Sperm Whale (Physeter macrocephalus)

Whaling

Numbers of sperm whales killed off Scotland and Ireland at the beginning of the century were relatively small compared to the large baleen whales (which were the main target of the whalers): 76 sperm whales were captured off the Hebrides, 19 taken off Shetland and 63 off Ireland (Brown 1976) (Thompson 1928).

Sperm whales were mainly caught in deep water off the continental shelf edge, concentrated in the Rockall Trough, and around Rockall, St. Kilda and the Flannan Isles (Thompson 1928), see also fig. 2. Small numbers were caught north of Shetland. Thompson (1928) noted that their distribution corresponded roughly with a warm current along the position of the 100 fathom depth contour. Sperm whales were caught between April and September, peaking in June-August (90% of catches) (Thompson 1928). The vast majority of catches were of lone males (Brown 1976) that were generally similar in size at around 54 feet long (Thompson 1928).

Sightings and Strandings

In British and Irish waters, the sperm whale mainly occurs off the edge of the continental shelf. Of 31 sightings recorded between 1966 and 1991, 22 have been at least 300 km west of the British Isles, with the remaining sightings west of Ireland or around the Shetland and Orkney Islands (Evans 1992). Most sightings occur between July and November (Evans 1992).

Strandings and sightings of sperm whales around Britain and Ireland appear to have increased this century, particularly since 1980, with 9 strandings between 1913-1948, 30 between 1949-1986 and 21 between 1987-90. Large numbers stranded in 1990 (Sheldrick 1979) (Berrow et. al. 1993). Strandings of sperm whales are reported in all months, but peak between November and March.

Sheldrick et. al. (1991) reported that between 1967 and 1990, strandings and sightings of sperm whales were concentrated around Shetland, Orkney and the outer Hebrides. In 1993, six sperm whales became 'trapped' in Scapa Flow, but were driven out by a flotilla of small boats. In December 1994, eleven sperm whales were stranded and died on Sanday, in the NW Orkney Isles (Davies 1995).

Sperm whales found in cool temperate, high latitude waters (such as those caught by whalers off Scotland) are generally males, although in the mid 1970's there were several sightings of small groups of females with calves (which usually remain in warmer, lower latitude waters year round) (Evans et. al. 1986) (Berrow et. al. 1993).

Gunnlaugsson and Sigurjonsson (1990) Sigurjonsson et. al. (1989) and Sigurjonsson et. al. (1991) reported sightings of sperm whales during surveys around Iceland and adjacent waters, around the Faroes, west of the British Isles and north, north-east and north-west of Shetland.

More recently, several studies have reported the presence of sperm whales off Scotland, including four sightings (a total of seven sperm whales) in early summer west of Shetland from the R.V. Charles Darwin (JNCC, unpublished) and a single sighting reported by Bloor et. al. (1996) between Shetland and Faroe. Twenty-nine encounters (visual and acoustic) with sperm whales were reported by observers on the Telco Dover, mainly between the 500 and 1,000 m depth contour, west of Shetland during late June and July, 1996.

Ecology

Sperm whales are primarily found in deep water, generally seaward of the continental shelf edge. They feed mainly on mesopelagic squid. The deep water troughs, slope edge, and basins north and west of the British Isles are thought to be important areas for sperm whales for feeding and migration (Evans 1987) (Martin 1990).

The migration patterns and routes of sperm whales are not known. Haldane (1908) described the migration of the sperm and right whale northward, following the coast of Scotland and then heading east and passing the Faroes to Iceland. It is uncertain whether the males, which are mainly seen in cold temperate and polar waters, undertake migrations to warmer waters where the females remain annually, or whether they stay at high latitudes for several years (Martin 1980). Sperm whales are oceanic whales and rarely enter shallow or semi-enclosed waters. The concentrations of strandings and sightings data around the Northern Isles indicate that their main approach to the land mass is from the north-west (Sheldrick et. al. 1991). Sperm whales appear to move north and south and feed in the deep water off the edge of the continental shelf to the west of the British Isles.

