• Eastern Atlantic harbor seal
  (Phoca vitulina vitulina)
• Western Atlantic harbor seal
  (Phoca vitulina concolor)
• Pacific harbor seal
  (Phoca vitulina richarii)
• Ungava seal
  (Phoca vitulina mellonae)
• Insular seal
  (Phoca vitulina stejnegeri)

Nomenclature

Of the harbor seal, Phoca vitulina (Linnaeus, 1758), commonly 4 subspecies are recognized: the Eastern Atlantic harbor seal, Phoca vitulina vitulina (Linnaeus, 1758), the Western Atlantic harbor seal, Phoca vitulina concolor (DeKay, 1842), the Insular harbor seal, Phoca vitulina stejnegeri (Allen, 1902), and the Pacific harbor seal, Phoca vitulina richardii (Gray, 1864). In addition, some authors consider the Ungava seal, Phoca vitulina mellonae (Doutt, 1942), a freshwater seal, a separate subspecies, but its status as a subspecies is doubtful.

Appearance

Distribution

Feeding

The diet consists mainly of inshore shallow water fish species, such as flounder, sole, herring, cod, whiting and eel, but also mussels, crabs and squid are eaten. They eat 5-8½ kg per day (Bonner, 1982).

Population dynamics and life history

Trophic relations

Not much is known about competition or predation. There is in some areas a potential for competition with the grey seal.

Interactions

Influences of human activities on harbor seal populations are abundant. There is a competition for resources with commercial fisheries. Consequently also net entanglement of seal occurs. Several areas, especially the Wadden Sea and the Baltic, are severely polluted and negative effects on the seal have been clearly demonstrated. Tidal flat areas, where harbor seals haul out at low tide, are often visited by tourist, which create disturbances. Another source of disturbances is air force activity in the Wadden Sea. Land reclamation projects, such as the Delta Project in the Netherlands, destroy the seal's habitat.

Population size

Bonner (1982) gives the following estimates for British areas:

• The Wash: 5,500-7,651
• Scotland: 950-1,250
• Shetland: 2,000
• Orkney: 2,000-3,000
• Outer Hebrides: 1,300
• Inner Hebrides: 3,500

The Wadden Sea population in 1980 was estimated at 4,000-5,000. In 1987 this had increased to around 10,000 animals. In 1988 a viral infection wiped out a large portion of the Wadden Sea population. The population size after the epizootic was about 3,000 animals (Reijnders, 1988). Since then, the population has recovered and was at 7,250 in 1992. (See also my reports on the seal epizootic and the current views on seal rehabilitation for more specific data on the current situation in the Dutch part of the Wadden Sea)

Exploitation

In the Wadden Sea area hunting is prohibited. In the UK there was an annual harvest of pups: Inner Hebrides: 250; Orkney: 200; Wash: 400 (Bonner, 1982). Currently, shooting licenses may be granted to protect fisheries, but there is no regular harvest. In Iceland and Norway 5,000-7,000 seals may be taken per year. In other areas there may be a seasonal hunt, but no data are available.

Threats to the population

The main threat to the harbor seal comes from pollution, especially in the Wadden Sea and the Baltic Sea. Land reclamation and construction works has caused the disappearance of the harbor seal from the southern part of the Netherlands (Reijnders, 1982a). (This population had already been severely reduced by over-exploitation and pollution). Incidental kill in fisheries also takes its toll among the harbor seals. A recent outbreak of a morbilli virus infection, the Phocid Distemper Virus (related to the Canine Distemper virus) (Osterhaus and Vedder, 1988), has severely reduced the Wadden Sea population (Reijnders, 1988). The population has recovered from that, but it is unclear what the long-term effects are.

IUCN Status

Insufficiently known

References

Bigg, M.A. (1981)

Harbour seal Phoca vitulina Linnaeus, 1758, and Phoca largha, Pallas, 1811. in:
Ridgway, S.H. and Harrison, R.J. (eds.): Handbook of Marine Mammals, vol. 2: Seals, pp. 1-77,
Academic Press Inc., Ltd, London

Bonner, W.N. (1979)

Harbour (Common) Seal. in:
Mammals in the Seas, volume II: pinniped species summaries and report on sirenians.
FAO Fisheries Series No. 5, Vol II, pp. 58-62

Bonner, W.N. (1982)

The status of seals in the United Kingdom. in:
Mammals in the Seas, Volume IV: small cetaceans, seals, sirenians and otters.
FAO Fisheries Series, No. 5, vol. IV, pp. 253-265

Bonner, W.N. (1982a)

Seals and Man. A study of interactions.
University of Washington Press, Seattle, 170pp.

