Arctocephalus philippii 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Otariidae

Scientific Name: Arctocephalus philippii (Peters, 1866)
Common Name(s):
English Juan Fernández Fur Seal
French Arctocéphale de Juan Fernandez
Spanish Lobo fino de dos pelos de Juan Fernández, Lobo fino de Juan Fernández, Oso Marino de Chile
Taxonomic Notes: In 2011 the genus of all Fur Seals other than Arctocephalus pusillus was changed from Arctocephalus 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 these species were returned to the genus Arctocephalus pending further research (Committee on Taxonomy 2013).

In earlier taxonomic reviews (Repenning et al. 1971) this taxon was referred to as Arctocephalus philippii, subspecies philippii, and was considered conspecific with A. townsendi, which was referred to as A. p. townsendi. Brunner (2003) argued that this species should belong to the genus Arctophoca, and considered philippii and townsendi to be subspecies. However, Higdon et al. (2007) used genetic evidence to argue that these are separate species, regardless of the generic name, as they split about 0.3 mya

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2015
Date Assessed: 2014-10-10
Assessor(s): Aurioles-Gamboa, D.
Reviewer(s): Trillmich, F., Bohórquez-Herrera, J. & Hernández-Camacho, J.
Contributor(s): Kovacs, K.M.
Facilitator/Compiler(s): Lowry, L., Ahonen, H., Chiozza, F. & Battistoni, A.
The present geographic range of the Juan Fernández Fur Seal is likely similar to that prior to exploitation since there are no records of the species using continental islands. Past abundance is also unknown, but given the documented extent of exploitation during most of the 19th century, the population likely would have comprised at least several hundred thousand individuals. The current population is very small by comparison and has a limited range on oceanic islands showing preferences for a particular rocky habitat. The limited breeding space available for the Juan Fernández Fur Seal, with no other oceanic islands nearby that may be colonized in the near future, is of concern. Reduced genetic variability may pose an additional challenge to population recovery. The Juan Fernandez Fur Seal does not meet any of the IUCN criteria for a threatened listing and is therefore listed as Least Concern.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Juan Fernández Fur Seals inhabit three islands in the Juan Fernández Archipelago (Alejandro Selkirk, Robinson Crusoe, and Santa Clara Islands) as well as the San Félix Islands (San Félix and San Ambrosio), also called “Islas Desventuradas”. The Juan Fernández Islands are located approximately 650 km west of Valparaiso, off the Chilean coast. The San Félix Islands are located approximately 910 km due west of the Bahia Chanaral de Las Animas on the coast of Chile´s Atacama Desert. Almost the entire population resides on the Juan Fernández Archipelago, with very few animals being found on the San Felix Islands (Osman 2007, National Geographic-Oceana 2013). The Robinson Crusoe (47.9 km²) and Alejandro Selkirk (49.5 km²) Islands are the largest and are home to the majority of the population (Osman 2007). The San Félix Islands are much smaller: San Ambrosio measures 2.2 km² while San Félix covers 1.4 km².

In 1990 and 1991, five adult female Juan Fernández Fur Seals from Alejandro Selkirk Island were instrumented with satellite transmitters that indicate they made foraging trips primarily south and west of the archipelago to locations up to 889 km away, with all tracked females at some time located over 550 km from the island (mean = 653 km; Francis et al. 1998). In another study conducted in 2005 (Osman 2007), satellite locations from seven instrumented adult females indicated some animals foraged near the Juan Fernández Archipelago while others travelled as far as 837 km toward the coast of Chile, reaching the continental shelf near Concepción Bay. The mean distance ravelled offshore by female Juan Fernández Fur Seals was 1,394 km. Juan Fernández Fur Seals have been sighted with regularity since 1983 at Punta San Juan, Perú (Majluf and Reyes 1989) which is considered here as the northern limit of their extent of occurrence. However, the northernmost record for the species comes from a vagrant male sighted on the San Francisco beach in Buenaventura Port, Colombia (3°53’N, 77°4’W; Avila et al. 2014). The southern limit is represented by the farthest distance recorded for instrumented animals from Alejandro Selkirk Island approximately 890 km to the southeast (Francis et al. 1998).
Countries occurrence:
Chile (Desventurados Is., Juan Fernández Is.); Peru
FAO Marine Fishing Areas:
Pacific – southeast
Additional data:
Estimated area of occupancy (AOO) - km2:1128008Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:3945710
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):5Lower depth limit (metres):170
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The number of Juan Fernández Fur Seals harvested between 1793 and 1807 has been estimated to be in the order of millions (Busch 1985, Hubbs and Norris 1971) but no reliable estimates are available. By 1872, approximately 38,000 animals had been killed for the fur trade with China, and during 1801, “a single ship carried one million skins to the London Market” (Bush 1985). By 1891, the Juan Fernández Fur Seal population was estimated to be just 300-400 animals; by 1900 and until the middle of the 20th century the species was presumed extinct (Scheffer 1958, Hubbs and Norris 1971, Gerber and Hilborn 2001). In 1965, the species was rediscovered when small groups of Fur Seals were sighted on Alejandro Selkirk and Robinson Crusoe Islands (Bahamonde 1966, Aguayo 1979). The overall abundance of the Juan Fernández Fur Seal recovered from 750 individuals in 1969 to 32,278 in 2005. On Robinson Crusoe Island, the number of pups increased from 125 in 1983 to 2,732 in 2005. On Santa Clara the number of pups increased from 575 in 1998 to 1,325 in 2005, and on Alejandro Selkirk Island 548 pups were sighted in 1983 while 6,941 were observed in 2005 (Osman 2007).