Strandings of sperm whales around the British Isles and northern Europe appear to be increasing in recent years. During the winter of 1994/95 some 21 sperm whales stranded around the North Sea (an unusually high number) (Law et. al. 1996), and in both 1988 and 1990, 32 sperm whales stranded on the Atlantic coasts of Britain and Norway (Berrow et. al. 1993). There have been recent reports of sperm whales entering the shallow North Sea, see for example (Smeenk and Addink 1993) (Law et. al. 1996). Indeed in late March 1997, a sperm whale was reported off the Firth of Forth, on the east coast of Scotland, which repeatedly stranded (eventually fatally) in the estuary.

Status

There are no population estimates for sperm whales in the North Atlantic. Since 1950 more than 20,000 have been captured by whalers around Iceland and further south off the Azores, Spain and Madeira (Evans 1992).

The selective whaling of large male sperm whales in other regions (e.g. off western South America) is known to have had a detrimental impact on the population structure, breeding success and populations of sperm whales such as those in the Galapagos Islands (Whitehead pers. comm.) (Whitehead et. al. unpublished). It is not known whether similar effects are occurring elsewhere.

Northern Bottlenose Whale (Hyperoodon ampullatus)

Whaling Records

Between 1903-1928 26 bottlenose whales were killed by the Scottish whalers, mainly around North Rona and north of Shetland (Thompson 1928) (Brown 1976). Between 1949 and 1971, 63 bottlenose whales were killed in the Shetland-Faroes region (Evans and Scanlan 1989). Northern bottlenose whales were heavily exploited, particularly by Norwegian whalers, between 1955-72. Catches off Scotland occurred between April and September and off the Faroe Islands, as early as March, but mostly in August and September (Thompson 1928). Bottlenose whales are still occasionally caught off the Faroes (Olafsson, 1990) (IWC, 1991b) (IWC 1996, unpublished).

Sightings and Strandings

There are regular reports of this species, which together with the pilot whale, may be one of the most common small whales in British and Irish waters (Evans and Scanlan 1989). Of 23 strandings reported around Britain and Ireland between 1967-1986, 6 were from the Hebrides, Shetland and Orkney (Sheldrick 1989). Thompson (1928) reported that the bottlenose whale was 'plentiful' on Scottish whaling grounds, and very often 'cast shore' on the coast. It was also described to be one of the most abundant species from the Moray Firth to Shetland at the beginning of the century (Taylor 1900). Recent sightings have been concentrated in deep waters outside the continental shelf, west of the British Isles (mainly in the south-west approaches), west of Ireland, off the Outer Hebrides and west and north of Scotland (Evans 1992). Reports of bottlenose whales peak between July and November (Evans et. al. 1986).

Overall, strandings and sightings have declined slightly over the past few decades. Between 1913-48 there were 55 strandings, this dropped to 44 between 1949-86. Sightings have declined since the early 1970ís, with 149 sighted between 1960-72, and 66 between 1973-1985 (Evans 1992).

Gunnlaugsson and Sigurjonsson (1990) reported several sightings of bottlenose whales around the Faroe Islands and the Shetland Isles.

Ecology

Whaling records indicate that a northward migration of northern bottlenose whales occurs in April-July, and a southward migration in late summer (IWC 1989) (Benjaminsen and Christensen 1979). As a deep water species, Northern bottlenose whales are thought to migrate along the edge of the continental shelf, passing west of Britain and Ireland in spring and autumn. There may also be some onshore movement during August and September, which is when sightings around the UK are concentrated (Evans 1992).

Status

There is much controversy surrounding the abundance of northern bottlenose whales in the North Atlantic (Holt 1977) (Klinowska 1991). Recent declines in sightings and strandings around Britain support widespread concerns that the species has been heavily over-exploited in the NE Atlantic (Sheldrick 1979) (Evans et. al. 1986) (Klinowska 1991). Although considerably depleted, it is not known how abundant the species is. NASS-87 surveys gave population estimates of just under 5,000 whales in Icelandic and adjacent waters, and 900 in Faroese waters (Gunnlaugsson and Sigurjonsson 1990). Overall abundance is not known.

