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Shetland Sea Mammal Group

 

 

Whales and Dolphins in Shetland Waters

Peter Evans

The Shetland isles, lying close to the edge of the European continental shelf and encircled by the waters of the North Atlantic, are amongst the richest areas for whales and dolphins (cetaceans) in the entire British Isles. Most of the larger whales in the region normally inhabit deep oceanic waters north and west of the shelf. However, since the edge of the shelf is only a short distance away from the northern shores of Unst it is not surprising that individuals stray into Shetland coastal waters. This was capitalised upon in the past centuries by Shetlanders who would drive ashore the normally pelagic Pilot Whales (known locally as Caain' Whales) just as the Faroese islanders do to this day.

Photo above: Humpback Whale off Sumburgh Head in 1995 - Lorne Gill / Scottish Natural Heritage

In 1903, two whaling stations, operated by Norwegian whaling companies, started in Shetland at Ronas Voe on northwest Mainland (Thompson 1928). The Shetland Whaling Company began whaling in April 1903 with a single whale catcher, the Frithjof. The Norrona Company started in June with the catcher Norrona, They both operated until September and each boat caught just over 60 whales In the following year, two more stations commenced operations, the Norwegian Alexandra Company from a station in Colla Firth, Yell Sound, using one boat in the first year and two boats in each subsequent year, and the Olna Whaling Company, owned by Christian Salveson & Company, opened a station in Olna Firth on the west Mainland coast. Four boats were used in most seasons (five in 1906 & 1907).

All four stations operated in each year from 1904 to 1914 when whaling was suspended in British waters for the war years by order of the Admiralty. The whaling season generally spanned April to September, and the grounds extended in an arc northwards from west to east of the islands and as far as 150 nautical miles from the stations. Between 1903 and 1914, a total of around 4,900 whales were caught. Two-thirds of these were Fin Whales, 30% were Sei Whales, and the rest of the catch comprised small numbers of Blue, Humpback, Right, Sperm and Northern Bottlenose Whales. The whale populations in the region clearly were unable to support such exploitation and catches in post-war years, 1920-29, numbered around 1,900 whales. Fin Whales, followed by Sei Whales, continued to be the main species caught whilst only two Humpbacks and no Right Whales were taken. These last two species remain rare in Shetland, indeed British waters and populations of the other large whales are also remnants of their former size.

Besides direct exploitation of whales, humans have probably affected Shetland cetacean populations by competing for the same food resources. Major changes in fish stocks have occurred this century, particularly with respect to North Sea herring whose stocks crashed by the mid-1960's. Most recently, concern has been expressed over possible effects of the rise in the industrial fisheries for sprat and sandeel, both of which have shown a decline in the spawning stock, although other oceanographic changes may also play a part. In addition, changes in the population sizes of small cetaceans are difficult to determine since their presence in coastal waters is usually ephemeral and unpredictable. The inshore harbour porpoise is the only species which can consistently be seen around the coasts of Shetland (although this species in fact does appear to have declined in our waters during recent years, and one possible reason for this is changes to its food supply), with records of other species irregular although increasing in frequency. Notable increases in records during recent years have included Killer Whales with a long-staying pod at Cat Firth in December 1992 giving many people the chance to view these animals at close range. In addition, at least one humpback whale has frequented the area around Sumburgh Head during the last few summers, often giving spectacular views as it swims close inshore; and large pods of up to 100 dolphins have been seen regularly during the summer months at many localities around the isles.

With the increased awareness of cetaceans around Shetland generated by the formation of the Shetland Sea Mammal Group the number of sightings of these animals in Shetland waters continues to increase - hopefully it will continue to do so for many years to come. To date, 22 species of whales & dolphins have been recorded in Shetland waters, they are as follows:

Northern Right Whale   Eubalaena glacialis

Between 1903 and 1914, a total of six Right Whales were taken in Shetland whaling operations, all close to the shelf edge north of Shetland. However, since then, there have been no sightings or strandings of this species in the region.

