Arctocephalus tropicalis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Otariidae

Scientific Name: Arctocephalus tropicalis (J.E. Gray, 1872)
Common Name(s):
English Subantarctic Fur Seal, Amsterdam Island Fur Seal
French Arctocéphale d'Australie
Arctocephalus elegans Peters, 1876
Arctocephalus tropicalis Peters 1876 ssp. tropicalis
Arctophoca tropicalis Peters 1876
Gypsophoca tropicalis J.E. Gray, 1872
Taxonomic Notes:

Subantarctic Fur Seals were formerly referred to as Arctocephalus elegens, Arctocephalus gazella and Arctocephalus tropicalis tropicalis. They are now known as Arctocephalus tropicalis (Repenning et al. 1971, Rice 1998). In 2011 the genus of this, and a number of other species of Fur Seals, was revised to Arctophoca, Peters 1866 (Committee on Taxonomy 2011) based on evidence presented in Berta and Churchill (2012). However, in 2013, based on genetic evidence presented in Nyakatura and Bininda-Emonds (2012), this change was considered to be premature and the genus reverted to Arctocephalus pending further research (Committee on Taxonomy 2013).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2014-12-10
Assessor(s): Hofmeyr, G.J.G.
Reviewer(s): Goldsworthy, S.D.
Facilitator/Compiler(s): Lowry, L., Pollock, C.M., Ahonen, H., Chiozza, F. & Battistoni, A.

Subantarctic Fur Seals should be listed as Least Concern despite a decline at one of the three major subpopulations. This decline is recent, relatively slow (a mean annual rate of -6.4 % for the period 2002/03 – 2012/13), and its causes are not yet understood. Abundance of the other major subpopulations is inferred to be stable. The global population was estimated to be over 400,000 animals in the early 2000s. About 99% of pup production occurs at three sites, with small subpopulations found at five other sites. Of concern is the absence of recent complete assessments of abundance for two of the major subpopulations, which together comprise an estimated 74% of the global total. No subpopulations are isolated and movement takes place between them. No subpopulation, nor the species as a whole, is likely to become extinct in the near future. The effects of global climate change on Fur Seal habitat, and the abundance and distribution of prey species, is a possible threat. This especially true in light of the reduced genetic diversity of this species as a result of the population bottleneck it was subject to. Other threats, including the impact of fishing industries and entanglement in anthropogenic debris, remain low.

Previously published Red List assessments:

Geographic Range [top]

Range Description:

Subantarctic Fur Seals are widely-distributed in the southern hemisphere. They breed on Subantarctic islands north of the Antarctic Polar Front, including Amsterdam and Saint Paul Islands (Guinet et al. 1994), the Îsles Crozet (Kingston and Gwilliam 2007), Gough (Bester et al. 2006), Macquarie (Goldsworthy et al. 2009, Lancaster et al. 2006), the Prince Edward Islands (Bester et al. 2003, Hofmeyr et al. 2006a) and Tristan da Cunha (C. Glass pers. comm. in SCAR EGS 2008). Pupping has also been recorded on Heard Island (a single individual in multiple years; Goldsworthy and Shaughnessy 1989, Page et al. 2003). Vagrants have been recorded widely. They have been encountered on the coasts of a number of continents: Antarctica (Shaughnessy and Burton 1986), southern South America (Bastida et al. 199, 9Aguiar-dos Santos and Haimovici 2001), Africa (Shaughnessy and Ross 1980, Bester 1989), as far north as Tanzania (Hofmeyr and Amir 2010), Gabon (Zanre and Bester 2011) and Australia (Gales et al. 1992, Shaughnessy et al. 2014). They have also been recorded on numerous islands including Madagascar (Garrigue and Ross 1996), New Zealand (Taylor 1990), 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), Bouvetøya (Hofmeyr et al. 2006b) and South Georgia (Payne 1979).

