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Overview

Brief Summary

Species Abstract

The Arctarctic fur seal (also Kerguelen fur seal; scientific name: Arctocephalus gazella) is one of 16 species of marine mammals in the family of Eared Seals which include sea lions and fur seals. Together with the families of True seals and Walruses, Eared seals form the group of marine mammals known as pinnipeds.

Eared seals differ from the true seals in having small external earflaps and hind flippers that can be turned to face forwards. Together with strong front flippers, this gives them extra mobility on land and an adult fur seal can move extremely fast across the beach if it has to. They also use their front flippers for swimming, whereas true seals use their hind flippers. Like other Eared seals, the male Antarctic fur seal is considerably larger than the female. Adults are covered with a dense velvety underpelt, which is both waterproof and windproof, and an outer layer of coarse grey-brown hair. The males can be distinguished from the females by their long mane of shoulder fur.

In the species polygynous mating system, a dominance hierarchy of males is established through displays and fights that occur while defending territories. The Antarctic fur seal is surprisingly agile on land, attaining terrestrial speeds of twenty kilometers per hour on smooth surfaces.

The breeding range of Antarctic fur seal is chiefly restricted to seasonally ice free islands south of the Antarctic Convergence, but some individuals have been found as far north as Brazil. South Georgia is the site of the greatest concentration of Antarctic fur seals, particularly on Bird Island. It is estimated that 95% of the species breed near the coast of South Georgia. Other breeding locations include King George Island, Bouvet Island, Crozet Islands, Heard Island, Kerguelen Islands, Macquarie Island, Marion Island, McDonald Islands, Prince Edward Islands, South Orkney Islands, South Sandwich Islands, and South Shetland Islands. The species population may be above four million.

As with other fur seals, the Antarctic fur seal was long hunted for its skin and oil and was nearly driven to extinction at one time.

  • Encyclopedia of Life; Peter Saundry. 2009. Antarctic fur seal. eds. Marion McClary, C.Michael Hogan, Cutler J.Cleveland. Encyclopedia of Earth. National Council for Science and the Environment. Washington DC
  • http://www.eoearth.org/article/Antarctic_fur_seal
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Distribution

Arctocephalus gazella, the Antarctic fur seal, has a very wide distribution. They are mostly found in waters south of the Antarctic Convergence, but some do inhabit areas slightly north of the Convergence. Most breeding populations are found on South Georgia Island and Bird Island, while other populations are found in the south Prince Edward, Crozet, Kerguelen, and Macquarie Islands. Vagrants, however, have been observed in the southern part of South America and the Juan Fernandez Islands. Populations in the south Indian Ocean, south of the polar front, are found on Heard and McDonald Islands and north of the polar front on distances and have been seen from these breeding islands up to the ice edge of the polar front. Females leave the breeding islands during the winter and between breeding seasons travelling south to the marginal ice zone and across the polar front. Bulls often remain at the breeding islands during winter. Pups stay close to the beaches where they were born but usually move on to the ocean as winter progresses.

Biogeographic Regions: antarctica (Native )

  • Forcada, J., I. Staniland. 2009. Antarctic Fur Seal Arctocephalus gazella. Pp. 36-42 in W Perrin, B Wursig, J Thewissen, eds. Encyclopedia of Marine Mammals, Vol. 2, 2nd Edition. New York: Elsevier.
  • Jefferson, T., M. Webber, R. Pitman. 2008. Marine Mammals of the World. New York: Elsevier.
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Range Description

Antarctic Fur Seals are widely-distributed in waters south, and in some areas slightly north, of the Antarctic Convergence (Bonner 1968). While most Antarctic Fur Seal breed at South Georgia (Boyd 1993) colonies are also found on the South Shetland Islands (Goebel et al. 2003), the South Orkney Islands (Boyd 1993), the South Sandwich Islands (Holdgate 1962), the Prince Edward Islands (Bester et al. 2003, Hofmeyr et al. 2006), Îles Crozet (Guinet et al. 1994), Îles Kerguelen (Guinet et al. 2000), Heard Island (Page et al. 2003), McDonald Island (Johnston 1982), Macquarie Island (Goldsworthy et al. 1999) and Bouvetøya (Hofmeyr et al. 2005). Vagrants have been recorded at Gough Island (Wilson et al. 2006) and on the coasts of Antarctica (Shaughnessy and Burton 1986), southern South America (Drehmer and De Oliviera 2000) and Australia (Stewardson 2007). Antarctic Fur Seals disperse widely when at sea. Distribution and movements are, however, not well known (Boyd et al. 1998).
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Physical Description