Haaften, J.L. van (1983)

The life-history of the harbour seal in the Wadden Sea. in:
Reijnders, P.J.H. and Wolff, W.J. (eds.): Marine mammals of the Wadden Sea. Report 7 of the Wadden Sea Working Group. in: Wolff, W.J. (ed.): Ecology of the Wadden sea, vol. 2, pp. 7/15-7/19,
A.A. Balkema, Rotterdam.

Heide-Jørgensen, M.-P., Härkönen, T.J. (1987)

Rebuilding seal stocks in theKattegat-Skagerrak. Mar. Mamm. Sci. 4(3): 231-246

Helle, E. (1983)

Hylkeiden elämää.
Kirjayhtymä, Helsinki, 171pp.

Henriksen, G., Gjertz, I. and Kondrakov, A. (1997)

A review of the distribution and abundance of harbor seals, Phoca vitulina, on Svalbard, Norway, and in the Barents Sea. Mar. Mamm. Sci. 13(1): 157-163

Osterhaus, A.D.M.E., Vedder, E.J. (1988)

Identification of virus causing recent seal deaths. Nature 335: 21

Reijnders, P.J.H. (1978)

Recruitment in the harbour seal (Phoca vitulina) population in the Dutch Wadden Sea. Neth. J. Sea. Res. 12(2): 164-179

Reijnders, P.J.H. (1982)

Verminderde vruchtbaarheid bij Nederlandse zeehonden als mogelijk gevolg van hoge PCB belasting. Tijdschr. Diergeneesk. 107(10): 363-367

Reijnders, P.J.H. (1982a)

On the extinction of the South Dutch harbour seal population. Int. Counc. Exp. Sea. CM 1982/N:2

Reijnders, P.J.H. (1983)

Threats to the harbour seal population in the Wadden Sea. in:
Reijnders, P.J.H. and Wolff, W.J. (eds.): Marine mammals of the Wadden Sea. Report 7 of the Wadden Sea Working Group. in:
Wolff, W.J. (ed.): Ecology of the Wadden sea, vol. 2, pp. 7/38-7/47,
A.A. Balkema, Rotterdam.

Reijnders, P.J.H. (1986)

Reproductive failure in common seals feeding on fish from polluted coastal waters. Nature 324: 456-457

Reijnders, P.J.H. (1988)

Gevolgen virus uitbraak voor zeehonden in het internationale Waddengebied. Waddenbulletin 23(4): 201-203

Reijnders, P.J.H., Drescher, H.E., Haaften, J.L. van, Bøgebjerg Hansen, E., Tougaard, S. (1983)

Population dynamics of the harbour seal in the Wadden Sea. in:
Reijnders, P.J.H. and Wolff, W.J. (eds.): Marine mammals of the Wadden Sea. Report 7 of the Wadden Sea Working Group. in:
Wolff, W.J. (ed.): Ecology of the Wadden sea, vol. 2, pp. 7/19-7/32,
A.A. Balkema, Rotterdam.

Toorn, J.D. van der (1984)

Seals: een simulatie programma. Een studie van de populatie dynamica van de gewone zeehond Phoca vitulina in het Nederlandse deel van de Waddenzee. Int. rep. RIN, Texel, 33pp.

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Nomenclature

The insular seal was earlier given the status of a species: Phoca insularis, and also Phoca kurilensis. In 1977 it was included as a subspecies in Phoca vitulina. Phoca vitulina richardsi was named by Gray in honor of "Capt. Richard" and hence was named richardii. Since the captain's name actually was "Richards", the name was corrected to richardsi. However, Rice (1998) notes that this correction is invalid and that the name P. v. richardii is the only valid name for this subspecies. The Baja California and California harbor seals have been called a separate subspecies, P. v. geronimensis, but this is no longer recognized. These populations are now considered to be P. v. richardii.

Appearance

Of P. v. stejnegeri the males measure 174-186 cm and weigh 87-170 kg. Females are 160-169 cm long and weigh 60-142 kg. At birth pups measure 98 cm and weigh 19 kg. Of P. v. richardii the males measure 161 cm and weigh 87 kg. Females are 148 cm long and weigh 65 kg. At birth pups measure 82 cm and weigh 10 kg. Both subspecies are similar in appearance. There are dark and light varieties. The light variety has a dark dorsal and pale sides and ventral with spots, that tend to coalesce. There are also pale areas around the eyes and snout. The dark variety has a nearly black background of densely packed spots of which some are light encircled.

Distribution

P. v. stejnegeri can be found on Pacific Islands: from Hokkaido (Japan) through the Kuril Island, along Kamchatka to the Commander Islands. P. v. richardii ranges from Cedros Island (Baja California) along the Pacific coasts of the United States, Canada and Alaska, through the Aleutian Islands to the Pribilof Islands.

