnes/year). However, all ships are required to have segregated ballast tanks by 2010, and this will reduce discharges of oily ballast water. Oil slicks on the sea are reported every year, and most of these are believed to be from illegal discharges from ships. Experience has shown that accidental spills and illegal discharges have the greatest environmental impacts, and most are probably unreported. Seabirds are particularly vulnerable, but it is difficult to estimate the magnitude of the impacts.

Source Norwegian Coastal Administration and Directorate of Fisheries

Tributyl tin (TBT) and other organotin compounds from ships’ anti-fouling systems are hazardous substances that can be absorbed by living organisms. However, under an IMO convention, a ban was adopted on the application of anti-fouling systems containing TBT from 2003, together with a requirement to remove older anti-fouling systems containing TBT by 2008. These measures are expected to reduce inputs of TBT to the environment.

We do not have sufficient information on how different types of vessels deal with waste on board, and it is difficult to estimate how much waste is delivered to port reception facilities, incinerated on board or discharged to the sea. However, much of the floating waste is assumed to be discharged from ships at a legal distance from shore. Plastic waste from fishing vessels and other ships has been shown to have negative impacts on many species of seabirds and marine mammals, which either become entangled in the waste and die as a result, or eat the waste, which then accumulates in the digestive organs, blocking or injuring them. A global ban on discharges of plastics was adopted by IMO (MARPOL) in 1998, but in spite of this, large volumes of plastic waste are still being found in the marine environment. The expert group ) concluded that waste drifting on the surface of the sea may have up to moderate impacts on surface-feeding seabirds such as kittiwakes. The IMO rules in this area are under revision.

5.4.3 Impacts of emissions to air

Emissions to air from maritime transport include greenhouse gases and acidifying substances from engines in addition to fugitive emissions of volatile substances from cargoes (petroleum and petroleum products). In the management plan area the total annual emissions of CO₂ from maritime transport and fishing vessels are estimated at approximately 755 000 tonnes. Norway’s total CO₂ emissions (2007) are estimated at approximately 45 million tonnes. It is not possible to identify direct impacts specifically from emissions from ships. Emissions of greenhouse gases from maritime transport act in combination with other emissions from national and international sources. The most serious impacts of greenhouse gases in the Norwegian Sea are expected to be ocean acidification and climate change. These topics are dealt with in Chapter 6.

In spite of a moderate increase in overall volume of maritime transport in the management plan area, and a considerable increase in tanker traffic, emissions to air are expected to be reduced, due to the rapid development and adoption of new technology. The improvements are being made in response to the stricter international rules governing operational discharges from ships. In 2008 the IMO adopted new and stricter rules on reductions in emissions of NO_x and SO₂in order to further reduce air pollution from ships. The tax on NO_x emissions in Norwegian waters will also result in the installation of NO_x-reducing technology on ships sailing between Norwegian ports, which will also reduce emissions. The new agreement between the Government and 14 trade organisations on measures to reduce NO_x emissions by 30 000 tonnes by 2010 will be a valuable tool for reducing emissions to air from a number of industries, including maritime transport and fisheries. A NO_x fund has been established and a large number of companies have joined it.

5.4.4 Introduction of alien organisms via maritime transport

Today the introduction of alien organisms is considered to be one of the most serious threats to biodiversity in marine ecosystems. Alien organisms can be a threat to species and habitats in several ways, but mainly by competing for food with native species or through overgrazing or overforaging of resources. However, knowledge about the effects of alien species is limited (see Chapter 9.3), and it is difficult to assess how serious their impacts could be.

The most important pathways of introduction (vectors) of alien species with maritime transport are ballast water and fouling of ships’ hulls. In 2004, IMO adopted the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (Ballast Water Convention). Norway has ratified the convention and is in the process of developing national legislation in accordance with it. Under the provisions of the convention, ballast water exchange must be conducted in open waters (at least 200 nautical miles, or if this is not possible, at least 50 nautical miles, from the nearest land and in water at least 200 m deep) during a transitional period. If these requirements cannot be met, ballast water exchange must be conducted in specific areas along the coast. The choice of such areas will take into account the risk that alien species will become established in the area. Closeness to existing shipping lanes will also be taken into consideration.