Morphology

Sexual dimorphism is very evident in Antarctic fur seals. Males are four to five times heavier than females and one and a half times longer. The average length of the males is 180 cm while the average length of females is 129 cm. The average weight of males is 133 kg and for females it is just 34 kg. Their body is covered in hair except for the areas around the rhinarium (area around the nostrils), ear tips, and the palmar surface of the flippers. They have two different layers of hair, the under-pelt, which is made up of fine fur for insulation, and the other layer, which has two different types of guard hairs. These seals have nails on their hind flippers that are well developed and used for grooming. Antarctic fur seals also have the longest facial vibrissae, or whiskers, of any other pinniped, reaching up to 45 cm in bulls. The bodies in both males and females are thick, with long necks. Males are grayish brown in color, while their face is a darker gray. The chest may appear to be a silvery gray color as well. They have a heavy, grizzled mane. Female coats are also grayish brown in color, but their chest and neck are often white to gray. Pups are born black, with a grayish brown belly. They later molt to be completely grayish brown. About one out of every 100 pups born is born with leucistic morph resulting in a creamy white or yellow white exposed skin, which is normally pigmented. They have large canines that are used in territorial fights among males. A strong correlation has been found between canina length, mass, and width in male Antarctic fur seals and body size.

Range mass: 34 to 133 kg.

Range length: 129 to 180 cm.

Sexual Dimorphism: male larger; ornamentation

Other Physical Features: endothermic ; bilateral symmetry

  • Acevedo, J., D. Torres, A. Aguayo-Lobo. 2008. Rare piebald and partially leucistic Antarctic fur seals, Arctocephalus gazella, at Cape Shirreff, Livingston Island, Antarctica. Polar Biology, 32/1: 41-45.
  • Hoffman, J., N. Hanson, J. Forcada, P. Trathan, W. Amos. 2010. Getting long in the tooth: A strong positive correlation between canine size and heterozygosity in Antarctic fur seals Arctocephalus gazella. Journal of Heredity, 101/5: 527-538.
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Ecology

Habitat

Antarctic fur seals spend much of their time in the ocean, hunting for food. While on land, they prefer to stay in rocky habitats but will go to beaches and zones of vegetation. Males can dive up to a maximum of 350 meters, while females can only reach up to 210 meters. Females can travel long distances in the open ocean for long periods of time between breeding.

Range depth: 350 (high) m.

Habitat Regions: polar ; terrestrial ; saltwater or marine

Aquatic Biomes: pelagic ; coastal

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Habitat and Ecology

Habitat and Ecology
Antarctic Fur Seals are a strongly sexually dimorphic species. Adult males are approximately 1.8 m long and weigh between 130 and 2,000 kg. Adult females are 1.2 - 1.4 m and 22 - 50 kg. Newborns weigh 6 - 7 kg (Laws 1993). Age of first reproduction is three years for females (Lunn et al. 1994) and seven years for males (McCann and Doidge 1987).

Antarctic Fur Seals are highly polygynous. Males arrive at the colonies in late October, some two to three weeks before the first females arrive and establish territories. Males continue to arrive and challenge one another for territories through much of the season. Territories are acquired and held by use of vocalizations, threat postures and fighting (Bonner 1968). Females begin to arrive in mid-November and most pupping and breeding occurs from late November to late December. They give birth one to two days after arrival at the colony and subsequently attend their pup for six to seven days. They come into oestrous, mate and then depart shortly afterwards for their first foraging trip of the season (Doidge et al. 1986, Payne 1977). Foraging trip and attendance periods vary by year depending on the availability of the lactating female’s chief prey, adult krill, but generally last four to five days at sea followed by two to three days attendance on shore (Boyd 1999, Costa et al. 1989, Guinet et al. 2000). Antarctic fur seals undertake short shallow dives, primarily at night (Boyd and Croxall 1992, Costa et al. 2000, Robinson et al. 2002). Mean dive depth and duration increase during the lactation period (Boyd 1999, Costa et al. 1989, Guinet et al. 2000).