In 2005, 63% of the total 10,998 pups were born on Alejandro Selkirk Island, which is the only clearly increasing colony (Osman 2007). Robinson Crusoe and Santa Clara populations are stable, suggesting that the quality of the breeding habitat may be important to the recovery of this species. Overall, the population is apparently stabilizing, as the per capita population growth rate oscillates between negative and positive values (Osman 2007). The current Juan Fernández Fur Seal population remains small and represents a much reduced fraction of its population prior to the seal exploitation period.

Mitochondrial DNA from 28 Fur Seals from both islands of Juan Fernández was used to evaluate the potential negative effect of the population bottleneck. Contrary to expectations, no significant reduction in genetic variability was identified (Goldsworthy et al. 2000). Similar results were obtained for the Guadalupe Fur Seal (Bernardi et al. 1998). However, when the genetic material from recent animals was compared to the genetic material from specimens collected prior to the seal exploitation, significantly reduced genetic variability was evident (Weber et al. 2004).
Current Population Trend:Increasing
Additional data:
Number of mature individuals:16000Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Unknown

Habitat and Ecology [top]

Habitat and Ecology:The Juan Fernández Fur Seal is a polygynous species. Based on sealer observations made during the late 18th century, the breeding season lasts from mid-November through the end of January, and the colonies are essentially vacated by early September, and no later than mid-October (Francis et al. 1998).

Juan Fernández Fur Seals are sexually dimorphic from the time of birth (Osman et al. 2010) and the differences in length and weight increase with age. Adult males reach 2 m length and weigh 140 kg. Lactating females are on average 1.42 m in length and 48.1 kg in weight (Francis et al. 1998). Newborn pups are approximately 65-68 cm long and weigh 6.2-6.9 kg, and are born with a black coat. Male pups are significantly larger and heavier than female pups at birth, but they do not grow faster than females nor do they show significant differences in body condition. Differences in the growth rates of male and female Juan Fernández Fur Seal pups appear to originate before birth and are not accentuated during the nursing period (Osman et al. 2010).

Males defend territories on land that typically cover about 36 m² and that include an average of four females; some males also hold larger territories in the water (Francis et al. 1998). Most adult females give birth within a few days of arriving at the rookery. Mean time from birth to the first foraging trip is 11.3 days. Although females can be gone for as little as a day, the mean length of foraging trips is 12.3 days, with the longest recorded trip lasting 25 days. Mean duration of pup attendance between foraging trips is 5.3 days with a range of 0.3–15.8 days. Based on the onset of pupping and the observations at vacant colonies in early September, pups appear to be weaned at 7-10 months old (Francis et al. 1998).

