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Lifespan, longevity, and ageing

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Maximum longevity: 42.9 years (captivity) Observations: After a 100 days period of delayed implantation, the active gestation lasts 240 days (Ronald Nowak 2003). In the wild, it has been estimated that females live up to 46 years (David Macdonald 1985), which is dubious. Record longevity in captivity is 42.9 years (Richard Weigl 2005).
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Reproduction

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An interesting case demonstrates a breeding difference between populations. Land-breeding gray seals are polygynous, with males competing to monopolize matings with as many as 7 females. Ice-breeding seals do not appear to be polygynous. Due to the instability of the early January ice, little is known of their habits. However, initial research indicates that a more monogamous system exists.

Mating System: monogamous ; polygynous

The breeding season of the grey seal varies greatly, occurring anywhere from mid-December to October, depending upon the location of the population. Breeding rookeries are formed on various types of habitat including sandy beaches, rocky islands, coasts, caves, and ice. During the months prior to the breeding season, seals actively feed. The females do so to grow for the future developing fetus and to build the fat reserves which will sustain them and the calf for the fasting which follows the birth, usually lasting for three weeks. The males also actively feed, because they too will fast for the breeding season, however their fasting will typically last for up to six weeks. The males ordinarily enter the rookeries once the females give birth and try to gain sole access to groups of females. Territory-related fighting occurs during the breeding season, although it is relatively minor compared to other seal species. Fighting in grey seal communities differs among populations, but generally increases as does the density of females. The successful males are able to mate with up to ten females, depending upon locality and density of the females.

Sixteen percent of female grey seals are sexually mature on their third birthday and give birth to their first young one year later. This figure rises to seventy-one percent by the fourth year and eighty-nine percent by the fifth year of life. The males also become sexually mature at age three, but due to competition for females, rarely mate before they are eight years old.

Once impregnated and following a gestation period of eleven months, females usually give birth a day after coming ashore at the rookery. Grey seals are attentive mothers and defend their pups against predation and intrusion. The pup is nursed for approximately 2 weeks after it is born, gaining around 1.5 kg per day. Once the pup is weaned, the female mates with one or more males and then leaves the pup at the rookery. The pup will remain on land, living off of its blubber reserves until it has fully molted, at which point it will feed at sea. The young seals generally disperse in many different directions from the rookery and are known to wander to distances of over 1,000 km.

Breeding season: The breeding season of the grey seal varies greatly, occurring anywhere from mid-December to October.

Average number of offspring: 1.

Average gestation period: 11 months.

Average weaning age: 14 days.

Average time to independence: 14 days.

Range age at sexual or reproductive maturity (female): 3 (low) years.

Range age at sexual or reproductive maturity (male): 3 to 8 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous

Average birth mass: 14000 g.

Average gestation period: 240 days.

Average number of offspring: 1.

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Untitled

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Pollution in the Baltic Sea has led to the declining population of the grey seal. The most dramatic increase in DDT and PCB levels in the Baltic occurred after 1955. Research conducted by Zakharov and Yablokov on skulls of grey seals investigated the notion that these increased pollutants result in skull asymmetry. Their study investigated whether morphological changes could be found in the grey seal population born during the major pollution episode that occurred after 1960. They studied skulls taken from seals born before 1940 and after 1960. It was shown that the pollution group had sharply increased levels of asymmetry in almost all characters analyzed. The findings indicate a dramatic change in the development stability of the Baltic grey seal during the period of heavy pollution after 1960, which could attribute to the rapid decline of the species (Zakharov 1990).

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Behavior

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Perception Channels: tactile ; chemical

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Conservation Status

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The grey seal species as a whole is under no special conservation status. In fact, many countries allow either monitored or unlimited hunting of the seals. For nearly a decade, from 1982 until 1993, Norway, Iceland and Canada offered bounties and local culls for the grey seal. Many fisherman believe that this species competes with them for fish, and seals damage nets and traps. Recently the species has been given great legal protection in Europe, and fewer culls are being authorized.

The Baltic Sea population of this species is much smaller than the two Atlantic population, probably due to hunting and pollution of its habitat. It has greater legal protection.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Benefits

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Grey seals are widely believed by commercial fisherman to be a pest. They may remove fish from nets, become tangled in nets, damage traps, and feed on farmed fish. These seals are also hosts for a parasitic roundworm called codworm (Pseudoterranova decipiens), that infects cod and other commercially harvested fish.

There is some dispute about the large-scale impacts of grey seals on the Atlantic fisheries, but they are at least occasionally a problem in local situations.

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Benefits

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In the past, grey seal pups were killed and harvested on a large commercial scale for their skins. There have been no recent large-scale hunts.

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Associations

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These seals are also hosts for a parasitic roundworm called cod worm (Pseudoterranova decipiens), that infects cod and other commercially harvested fish.

