Intersectoral Assessment of Impacts on Seabirds: Baseline Report for a Comprehensive Environmental Management Plan for the Norwegian Sea


Title: Intersectoral Assessment of Impacts on Seabirds: Baseline Report for a Comprehensive Environmental Management Plan for the Norwegian Sea
Publication Date:
January 01, 2008
Document Number: 338
Pages: 161

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Christensen-Dalsgaard, S.; Bustnes, J.; Follestad, A.; Systad, G.; Eriksen, J.; Lorentsen, S.; Anker-Nilssen, T. (2008). Intersectoral Assessment of Impacts on Seabirds: Baseline Report for a Comprehensive Environmental Management Plan for the Norwegian Sea. Report by Norwegian Institute for Nature Research (NINA). pp 161.

(The majority of the report is in Norwegian. However, there is an abstract in English.)


This report is part of an assessment process carried out in connection with the development of a comprehensive management plan for the Norwegian Sea. The Norwegian Institute for Nature Research (NINA) has, at the request of the Directorate for Nature Management, the Directorate of Fisheries, and the Norwegian Coastal Administration assessed the possible impacts of various factors affecting seabirds in the Norwegian Sea, including petroleum activities, shipping and fisheries, together with factors of external origin (climate changes, long-distance pollutants, acidification of the sea, petroleum activities outside of the Norwegian Sea, ship traffic outside of the Norwegian Sea, nomadic species, activities in the coastal zone, and introduced species). The assessment is made with regard to both current conditions and a possible future scenario (2025). It is based on existing knowledge and focusses on five indicator species (European shag, common eider, black-legged kittiwake, common guillemot, and Atlantic puffin), which represent various ecological bird guilds. In some cases, other species are also considered.


Current and potential impacts on seabirds in the area that are likely to be caused by the various factors are mainly assessed qualitatively, but as far as possible based on existing knowledge. Simulations of accidental oil spills from petroleum activities and shipping within the assessment area and from shipping outside of it, are however treated in a semi-quantitative manner. In these cases, analyses of the spatial overlap between oil and seabirds were made, using distribution data for seabirds at sea and the locations of breeding colonies and other important seabird habitats along the coast.


Petroleum (chapter 5) Petroleum industry activities may potentially affect seabird colonies in various ways. Based on current knowledge, and the levels of spills used as the basis of analyses for this report, it is considered that normal levels of day-to-day emissions (2006 and 2025 levels) will not have significant impacts for seabirds. The most serious effects will be a result of oil slicks on the sea surface. Seabirds are extremely vulnerable to both direct and indirect effects of oiling. Even small amounts of oil in the plumage can have fatal consequences for a seabird, as a result of feathers sticking together so that the plumage loses its waterproof, and thereby, insulating quality. In addition, oiled individuals are easily poisoned by oil, which is ingested during preening. The scale of impacts following an oil spill is dependent on season (time of year when the accident occurs), the location of the spill, and the species and numerical distribution of the seabirds present in the area at that time. In order to assess petroleum exploration and production activities, statistical oil drift models were used to simulate blowouts from various oilfields within the assessment area. These data were combined in a spatial analysis with the, predicted numerical distribution of seabirds in the area, as modelled from documented relationships between seabirds and different environmental factors. The results were part of the basis for qualitative assessments as to the areas and species which can potentially be hit, and the overall impacts such incidents can have for the affected populations.


Based on the distribution of seabirds and their population status and individual vulnerability, it was considered that surface spills from the Norne and Møre fields, and drilling in connection with petroleum exploration around Jan Mayan (all in the period March-August) would have serious consequences for seabirds. Surface blowouts at the Draugen field and seabed blowouts at the Norne and Møre field (both in the period March-August) together with surface blowouts from Norne and Møre (in the period September – February) would have moderate impacts, while the rest would have small or negligible impacts. Individual simulations were also run for the Norne (summer), Draugen (autumn/winter), and Heidrun (spring/summer) fields, Jan Mayen (summer), and Møre (winter). Here emissions from Norne were also the most serious, with serious consequences for all indicator species. Spills around Jan Mayen were assessed to have serious consequences for puffin, guillemot, and kittiwake, but only small effects on eider. For the Møre and Heidrun fields, moderate consequences were assessed for puffin, eider, and shag, while spills from the Draugen field would have moderate consequences for puffin and guillemot. In the other cases assessed, the consequences of spills were considered to be small and inconsequential.


Wind power (chapter 6) Wind power stations can have various effects on seabirds. Increased mortality can result as a consequence of collisions; birds can be affected by loss and fragmentation of important habitat, or reduced access due to barrier effects from avoidance of human structures, or disturbance from human presence.


Wind power stations in the coastal zone are considered to have negligible consequences for the five indicator species at today’s level of development. The 2025 scenario for the coastal zone is considered to have moderate consequences for kittiwakes, while the consequences for puffins, guillemots, eiders, and shags will be small.


Currently offshore wind power stations have not been established in the study area. The prognosis for 2025 is that one such station will have been built in Nordmøre or Sør-Trøndelag. The consequences have been assessed for the five indicator species. The area is used as foraging habitat for all species in both summer and winter, so there are possible negative consequences due to habitat loss if they do not gain access to important foraging areas if they are unwilling to go within the wind power installation perimeter. Similarly, there may be a barrier effect in that the wind power installation will lie in the path of natural movements between important foraging areas. From these considerations, the assessment for habitat loss and area conflicts together with barrier effects are set as ‘small’ for puffin, guillemot, eider and shag. Other consequences are considered negligible.