The proposed ballast water exchange areas will be provisional, since the above requirements will be replaced over a period of time by requirements for the treatment of ballast water. The latter requirements will only be introduced when the convention enters into force, which will be 12 months after at least 30 states representing 35 % of world merchant shipping tonnage have ratified it. It may well take several more years before the convention enters into force. However, draft Norwegian ballast water regulations provide for ships to install equipment to treat ballast water on a voluntary basis in order to test new technology. As such equipment is installed, the risk of negative impacts will be reduced. Studies indicate that about half of all identified alien species come from ships’ hulls. This is very difficult to prevent, and this route of introduction will therefore continue to be a problem in the time to come.

5.5 Impacts of long-range transboundary pollution, alien species and activities outside the management plan area

The state of the environment in the Norwegian Sea is also affected by activities outside the management plan area. Environmentally hazardous substances are transported over long distances by winds and ocean currents. The ocean climate is changing as a result of greenhouse gas emissions worldwide, ocean acidification is increasing and alien species can be introduced from other sea areas. Today the most important external pressures are climate change and long-range transboundary pollution. Over the long term ocean acidification is expected to have major impacts on the management plan area.

5.5.1 Long-range transboundary pollution

Long-range transboundary pollution is pollution that enters the Norwegian Sea from sources outside the area. Wind and ocean currents are the most important transport routes, but transport with ice and inputs via rivers may have local impacts.

Persistent organic pollutants (POPs) such as PCBs, DDT, toxaphene and brominated flame retardants are often the most important environmentally hazardous substances. In the management plan area, levels in water and sediment are generally low, as they are in fish from the Norwegian Sea. However, high levels of POPs, especially PCBs, have been found in birds in several locations in the management plan area, and particularly in seabirds high in the food chain, such as glaucous gulls and great black-backed gulls. POPs levels in certain glaucous gull colonies are probably so high that they could threaten the survival of these populations. Marine mammals high in the food chain such as killer whales and polar bears have elevated concentrations of hazardous substances in fatty tissue. Polar bears live mainly on seal blubber, and with time build up high concentrations of POPs in their bodies. Females transfer considerable amounts of these substances to cubs in milk, and may therefore have considerably lower levels than males, and it is not uncommon for cubs to have higher levels of such substances than their mothers. The immune system in polar bears on Svalbard has been shown to be weakened. Some killer whales have been found to contain such high levels of POPs that the same probably applies to this species. POPs are the most serious environmental problem in the northern parts of the management plan area.

Studies of organochlorine compounds in fish have shown that in the management plan area the levels are considerably lower than the EU limit values for hazardous substances in seafood. However, dioxins, PCBs and mercury have been found in certain large, long-lived species of fish that are high in the food chain, such as large halibut and Greenland halibut.

In spite of international efforts to reduce the use and releases of POPs, such substances are still entering the high-latitude areas, and are expected to be traceable in many animals for decades. Inputs of new substances with the characteristics of POPs, such as brominated flame retardants, are expected to rise. For example, rising levels of the extremely persistent compound perfluorooctyl sulphonate (PFOS) have been registered in Arctic animals.

Inputs of heavy metals to Norwegian areas have declined steeply since the 1970s, since restrictions on their use have been introduced in Europe. Inputs of cadmium and lead are declining but the decline in mercury inputs has stopped. There is therefore still cause for concern about possible adverse impacts of mercury in parts of the management plan area. However mercury levels are expected to decline gradually since its use in products is no longer permitted.

