Living Organisms / Animalia / Craniata / Mammalia / Carnivora / Phocidae / Halichoerus / Species
Halichoerus grypus - Grey seal (Click photographs/illustrations: full picture & further details)
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INFORMATION AVAILABLE

GENERAL & REFERENCES

APPEARANCE / MORPHOLOGY

LIFE STAGES / NATURAL DIET / PHYSIOLOGY

BEHAVIOUR

HABITAT & RANGE

CONSERVATION

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General and References

Alternative Names (Synonyms)

  • Gray seal
  • Atlantic seal
  • Great seal
  • Selkie
  • Selchie
  • Ron mor (Gaelic)
  • Morlo llwyd (Welsh)
  • Horse head (Canada)
  • Tęte de cheval (French)
  • Kegelrobe (German)

Names for new-borns / juveniles

Pup
Names for males  
Names for females  

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General Appearance

  • Variable colour, with males mainly dark brown or grey, females paler.
  • Head with convex (male) or flat (female) profile.

(B142).

Similar Species

Other seals. Within UK, differentiated from Phoca vitulina - Common seal by:
  • Fewer, larger spots.
  • Head larger, longer muzzle with flat or convex "Roman-nose" rather than concave profile, and top of head flattish rather than domed.
  • Nostrils almost parallel to one another, and well separated at base, rather than forming "V".

(B142)

Sexual Dimorphism
  • Males much larger than females (up to three times as big) and usually darker.
  • Massive shoulders, skin on shoulders and chest heavily folded and wrinkled, with heavy scarring.
  • Snout elongated and convex above muzzle (female has a straight dorsal profile).

(B142, B144, B147).

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References

Species Author

Debra Bourne

Major References

B51, B52, B141, B142, B143, B144, B147, B221

Husbandry references:

ORGANISATIONS
(UK Contacts)

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

  •  

Specific Needs Group referenced in Management Techniques

  •  

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Husbandry Information

Notes

--
Individual Techniques linked in Wildpro

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Appearance / Morphology

Measurement & Weight

Length
  • Male: Northumberland 213cm, Nova Scotia 228cm(B52); 2.07m (1.95-2.30m)(B142); up to 7ft/2.2m (B144); 1.95-2.3m (B147).
  • Female: Northumberland 183cm, Nova Scotia 200cm (B52);1.80m (1.65-1.96m) (B142); less than 6.5ft/2m (B144);1.65-1.95m (B147).
Height --
Adult weight General --
Male Northumberland: 270kg. Nova Scotia: 330kg (B52); 233kg (170-310kg) (B142).average 506 lbs./ 230kg, maximum 660 lbs./300kg (B144); 170-310kg eastern Atlantic, with Canadian sometimes > 400kg (B147).
Female Northumberland: 140kg. Nova Scotia: 170kg (B52); 155kg (105-186kg) (B142); maximum 330lbs. / 150kg (B144);105-186kg eastern Atlantic, with Canadian sometimes up to 256kg (B147).
New-born weight 14.5kg (B142); 33 lbs./15kg (B144);14kg (B147);.
Growth rate Weight increase average 1.7kg per day (females 1.6kg/day, males 1.9kg.day) (B142); about 45 kg (B142), 50 kg (B147) by end of lactation (16-21 days).

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Head

General Relatively large head with long muzzle, straight to convex profile and flat skull (B142).

Skull: Snout wide and long, frontonasal region elevated. Palate has evenly rounded posterior margin. Wide intraorbital region. (B142).

Nose: Long muzzle. Nostrils well separated at base and nearly parallel (B142).

Ears: no external pinna.

Dentition (Teeth)
  • I 3/3 C 1/1 P 4/4 M1-2/1 (B142, B147).
  • Deciduous teeth shed before birth. Permanent teeth erupt shortly afterwards.
  • Teeth large, peg-like.

(B52, B142, B147).

Eyes --

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Legs and Tracks

  • Forelimbs paddle-shaped, digits all within common integument.
  • Hindlimbs fan-like: digits joined by web (hair-covered).
  • Claws on all digits, long and slender on forelimb digit.

(B142)

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Tail

Short (B142).

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Coat / Pelage

Adult Female
  • Wide colour variation: grey, brown, black, silver (B142, B147)
  • Dorsal medium grey with darker patches
  • Ventral paler with variable dark spotting: may be almost uniformly pale, or mostly dark.