Feeding

The diet consists mainly of fish, including flounder, herring, cod and hake, but also includes squid. The daily consumption is estimated to be 2-3 kg.

Population dynamics and life history

The onset of maturity for females is at 2-5 years of age and for males at 3-6 years. The pregnancy rate is 88%. Gestation lasts 10½-11 months, including a delay of implantation of 2 months. Lactation lasts 4-6 weeks. Longevity is around 40 years. The mortality rate for the first year is 20%, for ages 1 to 5: 20% and for ages over 6 for males 26% and for females 15%.

Trophic relations

Interactions

There is some interaction with especially the gill net fisheries. In 1980 in California 132 seals were killed in gill nets (DeMaster et al, 1985).

Population size

Only for a few areas population estimates are available. The British Columbia population is about 35,000 animals. The Alaskan population is about 260,000. The population at San Miguel Island is between 1,445 and 2,168 seals (Yochem et al, 1987). The total Pacific population (both subspecies) is estimated at 312,000-317,000.

Exploitation

The harbor seal is protected in the United States and Canada. There has been a bountied hunt in Alaska, in which 8,000-12,000 animals were killed annually. Now the hunt is prohibited. Despite the protection presumably a lot of seals are shot by fishermen.

Threats to the population

None known.

IUCN Status

P.v. richardii: Insufficiently known
P.v. stejnegeri: Vulnerable

References

Bigg, M.A. (1981)

Harbour seal Phoca vitulina Linnaeus, 1758, and Phoca largha, Pallas, 1811. in:
Ridgway, S.H. and Harrison, R.J. (eds.): Handbook of Marine Mammals, vol. 2: Seals, pp. 1-77,
Academic Press Inc., Ltd, London

Bonner, W.N. (1979)

Harbour (Common) Seal. in:
Mammals in the Seas, volume II: pinniped species summaries and report on sirenians.
FAO Fisheries Series No. 5, Vol II, pp. 58-62

DeMaster, D., Miller, D., Henderson, J.R., Coe, J.M. (1985)

Conflicts between marine mammals and fisheries off the coast of California. in:
Beddington, J.R., Beverton, R.J.H. and Lavigne, D.M. (eds.): Marine Mammals and Fisheries, pp. 111-118,
George Allen & Unwin (Publishers) Ltd, London

Rice, D.W. (1998)

Marine mammals of the world - Systematics and distribution
Society of Marine Mammalogy Special Publication Number 4, 231 pp.

Yochem, P.K., Stewart, B.S., DeLong, R.L., DeMaster, D.P. (1987)

Diel haul-out patterns and site-fidelity of harbor seals (Phoca vitulina richardsi) on San Miguel Island, California, in autumn. Mar. Mamm. Sci. 3(4): 323-332

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Nomenclature

The harbor seals living in fresh water lakes in Canada are occasionally assigned to a separate subspecies, Phoca vitulina mellonae (Doutt, 1942), the Ungava seal, but its status as a subspecies is doubtful. Usually these seals are included in P. v. concolor (DeKay, 1842).

Appearance

The length of males ranges from 150 to 180 cm and the weight from 55 to 105 kg. Females measure 120-150 cm and weigh 45-87 kg. Pups measure 70-90 cm at birth and weigh 9-11 kg. The color of the harbor seal is variable: grey to brownish grey with black spots.

Distribution

The Western Atlantic harbor seal ranges from Maine north to Ellesmere Island in the Canadian Arctic and west to the Hudson Bay. This range includes Nova Scotia, Newfoundland, Labrador and Baffin Island. The seal is also found in Greenland. The Ungava seal can be found in the fresh water Seal Lakes in Ungava, Canada.

Feeding

They feed mainly on local fish, including herring and flounder.

Population dynamics and life history

Trophic relations

Interactions

Population size

Exploitation

In the USA the harbor seal is protected. In Canada there is some bounty hunting, with an estimated yearly harvest of 1,000 animals. In Greenland there is some hunting by aboriginals, who take 100-200 seals/year.

IUCN Status

Insufficiently known

References

Bigg, M.A. (1981)

Harbour seal Phoca vitulina Linnaeus, 1758, and Phoca largha, Pallas, 1811. in:
Ridgway, S.H. and Harrison, R.J. (eds.): Handbook of Marine Mammals, vol. 2: Seals, pp. 1-77,
Academic Press Inc., Ltd, London

Bonner, W.N. (1979)

Harbour (Common) Seal. in:
Mammals in the Seas, volume II: pinniped species summaries and report on sirenians.
FAO Fisheries Series No. 5, Vol II, pp. 58-62

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