Pups are weaned at about four months of age. After the pups are weaned, females are thought to disperse widely and are seldom seen at the colonies before the next breeding season. Breeding bulls also depart the rookery, but subadults and some adult males can be seen at rookeries on South Georgia all year (Bonner 1968, Payne 1977).

The diet of Antarctic Fur Seals varies by season and location. At South Georgia and Bouvet Island Antarctic Fur Seals feed primarily on krill (Bonner 1968, Klages et al. 1998, North et al. 1983). At Heard Island, Macquarie Island and the Prince Edward Islands krill is not available and lactating females prey primarily on cephalopods and fish such as myctophids and notothenids (Green et al. 1989, Green et al. 1991, Klages and Bester 1998, Robinson et al. 2002). Antarctic Fur Seals have also been known to eat penguins at a number of sites (Bonner 1968, Green et al. 1989, Hofmeyr and Bester 1993)

Antarctic Fur Seals are sympatric with other species of fur seals at three sites. Hybridization with Subantarctic Fur Seals occurs at the Prince Edward Islands (Hofmeyr et al. 2006) and the Îles Crozet (Guinet et al. 1994) and with both Subantarctic Fur Seals and New Zealand Fur Seals at Macquarie Island (Goldsworthy et al. 1999).

Systems
  • Terrestrial
  • Marine
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Depth range based on 8025 specimens in 2 taxa.
Water temperature and chemistry ranges based on 8025 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): -0.276 - 5.950
  Nitrate (umol/L): 19.829 - 26.774
  Salinity (PPS): 33.856 - 34.005
  Oxygen (ml/l): 6.975 - 8.072
  Phosphate (umol/l): 1.408 - 1.809
  Silicate (umol/l): 6.646 - 34.366

Graphical representation

Temperature range (°C): -0.276 - 5.950

Nitrate (umol/L): 19.829 - 26.774

Salinity (PPS): 33.856 - 34.005

Oxygen (ml/l): 6.975 - 8.072

Phosphate (umol/l): 1.408 - 1.809

Silicate (umol/l): 6.646 - 34.366
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Trophic Strategy

Antarctic fur seals mainly feed on fish, krill, crustacean, and cephalopods, such as squid and octopods. Fish consitute almost 75% of the diet in non-winter months. At the South Georgia Islands, the main fish prey is the mackerel icefish. However, they also consume krill in large quantities as well.  Lactating females mainly feed on krill. If krill is unavailable, they turn to fish.  During winter months, adult and sub-adult males feed on 50% krill and 50% fish. They also prey on some smaller penguins (4-8 kg) as well, such as rockhopper and macaroni penguins. Previous studies suggested that fur seals only attacked king penguins on land, but Charbonnier et al. (2007) observed that adult males attack king penguins at sea, too. Although adult male and female Antarctic fur seals chased king penguins at sea, only adult males were successful in catching and killing or injuring the penguins.

Animal Foods: birds; fish; aquatic crustaceans

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Eats non-insect arthropods)

  • Casaux, R., A. Baroni, A. Carlini. 1998. The diet of the Antarctic fur seal Arctocephalus gazella at Harmony Point, Nelson Island, South Shetland Islands. Polar Biology, 20/6: 424-428.
  • Charbonnier, Y., K. Delord, J. Theibot. 2007. King-size fast food for Antarctic fur seals. Polar Biology, 33/5: 721-724.
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Associations

Members of Antarctic fur seals are key predators of krill and various species of fish and squid. It has been found that there is a correlation between size of breeding colonies and prey availability, based upon short term environmental changes and the effect it has on the reproductive success of females.

Lungworms infect three members of the fur seals group. These parasites infect the lungs of their host.

