|Scientific Name:||Arctocephalus tropicalis|
|Species Authority:||(J.E. Gray, 1872)|
|Taxonomic Notes:||This species has formerly been referred to as Arctocephalus elegens, A. gazella and A. tropicalis tropicalis. It is now known as A. tropicalis (Repenning et al. 1971, Rice 1998).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Hofmeyr, G. & Kovacs, K. (IUCN SSC Pinniped Specialist Group)|
|Reviewer/s:||Kovacs, K. & Lowry, L. (Pinniped Red List Authority)|
Due to its large and apparently increasing population size, the Subantarctic Fur Seal should remain classified as Least Concern.
IUCN Evaluation of the Subantarctic Fur Seal, Arctocephalus tropicalis
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 Subantarctic 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 Subantarctic 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 Subantarctic 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 Subantarctic 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 Subantarctic fur seals is > 20,000 km².
B2. Area of occupancy (AOO): CR < 10 km²; EN < 500 km²; VU < 2,000 km²
The AOO of Subantarctic 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. Subantarctic Fur Seals are found at numerous breeding rookeries on eight islands or island groups. This 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
(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 Subantarctic Fur Seals is well in excess of 10,000. The number of mature individuals in 5 of 8 subpopulations is estimated to be over 1000. Approximately 50 % of individuals belong to the Gough Island 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 Subantarctic 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 Subantarctic Fur Seals.
Listing recommendation — Estimates indicate a Subantarctic Fur Seal abundance of several hundred thousand individuals breeding at numerous sites on eight islands or island groups. 95% of Subantarctic Fur Seals breed at just three of these sites: Gough Island, the Prince Edward Islands and Amsterdam Island. Two other subpopulations are estimated to contain of 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, Subantarctic Fur Seals may be affected by global climate change should it impact upon their abiotic environment or prey species. It should also be noted that Subantarctic 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 Subantarctic Fur Seals qualify for listing in the category Least Concern.
|Range Description:||Subantarctic Fur Seals are widely-distributed in the southern Hemisphere. They breed on sub-Antarctic islands north of the Antarctic Polar Front, including Amsterdam (Guinet et al. 1994), the Crozets (Guinet et al. 1994), Gough (Bester et al. 2006), Macquarie (Shaughnessy 1993), the Prince Edward Islands (Bester et al. 2003, Hofmeyr et al. 2006a), Saint Paul (Guinet et al. 1994) and Tristan da Cunha (C. Glass pers. comm. in SCAR EGS 2004). They have also been recorded breeding on Heard Island (Goldsworthy and Shaughnessy 1989). Vagrants have been recorded on the coasts of Antarctica (Shaughnessy and Burton 1986), southern South America (Aguiar-dos Santos and Haimovici 2001, Bastida et al. 1999), southern Africa (Bester 1989, Shaughnessy and Ross 1980), Madagascar (Garrigue and Ross 1996), Australia (Gales et al. 1992), and New Zealand (Taylor 1990), and on Bouvetøya (Hofmeyr et al. 2006b), the Comores (David et al. 1993), the Juan Fernandez Islands (Torres and Aguayo 1984), Îles Kerguelen (Wynen et al. 2000), Mauritius (David and Salmon 2003) and South Georgia (Payne 1979).|
Native:Argentina; French Southern Territories (the) (Amsterdam-St. Paul Is., Crozet Is., Kerguelen - Vagrant); Heard Island and McDonald Islands; Madagascar; Saint Helena, Ascension and Tristan da Cunha (Tristan da Cunha); South Africa (Marion-Prince Edward Is.)
Vagrant:Angola (Angola); Antarctica; Australia (Macquarie Is. - Native); Bouvet Island; Brazil; Chile (Juan Fernández Is.); Comoros; Mauritius; Namibia; New Zealand
|FAO Marine Fishing Areas:||
Atlantic – southeast; Indian Ocean – Antarctic; Indian Ocean – eastern; Indian Ocean – western; Pacific – southeast; Pacific – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The total population was estimated to be greater than 310,000 animals in 1987 and all indications are that it has been steadily growing since that time (SCAR EGS 2004). Subantarctic fur seals breed at numerous sites on eight islands or island groups. Some 95% of Subantarctic Fur Seals breed at three of these sites: Gough Island, the Prince Edward Islands and Amsterdam Island (Bester et al. 2003, Bester et al. 2006, Guinet et al. 1994, Hofmeyr et al. 2006a). Two other subpopulations are estimated to contain more than 1,000 adults (Guinet et al. 1994). All subpopulations are either stable or increasing (SCAR EGS 2004).|
|Habitat and Ecology:||
Subantarctic Fur Seals are sexually dimorphic, with adult males being up to 1.8 m long and weighing 70-165 kg; adult females are 1.19–1.52 m long and weigh 25-67 kg, with a mean of around 50 kg. Newborns weigh 4-4.4 kg (Laws 1993). Females attain maturity at 5 years of age (Bester 1995). Gestation lasts 51 weeks. Longevity is unknown (Reijnders et al. 1993).