Humpback Whale   Megaptera novaeangliae

Another species whose population size must already have been small at the start of modern whaling in Shetland water, 49 Humpbacks were taken between 1903-14, but only two between 1920-29. Since then, there have been a few records, in June 1992, May 1993, September 1993, and throughout the summers of 1994-98. Together with a recent handful of records elsewhere in Western Britain we may be seeing the first signs of recovery of this species in British waters.

Humpback Whale breaching 3 miles east of of Sumburgh Head in 1995 - Paul Harvey.

Fin Whale   Balaenoptera physalus

This is probably the most common large whale in Shetland waters, and between 1903-14 and 1920-29, over 4,300 Fin Whales were taken, particularly off the edge of the continental shelf in the Faeroe Channel north of Shetland, Small numbers continue to be seen in this region during pelagic cruises, but the species is scarcely ever recorded in Shetland coastal waters. Catches took place between April and October, mainly from May to August, with little indication for any latitudinal migration. The only recent record was off Noss on the 11th August 1994.

Blue Whale   Balaenoptera musculus

At least 85 Blue Whales were taken by the Shetland Whaling industry between 1903-14 and 1920-29, but as with the Humpback and Northern Right Whales, populations of this species almost certainly had been over exploited by 1930, Since then, there have been no sightings or strandings in Shetland waters.

 Sei Whale   Balaenoptera borealis

The second most commonly recorded large whale in Shetland waters, the Sei Whale was hunted extensively in the early years of this century, with over 1,800 taken between 1903-14 and 1920-29, Catches were predominantly from deep waters in the Faeroe Channel along the edge of the continental shelf. It is clear that the population in the region was quickly depleted. Up to 1914, annual catches per boat averaged 15.5, but after the respite caused by the war, within one year of activities numbers had declined to average annual catches of 5.0 Sei Whales per boat. The whale fishery started in April and continued through to October. However, very few Sei Whales were caught in April or September-October, with by far the most occurring in June. As with the Fin Whale, once the species entered the region in April/May, it remained there through the summer. The only recent record in Shetland waters was one off Muckle Skerry, Out Skerries, on the 27th August 1993.

Minke Whale   Balaenoptera acutorostrata

Of all the baleen whales, the Minke Whale is the most frequently observed species in Shetland coastal waters. It may be seen close to many headlands and small islands, mainly on the east side of Shetland, although there have also been several records from Fair Isle. Most sightings occur between April and October, particularly July to September.

Photo: Minke Whale stranded at Levenwick in 1997 - Paul Harvey

 Sperm Whale   Physeter macrocephalus

Although a deep-water species, the Sperm Whale has been recorded fairly regularly in Shetland waters, presumably because of its proximity to the Faroe Channel and Norwegian Trench. No strong seasonal pattern of occurrence is evident with sightings/strandings in most months, although unlike other large whales, numbers have been reported through the winter months. Most records are of adult males or immatures.

Narwhal   Monodon monoceros

The Narwhal is also an arctic species which occurs in British waters only as a vagrant. The only Shetland record is that of one 'driven ashore' at Weisdale after being observed entangled amongst rocks in September 1808. It subsequently died.

Northern Bottlenose Whale   Hyperoodon ampullatus

Another deep-water species, the Northern Bottlenose Whale has been subject to intensive exploitation in the Northeast Atlantic by a modern small whale fishery operating mainly west and north of Norway though some were also caught in the region of Shetland and the Faroe Islands. At the end of the last century, the species was described as 'very common' by Evans and Buckley (1899), animals being exclusively females or young males, Between 1903-28, 25 bottlenose whales were taken by the Shetland whaling vessels, mainly around North Rona and the north of Shetland. However, whereas an average of 0.24 whales were caught per catcher boat per year between 1903-14, in the period 1920-29 an average of only 0.07 whales per catcher boat per year were taken, suggesting that the population was already well in decline. Similarly, marked reductions in catches occurred elsewhere in the Northeast Atlantic in the first half of this century, and now the species appears to be relatively scarce. Since 1913, there have been only four strandings (in March 1946, the winter of 1982/83, September 1983, and June 1984).