Commensal/Parasitic Species:

  • Antarctic Treaty Consultative Meeting. Proposal to De-list Antarctic Fur Seals as Specially Protected Species. WP039. Edinburgh: Secretariat of the Antarctic Treaty. 2006. Accessed April 24, 2012 at http://www.scar.org/treaty/atcmxxix/atcm29_wp039.pdf.
  • Dailey,, M. 2009. A new species of Parafilaroides (Nematoda: Filaroididae) in three species of fur seals (Carnivora: Otariidae) from the Southern Hemisphere. American Society of Parasitologists, 95/1: 156-159.
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One major predator of Antarctic fur seeals are the leopard seals. They are a major contributor to high seal pup mortality rates especially between January and March before the pups are weaned. This has limited the growth of the colony at Elephant and Livingston Islands in the South Shetlands. Antarctic fur seals also are also preyed upon by killer whales and sharks.

Known Predators:

  • Boveng, P., L. Hiruki, M. Schwartz, J. Bengston. 1998. Population growth of the Antarctic fur seals: Limitation by a top predator, the leopard seal?. Ecology Society of America, 79/8: 2863-2877.
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Life History and Behavior

Behavior

Antarctic fur seals use vocalizations to communicate. Males use two main calls. One is a threatening roar which is directed towards other males. Else, it is used as a response to a specific threat, such as a predator. The other call they make is a "huff-chuff". This call is used when moving around breeding territories, interacting with females, and is used as a sign of status. Females can roar and "huff-chuff", but their main form of communication is with their pups. They use both sound and smell to establish a bond. The sound is a high pitched call that is reinforced after the pup is born so when the mother returns from hunting trips she can make the sound and the pup will recognize it. The mother and pup use smell at close distances to confirm each other's identity.

Communication Channels: acoustic ; chemical

Perception Channels: visual ; tactile ; acoustic ; chemical

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Life Expectancy

In captivity the lifespan of Antarctic fur seals has not been well studied and it remains unknown. In the wild, males live up to 15 years, while females can live up to 25 years.

Range lifespan

Status: wild:
25 (high) years.

Average lifespan

Sex: female

Status: wild:
23.0 years.

Average lifespan

Sex: male

Status: wild:
13.0 years.

  • de Magalhaes, J., J. Costa. 2009. A database of vertebrate longevity records and their relation to other life history traits. Journal of Evolutionary Biology, 22/8: 1770-1774.
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Lifespan, longevity, and ageing

Observations: The total gestation time probably includes a period of delayed implantation (Ronald Nowak 2003). In the wild, these animals have been estimated to live up to 23 years (David Macdonald 1985). Their longevity in captivity has not been studied in detail and hence their maximum longevity must be classified as unknown.
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Reproduction

Antarctic fur seals are polygynous and breed in colonies. Adult males arrive and establish territories, about one month before breeding females come ashore, which is around mid October or early November. Females give birth to pups conceived from the previous season. They mate again around six to seven days post-birth.  Maintaining territories is very costly for males. They lose about 1.5 kg in weight per day and obtain face injuries from territorial disputes. Consequently, males do not tend to hold territory until they are at least eight years old. This also encourages a dominance hierarchy on the breeding beaches. The most successful males defend the most desirable territories (those near the water but above the high water mark). The weaker males occupy territories higher up the beach. Each territorial male is associated with, on average, 15 females or between 1 to 27 females.

Mating System: polygynous

Once returning to shore females give birth to one pup, on average, conceived from the previous year. The gestation period is 11.75 months and implantation is possibly delayed. Newborn pups weigh 6 kg on average. Males and females return to breeding sites, even within a few meters of previous territories. Survival of their young from previous years probably encourages returning to the same spot year after year.  Pups are born in October or early November and weigh about six kilograms on average. While the mother is away, pups roam about and interact with each other. By early January some pups are already going to the water but cannot swim well until March. Females use vocalizations to find the pup once she is back on land and confirms the pup by scent. Pups are weaned at about 117 days and become reproductively mature at three or four years old.