Long-Finned Pilot Whale (Globicephala melas)

Whaling Records

Opportunistic drive fisheries for pilot whales occurred in Shetland (and also the Outer Hebrides and western Ireland) until the early 1920's. In 1845, for example, over 1.5 thousand pilot whales were killed in Shetland - the largest recorded catch (Evans and Buckley 1899). Drive fisheries still occur in the Faroe Islands, where they have operated for many hundreds of years, taking as many as several thousand whales each year (Klinowska 1991). Pilot whales are hunted in the Faroe Islands drive fishery year round (Bloch et. al. 1993).

Sightings and Strandings

Pilot whales are primarily a deep water offshore species, and are often seen around offshore islands such as the Faroes, Shetland and Orkney, and the Outer Hebrides. They are recorded throughout the year, although peaks in sightings have been reported in August-October in the Northern Isles, North Sea and Atlantic coast of Britain and Ireland (Evans and Scanlan 1989).

Between 1913 and 1986, 227 strandings were reported to the Natural History Museum from around Britain, the majority of which occurred between 1967 and 1986. Similarly there has been an increase in sightings over the past few decades (Evans 1992) (Sheldrick 1976). Data collected systematically from weather-ships west of Scotland also supports an increase in records (Evans 1992). Concentrations of pilot whales have been reported near the Hebrides, Shetland and Faroe Islands (Evans 1980) (Evans 1992) (McBrearty et. al. 1986).

Sightings of pilot whales are reported from all months of the year, peaking between July and September in offshore waters along the west coast of the British Isles (Evans 1992).

A Greenpeace vessel sighted pilot whales in deep water beyond the continental shelf edge to the north and west of the Hebrides during a survey in May 1992 (Mayer et. al. 1993).

NASS-87 and 89 surveys reported pilot whale sightings (Buckland et. al. 1993) (Sigurjonsson et. al. 1991). Considerable numbers of pilot whale sightings were made south-east of Iceland, and a few west of the Faroes and one west of Ireland.

Bloor et. al. (1996) reported that long-finned pilot whales are distributed widely throughout the waters between the Shetland and Faroe Islands, particularly along the edge of the Faroes Shelf and in the Faroe-Shetland Channel. Sightings peak in August, but numbers of individuals are greatest in February and March.

The SCANS survey of the North Sea and adjacent waters conducted in June and July 1994 recorded pilot whales between the Shetland Isles and Norway (Hammond et. al. 1995).

Several groups of pilot whales were sighted during surveys conducted from both the R.V. Charles Darwin. Four encounters with groups of pilot whale were reported from the Telco Dover during June and July 1996.

Ecology

Long-finned pilot whales are widely distributed and can range over large areas. They are capable of deep dives and feed mainly on squid, with which their movements are closely associated. Their appearance and abundance off the Faroes, for example, is correlated with the presence of squid (Desportes and Mouritsen 1993).

Pilot whales may move inshore in late summer and autumn (see Buckland et. al. 1993), which may again be associated with prey movements (Evans et. al. 1986).

Status

Surveys of the eastern North Atlantic have provided population estimates for long-finned pilot whales of 13,000-19,000 in Icelandic, and 72,000 in Faroese waters (IWC 1990). Various possible sources of bias in these estimates have been identified however (Klinowska 1991). Buckland et. al. (1993) present an estimate of over 750,000 for the total stock of pilot whales in the NE Atlantic in summer (with over 100,000 in Icelandic and Faroes waters), but state that there are several potential biases in these abundance estimates.

Killer Whale (Orcinus orca)

Whaling

Killer whales were a target of Norwegian commercial whaling between 1938 and 1981, when almost two and a half thousand animals were killed in Norwegian waters and north of the British Isles off Shetland, Orkney and the Northern Hebrides. Catches (see Oien 1988) peaked in May and June in the Norwegian Sea. Hammond and Lockyer (1988) reported that between 1955-1964 almost 300 killer whales were captured by Norwegian vessels on the Shetland whaling grounds, mostly between March and September.

Sightings and strandings

Historical records suggest that killer whales were common all year round throughout the Northern Isles (Evans and Scanlan 1989). There are strandings occasionally (21 around Britain and Ireland between 1967 and 1986) (Sheldrick 1989). Of these, 15 were from Scotland, Orkney, Shetland and the Hebrides.