Commensal/Parasitic Species:

  • cod worm (Pseudoterranova decipiens)
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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Trophic Strategy

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Halichoerus grypus is an opportunistic feeder consuming between four and six percent of its body weight in one feeding per day. The diet consists of a large variety of fish and the occasional crustaceans and mollusks. According to King, at least 29 different species of fish have been recorded as being eaten by these seals. Fish taken include nearly any species found at pelagic and midwater levels as well as bottom dwelling fish at depths of seventy or more meters.

The feeding methods of the grey seal vary among populations, however they are most often social feeders. Social feeding reduces the opportunity for the prey to escape thereby increasing the feeding efficiency. When small fish are caught by the seal, they are usually consumed underwater and are swallowed whole. However, when large fish are captured, they are brought to the surface and held in the prehensile front flippers. The fish head is then bitten off and discarded, while the remainder of the fish is broken into small pieces able to be swallowed.

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Julia Smith, University of Michigan-Ann Arbor
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Distribution

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The grey seal (Halichoerus grypus) occurs in temperate and subarctic waters on both sides of the North Atlantic ocean resulting in three distinct populations. The western Atlantic population is found in the Canadian maritime provinces located from Cape Chidley on the Labrador coast to Nova Scotia. Grey seals located on the southwestern coasts of Iceland, on the Faeroe Islands and the British Isles comprise the eastern Atlantic population. In addition, the eastern Atlantic population extends further onto the coasts of Norway, northwestern Russia, and even French, Dutch, Gernman and Portugal coasts. The third population is found in the Baltic Sea.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); atlantic ocean (Native )

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Julia Smith, University of Michigan-Ann Arbor
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Habitat

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The habitat of the grey seal differs among each individual group of seals. Some are found along rocky continental coasts, while others are comfortable on isolated islands. There are also many grey seal populations around that haul out on icebergs and ice shelves.

Habitat Regions: temperate ; polar ; terrestrial ; saltwater or marine

Terrestrial Biomes: icecap

Aquatic Biomes: coastal ; brackish water

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Julia Smith, University of Michigan-Ann Arbor
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Life Expectancy

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Their lifespan ranges from 15 to 25 years, with the oldest recorded wild female grey seal living to be 46 years of age.

Range lifespan
Status: wild:
46 (high) years.

Typical lifespan
Status: wild:
15 to 25 years.

Average lifespan
Sex: male
Status: captivity:
43.0 years.

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Julia Smith, University of Michigan-Ann Arbor
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Morphology

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At birth, grey seal pups weigh approximately 16 kg and have long, creamy white fur which is shed after the first three weeks of life. They fatten quickly on the rich milk from their mothers, and by moulting age have nearly quadrupled in body mass. At this time the young seals show coat patterns which differentiate the sexes. The female grey seal is silver-grey in colour, with small scattered dark spots, while the males are a dark grey with silver grey spots. The three populations of grey seals differ in exact colorings (grey, brown, silver), however the patterns are similar among the individual sexes -- female grey seals have dark spots on a lighter background while the males have a lighter spotting on a dark background fur, but both sexes in the three populations have a relatively dark back and lighter belly.

In addition to coat markings, the nose of a grey seal can distinguish a male from a female. The male grey seal has a long-arched roman nose which is the basis for its Latin name, Halichoerus grypus, meaning the hooked-nose sea pig. The shoulders of the male are massive with the overall bulk supplemented by a buildup of scar tissue from fighting during breeding seasons. The average adult male reaches his maximum size of 2.2 meters long and 220 kg at 11 years of age. The female is smaller and does not attain full size until approximately 15 years of age, reaching an average weight of 150 kg and length of 1.8 meters (measured from nose to tail). She has a more narrow, short nose and a straight profile to the dorsal surface of the head.

Range mass: 150 to 220 kg.

Range length: 1.8 to 2.2 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes shaped differently

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Smith, J. 2008. "Halichoerus grypus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Halichoerus_grypus.html
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Julia Smith, University of Michigan-Ann Arbor
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Biology

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Grey seals feed on a wide range of fish species, and also take crustaceans, cephalopods and the occasional seabird. When feeding they can dive to depths of 30 to 70 metres (3). In autumn females congregate at traditional pupping sites, called rookeries. At birth the pups weigh 14 kilograms, but as the mother's milk contains 60 percent fat, they rapidly put on weight and develop the blubber layer essential for maintaining body temperature when at sea (4). Males come ashore at the pupping sites to mate; they compete for sole access to a group of females (3), and successful dominant males can secure access to up to as many as ten females (3). After mating the seals disperse. The pups stay in the rookery surviving on their blubber reserves until after the moult, they then go to sea and may disperse over large distances (3).
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Conservation

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Several important grey seal sites in EC member countries have been proposed as Special Areas of Conservation. In August 1999 the location of the world's third largest island-based grey seal breeding colony, the uninhabited island of Linga Holm in the Orkney Islands was purchased by the Scottish Wildlife Trust as a sanctuary for grey seals (3). It has been suggested that human access to breeding sites could be restricted. This has occurred at Berry Head in Devon, where video monitors have been used to show the breeding seals to visitors, so pressures on the breeding site are reduced (9).
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Description