Cuvier's Beaked Whale   Ziphius cavirostris

In the British Isles, the Cuvier's Beaked Whale is most frequently recorded from the Outer Hebrides and west of Ireland, suggesting a generally pelagic Atlantic distribution. There are only four records of the species from Shetland: one was found stranded in August 1932 another was found in a geo on the east side of Fair Isle in late February/early March 1949, one stranded near Sandwick in April 1983, and one was found decomposed at Woodwick, along the west side of Unst in May 1993.

Sowerby's Beaked Whale   Mesoplodon bidens

This species appears to have its distribution centred upon the deep waters of the Norwegian Basin and the adjacent Faeroe-Shetland Channel. Most strandings in the British Isles come from northern North Sea coasts. In Shetland. there have been seven strandings since 1913; in July 1923, November 1948, December 1949, August 1984, May 1987, January 1989 and December 1994. Like most beaked whales, the species is scarcely ever sighted at the surface and indeed there have been no positive sightings in Shetland waters.

Harbour Porpoise   Phocoena phocoena

The commonest of all cetaceans in Shetland waters, the Harbour Porpoise nevertheless has shown distinct signs of decline during the 1980's. During 1982 and 1983, the entire coastline of Shetland was regularly covered by Pete Ewins as part of an inshore survey for Black Guillemots. During 1990, Lucy Gilbert and Peter Evans conducted fifty further land based watches (each of 100 minutes duration). Both sets of results indicate that although porpoises are widely distributed around Shetland, there are definite areas where concentrations occur. These include East Yell Sound, the Whalsay area, Mousa area, and Quendale Bay (the last particularly between November and April). On the other hand, much of the west coast of Shetland appears to have comparatively few porpoises, the only exceptions being in the vicinity of Scalloway and West Burra Isle.

Common Dolphin   Delphinus delphis

The Common Dolphin has a predominantly warm temperate distribution in the North Atlantic, so that in the British Isles, it is seen most frequently off-shore from Southwest Britain. Nevertheless, particularly when there is a strong flow of the relatively warm Gulf Stream, the species may be seen in north Scottish waters. There are seven documented strandings of this species in Shetland this century, February 1936, June 1966, May 1985, December 1985, August 1986, May 1989 and March 1997. Other than these, a common dolphin was captured at Urafirth in 1985. Since the UK Mammal Society's sighting scheme was initiated in 1973, there have been several sightings of Common Dolphins in Shetland waters, mainly between June and September.

Bottle-nosed Dolphin   Tursiops truncatus

This species has been scarcely reported from Shetland (and Orkney). Neither Evans and Buckley (1899) or Venables and Venables (1955) give any records and there have been no strandings since the British Museum Stranding Scheme started in 1913. Although there are a number of recent sightings of unidentified dolphins which may have been this species, there are very few definite Bottle-nosed Dolphin sightings, all between April and September.

Atlantic White-sided Dolphin   Lagenorhynchus acutus

As indicated by its name, this species has a predominantly Atlantic distribution, generally occurring further off-shore than its relative, the white-beaked dolphin with which it is often confused, Occasionally groups enter a voe in Shetland and some may strand, as occurred for example in Clousta Voe in October 1987 and in Weisdale Voe in August 1929. Since 1913, at least 25 animals of this species have stranded along the coasts of Shetland, mainly between July and November. The vicinity of Scalloway on the west coast appears to be frequently visited by white-sided dolphins. In July 1926, when at least 30 stranded at Scalloway, 'thousands' were said to be around the boat a mile off-shore. In July 1919, a group of about 100 White-sided Dolphins entered Scalloway harbour and at least two of these were stranded. In October 1936, 30-40 were seen over a period of several days between Burra Isle and Scalloway and in September 1990 about 50 remained in Whiteness Voe for several days. Most recent sightings also come from the west side of Shetland, although large groups have been seen off the northeast of Shetland and between Sumburgh Head and Fair Isle. Most sightings occur between June and November.