Sightings off the UK are concentrated around the Hebrides, west of Scotland and between Scotland and Norway, with most sightings in summer. The species is recorded annually from around the Shetland and Orkney Islands (Evans et. al. 1986) (Evans 1988) and sightings are common around the Hebrides, where some individuals may be resident (Evans et. al. 1993) (Gill pers comm.).

Killer whales seem to favour deep waters, seaward of the continental shelf. Sightings occur during all months of the year but are highest between April and October, particularly June, July and August. McBrearty et. al. (1986) reported observations from British waters between June and September, and concentrations off north and west Scotland in early summer.

There are also regular sightings of killer whales from weather-ships several hundred miles west of Scotland (Evans 1992). Land-based sightings from two positions, Fair Isle (Shetland Isles) and Cape Clear (County Cork, Ireland) have been recorded over an extended period. Most sightings are recorded between May and October, peaking in May-June in the mid Atlantic and August-September at Fair Isle and Cape Clear (Evans 1992).

In British waters killer whales appear to range widely, and movements may coincide with seasonal prey distribution, e.g. the spawning of herring, cod and mackerel (Evans 1988) (Evans 1992).

Off the Faroe Islands, killer whales are frequently reported from inshore and pelagic waters (Bloch and Lockyer 1988), particularly during the summer months. Sightings by mackerel fishermen indicate that killer whales may move offshore in winter. The distribution of killer whales appears to be continuous from Scotland, up around Shetland and Orkney to the Faroes (Bloch and Lockyer 1988).

NASS-87 surveys sighted killer whales around the Faroe and Shetland Isles (Gunnlaugsson and Sigurjonsson 1990). Later surveys (NASS-89) sighted killer whales off the south-east coast of Iceland (Sigurjonsson et. al. 1991).

Hammond et. al. (1995) reported sightings of killer whales north of Scotland and between Shetland and the Faroes during the SCANS survey.

Killer whales were the most frequently sighted cetacean during surveys conducted west of Shetland in summer from the R.V. Charles Darwin. Twelve sightings were recorded, with groups of up to 15 animals (JNCC, unpublished). The Telco Dover, operating west of Shetland during June and July 1996, recorded seven encounters with groups of killer whales.

Status

Surveys between the Faroes and Iceland have provided population estimates of between 3,500 and 12,500 individuals (Gunnlaugsson and Sigurjonsson 1990). Overall population estimates for the north-east Atlantic do not exist.

Risso's Dolphin (Grampus griseus)

There are regular sightings of Risso's dolphin from both Shetland and Orkney waters (Evans 1981) (Evans et. al. 1986) (Maxwell 1952) (Evans et. al. 1993) (Evans 1995). They may be present year round, although sightings are most frequent between May and September. Since 1967, there have been 35 strandings, 13 of which were on the west coast of Scotland, the Hebrides, Orkney or Shetland (Sheldrick 1989).

Studies in the Hebrides indicate that Risso's dolphins show strong site fidelity to particular coastal sites over extended periods of time (Evans 1992). Re-sights of individuals indicate that some animals may be resident there (Gill and Atkinson 1996). Risso's dolphins feed on cephalopods at a wide variety of depths. They generally show a preference for deep offshore waters, but also inhabit coastal waters around islands and where the continental shelf is narrow. They appear to favour areas of steep bottom topography, with much upwelling and high local productivity, feeding on vertically migrant and mesopelagic prey (Clarke and Pascoe 1985).

Bloor et. al. (1996) reported Risso's dolphins in all months between April and December, except May and November. Most sightings were in August and September, and sightings were scattered over the continental shelf, with most west of Cape Wrath.

SCANS survey recorded Risso's dolphins offshore, north of the Hebrides and Cape Wrath (Hammond et. al. 1995). A Greenpeace survey sighted Risso's dolphins both inside the Hebrides and further offshore to the north of the Hebrides in May 1992 (Mayer et. al. 1993). Scottish Natural Heritage staff have reportedly encountered Risso's dolphins around Lewis and the Flannan Isles (Gill and Atkinson 1996).

Status

The status of Risso's dolphins is unknown, and there is little information on the species abundance, distribution and social structure - particularly for British and Irish waters. There is no quantitative population estimate for Risso's dolphins in these waters.