Countries occurrence:
French Southern Territories (Amsterdam-St. Paul Is., Crozet Is., Kerguelen - Vagrant); Saint Helena, Ascension and Tristan da Cunha (Tristan da Cunha); South Africa (Eastern Cape Province - Vagrant, KwaZulu-Natal - Vagrant, Marion-Prince Edward Is., Northern Cape Province - Vagrant, Western Cape - Vagrant)
Angola; Antarctica; Argentina; Australia (Macquarie Is. - Native, New South Wales, South Australia, Tasmania, Victoria, Western Australia); Bouvet Island; Brazil; Chile (Juan Fernández Is.); Comoros; Heard Island and McDonald Islands; Madagascar; Mauritius; Mozambique; Namibia; New Zealand (Antipodean Is., North Is., South Is.); South Georgia and the South Sandwich Islands (South Georgia)
FAO Marine Fishing Areas:
Atlantic – southwest; Atlantic – Antarctic; Atlantic – southeast; Indian Ocean – eastern; Indian Ocean – western; Indian Ocean – Antarctic; Pacific – southeast; Pacific – southwest
Additional data:
Estimated area of occupancy (AOO) - km2:13434900Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:39445704
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):50Lower depth limit (metres):208
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The global population of Subantarctic Fur Seals was estimated to be greater than 400,000 animals in the early 2000s (SCAR EGS 2008). Subantarctic Fur Seals breed at numerous sites on eight islands or island groups, and approximately 99% of Subantarctic Fur Seals breed at three of those sites. Some 63% of global pup production is estimated to take place at Gough Island (Bester et al. 2006), 25% at the Prince Edward Islands (Hofmeyr et al. 2006a, Bester et al. 2009, Wege et al. In prep) and 11% at Amsterdam Island (Guinet et al. 1994). Pup production at other sites is a few tens or hundreds at each site (SCAR EGS 2008). These estimates are subject to two provisos. First, of the five islands within the Îsles Crozet, the abundance of Fur Seals has been determined only on Île de la Possession (Guinet et al. 1994). Second, due to the nature of their terrestrial habitat and the isolation of their haulout sites, determining Subantarctic Fur Seal abundance is difficult and it is often inferred from counts of small portions of a subpopulation (Guinet et al. 1994, Bester et al. 2006).  

The estimated abundance of the three main subpopulations has increased over the last few decades and is currently either largely stable or decreasing. The Gough Island subpopulation was stable or had increased slightly between 1975 and 2005, as inferred from counts of selected sites (Bester et al. 2006). The Amsterdam Island population was inferred to be stable between 1982 and 2002, also based on counts of selected sites (Guinet et al. 1994, Guinet pers. comm. in SCAR EGS 2008). More recent estimates of abundance are needed for both Gough and Amsterdam Islands. Complete pup counts indicate that Subantarctic Fur Seal abundance at both islands within the Prince Edward Islands (PEI) increased steadily from 1981 to the early 2000s (Bester et al. 2003, Hofmeyr et al. 2006a). However, pup production at Marion Island (within the Prince Edward Islands) declined by 6.4% between 2003/2004 and 2012/2013 (Wege et al. in prep.). At Prince Edward Island itself, pup production remained very close to stable between 2001/2002 and 2008/2009 (0.3% mean annual decline; Bester et al. 2009) but it is unknown whether it has since experienced a reduction since then like that at Marion Island. Early evidence indicates that the decline at Marion Island might have been due to a reduction in female fecundity following a density dependent limitation of prey resources (Wege et al. in prep.).