White-beaked Dolphin   Lagenorhynchus albirostris

Although it is possible that this species has increased in Shetland waters in recent years, it is likely that in former times it was under-recorded. Venables and Venables (1955) did not even list the species and instead referred to the Atlantic White-sided Dolphin as 'the commonest dolphin to be seen in Shetland waters'. However, observers frequently confuse the species with White-beaked Dolphins since the latter also have conspicuous areas of white on their flanks. Our own experience since the late 1970's is that the white-beaked dolphin is by far the commonest dolphin in Shetland coastal waters, as exemplified by ferry crossings between Grutness and Fair Isle and research cruises we have conducted east of Shetland (Evans 1981, Evans et al. 1986). Sightings occur in most months of the year, but are most common between May and September. Despite the high frequency of sightings, there have been only three strandings in Shetland, in January 1960, February 1986 and March 1996.

Striped Dolphin   Stenella coeruleoalba

The only records are four strandings. Singles stranded in Bixter Voe on the 14th July 1993, at Muckle Roe on the 1st January 1995, Whal Firth on the 2nd March 1998, and one was washed ashore freshly dead at Spiggie beach on the 16th November 1999. Striped Dolphin has a world-wide distribution in tropical and warm temperate waters (Evans 1991). In Britain, it is regarded as rare, normally being stranded in the south-west of England, and in recent years in Wales.

Photo: Striped Dolphin stranded at Bixter Voe - Neil Anderson

Killer Whale   Orcinus orca

This species is a regular visitor to Shetland waters with the number of sightings in recent years increasing significantly. Most sightings occur between April and July when pods of up to half a dozen animals may be seen regularly, although the species has also been observed occasionally during the winter months November-February when many of the strandings have also taken place. There have been eleven strandings since 1913; in December 1932, September 1937, February 1944, March 1965, February 1966, March 1966, August 1976, December 1980, December 1983, November and December 1994, and April 1995.

Photo: Killer Whales at Quendale Bay - Alan Blain

False Killer Whale   Pseudorca crassidens

This species only occasionally comes onto coastal waters of the British Isles, being normally a pelagic species living far off-shore. There has been only one stranding of the species in Shetland, in February 1944, and no sightings.

Long-finned Pilot Whale   Globicephala melaena

This, the commonest whale in Shetland waters, may be seen in most months of the year, although it is generally a pelagic species and sightings in coastal waters are most frequent in the winter months November to March. For centuries, this species was the object of an opportunistic drive fishery similar to that which exists to this day in the Faroe Islands. The last drive organised in Shetland was a kill of 83 whales in Weisdale Voe in February 1903 (Venables and Venables 1955) although there is a record of the species being killed at Reawick in 1928. The largest catch on record was of 1,540 animals in Quendale Bay in September 1845 (Evans and Buckley 1899). Since the British Museum stranding scheme was initiated in 1913 there have been at least 21 stranding events. Included amongst these are two mass strandings, of 5 (probably more) at Basta Voe in December 1982, and 32 (+8 successfully returned to the sea) at Ura Firth, Hillswick in October 1983.

Risso's Dolphin   Grampus griseus

This species is a regular visitor to Shetland, mainly between April and September. Sightings have been most frequent on the south and east sides of Shetland, particularly Balta Sound, Yell Sound, Out Skerries and Whalsay, and between Noss and Sumburgh Head. There have been at least seven strandings of this species since 1913; in May 1947, February 1982, May 1987, April 1988, May 1989, September 1989, September 1990, May 1993, and July 1993. As with other small cetaceans, it is very likely that strandings of this species are much under-recorded.

Beluga   Delphinapterus leucas

 There are two confirmed records. During the late afternoon of 4th September 1996 a single animal fed in the waters between Hoswick, Broonies Taing, Levenwick and Channerwick in the South Mainland. It was estimated to measure around 12-14 feet in length. The other record also involved a single animal - seen feeding in shallow water off Lunda Wick, Unst on the 18th August 1997.

Beluga Whales are distributed across the entire Arctic Ocean and rarely penetrate temperate waters. There have been less than twelve records of the species in British waters including an animal reported off Muness, Unst during the summer of 1976 (Alan Whitfield pers.comm). There have also been a number of recent sightings from the Danish, German and Dutch coast suggesting that a small percentage of the Barent's Sea population may move south and remain in North Sea waters.

 

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