Breeding interval: Antarctic fur seals breed once a year.

Breeding season: Antarctic fur seals breed during the month of December.

Range number of offspring: 0 to 2.

Average gestation period: 11.75 months.

Average weaning age: 117 days.

Range age at sexual or reproductive maturity (female): 3 to 4 years.

Range age at sexual or reproductive maturity (male): 3 to 4 years.

Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; delayed implantation

Average birth mass: 6000 g.

Average gestation period: 257 days.

Average number of offspring: 1.

Female Antarctic fur seals have to regularly forage for food during the growth of their pups. Females alternate foraging trips with short suckling bouts until the pups are weaned after about 117 days. They forage at sea for 1 to 13 days at a time with an average trip duration of 5 days. They then return to feed the pup for about two days before returning to sea.

Parental Investment: female parental care ; pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)

  • Hoffman, J., I. Boyd, W. Amos. 2003. Male reproductive strategy and the importance of maternal status in the Antarctic fur seal Arctocephalus gazella. Evolution, 57/8: 1917-1930.
  • Hoffman, J., J. Forcada. 2011. Extreme natal philopatry in female Antarctic fur seals (Arctocephalus gazella). Mammalian Biology, 77/1: 71-73.
  • Nowak, R., E. Walker. 2003. Arctocephalus gazella. Pp. 77-78 in Walker's Marine Mammals of the World, Vol. 6, Sixth Edition. Baltimore: The Johns Hopkins University Press.
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Conservation

Conservation Status

The number of Antarctic fur seals were reduced to below 3,000 individuals in the 1800s. In 1964, they became a “specially protected species,” which is a term given only to the “most vulnerable and endangered species,” (Proposal to De-list, 2006). Since then, Antarctic fur seals have greatly extended their range and are at little risk of extinction. Total population numbers are estimated at four to seven million seals and are increasing. In the CITES appendices Antarctic fur seals are listed in Appendix II, indicating that while they are not currently threatened with extinction they may become so unless trade is closely controlled.

US Federal List: no special status

CITES: appendix ii

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2014

Assessor/s
Hofmeyr, G.

Reviewer/s
Kovacs, K.M. & Lowry, L.

Contributor/s

Justification
Due to its large and apparently increasing population size, the Antarctic Fur Seal should remain classified as Least Concern.

IUCN Evaluation of the Antarctic Fur Seal, Arctocephalus gazella
Prepared by the Pinniped Specialist Group


A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.

All subpopulations of Antarctic Fur Seals are currently either increasing or stable.

A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.

All subpopulations of Antarctic Fur Seals are currently either increasing or stable.

A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.

A population reduction of Antarctic Fur Seals is not expected in the future. It is possible, however, that global climate change may alter environmental conditions to the detriment of this species.

A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.

All subpopulations of Antarctic Fur Seals are currently either increasing or stable. While a population reduction is not expected in the future, it is possible that global climate change may alter environmental conditions to the detriment of this species.

B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km²; EN < 5,000 km²; VU < 20,000 km²

The EOO of Antarctic fur seals is > 20,000 km².

B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²

The AOO of Antarctic fur seals is > 2,000 km².

AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.

Subpopulations are not severely fragmented and the number of breeding locations is > 10. The species is not experiencing continuing decline or extreme fluctuations in extent of occurrence, area of occupancy, number of subpopulations, number of mature individuals or area, extent or quality of habitat.

C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1 generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
or
(a ii) % individuals in one subpopulation: CR = 90–100%; EN = 95–100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.

The current abundance of Antarctic fur seals is well in excess of 10,000. The number of mature individuals in 9 of 11 subpopulations is estimated to be over 1,000. Approximately 90% of individuals belong to the South Georgia subpopulation.

D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km² or number of locations < 5

The current abundance of mature Antarctic fur seals is well in excess of 1,000, the AOO is far larger than 20 km² and the number of locations is > 5.

E. Quantitative analysis
Indicating the probability of extinction in the wild to be: Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years

There has been no quantitative analysis of the probability of extinction of Antarctic Fur Seals.