There are three main sources of radioactive pollution in Norwegian sea areas: fallout from atmospheric nuclear testing almost 50 years ago, releases from European reprocessing plants for spent nuclear fuel and fallout from the Chernobyl accident in 1986. However, according to current knowledge, the concentrations of radioactive substances of anthropogenic origin in the Norwegian Sea are not high enough to cause adverse environmental impacts. On the other hand, this knowledge is limited and we also know little about possible combined effects of radioactivity and other pressures on species and ecosystems. There are also other sources of radioactive pollution, such as produced water from oil and gas activities on the continental shelf in the North Sea and the Norwegian Sea. If there are no accidents, and if releases of radioactive substances to the sea are reduced in accordance with international commitments, levels of man-made radioactive substances in sea water, sediments and marine organisms in the Norwegian Sea are expected to decline. However, an accident involving releases of radioactivity could result in considerably higher inputs of radioactive substances. The large stocks of liquid high-level waste at Sellafield are considered to pose a very high risk, and a worst-case scenario has been developed for the impacts on the Barents Sea of large releases of waste from Sellafield. This study, which is also relevant to the Norwegian Sea, showed that releases on this scale could result in substantial inputs of Cs-137 and Sr-90 via ocean currents, and a rise in activity concentrations of these substances. Increased releases of man-made radioactive substances could also result in higher concentrations in marine organisms, especially in seabirds. Nevertheless, the estimated doses to marine organisms are low. However, we do not know enough about the impacts of low-dose radiation on the environment and it is therefore difficult to assess the consequences for the Norwegian Sea.

5.5.2 Introduction of alien organisms

Today, the introduction of alien organisms is considered to be one of the most serious threats to biodiversity in marine ecosystems. The most important pathways of introduction (vectors) of alien species are via ballast water and fouling of ships’ hulls, as described in section 5.4.4. In addition, organisms that have already been introduced to Europe or other nearby areas may spread further to the Norwegian Sea (secondary introduction) for example with the coastal current and Atlantic water or other means of dispersal. Alien organisms can threaten marine ecosystems and valuable marine resources in several ways, but mainly by competing for food with native species or through overgrazing or overforaging of resources. The establishment of a number of alien species in or adjacent to the Norwegian Sea has been documented, for example the red alga Heterosiphonia japonica, japweed ( Sargassum muticum), Japanese skeleton shrimp ( Caprella mutica) and the comb jelly Mnemiopsis leidyi.

Globalisation, international trade and transport will very probably contribute to the spread of alien species in the Norwegian Sea in the years ahead.

5.5.3 Petroleum activities outside the management plan area

Some petroleum activity in the North Sea is located relatively close to the management plan area. The potential consequences of any discharges from activities in the northernmost parts of the North Sea will be greater than for other adjacent sea areas, because they could be transported from the North Sea to the Norwegian Sea via ocean currents. Operational discharges have a more localised impact, and such discharges in the North Sea will probably not affect the Norwegian Sea. However, acute pollution from petroleum activities in the northern parts of the North Sea would affect parts of the Norwegian Sea if the oil were to drift northwards. This could affect important herring spawning grounds and important areas for seabirds and coastal seals in the same way as activities in the Norwegian Sea itself. The location, scale and timing of a spill, together with wind and weather conditions, will determine the impacts on species and habitats.

5.5.4 Maritime transport outside the management plan area

Maritime transport in areas outside the Norwegian Sea can affect the management plan area, and maritime transport in the internal waters, inside the baseline, is important in this context. Operational discharges from maritime transport outside the management plan area are so small that they are not likely to have much impact on the Norwegian Sea environment. However, discharges of oil from tank cleaning operations are a larger source of pollution and could probably harm seabirds that at certain times of year are outside the management plan area.

Emissions to air from ships in the North Sea and internal waters may be transported in the atmosphere and deposited in the management plan area. However, it is difficult to quantify the scale of this process.

Spills from tankers wrecked inside the baseline in the Norwegian Sea could have more serious consequences, particularly on coastal and nearshore species and habitats, such as seabirds, and marine mammals and the shoreline than similar accidents outside the baseline, because of their proximity to land and because the probability of affecting vulnerable species and areas is higher. Whether or not an accident has consequences for fish eggs and larvae will depend on whether it occurs in an area and at a time of year when eggs and larvae are present. In the same way as for accidents occurring in the management plan area itself, the location and timing of an accident will determine what consequences it may have for the Norwegian Sea environment.