Juan Fernández Fur Seal females travel long distances to find adequate quantities of prey making some of the longest foraging trips of any otariid (Francis et al. 1998, Osman 2007). Most trips were made to the southwest and west of the Juan Fernández Islands, far offshore, to deep oceanic areas more than 550 km from the island (mean = 653 km) and up to 889 km distant. The mean dive depth was only 12.3 m and the mean dive duration was 51 seconds, suggesting mostly surface feeding (Francis et al. 1998). Osman (2007) analysed 27,541 dives made by five females from Alejandro Selkirk Island during a single foraging trip, obtaining a median dive depth of 4 m and median dive duration of 0.33 minutes. Maximum depth attained by any seal was 169.5 m during a dive lasting 3.1 minutes and the longest dive lasted 5.1 minutes with a maximum depth of 24 m. The median maximum depths ranged from 3.5 m to 4.5 m (Osman 2007). Francis et al. (1998) reported that nearly all foraging-type dives occur at night; however (Osman 2007) found feeding during daytime to be more frequent.

Juan Fernández Fur Seals feed extensively on vertically-migrating prey (Francis et al. 1998). Their diet is one of the least diverse of any otariid. Coupled with the long foraging trips made by lactating females, this pattern reflects the low productivity of their oceanic feeding areas (Acuña and Francis 1995). The diet composition of Juan Fernández Fur Seals was assessed by analysing 437 scats collected during five reproductive seasons (1987–1991). The study yielded 4,172 fish otoliths and cephalopod beaks, with 13 prey species identified. Myctophidae represented most of the items (80.3%), followed by Scomberesocidae (10%), Carangidae (9.5%), Engraulidae (1.0%), and Bathylagidae (0.7%). Cephalopod families included Onychoteuthidae (27.1%), Ommastrephidae (3.7%), and Tremoctopodidae (0.7%) (Acuña and Francis 1995). Scat samples from females contained larger numbers of the Squid Onychoteuthis banksi than did the samples from subadult males and juveniles.

Two-thirds of the 60 Juan Fernández Fur Seal pups found dead on Alejandro Selkirk Island during the 1991 and 1992 breeding seasons had Hookworms (Uncinaria sp.), with a mean infection of 17 parasites per host (Sepúlveda 1998). Blue Sharks, Great White Sharks, and Killer Whales are suspected predators, and Leopard Seals that infrequently visit the islands may also prey on Juan Fernández Fur Seals (Torres 1987).
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: Juan Fernández Fur Seals were hunted to the brink of extinction by commercial sealers trading pelts mostly in China. Intensive sealing began in the late 18th century and ended in the late 19th century when few seals could be found. Small numbers were seen in the early 20th century and the species was thought to have gone extinct shortly thereafter. In 1965, the species was rediscovered when small groups of Fur Seals were sighted on Alejandro Selkirk and Robinson Crusoe Islands (Bahamonde 1966, Aguayo 1979). Hunting of Juan Fernández Fur Seals has been prohibited since 1965 (Aguayo 1979).

Threats [top]

Major Threat(s): Juan Fernández Fur Seals were hunted to the brink of extinction by commercial sealers trading pelts in China. Intensive sealing began in the late 18th century and ended in the late 19th century when few seals could be found. Small numbers were seen in the early 20th century and the species was thought to have gone extinct shortly thereafter. The species was rediscovered in the mid- 20th century, and has since been making a slow comeback.

The limited population size and geographical range, coupled with the fact that the species passed through a genetic bottleneck, makes Juan Fernández Fur Seals vulnerable to catastrophic events and stress from disease outbreaks, oil spills, environmental regime shifts, disturbances, and fisheries. Seals have been sighted with plastic bands and fishing net debris around their necks since 1982 (Torres 1990). During the summers of 2003, 2004, and 2005, about 20 animals were sighted with scars around their necks and heads from entanglement in nets or marine debris. All age and sex categories were represented (Osman et al. 2007, Osman 2007). Mortality rate due to these entanglements is unknown. Pelagic fisheries that usually operate with little regulation may increase the vulnerability of this species, which spends most of its time offshore.

The effects of global climate change on Juan Fernández Fur Seals are uncertain. However, for a species that undertakes such long foraging trips during the pup dependency period any negative disruption of the ecosystem is likely to be a threat.

Conservation Actions [top]

Conservation Actions: Hunting of Juan Fernández Fur Seals has been prohibited since 1965 (Aguayo 1979). In 1978, the status of total protection was conferred to all Arctocephalus species in Chile (Torres 1987, Reijnders et al. 1993).

Citation: Aurioles-Gamboa, D. 2015. Arctocephalus philippii. The IUCN Red List of Threatened Species 2015: e.T2059A61953525. . Downloaded on 23 September 2018.
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