Bottlenose Dolphin (Tursiops truncatus)

The bottlenose dolphin appears to be rare in north-west Scotland, Shetland and Orkney, where there are only occasional sightings and strandings (Evans 1992). Of 43 bottlenose dolphins stranded around Britain and Ireland between 1967-1986, only one was reported from the Outer Hebrides, and none from Shetland (Sheldrick 1989).

Bottlenose dolphins are resident in the Moray Firth (Wilson 1995) and found year round in parts of western Ireland, Wales, the Irish Sea and south-west England (Evans 1992) but are rarely seen elsewhere (Hammond et. al. 1995). There are occasional incidental sightings of bottlenose dolphins as far north as Iceland and northern Norway (Oien unpublished). Bloor et. al. (1996) reported five sightings of bottlenose dolphins, mostly in coastal locations, but several offshore between the Shetland and Faroe Islands.

Status

Some populations of bottlenose dolphin around Britain and Ireland are well-known due to photo-identification studies. Over 100 individuals have been identified in both Cardigan Bay and the Moray Firth. There are no overall abundance estimates for the bottlenose dolphin (Evans 1992).

White-Beaked Dolphin (Lagenorhynchus albirostris)

During the period 1966-1990, there have been 760 sightings of white-beaked dolphins in British and Irish waters (Evans 1992) and between 1967-1986, 65 animals stranded (several in Orkney, Shetland and the Hebrides) (Sheldrick 1989). The species distribution seems to be centred on the central and northern North Sea and adjacent waters (Evans and Scanlan 1989). The species may be the most common small cetacean in Shetland coastal waters, although sightings appear to have decreased somewhat since 1993 (Evans 1995). The white-beaked dolphin is the most frequently recorded cetacean in waters between the Shetland and Faroe Islands (Bloor et. al. (1996).

Sightings and strandings of the white-beaked dolphin indicate that it is most abundant in late summer (July to September), with a smaller peak in March to April (Evans et. al. 1986) (Bloor et. al. 1996). Sightings occur in all months of the year, but are most common between May and September (Evans 1981) (Evans et. al. 1986). White-beaked dolphins were recorded off the Hebrides, and sightings during a survey there peaked in August (Evans et. al. 1993).

The SAST cetacean sightings database analysis (Northridge et. al. 1995) showed that the distribution of white-beaked dolphins is centred around Scotland, with particularly high sightings rates off the Outer Hebrides. To the north and west of Scotland, sightings were confined to the continental shelf, north to the Shetland Islands, and south to the Hebrides and Malin shelf. The distribution of white-beaked dolphin does not appear to change seasonally. The white-beaked dolphins around Scottish and north-east English waters may be a local population, isolated to some extent from animals found further north (there appear to be relatively few observations in southern Norwegian, Faroese and Icelandic waters) (Northridge et. al. unpublished).

White-beaked dolphins were sighted several times during the SCANS survey offshore north of the Hebrides and west of Orkney and south of Shetland (Hammond et. al. 1995). A survey from M.V. Solo encountered white-beaked dolphin offshore north of Cape Wrath and west of Orkney (Mayer et. al. 1993). Sighting of white-beaked dolphins were reported from the R.V. Charles Darwin (the dolphins were seen at the northern end of the Minch in the Hebrides, close to several minke whales (JNCC, unpublished).

Status

Hammond et. al. (1995) presented abundance estimates for white-beaked dolphins in the North Sea and adjacent waters in July of 7,856 (confidence limits 4,000-13,300).

Atlantic White-Sided Dolphin (Lagenorhynchus acutus)

White-sided dolphins have been hunted opportunistically in Norway and the Faroe islands for hundreds of years (Evans and Scanlan 1989).

The white-sided dolphin is a generally pelagic species, common in offshore waters around the Outer Hebrides, Northern Isles and northern North Sea (Evans 1992). There are many reports of the species from around the Northern Isles (Evans 1995). Surveys in the Hebrides and Minch indicate that the species is common (Evans et. al. 1993) (Gill pers. comm.). There has also been an increase in strandings of this species (Sheldrick 1979). Between 1967-1986, 37 white-sided dolphins were reported stranded around Britain and Ireland, 6 of which were found in Shetland, or off western Scotland (Sheldrick 1989).