5.5.5 Fisheries activities outside the management plan area

Most of Norway’s commercial fish stocks are shared with other coastal states. External pressures on these stocks include fisheries outside the management plan area, and stocks that are found in the Norwegian Sea are also harvested in other sea areas. This is due to seasonal migration, which means that the stocks congregate in other areas at certain times of year for overwintering or spawning. Blue whiting migrate southwards from the Norwegian Sea and spawn west and south of the UK and Ireland in March–April. Mackerel is another species that only occurs in the Norwegian Sea at certain times of year. After spawning, mackerel migrate into the Norwegian Sea, but in autumn they gather in the northern parts of the North Sea, where most fishing for mackerel takes place. Norwegian spring-spawning herring also migrate between overwintering areas, spawning grounds and feeding areas. International agreements have been concluded for all these stocks in order to ensure sustainable harvesting.

5.6 Risk of acute pollution

Risk management, the risk of acute oil pollution and oil spill response systems are discussed in Chapter 7.5. In the present chapter the potential environmental consequences and the environmental risks are discussed using sample scenarios developed for the Norwegian Sea.

Scenarios were developed for accidents involving spills of oil, chemicals and radioactive waste. The rules for the carriage of chemicals divide chemicals into categories according to toxicity, and the special rules for carriage of the most toxic categories are designed to reduce both the probability of spills and the consequences of accidents. The small volumes of chemicals involved and the strict rules mean that both the probability of releases and the level of environmental risk during chemicals transport are considered to be low. Modelling of accident scenarios involving releases of radioactivity has shown that such incidents will result in substantial inputs of radioactive substances and a rise in the level of radioactive pollution, which will still persist five years after the accident. Modelling indicates that levels of radioactivity to which organisms are exposed after an accident are likely to be below the threshold levels at which damage is expected. However, we know too little about the effects of radioactive contamination on the natural environment.

Both petroleum activities (oil production and exploration drilling) and maritime transport in the Norwegian Sea involve a risk of oil spills. In both these sectors, there are several different types of incidents that may occur and that contribute to the overall risk level. In 2007 a total of 166 oil spills from petroleum activities were reported, 12 of them with a volume of more than 1 m. This is a rise of 44 compared with the previous year, and is the highest number of oil spills since 2002, when the number declined considerably. The total volume of acute discharges of oil in 2007 was 4 488 m (4 400 m of which was from the Statfjord A spill) (see Figure 5.9). No environmental impacts have been identified after any of the spills. The number of spills from ships has remained fairly constant over the last 11 years (see Figure 5.10). However, the total volume in 2007 was larger than in the rest of the period, particularly the two previous years. Several of the major spills from ships have had impacts on seabirds and have resulted in extensive contamination of the shoreline. A large proportion of the total volume of acute discharges from both ships and petroleum activities consisted of spills larger than 1 m.

Source Norwegian Pollution Control Authority

The probability of a major oil spill varies according to a range of on-site operational and actor-specific factors. The probability (which can also be expressed as the recurrence frequency or recurrence interval) is normally calculated on the basis of historical data. The volume and duration of the spill vary from one incident or scenario to another, and a particular oil spill scenario may have a range of possible outcomes with different probabilities. Generally, the probability of a spill occurring is highest (the recurrence interval is lowest) for the smallest spills, and highest (longest recurrence interval) for the largest spills. It is generally assumed that the potential for serious environmental consequences is lower for small oil spills than for major spills, although there are exceptions to this rule. For both maritime transport and petroleum activities, the assessments of environmental impacts at current levels of activity are based on a number of different oil spill scenarios.