Subantarctic Fur Seals are polygynous; males defend territories with vocal and postural displays and fighting (Bester 1981, Kerley 1983). They prefer rough rocky or boulder beaches with sources of shade or exposure to prevailing winds (Bester 1982). Pups are born from late October to early January, with a peak in mid-December. Females give birth within 6 days of arriving at the colony with oestrous and mating occurring 8-12 days later. Females spend the time between the births of their pups and oestrous, with their newborn before mating and departing for the first of a series of foraging trips they will make before weaning their pup at approximately 11 months of age (Bester 1981, Kerley 1983). Trip durations of mothers increase over the course of lactation from 6-10 days to 23-28 days (Georges and Guinet 2000, Kirkman et al. 2002). Dives become deeper and slightly longer over the summer, starting at a mean depth of 16.6 m and increasing to 19 m. Dives are seldom deeper than 100 m or longer than 4 minutes (Georges et al. 2000).
Subantarctic Fur Seals are sympatric with other species of fur seals at three sites. Hybridization with Antarctic Fur Seals occurs at the Prince Edward Islands (Hofmeyr et al. 2006a) and the Îles Crozet (Guinet et al. 1994), and with both Antarctic Fur Seals and New Zealand Fur Seals at Macquarie Island (Goldsworthy et al. 1999).
Subantarctic Fur Seals are opportunistic and pelagic foragers. They feed on myctophid and notothenid fish, cephalopods, and small numbers of crustaceans at the Prince Edward Islands (Klages and Bester 1998) and at Macquarie Island (Robinson et al. 2002). At Amsterdam Island they are know to take Rockhopper Penguins (Paulian 1964).
Similar to all of the other southern fur seals, Subantarctic Fur Seals were over-exploited by sealers in the 18th and 19th century and were reduced to the brink of extinction at the beginning of the 20th century. Since then their population has increased rapidly and they have reoccupied much of their former range. This population bottleneck has reduced their genetic variation and may render this species vulnerable to disease or climate change (Wynen et al. 2000).
Tourist visits at Subantarctic Fur Seal haulout sites are rare and thought to cause minimal disturbance (Kirkwood et al. 2003, Shirihai 2002). Few fisheries take place in waters occupied by this species (Hanchet et al. 2003). Entanglement in marine debris occurs at the Prince Edward Islands, but with incidences of less than 1% (Hofmeyr et al. 2002).
While the impact of climate change on fur seals is unknown, it is potentially detrimental (Chown et al. 1998, Learmonth et al. 2006). Fur seals are also at risk of mass mortality from infectious diseases, though breeding on isolated islands affords some species a higher degree of protection from disease (Chown et al. 1998, Lavigne and Schmitz 1990).
|Conservation Actions:||Subantarctic Fur Seals live in some of the most remote oceanic areas and breed on many of the most isolated islands on earth. All of the breeding islands are managed as protected areas or parks by the governments that claim these territories. Seals on the Prince Edward Islands are protected by the South African Sea Bird and Seal Protection Act of 1973 and also inhabit a special nature reserve (PEIMC 1996). Seals on Gough and Tristan Islands are protected by the Tristan da Cunha Conservation Ordinance of 1976. Amsterdam and Saint Paul Islands are regulated by the French Chamber of Deputies, while at Macquarie Island, the fur seals are protected by the Tasmanian Department of Parks, Wildlife, and Heritage (Reijnders et al. 1993). Listed on CITES Appendix II.|
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Bastida, R., Loureiro, J., Quse, V., Bernadelli, A., Rodriguez, D. and Costa, E. 1999. Tuberculosis in a wild subantarctic fur seal from Argentina. Journal of Wildlife Diseases 35: 796-798.
Bester, M. N. 1981. Seasonal changes in the population composition of the fur seal Arctocephalus tropicalis at Gough Island. South African Journal of Wildlife Research 11: 49-55.
Bester, M. N. 1982. Distribution, habitat selection and colony types of the Amsterdam Island fur seal Arctocephalus tropicalis at Gough Island. Journal of Zoology (London) 196: 217-231.
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Bester, M. N. 1995. Reproduction in the female subantarctic fur seal, Artocephalus tropicalis. Marine Mammal Science 11(3): 362-375.
Bester, M. N., Ryan, P. G. and Dyer, B. M. 2003. Population numbers of fur seals at Prince Edward Island, Southern Ocean. African Journal of Marine Science 25: 549-554.
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David, J. H. M. and Salmon, L. 2003. Records of the subantarctic fur seal from Rodrigues and Mauritius, Indian Ocean. African Journal of Marine Sciences 25: 403-405.
David, J. H. M., Mercer, J. and Hunter, K. 1993. A vagrant subantarctic fur seal Arctocephalus tropicalis found in the Comores. South African Journal of Zoology 28: 61-62.
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Hanchet, S., Horn, P. and Stevenson, M. 2003. Fishing in the ice: is it sustainable? Water & Atmosphere 11: 24–25.
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|Citation:||Hofmeyr, G. & Kovacs, K. (IUCN SSC Pinniped Specialist Group) 2008. Arctocephalus tropicalis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 21 May 2013.|
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