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Eight marine mammal species occur regularly over large parts the North Sea: harbour seal, grey seal, harbour porpoise, bottlenose dolphin, white-beaked dolphin, Atlantic white-sided dolphin, killer whale and minke whale. A further 15 cetacean species and five pinniped species are reported less frequently in the region.

This report describes the distribution and abundance of these mammals and their ecological importance. The harbour porpoise the most numerous marine mammal in the North Sea, with a population estimated at 268,000 in summer 1994. The northern and central SEA2 areas are particularly important areas for the harbour porpoise.

Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals.

The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. Large whales can be killed by being struck by ships; increased shipping traffic in an area would increase this threat.

The report was prepared by scientists from the Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews.

Eight marine mammal species occur regularly over large parts the North Sea: harbour seal, grey seal, harbour porpoise, bottlenose dolphin, white-beaked dolphin, Atlantic white-sided dolphin, killer whale and minke whale. A further 15 cetacean species and five pinniped species are reported less frequently in the region.

This report describes the distribution and abundance of these mammals and their ecological importance. The harbour porpoise the most numerous marine mammal in the North Sea, with a population estimated at 268,000 in summer 1994. The northern parts of the SEA3 area are important for the three most abundant cetacean speciesin the North Sea: minke whale, harbour porpoise and white-beaked dolphin. Harbour seals occur widely in the SEA3 area.

Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals.

The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. Large whales can be killed by being struck by ships; increased shipping traffic in an area would increase this threat.

The report was prepared by scientists from the Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews.

Twelve marine mammal species occur regularly in the SEA4 area: grey seal, harbour seal, hooded seal, harbour porpoise, white-beaked dolphin, Atlantic white-sided dolphin, Risso's dolphin, long-finned pilot whale, killer whale, minke whale, fin whale and sperm whale. A further eleven cetacean species and four pinniped species are occasional visitors. 

This report describes the distribution and abundance of these mammals and their ecological importance. The SEA4 area is an important area for cetaceans, but little is known about the abundance or seasonal distribution of many species.

Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals. However, current understanding of the effects of noise on marine mammals is rudimentary.

The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. The diseases to which they are subject are briefly discussed, as are non-oil management issues such as fisheries bycatch. Finally, the national and international frameworks for the protection of marine mammals are reviewed.

Eight marine mammal species are known to occur regularly in this area: grey seal, harbour seal, harbour porpoise, white-beaked dolphin, bottlenose dolphin, Atlantic white-sided dolphin, killer whale, and minke whale. Long-finned pilot whales and Risso’s dolphins are regularly seen in waters around Shetland.

There are occasional at-sea records of at least a further five cetacean species (humpback whale, fin whale, sperm whale, striped dolphin and short-beaked common dolphin) and four pinniped species (hooded seal, bearded seal, ringed seal and walrus).

Report prepared by the Sea Mammal Research Unit, St Andrews University.

Seven marine mammal species are known to occur regularly in the SEA6 area. A relatively small but fairly discrete population of grey seals utilises all but the northwest Irish Sea. Harbour seals are found primarily in the far north of the area. Harbour porpoises are seen year round throughout the area and bottlenose dolphins are present year round off Wales. Minke whales, Risso's dolphins and short-beaked common dolphins are regularly seen in summer mainly in the far south. The report discusses the distribution and abundance of these mammals and their ecological importance.

Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals.

The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. The prevalence of disease among the marine mammal populations is reviewed.

The report was prepared by the Sea Mammal Research Unit, Gatty Marine Laboratory, University of St Andrews.

In advance of SEAs for areas 6, 7 & 8, a series of data assessment projects were instigated. The purpose of these projects was to assess the extent, quality and accessibility of data relating to specific environmental factors. In some cases, the project leaders produced brief explanatory notes describing the environmental factor being considered, in other cases the project was limited to a data search alone.

The contractors were asked, where possible, to enter the data onto an "End-Note®" database file in order that bibliographic searches may be made.

Please note that the boundary between SEAs 6 and 7 changed during the time these reports were produced, so may appear in a different position in some reports.

SEA7 Technical Report - Marine Mammals

Twenty-one cetacean species have been recorded in the SEA7 region. Of these, ten species are known to occur regularly: harbour porpoise, bottlenose dolphin, short-beaked common dolphin, Risso’s dolphin, white-beaked dolphin, Atlantic white-sided dolphin, long-finned pilot whale, killer whale, sperm whale and minke whale.

Five further species, though not very often recorded, and primarily associated with deep water, probably also occur regularly: striped dolphins, fin whales, northern bottlenose whales, Cuvier’s beaked whale and Sowerby’s beaked whale.

There are occasional at-sea records of a further 6 species: Sei whale, humpback whale, blue whale, northern right whale and false killer whale. Pygmy sperm whales and at least three further species of beaked whale might also be expected in the general area on occasion.

Quantitative abundance is limited to areas of overlap with the NASS surveys, conducted in North Atlantic waters by Iceland, the Faroes and Norway.

The most recent NASS survey (2001) was denied access to UK waters, so there are no recent abundance estimates available for these waters. The NASS-95 survey resulted in estimates of some of the large whale species that may be relevant to this area.

The SCANSII survey, conducted during the summer of 2005, covered the continental shelf zone of the SEA-7 area. Abundance estimates from this survey are not yet available, but will be by the summer of 2006.

Relative abundance data are available from platform of opportunity sightings data (see Reid et al., 2003), as well as some small-scale coastal survey work conducted by organisations such as the Hebridean Whale and Dolphin Trust (HWDT).

In this report, each of the more abundant species is briefly described with particular reference to its distribution and abundance in the SEA-7 area.

This report was prepared by P S Hammond, S P Northridge, D Thompson, J C D Gordon, A J Hall, C D Duck, G Aarts, L Cunningham, C B Embling and J Matthiopoulos of the Sea Mammal Research Unit.