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Grey seals are the larger of Britain's two species of breeding seal (2). The coat colour varies from grey to brown to silver, often with blotches (4). Males (bulls) can be distinguished from females by the pattern of darker and lighter fur colour. In males, the continuous background colour is dark, but in females is it light. Juveniles are born with a creamy white natal coat (6). The nostrils are parallel (4), and the 'Roman' nose is characteristic, especially in males (7); the scientific name derives from the Greek for 'hooked-nose sea-pig' (8).
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Habitat

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Grey seals usually haul out on uninhabited offshore islands, but occasionally on quiet mainland beaches (6).
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Range

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The grey seal is found on both sides of the north Atlantic in temperate and sub arctic waters (6). Three distinct populations occur; the western Atlantic population, the north-eastern or Baltic population which is endangered, and the eastern Atlantic population (3) which is centred around British coasts, particularly around Scotland (2).
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Status

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Classified as Least Concern (LC) on the IUCN Red List (1). Protected in Europe under Annex II and V of the EC Habitats Directive, and Appendix III of the Bern Convention (3). In Britain it is protected under the Conservation of Seals Act 1970 (closed season from 1 September until 31st December) (4), and listed under Schedule 3 of the Conservation Regulations (1994) (5).
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Threats

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In 1914 the UK grey seal population was thought to number just 500, and the Grey Seals Protection Act was introduced that year (9). The Sea Mammal Research unit estimated that the British grey seal population numbered 124,300 in the year 2000, representing 40% of the world population (2). The population is increasing, which has led to highly controversial (7) concerns by fishermen that they pose a threat to fish stocks (9). Although protected between 1 September and 31st December by the Conservation of Seals Act (1970), they can still legally be shot during this time if they are damaging fishnets (4), furthermore illegal shooting continues (3). Grey seals are sensitive to disturbance by people and dogs, particularly when lactating. They are also susceptible to oil and chemical pollution and often become tangled up in fishing nets, which may be fatal (3).
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Brief Summary

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Grey seals are true sporters. They easily swim from the Wadden Sea to England and back again.They are less shy and much more curious than harbour seals. The pups are born in the middle of the winter on undisturbed sandbanks in the Wadden Sea. The vicious wind blows constantly in their faces but these tough young animals have a thick white winter coat during their first few weeks to protect them.
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Parasitic Ecology

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The Grey seal may suffer parasitic as well as bacterial attacks; either circumstance may weaken the individual and may be a cause for stranding on land, sometimes with resulting death. In a number of locations humans carry out rescue efforts to foster such weakened animals, when it is clear that the seal is likely to die without intervention. An example parasite which the Grey seal may host is a roundworm known as codworm (Pseudoterranova decipiens), a species that infects cod and certain other commercially harvested fish. This parasite in its larval stage typically resides in musculature or body cavities of juvenile cod and other benthophagous fishes. The Grey seal may also acquire this parasite by eating sculpins, who in tern have consumed cod.

Studies at Sable Island in Nova Scotia and other locations imply that the breeding season can be an important time for spread of the codworm parasite. It is thought that pups lack resistance to this parasite, and their concentrations in breeding areas are correlated with incidence of marine transmission to certain fisheries. For example several thousand pups may be born at Sable Island annually and the subsequent incidence of cod worm is correlated temporally with dispersal patterns of the pups, with the seal breeding grounds at the epicenter, according to Anderson.
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Encyclopedia of Earth. Authors; Encyclopedia of Life; Peter Saundry. 2011. "Grey seal". Topic ed. C.Michael Hogan. Ed.-in-Chief. Cutler J.Cleveland
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Diagnostic Description

provided by FAO species catalogs
Grey seals are robust and sexually dimorphic; males grow noticeably larger, with a proportionately larger and broader head. The distinctive muzzle is particularly long, and wide at the end, with a fleshy mystacial area that somewhat obscures the lower jaw. In adult males, the top of the muzzle is convex. In adult females and subadults, it is flat, very slightly convex (as in adult males), or slightly concave; the latter having only a barely noticeable forehead. The shape of the head has led to the locally used common name "horsehead". The nostrils are widely separated and almost parallel to each other, forming almost a W-pattern as opposed to the Vshaped pattern of seals of the genus Phoca. The eyes are small in proportion to the size of the head and somewhat widely separated. The foreflippers are short, on adult males, and are wide and relatively thick. Typically, adult males are somewhat thicker through the neck than females.

Pelage colour and pattern are individually variable. Most grey seals are shades of grey, slightly darker above than below. There are usually numerous irregular blotches and spots on the back and sometimes a few below. Many males darken with age. Subadults are paler, with few, if any, blotches; some are light tan just prior to moult. Others are orange to reddish on the neck, underside, and flippers. Newborns have a silky, creamy white lanugo, occasionally with a greyish tinge. In 2 to 4 weeks, this coat is replaced by one like that of the female, but with more subtle markings.