The species is recorded all year round, but is sighted most frequently between July and September (Evans 1992). Juveniles are first sighted in June, and there is usually an increase in sightings in continental shelf waters in summer.

White-sided dolphins are thought to make seasonal movements and may move offshore into deep waters in winter in the eastern Atlantic (Northridge et. al. unpublished). Bloor et. al. (1996) report records of this species for April, May, September and November in waters west of Scotland and south of the Faroe Islands.

SCANS survey recorded a sighting of a white-sided dolphin offshore west of Orkney and north of Cape Wrath (Hammond et. al. 1995). White-sided dolphins were reported on five occasions by observers on the R.V.Charles Darwin, all in deep water, with group size ranging from 5 to 25 animals (JNCC, unpublished).

Status

Hammond et. al. (1995) presented abundance estimates for white-beaked and white-sided dolphins in the North Sea and adjacent waters in July of 11,760 (confidence limits 5,900-18,500).

Common Dolphin (Delphinus delphis)

Primarily offshore in distribution, the common dolphin is regularly recorded west of Scotland (Evans 1980) (Evans et. al. 1986), and there are occasional strandings in Shetland (Sheldrick 1989). The species was found to be abundant in waters around the southern Hebrides (Evans et. al. 1993), and has increasingly been recorded further north (Mayer et. al. 1993) (Hammond et. al. 1995) up to waters around Orkney and Shetland (Evans 1992). Reports also originate from as far north as Northern Norway, where they are considered as occasional visitors (Haug et. al. 1981). The common dolphin is mainly found in deep waters. Sightings from weather-ships, far west of Scotland, have increased significantly since 1986 (Evans 1992).

Sightings occur during all months of the year, but mostly between June and September, peaking in August. Calving appears to occur in summer, and as with some other species, there may be a movement onto the continental shelf following calving (Evans 1992).

Status

The abundance of common dolphins in British and Irish waters is not known.

Striped Dolphin (Stenella coeruleoalba)

Mainly considered to be a tropical and warm temperate species, the striped dolphin is rare in British waters (Evans 1992). Although sightings of this species generally occur south-west of Britain, there are records of the species further north in the pelagic waters west of Scotland. Records of striped dolphin off Shetland date back to the beginning of the century (Taylor 1901, cited in Evans and Scanlan 1989). Sightings off northern Britain appear to be increasing (Evans 1992). The species is occasionally reported from as far north as Northern Norway (Oien unpublished).

There have been several strandings in the past decade around Scotland, the Hebrides, Shetland, Faroes and one in Iceland (Bloch et. al. 1996). These northerly records of a generally tropical and temperate species may be related to shifts in water temperature.

Status

The abundance of the striped dolphin in British and Irish waters is not known.

Harbour Porpoise (Phocoena phocoena)

Historical records indicate that the harbour porpoise was common year round throughout northern and western Scotland including the Hebrides and Northern Isles (Evans and Scanlan 1989). The Northern Isles are probably the most important region for the species in Britain. Around northern and western Scotland and Shetland, harbour porpoises are considered to be relatively abundant (Evans 1980) (Evans 1992) (Evans et. al. 1986) (Northridge et. al. 1995). Harbour porpoises were frequently encountered during surveys of Hebridean coastal waters, and abundance peaked at the beginning of August (Evans et. al. 1993) (Gill pers. comm.).

The species is generally considered to be coastal in distribution, occurring throughout the year in Shetland waters, although abundance peaks between July and October (Evans 1992). There is some indication of off-shore/on-shore movements, with porpoises being found at greater distances from land in late winter and spring (Evans et. al. 1986), possibly moving offshore to give birth.