Shipping (chapter 7) It is considered that emissions due to normal shipping operations will have negligible or small effects on seabirds. Spillage levels permitted by MARPOL 73/78 can be assumed to have relatively little consequence for seabirds. Individuals can be affected by the small amounts of oil floating on the sea, but probably not to a degree which will be noticeable at the population level. The only exception is the possible consequences of litter on surface-feeding seabird species. Chronic oil pollution must be considered the most serious potential problem with regard to the possible consequences of today’s level of ship traffic (without taking acute spillages into account). If large amounts of oil are released illegally, this may have serious consequences for seabirds.


Acute oil spills have the potential for making serious impacts on the seabird populations in the affected area. For shipping, three simulated accidents were assessed. To give an impression of possible differences in effects, the three events were simulated in different places and at different times of the year. The scale of effects following an oil spill are dependent on season (i.e. at which time of year the spill occurs), the location, the species found in the area, and their numerical distribution at the time. The assessment of these three simulated events gives therefore only a snapshot of the impacts that can be expected.


Event 2.1 occurred north of Stad, while event 10 was in Vestfjorden. The influence area for event 2.1 affected to a strong degree the foraging areas of important populations of guillemot and puffin (pelagic diving species), kittiwake (pelagic surface feeder), shag and to some extent eider (coastal diving species), together with a number of other seabird species. The spill from event 10 was of relatively long duration, and affected therefore both overwintering populations and populations on the way back to breeding localities in spring. In both cases it is considered that there would be serious consequences for all indicator species.


Event 12 occurred in open sea near Bear Island (Bjørnøya), and this was reflected in the impacts on seabirds. For guillemot and puffin (pelagic divers) and kittiwake (pelagic surface feeder) the consequences were considered to be moderate, even if the consequences for the pelagic species in the area will always depend on the distribution of prey fish in the area.


Fisheries (chapter 8) Both direct consequences in the form of bycatch of seabirds in fishing equipment and indirect consequences through competition with fisheries for the same food sources were considered.


The largest impact of fisheries on seabirds is through the effect on the birds’ food base. Trophic interactions between seabirds and fisheries, isolated or in combination with other factors, are very complex relationships to uncover. Many seabird species experience direct and/or indirect competition with fisheries, and in recent decades reduced populations of prey has been identified as a serious threat to many seabird populations. It is nevertheless not easy to determine the cause of even the most serious changes. Harvest of fish by fisheries can be a cause of reduction in access to prey, but trophic interactions caused by variations in climate can also be an important explanatory factor. Overall, the consequence for seabirds of the fish harvest by fisheries is considered to be moderate.


There is today little documentation available on the scale of bycatch of seabirds in the study area; it is therefore difficult to determine the consequences of bycatch for seabird populations. Net fishing affects primarily coastal and pelagic diving seabirds, while the surface-feeding species will be most affected by long-line fishing. The population impact of direct mortality through bycatch will vary with the time of year, the status of the affected population, and the sex and age structure of the birds killed. Even a numerically low bycatch may be a threat to red-listed species such as common guillemot, Slavonian grebe, white-billed diver, Steller’s eider and velvet scoter. It is considered that net fishing together with traps and lobster pots will have moderate consequences for both pelagic and coastal diving seabirds (indicator species: puffin, guillemot, eider and shag), whereas the other types of fishing gear are most likely to have little or negligible impacts on seabirds.


Factors of external origin (chapter 9) The factors of external origin that were assessed included climate change, long-distance pollutants, acidification of the sea, petroleum industry activities outside of the Norwegian sea, shipping outside of the Norwegian sea, nomadic species, human activities in the coastal zone, and introduced species were assessed. As many factors are considered in this chapter, the summary is divided into direct effects and indirect effects via changes in diet choice and habitat.


It is considered that oil spills caused by serious accidents in connection with the petroleum industry and shipping outside of the study area may have serious direct consequences for seabirds in the study area. Long-distance transported pollution will likewise have serious consequences for seabirds. Species at the top of the food chain are most vulnerable to the accumulation of environmental pollutants and many seabirds belong to this group. Other direct effects can be due to mortality caused by bycatch in fisheries equipment in the coastal zone.


It is considered that indirect effects via diet choice may especially occur as a result of climate change, which will affect the density and distribution of prey. This may have substantial consequences for seabirds, both with regard to distribution, density, and reproductive success (production of young). There is little knowledge available on the effects of acidifcation of the sea, but it is considered that this may be a factor which can have serious consequences at lower trophic levels, and thereby for seabirds through changes in food availability. Aquaculture and dumping of waste and litter may increase food resources for some species, while introduced species may compete with seabirds for the food base.


Indirect consequences through disturbance to, and/or changes or destruction of habitat may result from many of the factors assessed. In many areas it is considered that seabird habitats can be affected by runoff from the land, aquaculture, seaweed trawling, wind turbines, constructions, and other development, together with tourism and increased traffic. It is however difficult to quantify the scale of these factors. Depending on location and scale, these factors may have from negligible to serious consequences.


Combinatory effects (chapter 10) The sectoral assessments assess the effects on seabirds of single factors independently, but in reality seabirds are usually exposed to a number of these factors at the same time. Under particular conditions, the effects of one factor can strengthen the effects of another in such a way that the final impacts both at the individual and population level are higher than the sum of impacts from each factor assess alone (so-called synergistic effects). Increased mortality caused by bycatch can, for example, be an extra stress factor for populations already affected by habitat destruction, climate variations, or oil pollution. The report therefore concludes with an intersectoral summary.


Norwegian Title: Tverrsektoriell vurdering av konsekvenser for sjøfugl: Grunnlagsrapport til en helhetlig forvaltningsplan for Norskehavet

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