(B142, B147)

Variations (If present)
  • Males: Dorsal mainly dark grey/brown, few paler patches, ventral paler than dorsal and with pale spotting. (B142, B147)
  • Individual variation: females may be creamy-white with few dark dorsal markings. Males (and some females) may be black with no or only few pale ventral markings (B142, B147).
  • Pelage may be brown or fawn close to moulting (B142).
  • Ginger colour sometimes seen, particularly on head.(B142).
Moult
  • Eastern Atlantic: January to March; Western Atlantic: May; Baltic ice: April and May (B147).
  • Britain: females January to March, males March to May. Pups first moult at 2-3 weeks, with second moult after about 15 months (B142).
New-born / Juvenile Creamy-white, silky (B142, B147).

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Neonate (New-born) Characteristics

76 cm long, creamy-white silky pelage (B147); 90-105cm long (B142).

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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Gastro-intestinal: simple stomach (B52).

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Life Stages / Natural Diet / Physiology

Reproductive Stages

Breeding Season
  • At end of lactation: about three weeks after birth of previous pup.
  • Territorial behaviour by males starts when first pups born.

(B142, B147)

Oestrus / Ovulation
  • Oestrus within three weeks of previous birth: at end of lactation (B147).
  • May be polyoestrus (B142)
  • Occasionally sexual activity in spring (B142).
Gestation / Pregnancy
  • Delayed implantation:
  • Development to blastocyst stage (8-10 days) followed by delayed implantation (100 days) (B147); 125 days (B142) three months (B144), before active gestation (240 days) (B147); about 214 days (B142).
  • Total pregnancy about 11.5 months (B144, B147).
Parturition / Birth
  • British Isles mainly September to December, occasionally March to May. In Wales peak September, in Orkneys October, in Farne Islands November, in Scroby Islands late December/early January.
  • Iceland and Norway peak October.
  • Baltic peak late February/early March
  • Western Atlantic, peak mid January-mid February.

(B52, B147)

Neonatal development
  • Birth: able to swim at birth. Fed every 5-6 hours.
  • First moult to adult-type coat by time of weaning.
  • Usually remain on land until 2-4 weeks after weaning, then go to sea.

(B147).

Litter size
  • Normally one.
  • Twins have been recorded but are very rare in pinnipeds.

(B52, B142, B144, B147)

Time between Litters / Litters per year
  • One per year (B147).
Lactation / Milk Production
Sexual Maturity
  • Females first pup at 4-5 years old. Continue growing to 15 years (B147).
  • Females sexually mature 3-5 years (B142); 5-5.5years first pup (B52).
  • Males sexually mature about 6 years old (4.2 years in Nova Scotia), likely to appear at breeding grounds at eight years old (earliest age likely to mate), may be successful at breeding by 10 years, breeding bulls mainly 12-18 years old. Continue growing to 11 years old. (B52, B142, B147).
  • 4-7 years, but males socially unlikely to mate before 10 years (B144).
Longevity
  • Males 31 years, 43 in captivity; females 46 years (B52).
  • Females maximum 46 years but few more than 35 years, males maximum 26 years, few more than 20 years (B142).
  • More than 40 years (B144).
  • Maximum 46 years (B147).

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Natural Diet

  • Fish (migratory, open sea and bottom-dwelling fish) including salmon, cod, herring, skates, mackerel, flounder.
  • Also occasionally octopus, squid, crustaceans.
  • Seabirds at sea surface may also be eaten.
  • Diet varies seasonally and between different areas.
  • About 5kg fish per day required, but do not always feed daily.
  • Fast during breeding season (females for three weeks, male up to 6 weeks).

(B52, B142, B144, B147)

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Temperature --
Pulse --
Respiration --
Faeces --
Haematology / Biochemistry --
Chromosomes 2n = 32, FNa = 60 (B142).
Other --

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Behaviour

Feeding Behaviour

  • Opportunistic foraging - most abundant species are taken
  • Possibly benthic as most dives appear to reach close to bottom.

(B143, B147)

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Parental Behaviour

  • Female may remain with pup until it is weaned, or may leave temporarily while foraging.
  • Female suckles pup and defends against other individuals
  • Abandons pup at weaning (about three weeks).
  • Some females adopt other pups rather than consistently feeding own pup

(B142, B147)

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Social Behaviour / Territoriality

Intra-specific
  • Ranges up to 100km B143.
  • Congregate in breeding season.
  • Males aggressive / establish territory in breeding season.
  • Disperse from breeding sites outside breeding season, although may remain in local area.
  • Some sites, after pupping, large post-breeding assemblies may be found.
  • Variable group size, individuals may segregate by age and sex.