The dental formula of adults is I 3/2, C1/1 ,PC 5-6/5.

Can be confused with: Five phocids share the grey seal's range. The grey seal is larger, with a relatively larger head and longer muzzle, and a decidedly different set of pelage markings than harbour seal, harp seal , and ringed seal. The characteristics of the head, muzzle, and nose, and overall colour and markings will help separate grey seals from the comparably sized bearded seal and hooded seal.

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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Size

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Adult males are up to 2.3 m long and weigh 170 to 310 kg, females to 2 m and 105 to 186 kg. Pups are 90 to 105 cm and 11 to 20 kg at birth.
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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Brief Summary

provided by FAO species catalogs
Grey seals are polygynous. Males actively compete for females, but actually fight little, relying instead on threat gestures and vocalizations. They do not defend territories or herd females. Pupping and breeding occur between late September and early March. Seals in the British Isles breed earliest, followed by those in Norway and Iceland, and finally those off Canada and in the Baltic Sea.

Grey seals disperse widely from their rookeries during the non-breeding season, but reassemble to moult. When ashore, they are generally gregarious, hauling out near each other, as well as with harbour seals. In the water they are usually solitary, or in small dispersed groups. They regularly maintain a vertical "bottle" position, treading water with only the head exposed.Grey seals feed in inshore benthic habitats, on a wide variety of fishes and invertebrates. They also feed on schooling fish in the water column, and occasionally take seabirds.

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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Benefits

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Grey seals have been the target of subsistence hunting, followed by commercial hunting and, finally, government-sponsored culls to control their numbers as pests to fisheries. IUCN:

Insufficiently known.

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Marine mammals of the world. Jefferson, T.A., S. Leatherwood & M.A. Webber - 1993. FAO species identification guide. Rome, FAO. 320 p. 587 figs. . 
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Grey seal

provided by wikipedia EN

The grey seal (Halichoerus grypus) is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or "earless seals". It is the only species classified in the genus Halichoerus. Its name is spelled gray seal in the US; it is also known as Atlantic seal[2] and the horsehead seal.[2][3]

Taxonomy

There are two recognised subspecies of this seal:[4]

  • Halichoerus grypus grypus (Baltic Sea), earlier known as H. g. macrorhynchus and H. g. balticus
  • Halichoerus grypus atlantica (North Atlantic)

The type specimen of H. g. grypus (specimen ZMUC M11-1525, caught off the island of Amager) was rediscovered in 2016, and a DNA test showed it belonged to a Baltic Sea specimen rather than from Greenland, as had previously been assumed. The name H. g. grypus was therefore transferred to the Baltic subspecies (replacing H. g. macrorhynchus), and the name H. g. atlantica resurrected for the Atlantic subspecies.[5]

Molecular studies have indicated that the eastern and western Atlantic populations have been genetically distinct for at least one million years, and could potentially be considered separate subspecies.[6]

Description

This is a fairly large seal, with bulls in the eastern Atlantic populations reaching 1.95–2.3 m (6 ft 5 in–7 ft 7 in) long and weighing 170–310 kg (370–680 lb); the cows are much smaller, typically 1.6–1.95 m (5 ft 3 in–6 ft 5 in) long and 100–190 kg (220–420 lb) in weight. Individuals from the western Atlantic are often much larger, with males averaging up to 2.7 m (8 ft 10 in) and reaching a weight of as much as 400 kg (880 lb) and females averaging up to 2.05 m (6 ft 9 in) and sometimes weighing up to 250 kg (550 lb). Record-sized bull grey seals can reach about 3.3 m (10 ft 10 in) in length.[7][8][9][10] A common average weight in Great Britain was found to be about 233 kg (514 lb) for males and 154.6 kg (341 lb) for females whereas in Nova Scotia, Canada adult males averaged 294.6 kg (649 lb) and adult females averaged 224.5 kg (495 lb).[8][11][12] It is distinguished from the smaller harbour seal by its straight head profile, nostrils set well apart, and fewer spots on its body.[13][14] Wintering hooded seals can be confused with grey seals as they are about the same size and somewhat share a large-nosed look but the hooded has a paler base colour and usually evidences a stronger spotting.[15] Grey seals lack external ear flaps and characteristically have large snouts.[16] Bull Greys have larger noses and a less curved profile than common seal bulls. Males are generally darker than females, with lighter patches and often scarring around the neck. Females are silver grey to brown with dark patches.