Listing recommendationEstimates indicate an Antarctic Fur Seal abundance of several million individuals breeding at numerous sites on 11 islands or island groups. While over 90% of Antarctic fur seals breed on the island of South Georgia, eight other subpopulations are estimated to contain more than a 1,000 adults. All subpopulations are either stable or increasing. No major threats currently affect any subpopulations and it is unlikely that any will do so in the near future. This being said, Antarctic Fur Seals may be affected by global climate change if their prey species are effected by changes in the environment. It should also be noted that Antarctic Fur Seals experienced a severe population bottleneck during the 19th and 20th Centuries that has reduced their genetic variation and which may render this species vulnerable to disease or climate change. Under present conditions Antarctic fur seals qualify for listing in the category Least Concern.
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Population

Population
The island of South Georgia supports approximately 95% of all Antarctic Fur Seals. The total population of this site in 1999/2000 was estimated to be between 4.5 and 6.2 million and is believed to have increased by between 6 and 14 % since the 1990/91 season (Boyd pers. comm. in SCAR EGS 2004). The second largest population, at Bouvetøya supported some 66,000 individuals in the 2001/02 season (Hofmeyr et al. 2005). Other populations range in size from a few hundred to a few thousand (SCAR EGS 2004). All populations are believed to be either increasing or stable (SCAR EGS 2004).

Population Trend
Increasing
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Threats

Major Threats
Commercial sealing drove this species to the brink of extinction by the late 19th century. It is now believed that this species survived this period of over-exploitation in very small numbers at three sites: South Georgia, Bouvetøya and the Îles Kerguelen (Hofmeyr et al. 2005, Wynen et al. 2000). The species has probably lost considerable genetic diversity due to the historical population bottleneck (Wynen et al. 2000) and may now be at increased risk from disease outbreaks and environmental change.

Waters inhabited by Antarctic Fur Seals are exploited by few fisheries, but these may expand in the future (Hanchet et al. 2003). This species has been recorded entangled in marine debris such as discarded fishing line, nets, packing bands and other objects. The numbers of Antarctic Fur Seals entangled in anthropogenic debris annually has been estimated to be as high as 1% of the total population. The majority of entangled animals are juvenile and subadult seals. In approximately 30% of cases recorded, the debris caused injury. Most entangled seals are expected to die as a result of their entanglement (Bonner and McCann 1982, Croxall et al. 1990).

Leopard Seals have been noted to take as many as a third of pups born at sites in the South Shetland Islands (Hiruki et al. 1989). Levels of predation may be high enough to cause a population decline at this site (Boveng et al. 1998).

The risk of transfer of diseases, such as morbillivirus from other pinnipeds or terrestrial animals to Antarctic Fur Seals is unknown. Antarctic fur seals are considered to be one of several pinnipeds at high risk of future disease outbreaks because of their rapidly expanding population, tendency for most animals to congregate in large dense aggregations, and effect of environmental changes associated with global warming on the spread of diseases (Lavigne and Schmitz 1990). Tourism takes place at several locations, but due to the isolation of haulout sites, visits by tourists are rare (Kirkwood et al. 2003)

The effect of global climate change on Antarctic Fur Seals is unknown, but it has been suggested that warming may result in population declines (Learmonth et al. 2006).
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Management

Conservation Actions

Conservation Actions
The Antarctic Treaty and the Convention for the Conservation of Antarctic Seals protect populations of this species of fur seal below 60ºS. North of the Antarctic Treaty area, Antarctic Fur Seals are protected by the nations that govern the islands on which they breed. The Falkland (Malvinas) Islands Dependencies Conservation Ordinance provides protection for Antarctic fur seals on South Georgia and the South Sandwich Islands (Reijnders et al. 1993). Seals on the Prince Edward Islands are protected by virtue of these islands status as a special nature reserve and also by the South African Seabirds and Seals Protection Act (PEIMC 1996). It is listed on CITES Appendix II.
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Relevance to Humans and Ecosystems

Benefits

There are no known adverse effects of Antarctic fur seals on humans.