Source Norwegian Coastal Administration

5.6.1 Acute oil pollution from ships

In all areas where ships sail, there is a certain risk of accidents (collisions, groundings and shipwrecks). A number of accident scenarios have been modelled involving oil pollution along the coast in order to illustrate different possible outcomes as regards environmental consequences and risk. The scenarios include accident sites that will affect some of the most valuable areas along the coast. The assessment of consequences and risk do not include the effects of protective measures in the form of oil spill response systems, which generally reduce the consequences and risk of an oil spill. The outcomes of these scenarios were used to assess the potential consequences of accidents in other parts of the management plan area. However, there are great variations in the volume of traffic within this area and consequently in the risk of accidents and acute pollution. Ship traffic density is particularly high in the coastal waters between Røst (southern tip of the Lofoten Islands) and Stad at 62^oN, while traffic in the rest of the Norwegian Sea is small compared with the coastal traffic. The area from Stad and northwards along the coast of Møre og Romsdal has particularly dense traffic. There are four main traffic streams in the Norwegian Sea (see Figure 5.8 and Chapter 4.1), which meet relatively close to the coast off Stad. Almost all traffic passes less than 25 nautical miles from the coast in this area. The recurrence interval for ship accidents is shortest off Møre og Romsdal for all types of oil spills (crude oil, refined oil and bunker fuel). The probability of spills is highest for bunker fuel (recurrence interval 13 years, with the highest probability for spills of less than 400 tonnes), and lowest for major spills of crude oil (recurrence interval of over 800 years per 100 000 km sea area and highest probability for spills of 2 000 to 20 000 tonnes). In other areas of the Norwegian Sea the recurrence intervals are much longer for all kinds of spills.

A general increase in traffic in the Norwegian Sea is projected in the period up to 2025, and the largest and most important rise will be in tanker traffic to and from Russia. These increases may result in a rise in the frequency of accidents during this period unless preventive measures are taken.

Ship accidents can have substantial environmental consequences. Their magnitude depends on several factors, particularly time, place and whether vulnerable species and habitats are present in the area. The main measures to reduce the probability of major oil spills occurring from ships are the introduction of a minimum sailing distance from the coast and traffic separation schemes and other routeing measures. Requirements relating to ship construction, crews and shipowners are also important protective measures. Risk management is described in more detail in Chapter 7.5.

In general, the modelled accident scenarios show that the potential consequences of an oil spill are greatest for seabirds, the shoreline, marine mammals, and fish eggs and larvae, all of which are extremely vulnerable to exposure to oil. However the various scenarios show great variations in the scale of the consequences. For example, the results indicate that major oil spills resulting from accidents to ships off Stad and in the Vestfjorden could have up to majorconsequences, with long recovery periods for large, important seabird colonies in these areas, while the consequences for seabird populations in the management plan area as a whole are likely to be smaller. Another scenario that was modelled was an oil spill off Jan Mayen; in this case, the slick remained in the open sea and seabirds were not as badly affected. The consequences were assessed as less serious (up to moderate for certain species present in the open sea). The potential consequences for fish eggs and larvae in the water column are greatest in areas and during periods when they are present in high concentrations. Recruitment is only reduced to an extent that gives population-level impacts if part of the stock (a year class) is exposed to oil concentrations resulting in death or permanent injury. This means that there must be an overlap between the parts of the oil slick where oil concentrations exceed the estimated effect level and the drift trajectory of fish eggs and larvae and/or areas of the seabed where eggs and larvae are present. In the worst-case scenario, a shipwreck on or near a spawning ground, a qualitative assessment indicates that there may be up to moderate consequences for fish eggs and larvae.

In periods when seals congregate in large numbers (especially in the breeding season), an oil spill may affect a significant proportion of a population. The modelled scenarios indicate that in general the consequences are likely to be insignificant, rising to minor to moderate for common seals. The vulnerability of the shoreline to oil varies considerably depending on morphology, type and so on, and the time needed for recovery also differs from one type of shoreline to another. Previous experience of oil spills has shown that the negative impacts on beaches may vary in extent and duration, from almost complete loss of biological communities to marginal, sub-lethal impacts on individuals. A spill of moderate size rarely seems to cause serious damage over a large area, but the recovery period can be long in certain localities. The consequences for the shoreline in the event of oil spills in the area extending from Stad to the Vestfjorden will vary from minorto major, depending on the volume of oil, weather conditions, location of the spill and course of events.