(B52, B142, B143, B144, B147)

Inter-specific --

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Sexual Behaviour

  • Polygynous breeding groups.
  • Males compete for proximity to females.
  • Nearest established male mates with oestrus female.
  • Variable 1:1 to 1: 10 male:female ratio, depending on characteristics of site and population density.

(B142, B144, B147)

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Predation in Wild

  • Killer whales occasionally take adults.
  • Great white sharks take pups leaving rookeries (Canadian coast).

(B142, B144)

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Activity Patterns

  • Dives may be 70m (B147) 100m or deeper (B143).
  • Fast during breeding season and also mainly during moult.
  • Return to birth site or same area for breeding, and to same site each year.
  • Mostly resting when on land.
  • Do not appear to porpoise while swimming (B142).
  • Foreflippers used to take weight on land.

(B52, B142, B143, B147)

Circadian Some indication of tidal rhythm in haul-out behaviour, but individual variation (B142).

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Habitat and Range

General Habitat Type

  • Breeding: exposed rocky or cliff-backed coasts, shelves, shingle beaches, small off-shore islands.
  • Forage adjacent to such areas mainly.
  • Also common in estuaries, particularly when salmon present.
  • Some colonies on sandy beaches, some in sea caves, also grassy slopes and ice.
  • On ice in Baltic and in Gulf of St Lawrence.
  • Non-breeding: assemble on tidal rocks, reefs, sandbanks; separate from breeding areas.
  • Intertidal flats may be used for hauling-out.

(B52, B142, B143, B144, B147)

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Nests / Burrows / Shelters

--

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Distribution and Movement (Migration etc.)

Normal North Atlantic. Three stocks:
  • West Atlantic (Cape Chidley in north of Labrador through Newfoundland, Nova Scotia, New England, Gulf of St Lawrence and associated islands off Nova Scotia southwards to Nantucket).
  • East Atlantic stock. Europe: Northern limit Iceland to White Sea, Norway and Kola Peninsula,. Faeroes, around British Isles and associated islands (80% of population), along Atlantic and North Sea coasts south to Brittany (France).
  • Baltic stock: Gulf of Bothnia, Gulf of Finland, Gulf of Riga, southward to Gulf of Danzig, Polish-German border, Malmö on coast of Sweden.

(B51, B52, B142, B143, B147).

Movements:

  • Not migratory but pups disperse long distances although probably return to natal beaches for breeding (B147).
  • Generally use different sites for moulting than for breeding (B147).
Occasional and Accidental New Jersey, Svalbard, continental coast of North sea, Portugal, northern Labrador (B52, B147).
Introduced

--.

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Conservation

Intraspecific variation

  • None (B143).
  • Halichoerus gryphus macrorhynchus, Baltic subspecies (B147).

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Conservation Status

Wild Population -
(Importance)
Not globally threatened (B144).
  • East Atlantic: Stable or growing, with British population estimated 111,000 in 1997 and Northern population 20,000, although only a few hundred in eastern North Sea (B143).
  • West Atlantic: 80,000-110,000 in 1987 B143.
  • Baltic: Has been declining. Recently estimated 5,000 (B143); fallen from more than 100,000 to less than 3,000 (B147).
  • In Britain: native, locally common. Pre-breeding population estimate of about 93,5000 including 5,500 in England, 86,400 in Scotland, 1,600 in Wales. Population estimate is considered reliable and likely to be inaccurate by no more than 10% in either direction (B221)
General Legislation:
  • Bern Convention, Appendix III B143
  • Bonn convention, Appendix II (Baltic Sea population only)
  • EU Habitats & Species Directive, Annex II, Annex V
  • Protected in Britain over breeding period, but with provision for some culling (B147).
  • Conservation of Seals Act 1970 closed season Great Britain 1 September to 31st December. Seals may only be killed during this period under licence. (B142)
  • Grey Seal Protection Act, 1932, closed season Northern Ireland 1 September to 31st December. Seals may only be killed during this season under licence (B142).
  • Irish Wildlife Act: also gives protection (B142).
CITES listing --
Red-data book listing Endangered (Baltic Sea population only) (B143, B147).
Threats
  • Fishing nets drown 15-20% of pups in Baltic.
  • Pollution (has reduced fertility).
  • Killed as perceived competitor for commercial fish species.
  • Breeding site disturbance in highly human-populated areas may lead to high mortality. 
  • Potential threat from oil spills

(B52, B142, B143, B221)

Captive Populations --
Trade --

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