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In the 1800 and 1900s Antarctic fur seals were widely hunted for their fur. Since this time, however, Antarctic fur seals have had little economic importance to humans. Although, increasing commercial krill harvesting could affect populations in the future.

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Wikipedia

Antarctic fur seal

The Antarctic fur seal (Arctocephalus gazella) is one of eight seals in the genus Arctocephalus, and one of nine fur seals in the subfamily Arctocephalinae. As its name suggests, the Antarctic fur seal is distributed in Antarctic waters. Around 95% of the world population breeds at the Island of South Georgia. It is named after the German naval vessel, the corvette SMS Gazelle, which collected the first specimen from Kerguelen Island. The species is also known as the Kerguelen fur seal.

Description[edit]

The fur seal, Deception Island

This fur seal is a fairly large animal and has a short and broad snout compared with others in the family. Adult males are dark brown in colour. Females and juveniles tend to be grey with a lighter undersides. Colour patterns are highly variable, and some scientists believe some hybridisation with subantarctic fur seals has occurred. Pups are dark brown, nearly black at birth. About one in 1000 Antarctic fur seals are pale 'blonde' variants.

Males are substantially bigger than females. Antarctic fur seals grow up to 2 m (6.5 ft) long and weigh 91 kg (201 lb) to 215 kg (474 lb).[2] Males live for about 15 years and females up to 25.

Antarctic fur seals appear to act alone when foraging and migrating. Males breed polygynously; a strong male may have more than a dozen female partners in a single season. Territories are established on breeding grounds in October to early November, when the musty-smelling males are extremely aggressive in defence of their harems. Females gestate for just over a year - giving birth in November or December. Pups are weaned at about four months old. Juveniles may then spend several years at sea before returning to begin their breeding cycles.

The usual food supply is krill, of which each Antarctic fur seal eats about a ton in a year. Due to the enormous and growing populations of these seals, their food is a significant proportion of South Georgia's krill stocks.

Distribution and population[edit]

Male Antarctic fur seal on the Kerguelen Islands

The Antarctic fur seal breeds in summer on islands ranging from South Georgia at 70° W round to about 80° E (Kerguelen Islands). Additionally, there is a breeding ground at Macquarie Island, 165°E - south of New Zealand. All these islands lie between 45° S and 60° S. The animal's winter range is not known. During these long dark months, the seal spends its time almost surely at sea close to the Antarctic ice.

A population count is due in 2007 or 2008, and estimates can only be very rough until this is carried out. Best guesses suggest there may be two to four million individuals breeding at South Georgia and 15,000 at Heard Island. The concentrations at South Georgia are the densest aggregations of marine mammals on earth. These populations are believed to have grown to such levels because the removal of whales by the intensive whaling of the 20th century left a surplus of krill. Other islands in Antarctic waters may have a few hundred to a thousand such seals.

Diet and ecology[edit]

Antarctic fur seals typically feed on krill, squid and fish.[3]

Behavior[edit]

Adult and subadult males may form groups while moulting along the Antarctic Peninsula in late summer and early autumn.[4] Adult females are gregarious but relatively asocial other than the strong bond they establish with their pups, although there are occasional aggressive encounters with nearby females or other pups and brief interactions with adult males to mate. These seals appear to be solitary when foraging and migrating. Females evidently remain at sea continually between breeding seasons, and juveniles may spend several years at sea before returning to natal sites to mate for the first time. The deepest recorded dive is about 180 m deep; the longest dive lasted 10 minutes. The diving ability of pups substantially improves during the first few months of life, and by about four months old their diving patterns are similar to those of adult females. Leopard seals eat Antarctic fur seal pups.[5] Survival of suckling pups may be particularly low in years when krill abundance near a colony is insufficient to allow lactating females to forage effectively.[6][7]

Reproduction[edit]

The breeding system of the Antarctic Fur Seal is polygynous, and dominant breeding males mate with as many as 20 females during a successful season. Adult males establish breeding territories on beaches in late October to mid November, preferably just along the shoreline. They are fiercely territorial during the breeding season and aggressively defend access to estrous females from other males, mostly with stereotyped physical displays, lunges, and vocalizations. These fights can be very damaging. Many bulls die from their wounds. Males may fast during the breeding season for six to eight weeks, losing up to 1.5 kg a day. The gestation period lasts about a year. Females give birth to a single pup between mid November and late December. They mate about 7 to 10 days later and then begin a series of foraging trips at sea that lasts for several days each. In between, they are ashore for one to several days to nurse their pups. Pups are weaned at about four months old.