Ecology and distribution

 src=
Group of grey seals on sands at Stiffkey, Norfolk
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Grey seals on the Jökulsárlón glacial lake, Iceland

In the United Kingdom and Ireland, the grey seal breeds in several colonies on and around the coasts. Notably large colonies are at Blakeney Point in Norfolk, Donna Nook in Lincolnshire, the Farne Islands off the Northumberland Coast (about 6,000 animals), Orkney and North Rona.[17] off the north coast of Scotland, Lambay Island off the coast of Dublin and Ramsey Island off the coast of Pembrokeshire. In the German Bight, colonies exist off the islands Sylt and Amrum and on Heligoland.[18]

In the Western North Atlantic, the grey seal is typically found in large numbers in the coastal waters of Canada and south to Nantucket in the United States. In Canada, it is typically seen in areas such as the Gulf of St. Lawrence, Newfoundland, the Maritimes, and Quebec. The largest colony in the world is at Sable Island, NS. In the United States it is found year-round off the coast of New England, in particular Maine and Massachusetts. Archaeological evidence confirms grey seals in southern New England with remains found on Block Island, Martha's Vineyard and near the mouth of the Quinnipiac River in New Haven, Connecticut.[19] Its natural range now extends much further south than previously recognised with confirmed sightings in North Carolina. Also, there is a report by Farley Mowat of historic breeding colonies as far south as Cape Hatteras, North Carolina.[3]

An isolated population exists in the Baltic Sea,[1] forming the H. grypus balticus subspecies.

Besides these very large colonies, many much smaller ones exist, some of which are well known as tourist attractions despite their small size. Such colonies include one on the Carrack rocks in Cornwall.

During the winter months grey seals can be seen hauled out on rocks, islands, and shoals not far from shore, occasionally coming ashore to rest. In the spring recently weaned pups and yearlings occasionally strand on beaches after becoming separated from their group.

Grey seals are vulnerable to typical predators for a pinniped mammal. Large sharks are known to prey on grey seals in Canada, particularly great white sharks but also, upon evidence, additionally Greenland sharks.[20][21] In the waters of Great Britain, grey seals are a fairly common prey species for killer whales.[22][23] Apparently, grey seal pups are sometimes taken alive by white-tailed eagles, as well.[1]

Diet

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Grey seal food web in the Baltic Sea [24]
A short video on monitoring and conservation of grey seals at Skomer Island
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Captive grey seal being fed, showing snout shape

The grey seal feeds on a wide variety of fish, mostly benthic or demersal species, taken at depths down to 70 m (230 ft) or more. Sand eels (Ammodytes spp) are important in its diet in many localities. Cod and other gadids, flatfish, herring,[25] wrasse[26] and skates[27] are also important locally. However, it is clear that the grey seal will eat whatever is available, including octopus[28] and lobsters.[29] The average daily food requirement is estimated to be 5 kg (11 lb), though the seal does not feed every day and it fasts during the breeding season.

Recent observations and studies from Scotland, The Netherlands and Germany show that grey seals will also prey and feed on large animals like harbour seals and harbour porpoises.[30][31][32] In 2014, a male grey seal in the North Sea was documented and filmed killing and cannibalising 11 pups of its own species over the course of a week. Similar wounds on the carcasses of pups found elsewhere in the region suggest that cannibalism and infanticide may not be uncommon in grey seals. Male grey seals may engage in such behaviour potentially as a way of increasing reproductive success through access to easy prey without leaving prime territory.[33]

Reproduction

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Cow (l) and bull (r) grey seals mating, Donna Nook, Lincolnshire, U.K.

Grey seals are capital breeders; they forage to build up stored blubber, which is utilised when they are breeding and weaning their pups, as they do not forage for food at this time. They give birth to a single pup every year, with females' reproductive years beginning as early as 4 years old and extending up to 30 years of age. All parental care is provided by the female. During breeding, males don't provide parental care but they defend females against other males for mating.[34] The pups are born at around the mass of 14 kg.[35] They are born in autumn (September to December) in the eastern Atlantic and in winter (January to February) in the west, with a dense, soft silky white fur; at first small, they rapidly fatten up on their mothers' extremely fat-rich milk. The milk can consist of up to 60% fat.[35] Grey seal pups are precocial, with mothers returning to sea to forage once pups are weaned. Pups also undergo a post-weaning fast before leaving land and learning to swim. [36]Within a month or so they shed the pup fur, grow dense waterproof adult fur, and leave for the sea to learn to fish for themselves. In recent years, the number of grey seals has been on the rise in the west and in the U.S.[37] and Canada[38] there have been calls for a seal cull.

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Seal pup a few days after birth

Seal pup first year survival rates are estimated to vary from 80-85%[39][40] to below 50%[41] depending on location and conditions. Starvation, due to difficulties in learning to feed, appears to be the main cause of pup death.[42]

Status

After near extirpation from hunting grey seals for oil, meat and skins in the United States, sightings began to increase in the late 1980s. Bounties were paid on all kinds of seals up until 1945 in Maine and 1962 in Massachusetts.[43] One year after Congress passed the 1972 Marine Mammal Protection Act preventing the harming or harassing of seals, a survey of the entire Maine coast found only 30 grey seals.[43] At first grey seal populations increased slowly but then rebounded from islands off Maine to Monomoy Island and Nantucket Island off of southern Cape Cod. The southernmost breeding colony was established on Muskeget Island with five pups born in 1988 and over 2,000 counted in 2008.[44] According to a genetics study, the United States population has formed as a result of recolonisation by Canadian seals.[44] By 2009, thousands of grey seals had taken up residence on or near popular swimming beaches on outer Cape Cod, resulting in sightings of great white sharks drawn close to shore to hunt the seals.[45] A count of 15,756 grey seals in southeastern Massachusetts coastal waters was made in 2011 by the National Marine Fisheries Service.[46] Grey seals are being seen increasingly in New York and New Jersey waters, and it is expected that they will establish colonies further south.