To assess the environmental risk associated with oil spills from ship accidents, the potential consequences must be considered together with the probability of an accident. According to the results of the accident scenarios, both the probability of accidents involving oil spills and the potential consequences, particularly for seabirds, are greatest in the area from Stad and northwards along the coast of Møre og Romsdal, which means that the environmental risk associated with accidents is probably highest in this area. Similarly, the probability of accidents and their potential consequences is higher along the coast from Røst to Stad than in the remainder of the management plan area. A major oil spill off Jan Mayen could for example have major impacts on seabirds, but since the volume of traffic in this area is very small, the probability of an accident involving a major oil spill is also low. The environmental risk is therefore ranked as low.

5.6.2 Risks associated with acute oil pollution from petroleum activities

The probability of accidents involving oil spills occurring can never be reduced to zero, but one of the main objectives of risk management in the petroleum industry today is to reduce the environmental risk of petroleum activities as far as is practicable. This is done by building knowledge of how accidents happen and systematically implementing measures that reduce the probability that an accident will happen and the environmental consequences if an accident does happen. This is treated in more detail in Chapter 7.5.

There is always a possibility of acute oil pollution during oil production or drilling in oil-bearing formations. During exploration drilling, acute oil pollution may generally result from a blowout. During production acute oil pollution may result from pipeline leakages or large-scale process leakages from installations, leakages during loading or blowouts, although a blowout is the least probable event. However the probability of a major spill is highest in the event of a blowout (probability of oil volumes of 2 000–20 000 tonnes over 40 %, and 30 % probability of larger oil volumes), and blowouts have therefore been used as a basis for assessing potential consequences. However, the recurrence interval is longer (i.e. the probability is lower) for blowouts than for other types of accidents, which are likely to involve smaller volumes of oil. For the management plan area as a whole, and for all petroleum activities, the recurrence frequency for a blowout has been estimated at one every 83 years. For the individual fields, the recurrence frequency for a blowout varies from one every 270 years to one every 20 000 years. The recurrence frequency for a major pipeline leak is assessed at one every 108 years, while minor oil spills such as leakages from pipelines within a field may occur once every second year for the management plan area as a whole. The volume of oil involved in such leakages depends on a number of factors, the most important of which is the time that elapses before the leak is detected and the pipeline closed. The magnitude of a spill varies from a few to several hundred cubic metres, depending on the pipeline diameter and length, the diameter of the hole, the wellstream and the topography of the seabed. The probability of small-scale spills is highest, and the largest spills occur much more rarely.

Historical data on oil spills on the Norwegian continental shelf show that the level of activity has increased substantially without a corresponding rise in the frequency or volume of oil spills. The typical pattern is varying numbers of minor spills and occasional large spills. Since the start of petroleum activities on the Norwegian continental shelf about 40 years ago, there have been only three oil spills larger than 1000 m³: the Ekofisk Bravo blowout in 1977, the Statfjord C oil leak in 1989 and the Statfjord A oil spill in 2007. No environmental damage has been demonstrated as a result of these oil spills. Figures for incidents on the Norwegian shelf show only a small number of major accidents but a large number of small spills (see Figure 5.9). Although this is not a guarantee as regards future activities, it does show that risk management by the authorities and the oil and gas industry has so far helped to maintain a low risk of acute pollution in the Norwegian oil and gas industry.

The outcome of a blowout may vary considerably, even between two blowouts in the same field. Whether the oil spill occurs on the seabed or the sea surface, the duration of the blowout, wind and wave conditions and the time of year are all important factors. In general, formation pressure is higher in the Norwegian Sea than in the Barents Sea, which means that a blowout in the Norwegian Sea could result in a much larger or more long-lasting oil spill than one in the Barents Sea. Projections for developments in the management plan area indicate that a number of existing oil fields are expected to shut down, which will eliminate the risk of oil spills from these fields. The projections also show that a number of gas fields are likely to be developed in the area, which means that there will probably be fewer activities carrying a risk of an oil spill. Furthermore there are grounds for assuming that knowledge development, improvements in operations and technology, and legislative developments will reduce the risk of oil spills in the future.