Recent analysis of SAST sightings database records indicates that the harbour porpoise is widely distributed west of Britain, with important concentrations off the west coast of Scotland and Ireland (Northridge et. al. 1995) (Bloor et. al. 1996). According to Bloor et. al. (1996), harbour porpoises are the second most frequently reported cetacean in the waters between the Shetland and Faroe Islands. The SAST sightings also reveal that, in contrast to the common impression that the harbour porpoise is predominantly nearshore in distribution, sightings were also made far offshore in deep water areas between Iceland and the Faroes, and over the Rockall and Faroe Banks (see also Bjorge and Oien 1990). There was little evidence for seasonal movements within the area (Northridge et. al. 1995). A survey by Greenpeace similarly reported a harbour porpoise sighting in offshore waters, north of the Hebrides and west of the Orkney Isles (Mayer et. al. 1993). Hammond et. al. (1995) recorded many sightings of harbour porpoises around Shetland and Orkney, and to the north and west, both in coastal and offshore positions.

Status

Hammond et. al. (1995) present abundance estimates for harbour porpoises in the North Sea and adjacent waters in July of 341,366 (confidence limits 260,000-449,000). In the Northern North Sea, an estimate of harbour porpoise abundance of 61,000 was made from the results of the Norwegian NASS-89 survey (Bjorge and Oien 1990).

Sowerby's Beaked Whale (Mesoplodon bidens)

This is a deep water species, which is little known and rarely observed. Records indicate that the species is found in cold temperate waters of the North Atlantic. Records from around the British Isles are reported all year round (Klinowska 1991).

Several strandings of the species in Scotland are reported by Taylor (1900). Most of the 21 strandings reported around Britain and Ireland between 1967-1986 have occurred in Scotland and the Northern Isles (Sheldrick 1989), most recently in Shetland, 1994 (Evans pers. comm.). McBrearty et. al. (1986) reported two sightings of Sowerby's beaked whale close to the 100 m depth contour, north of mainland Scotland and west of the Orkney Islands, in June and October. Evans (1980) reported a sighting in the Minch, off North-west Scotland in August 1977. Following this sighting, two Sowerby's beaked whales stranded nearby (Evans 1992).

Beaked whales are deep diving whales which feed on cephalopods, and it has been suggested that their distribution may centre on deep waters of the Norwegian Basin and adjacent Faroe-Shetland Channel (Evans 1980) (Evans and Scanlan 1989).

Status

All beaked whales are poorly known and difficult to identify. Abundance estimates are not available.

Cuvier's Beaked Whale (Ziphius cavirostris)

Cuvier's beaked whale is also an offshore, deep water odontocete. Of 39 recorded strandings between 1913 and 1986 most have been in north and west Scotland and Ireland, suggesting a pelagic Atlantic distribution (Evans 1992) (Sheldrick 1989). There are several reported sightings off western Scotland and Ireland in the past decade (Evans 1992), and a recent stranding in the Shetland Islands in 1993 (Evans unpublished). Re-examination of the skull of a suspected True's beaked whale in the Outer Hebrides from 1913 has recently identified the whale as Cuvier's beaked whale (Kitchener and Herman 1995).

Status

Evans (1992) suggests that Cuvier's beaked whale is probably more common in the north-east Atlantic than scarce records suggest, although there are no abundance estimates for the species.

False Killer Whale (Pseudorca crassidens)

Although generally a warm temperate and tropical deep water species, there are occasional reports of false killer whales north of the British Isles. There are several reports of mass strandings: 150 false killer whales stranded in Sutherland in 1927 (Richie 1927), and then restranded elsewhere (Fraser 1934). More recently there have been several sightings of the species off NE Scotland and western Scotland (Evans 1992).

Status

This is a rarely observed, pelagic species, whose status in the waters around the British Isles is not known.

Beluga (Dephinapterus leucas)

The beluga is an arctic species, which is recorded as an occasional visitor to British waters. Records are mainly from between April and November. Sightings have been reported near Skye in 1950, Orkney in 1960 and several off the east coast of northern Britain (Evans 1992). The most recent sighting is a beluga whale reported from Shetland in September 1996 (Shetland Times, 13th September 1996).

Status

An occasional and unusual visitor to British waters, probably originating from the population which breeds in the Barents Sea (Evans 1992).

Narwhal (Monodon monoceros)

This is a high arctic species which is very occasionally reported in British waters. There have been no reports since 1949 when two narwhals were sighted off Orkney (Evans and Scanlan 1989).