In the UK seals are protected under the Conservation of Seals Act 1970; however, it does not apply to Northern Ireland. In the UK there have also been calls for a cull from some fishermen claiming that stocks have declined due to the seals.

The population in the Baltic Sea has increased about 8% per year between 1990 and the mid 2000s, with the numbers becoming stagnant since 2005. As of 2011 hunting grey seals is legal in Sweden and Finland, with 50% of the quota being used. Other anthropogenic causes of death include drowning in fishing gear.[47]

Captivity

Grey seals have proved amenable to life in captivity and are commonly found zoo animals around their native range, particularly in Europe. Traditionally they were popular circus animals and often used in performances such as balancing and display acts. At least one grey seal, probably escaped from captivity, has been observed in the Black Sea near the coasts of Ukraine.[48]

See also

References

  1. ^ a b c d Bowen, D. (2016). "Halichoerus grypus". IUCN Red List of Threatened Species. IUCN. 2016: e.T9660A45226042. doi:10.2305/IUCN.UK.2016-1.RLTS.T9660A45226042.en.
  2. ^ a b Sokolov, Vladimir (1984). Пятиязычный словарь названий животных. Млекопитающие. Moscow.
  3. ^ a b Mowat, Farley, Sea of Slaughter, Atlantic Monthly Press Publishing, First American Edition, 1984.
  4. ^ Wozencraft, W.C. (2005). "Order Carnivora". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
  5. ^ Olsen, Morten Tange; Galatius, Anders; Biard, Vincent; Gregersen, Kristian; Kinze, Carl Christian (April 2016). "The forgotten type specimen of the grey seal [Halichoerus grypus (Fabricius, 1791)] from the island of Amager, Denmark". Zoological Journal of the Linnean Society. 178 (3): 713–720. doi:10.1111/zoj.12426.
  6. ^ Boskovic, R.; et al. (1996). "Geographic distribution of mitochondrial DNA haplotypes in grey seals (Halichoerus grypus)". Canadian Journal of Zoology. 74 (10): 1787–1796. doi:10.1139/z96-199.
  7. ^ Gray Seal (marine mammals) Archived 9 October 2018 at the Wayback Machine . what-when-how.com
  8. ^ a b FAO Advisory Committee on Marine Resources Research (1982) Working Party on Marine Mammals; Mammals of the Sea, Volume 4. Food and Agriculture Organization of the United Nations, Rome.
  9. ^ Naughton, D. (2014). The Natural History of Canadian Mammals: Opossums and Carnivores. University of Toronto Press.
  10. ^ Bjärvall, A., & Ullström, S. (1986). The mammals of Britain and Europe. London: Croom Helm.
  11. ^ Lidgard, D. C., Boness, D. J., & Bowen, W. D. (2001). A novel mobile approach to investigating mating tactics in male grey seals (Halichoerus grypus). Journal of Zoology, 255(3), 313-320.
  12. ^ Baker, S. R., Barrette, C., & Hammill, M. O. (1995). Mass transfer during lactation of an ice‐breeding pinniped, the grey seal (Halichoerus grypus), in Nova Scotia, Canada. Journal of Zoology, 236(4), 531-542.
  13. ^ "How to identify British seals". BBC Wildlife. BBC. Retrieved 23 October 2015.
  14. ^ Middleton, Kevin. "Get the lowdown on seals". RSPB. Retrieved 23 October 2015.
  15. ^ Perrin, W. F., Würsig, B., & Thewissen, J. G. M. (Eds.). (2009). Encyclopedia of marine mammals. Academic Press.
  16. ^ Schuster, Marreno; Glen, Megan (2011). Marine Science: The Dynamic Ocean. US Satellite Laboratory: Pearson. p. 107. ISBN 978-0-13-317063-4.
  17. ^ Stewart, J.E.; et al. (2014). "Finescale ecological niche modeling provides evidence that lactating grey seals (Halichoerus grypus) prefer access to fresh water in order to drink" (PDF). Marine Mammal Science. 30 (4): 1456–1472. doi:10.1111/mms.12126.
  18. ^ Hahn, Melanie (13 January 2010). "Kegelrobben-Geburtenrekord auf Helgoland". Nordseewolf Magazin (in German). Archived from the original on 31 March 2016. Retrieved 20 November 2011.
  19. ^ Waters, Joseph H. (February 1967). "Gray Seal Remains from Southern New England Archeological Sites". Journal of Mammalogy. 48 (1): 139–141. doi:10.2307/1378182. JSTOR 137818.
  20. ^ Brodie, P., & Beck, B. (1983). Predation by sharks on the grey seal (Halichoerus grypus) in eastern Canada. Canadian Journal of Fisheries and Aquatic Sciences, 40(3), 267-271.
  21. ^ Lucas, Z. N., & Natanson, L. J. (2010). Two shark species involved in predation on seals at Sable Island, Nova Scotia, Canada. Proceedings of the Nova Scotian Institute of Science (NSIS), 45(2).
  22. ^ Weir, C. R. (2002). Killer whales (Orcinus orca) in UK waters. British Wildlife, 14(2), 106-108.
  23. ^ Bloc, D., & Lockyer, C. (1988). Killer whales (Orcinus area) in Faroese waters. Rit Fiskideildar.
  24. ^ Karlson, A.M., Gorokhova, E., Gårdmark, A., Pekcan-Hekim, Z., Casini, M., Albertsson, J., Sundelin, B., Karlsson, O. and Bergström, L. (2020). "Linking consumer physiological status to food-web structure and prey food value in the Baltic Sea". Ambio, 49(2): 391–406. doi:10.1007/s13280-019-01201-1