Except in cases where there are large congregations of seabirds in the open sea, the most serious consequences of an oil spill are generally expected in the coastal zone and when oil drifts ashore. Modelling based on the scenario for the current level of activity, with nine fields on stream, indicates that a blowout on the Norne field would affect the largest area of sea and involve the largest volume of oil. This is because oil from the Norne field is very persistent, so that a slick would have a long lifetime in the sea. Results for the other fields generally indicate a smaller impact area, smaller volumes of oil and a probability of drifting ashore of less than 5 %. The Draugen field is an exception, since the distance to shore is shortest, and an oil spill from this field has the highest probability (16 %) of reaching the coast. As part of the 2025 scenario, the potential consequences of a blowout on a hypothetical oilfield have been investigated. The field was assumed to have a lighter type of crude oil and to be located closer to the coast, off the coast of Møre og Romsdal. The results showed that this field would have consequences for the smallest area of sea, both on the surface and in the water column, because a light oil evaporates and mixes more rapidly with the water masses and therefore has a shorter lifetime in the sea. However, the short distance from land means that oil from the Møre field would have a relatively high probability (27 %) of drifting ashore.

Two similar oil spills occurring in different places or at different times may have very different consequences. The potential consequences for fish eggs and larvae in the water column are most serious in areas and periods when they are present in high concentrations. Recruitment is only reduced to an extent that gives population-level impacts if part of the stock (a year class) is exposed to oil concentrations resulting in death or permanent injury. This means that there must be an overlap between the parts of the oil slick where oil concentrations exceed the estimated effect level and the drift trajectory of fish eggs and larvae and/or areas of the seabed where eggs and larvae are present.

Experts disagree on how large a proportion of a year class may be lost as a result of an oil spill and how this may affect recruitment to the fish stocks concerned. The consequences of accidents in connection with petroleum activities in the management plan area have been modelled by Det Norske Veritas. The modelled scenarios for different types of accidents showed that in the event of an oil spill the potential consequences for eggs and larvae would be insignificant or minor. Models of an overlap between the distribution of larvae of Norwegian spring-spawning herring and Norwegian Arctic cod in oil-contaminated seawater (using 250 ppb as the threshold value for damage), indicated that in the event of a blowout from the Norne field or the hypothetical Møre field the proportion of fish eggs and larvae lost would be in the range less than 1 % to 5.6 %, with an expected value of less than 1 %. On the basis of this model, the potential consequences of a spill are ranked as minor.

The Institute of Marine Research believes that losses could be much higher than modelling indicates, particularly in periods when the stock is low. The institute bases its opinion on the fact that under normal conditions only a small proportion of eggs and larvae survive and contribute to recruitment. Thus the institute considers that a blowout or an oil spill that affects the proportion of eggs and larvae that is necessary for recruitment could result in the loss of up to 100 % of a year class. However, the probability of a loss of this magnitude is very low.

Seabirds as a group are particularly vulnerable to oil pollution. The slow sexual maturation and low recruitment rates of many of these species mean that populations have a relatively long recovery period. Modelling show relatively large differences between the potential consequences of blowouts from different oil fields, and considerable variations in the course of the year. Blowouts from the Norne field and the hypothetical Møre field were found to have the greatest consequences for seabirds, varying from insignificant to major depending on the outcome of the accident. The potential consequences were greatest for puffins in the event of blowout in the Norne field in spring/summer. The potential consequences were assessed as major for puffins, minor for common guillemot, common eider and shag, and minor for kittiwake. However, the probability of accidents that might have major consequences was assessed as low in the situations modelled.