Generation length has been calculated at 10.7 years (Pacifici et al. 2013). Population change over the three generations from 1981–2012 has been positive (Guinet et al. 1994, SCAR EGS 2008, Bester et al. 2009, Wege et al. in prep.).
Current Population Trend:Stable
Additional data:
Number of mature individuals:200000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

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 4.0-4.4 kg (Laws 1993). Females attain sexual maturity at five 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 six days of arriving at the colony with oestrous and mating occurs eight to 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, Goldsworthy 1999). Trip durations of mothers increase over the course of lactation from six to 10 days to 23-28 days (Goldsworthy 1999, Georges and Guinet 2000, Kirkman et al. 2002). Dives become deeper and slightly longer over the summer. Dives are seldom deeper than 100 m (but up to 208 m) or longer than four minutes (Georges et al. 2000). Foraging behaviour varies between subpopulations (Robinson et al. 2002, Beauplet et al. 2004, Bailleul et al. 2005, de Bruyn et al. 2009).

Subantarctic Fur Seals are opportunistic and pelagic foragers. They feed on myctophid and notothenid fish, cephalopods, and small numbers of crustaceans at Gough Island (Bester and Laycock 1985), the Prince Edward Islands (Klages and Bester 1998, Makhado et al. 2013), Macquarie Island (Goldsworthy et al. 1997, Robinson et al. 2002) and the Isles Crozet (Cherel et al. 2007, Kernaléguen et al. 2012). At Amsterdam Island they have been recorded to take Rockhopper Penguins (Paulian 1964).

Subantarctic Fur Seals are sympatric with other species of Fur Seals at three sites. Low levels of hybridization with Antarctic Fur Seals occurs at the Prince Edward Islands (Hofmeyr et al. 2006a) and the Îles Crozet (Kingston and Gwilliam 2007). Hybridization  occurs with both Antarctic Fur Seals and New Zealand Fur Seals at Macquarie Island (Lancaster et al. 2006, Goldsworthy et al. 2009, Lancaster et al. 2010).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):10.7
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade:

Subantarctic Fur Seals were last harvested in 1921 when 785 were taken at the Prince Edward Islands (Kerley 1987). This species has not been exploited since.

Threats [top]

Major Threat(s): 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 (Bester 1987, Kerley 1987, Roux 1987, Guinet et al. 1994). While the abundance of two of the major subpopulations are thought to be stable (Guinet et al. 1994, Bester et al. 2006, SCAR EGS 2008), that of the third has recently decreased (Bester et al. 2009, Wege et al. in prep.). Wege et al. (in prep.) suggest that this may be due to the effects of density dependent food limitation on adult female fecundity. It is also possible that climate change has played a role in the decline. Climate change is potentially detrimental to Fur Seals through impacts on the abundance and distribution of prey species and changes in environmental conditions (Learmonth et al. 2006, Kovacs et al. 2012, McDonald et al. 2012, McBride et al. 2014).

Few fisheries take place in waters occupied by this species but fisheries may expand in their range (Hanchet et al. 2003). Anthropogenic marine debris, primarily from the fishing industry is responsible for entanglements. At the Prince Edward Islands incidences of debris entanglement are less than one percent for the combined Antarctic/Subantarctic Fur Seal populations (Hofmeyr et al. 2002).

Fur seals are also at risk of mass mortality from infectious diseases because of they congregate in large numbers, and because they were subject to a population bottleneck that has reduced their genetic variation (Lavigne and Schmitz 1990, Wynen et al. 2000). The isolation of their breeding habitat, however, affords them some degree of protection (Lavigne and Schmitz 1990, Chown et al. 1998). The small recovering population at Macquarie Island is at risk from predation by New Zealand Sea Lions and hybridization (Robinson et al. 1999, Goldsworthy et al. 2008).

Conservation Actions [top]

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 and a marine protected area (PEIMP 2010). 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) and by the Australian Government’s Environment Protection and Biodiversity Conservation Act (1999), under which they are listed as a Threatened Species (Vulnerable category) based on the low number of individuals breeding in the Australian region.

Citation: Hofmeyr, G.J.G. 2015. Arctocephalus tropicalis. The IUCN Red List of Threatened Species 2015: e.T2062A45224547. . Downloaded on 20 September 2018.
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