  25. ^ Stenman, Olavi (2007). "How does hunting grey seals (Halichoerus grypus) on Bothnian Bay spring ice influence the structure of seal and fish stocks?" (PDF). International Council for the Exploration of the Sea. Retrieved 23 January 2017. Analysis of fish otolithes and other hard particles in the alimentary tract showed clearly that the herring (Clupea harengus) was the most important item of prey.
  26. ^ Ridoux, Vincent; Spitz, J.; Vincent, Cecile; Walton, M. J. (2007). "Grey seal diet at the southern limit of its European distribution: combining dietary analyses and fatty acid profiles" (PDF). Journal of the Marine Biological Association of the United Kingdom. 87 (1): 255–264. doi:10.1017/S002531540705463X. Retrieved 24 January 2017.
  27. ^ Savenkoff, Claude; Morissette, Lyne; Castonguay, Martin; Swain, Douglas P.; Hammill, Mike O.; Chabot, Denis; Hanson, J. Mark (2008). "Interactions between Marine Mammals and Fisheries: Implications for Cod Recovery". In Chen, Junying; Guo, Chuguang (eds.). Ecosystem Ecology Research Trends. Nova Science Publishers. p. 130. ISBN 978-1-60456-183-8.
  28. ^ "Grey seal". Wales Nature & Outdoors. BBC Wales. 25 February 2011. Retrieved 20 November 2011.
  29. ^ "The Grey Seal". Ask about Ireland. Retrieved 20 November 2011.
  30. ^ Leopold, Mardik F.; Begeman, Lineke; van Bleijswijk, Judith D. L.; IJsseldijk, Lonneke L.; Witte, Harry J.; Gröne, Andrea (2014). "Exposing the grey seal as a major predator of harbour porpoises". Proceedings of the Royal Society. 282 (1798): 20142429. doi:10.1098/rspb.2014.2429. PMC 4262184. PMID 25429021.
  31. ^ van Neer, Abbo; Jensen, Lasse F.; Siebert, Ursula (2015). "Grey seal (Halichoerus grypus) predation on harbour seals (Phoca vitulina) on the island of Helgoland, Germany". Journal of Sea Research. 97: 1–4. doi:10.1016/j.seares.2014.11.006.
  32. ^ Hillmer, Angelika (16 February 2015). "Kegelrobben mit großem Appetit auf Schweinswale" [Grey seals with a great appetite for porpoises]. Hamburger Abendblatt (in German).
  33. ^ First video footage of seal drowning and eating a pup. New Scientist (15 February 2016)
  34. ^ Bubac, Christine M.; Coltman, David W.; Don Bowen, W.; Lidgard, Damian C.; Lang, Shelley L. C.; den Heyer, Cornelia E. (June 2018). "Repeatability and reproductive consequences of boldness in female gray seals". Behavioral Ecology and Sociobiology. 72 (6). doi:10.1007/s00265-018-2515-5. ISSN 0340-5443.
  35. ^ a b "Autumn spectacle: grey seal colonies". BBC Earth. 10 October 2014. Retrieved 3 January 2015.
  36. ^ Bowen, William D.; Heyer, Cornelia E. den; McMillan, Jim I.; Iverson, Sara J. (1 April 2015). "Offspring size at weaning affects survival to recruitment and reproductive performance of primiparous gray seals". Ecology and Evolution. 5 (7): 1412–1424. doi:10.1002/ece3.1450. ISSN 2045-7758. PMC 4395171. PMID 25897381.
  37. ^ Bidggod, Jess (16 August 2013) Thriving in Cape Cod’s Waters, Gray Seals Draw Fans and Foes. New York Times
  38. ^ Plan to cull 70,000 grey seals gets Senate panel's approval – Newfoundland & Labrador – CBC News. Cbc.ca. 23 October 2012.
  39. ^ Ailsa j, Hall; Bernie j, Mcconnell; Richard j, Barker (2008). "Factors affecting first-year survival in grey seals and their implications for life history strategy". Journal of Animal Ecology. 70: 138–149. doi:10.1111/j.1365-2656.2001.00468.x.
  40. ^ https://www.researchgate.net/publication/229788805_Mortality_and_morbidity_in_Grey_seal_pups_Halichoerus_grypus_Studies_on_its_causes_effects_of_environment_the_nature_and_sources_of_infectious_agents_and_the_immunological_status_of_pups
  41. ^ http://friendsofhorseyseals.co.uk/
  42. ^ http://friendsofhorseyseals.co.uk/
  43. ^ a b Barbara Lelli; David E. Harris & AbouEl-Makarim Aboueissa (2009). "Seal Bounties in Maine and Massachusetts, 1888 to 1962". Northeastern Naturalist. 16 (2): 239–254. doi:10.1656/045.016.0206.
  44. ^ a b Wood, S.A.; Frasier, T.R.; McLeod, B.A.; Gilbert, J.R.; White, B.N.; Bowen, W.D.; Hammill, M.O.; Waring, G.T.; Brault, S. (2011). "The genetics of recolonization: an analysis of the stock structure of grey seals (Halichoerus grypus) in the northwest Atlantic". Canadian Journal of Zoology. 89 (6): 490–497. doi:10.1139/z11-012.
  45. ^ Once again, coastal waters getting seals’ approval Boston Globe. 3 October 2009.
  46. ^ Gray Seal (Halichoerus grypus grypus): Western North Atlantic Stock (PDF) (Report). NMFS, NOAA. April 2014. pp. 342–350. Retrieved 15 June 2015.
  47. ^ Bäcklin, Britt-Marie; Moraeus, Charlotta; Kunnasranta, Mervi; Isomursu, Marja (2 September 2011). "Health Assessment in the Baltic grey seal (Halichoerus grypus)". HELCOM Indicator Fact Sheets 2011. HELCOM. Archived from the original on 3 November 2011.
  48. ^ Kovtun O.O. (2011) Rare sightings and video-recording of the grey seal, Halichoerus grypus (Fabricius, 1791), in coastal grottoes of the eastern Crimea (Black Sea). Marine Ecological Journal Archived 3 August 2012 at the Wayback Machine, 10(4):22. (in Russian)