Seals congregate in large numbers in limited areas at certain times of year and are more vulnerable to oil during the breeding season. For the common seal the potential consequences of an oil spill are ranked as insignificant, with a certain probability of minor and moderate consequences in the case of a blowout from two of the fields (Draugen and the hypothetical Møre field). The most serious consequences would arise if large concentrations of animals are exposed to oil during periods when they are most vulnerable. If oil reaches the shore, the probability of minor consequences for the shoreline is 22 % for Norne, 5 % for Heidrun, 12 % for Draugen and 57 % for the hypothetical Møre field. These levels are generally lower during the spring and summer. For the Norne field and the hypothetical Møre field the probability of major consequences is 1 % and 3.7 % respectively. Such consequences would be limited to certain localities in the affected area. The above probabilities have been calculated without factoring in oil spill response measures. These reduce the consequences of oil spills, since the oil is recovered as close to the source as possible to the source of the spill. The results discussed here are based on scenarios that have been modelled. Future changes in for example the geographical location of activities or an accident with different features from those modelled could change the potential consequences and environmental risk in the event of oil spills.

Risk scenario for acute pollution from the hypothetical Møre field

The 2025 scenario includes a hypothetical oil field near the coastline. A light type of crude oil and a location about 40 km from the coast of Møre of Romsdal were chosen as the basis for the dispersion models and impact assessment. Production mode is assumed to be subsea templates tied to an onshore facility.

Petroleum production will result in a certain probability of an accident involving an oil spill to the sea, which could have environmental consequences. In order to reduce these consequences, petroleum companies are required to establish an oil spill response system. These factors determine the risk of acute oil pollution from petroleum activities.

The probability of a major oil spill from the hypothetical field has been calculated. The probability of an accident involving a major spill of crude oil is very low. A major spill may be caused by a blowout, pipeline rupture or leakage, or a by a ship colliding with an installation. If there are assumed to be 12 wells on the Møre field, the generic recurrence interval for a blowout would be every 1400 years. Since the hypothetical Møre field is assumed to have a subsea production templates, the possibility of a ship collision is limited to the drilling period, which with 12 wells is assumed to last for one to two years. The recurrence interval for a ship collision is found to be 12 300 years. Assuming that the oil pipeline to shore has a diameter of 18 inches, and that the distance to shore is about 40 km, the maximum volume of oil in the pipeline would be about 6 300 m. The recurrence interval for a pipeline leakage is 3 200 years. The maximum size of the spill would be 6 300 m, or the total volume of oil in the pipeline.

The potential consequences of a blowout have also been calculated. The most serious environmental consequences are expected if a large volume of oil reaches the coastal zone and possibly drifts ashore. The probability of oil drifting ashore from the Møre field is estimated at 27 %. If oil drifts ashore Det Norske Veritas has estimated that the probability of major consequences for the shoreline, meaning that recovery takes 3 to 10 years, is 3.7 %. The Norwegian Institute for Nature Research has conservatively estimated the maximum losses to seabird populations on the open sea as a result of a blowout on the Møre field at 4.3 % for common guillemots and 3.4 % for puffins in the summer, and 4.9 % for razorbills in the autumn. Det Norske Veritas has further estimated an expected loss of less than 1 % of a years class of herring. Fish are most vulnerable during the spawning period (and the early larval stages), which for herring in the Møre field mainly stretches from February to April. The Institute of Marine Research believes that losses could be considerably higher than modelling indicates, particularly in periods when stocks are low (see above). Det Norske Veritas has estimated a probability of 18 % for moderate consequences for common seals, which means that the population would recover within 1 to 3 years. Coastal seals are most vulnerable during the moulting and whelping periods.

All these examples show that for the hypothetical Møre field, the probabilities of environmental consequences resulting in a 3- to 10-year recovery period are low. In this impact assessment oil spill response measures are not taken into account. Analysis by the SINTEF Group state that a normal effort of mechanical oil spill containment and recovery in the event of a blowout in the Møre field would reduce the extent of affected sea area by 50 % and contamination of shoreline by over 75 %. Given the location of the field, there is a 5 % probability of an oil spill from the field reaching shore within 1 to 2 days. Drift time to shore is shortest when there are continual gale-force winds. In such situations, mechanical containment and recovery equipment is of little relevance, since the waves mix the oil into the water masses and speed up the natural degradation process. Under normal weather conditions there is sufficient time to mobilise oil spill response equipment and several time windows when conditions are good for mechanical oil spill response measures.