Interactions with humans[edit]

Baby fur seal, South Georgia
Antarctic fur seals, South Georgia

The Antarctic fur seal was very heavily hunted in the 18th and 19th centuries for its pelt by sealers from the United States and the United Kingdom. By the early 20th century, the seal was regarded as commercially extinct, and perhaps completely extinct. In fact, a small population continued to exist, breeding on Bird Island in South Georgia. This colony has expanded rapidly over the course of a century. The current populations on the other Antarctic islands are believed to be off-shoots of this one colony.

The species is still protected by the governments in whose waters it resides (Australia, South Africa, France) and by the Convention for the Conservation of Antarctic Seals in waters south of 60° S. The animal is also listed in Appendix 2 of CITES. However, some governments with interests in the Antarctic, for instance, the United Kingdom, say some of these protections should be lifted, as the species is causing damage to vulnerable Antarctic plants.

A study at South Georgia indicated that several thousand Antarctic fur seals were entangled in man-made debris from fishing vessels.[8] Consequently, CCAMLR campaigned for compliance with MARPOL provisions relating to waste disposal at sea, and for cutting of any material jettisoned which could form collars to entangle seals. Subsequent monitoring of entangled fur seals confirmed that entanglement is still a persistent problem, but it has halved in recent years.[9] However, the South Georgia fur seal population has approximately doubled in the same period, so that the overall total of animals entangled may even have increased. The particular reduction in entanglement due to packing bands and the fact that all such bands washed ashore over the last 2 years have been cut, does suggest a general improvement in standards of waste disposal on Southern Ocean fishing vessels.

References[edit]

  1. ^ Aurioles, D. & Trillmich, F. (2008). Arctocephalus gazella. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 January 2009.
  2. ^ Kindersley, Dorling (2001,2005). Animal. New York City: DK Publishing. ISBN 0-7894-7764-5. 
  3. ^ Connection, Antarctica. "Antarctic Fur Seal". Antarctic Connection. Wildlife of Antarctica. Retrieved 19 April 2011. 
  4. ^ Boyd, I.L., McCafferty, D.J., Reid, K., Taylor, R., Walker, T.R. (1998) Dispersal of male and female Antarctic fur seals. Canadian Journal of Fish and Aquatic Sciences. 55: 845-852.
  5. ^ Walker, T.R., Boyd, I.L., McCafferty, D.J., Huin, N., Taylor, R.I., Reid, K. (1998) Seasonal occurrence and diet of leopard seals, Hydrurga leptonyx at Bird Island, South Georgia. Antarctic Science. 10(1): 75-81.
  6. ^ McCafferty, D.J., Boyd, I.L., Walker, T.R., Taylor, R.I. (1998) Foraging responses of Antarctic fur seals to changes in the marine environment. Marine Ecology Progress Series. 166: 285-299.
  7. ^ Boyd, I.L., McCafferty, D.J., Walker, T.R. (1997) Variation in foraging effort by lactating Antarctic fur seals: response to simulated increased foraging costs. Behavioural Ecology and Sociobiology. 40: 135-144.
  8. ^ Walker, T.R., Reid, K., Arnould, J.P.Y., Croxall, J.P. (1997) Marine debris surveys at Bird Island, South Georgia 1990-1995. Marine Pollution Bulletin. 34(1): 61-65.
  9. ^ Walker, T.R. (1995) Entanglement of Antarctic fur seals Arctocephalus gazelle in man-made debris at Bird Island, South Georgia during the 1994 winter and 1994/95 pup-rearing season. SC-CAMLR-XIV/BG/8. Hobart, Australia.
  • Randall R. Reeves, Brent S. Stewart, Phillip J. Clapham and James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0375411410. 

Further reading[edit]

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