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Grey seal: Brief Summary

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The grey seal (Halichoerus grypus) is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae, which are commonly referred to as "true seals" or "earless seals". It is the only species classified in the genus Halichoerus. Its name is spelled gray seal in the US; it is also known as Atlantic seal and the horsehead seal.

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Biology

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Grey seals breed during winter. They are less shy and more curious than the harbour seal. Young, grey seals must stay out of water until they have gained weight and moulted and for this reason they remain in a raised location for the first few weeks of their life.

Grey seals feed mainly on mackerel, young cod and other round fish, but also on cephalopods and crustaceans, in contrast to harbour seals which eat more flatfish.

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North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
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Diet

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Fish, crustaceans, squid
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North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
Contributor
Mary Kennedy [email]

Distribution

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cold temperate to subarctic North Atlantic
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North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
Contributor
Jacob van der Land [email]

Distribution

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North America
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North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
Contributor
Mary Kennedy [email]

Morphology

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Distinguishing characteristics: medium size seal, long head ("horsehead"), W-shaped nostrils, coat is mottled, female has light coat with dark spots, male has dark coart with light spots (when wet looks grey or dark).
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North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
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Morphology

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Grey seal males attain 1.7 m in length and a weight of 120 kilos, whereas females are smaller reaching just 1.5 m and 90 kilos. Sexual dimorphism here is more pronounced than in any other seal species. The male is darker possessing light spots and an elongated snout. In contrast, females are lighter with darker spots.

Reference

Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. Rapport Instituut voor Natuurbehoud, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp.

license
cc-by-4.0
copyright
WoRMS Editorial Board
bibliographic citation
North-West Atlantic Ocean species (NWARMS) Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. Stienen, E.W.M.; Van Waeyenberge, J.; Kuijken, E. (2003). Zeezoogdieren in Belgisch mariene wateren [Marine mammals in Belgian marine waters]. <i>Rapport Instituut voor Natuurbehoud</i>, A.2003.152. Instituut voor Natuurbehoud: Brussel, Belgium. 15 pp. van der Land, J. (ed). (2008). UNESCO-IOC Register of Marine Organisms (URMO). North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) North-West Atlantic Ocean species (NWARMS) Gladilina, E.V.; Kovtun, O.A.; Kondakov, A.A.; Syomik, A.M.; Pronin, K.K.; Gol'din, P.E. (2013). Grey seal Halichoerus grypus in the Black Sea: the first case of long-term survival of an exotic pinniped. Marine Biodiversity Records 6, e33. doi:10.1017/S1755267213000018
Contributor
[email]