Arctocephalus galapagoensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Carnivora Otariidae

Scientific Name: Arctocephalus galapagoensis Heller, 1904
Common Name(s):
English Galápagos Fur Seal, Galapagos Islands Fur Seal
French Arctocéphale des Galapagos
Spanish Lobo de dos pelos de Galápagos, Lobo fino de Galapágos, Oso Marino de las Galápagos
Arctocephalus australis ssp. galapagoensis Heller, 1904
Arctophoca australis ssp. galapagoensis (Heller, 1904)
Arctophoca galapagoensis (Heller, 1904)
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).

This species was formerly referred to Arctocephalus australis galapagoensis (Repenning et al. 1971). New genetic information suggests that it is indeed very close to A. australis and may also be categorized as A. australis galapagoensis (Wolf et al. 2007). The population shows strong matrilineal structure where geographically close colonies display separate mitochondrial haplotypes, but it is well connected and mixed through gene flow presumably caused by male dispersal (Lopes et al. 2015).

Assessment Information [top]

Red List Category & Criteria: Endangered A2ab ver 3.1
Year Published: 2015
Date Assessed: 2014-10-30
Assessor(s): Trillmich, F.
Reviewer(s): Aurioles-Gamboa, D.
Facilitator/Compiler(s): Lowry, L., Ahonen, H., Chiozza, F. & Battistoni, A.
The Galápagos Fur Seal population declined by 77-80% from 1977/78 to 2001. Since then it is thought that the population has increased but is likely still reduced by 50% over the last 24-35 years. Generation length for this species may be anywhere between 8 and 11.7 years, with a best estimate of 10 years. The causes of the reduction are partly understood, have not ceased, and may not be reversible. Impacts from El Niño events and infectious diseases continue to threaten the population. Galápagos Fur Seals qualify for listing as Endangered under criterion A2ab. However, the lack of quantitative survey information for the past 12 years greatly increases the uncertainty of this assessment.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Galápagos Fur Seals are observed throughout the Galápagos Archipelago. Lactating females make trips of relatively short duration, which usually take them 10-20 km out to sea, but during the warm season trips last longer and go further offshore. Foraging by males outside the breeding season is unknown. Most breeding colonies are located in the western and northern parts of the Archipelago, close to productive upwelling areas offshore. Vagrants are occasionally observed including in southern Mexico during El Niño events (Aurioles-Gamboa et al. 2004) and pups have been reported to be born on the coast of mainland Ecuador, but that has not been confirmed.
Countries occurrence:
Ecuador (Ecuador (mainland) - Vagrant, Galápagos)
FAO Marine Fishing Areas:
Pacific – southeast
Additional data:
Estimated area of occupancy (AOO) - km2:109400
Extreme fluctuations in area of occupancy (AOO):No
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):115
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Age-structure data are not available for the Galápagos Fur Seal population so the generation time cannot be calculated precisely. With sexual maturity attained at about 4-6 years of age and a maximum longevity of approximately 20 years, the average age of reproducing individuals may be anywhere between 8 and 11.7 years (based on generation length estimates for other Arctocephalus species; Pacifici et al. 2013), but the best estimate is about 10 years (similar to the generation time reported for Arctocephalus gazella by Forcada et al. 2008). The number of mature animals in the population is likely to be about two-thirds of the total.

Whalers and sealers harvested Galápagos Fur Seals indiscriminately during the 19th century and there were few left by 1900 (Trillmich 1987). Although there was little documentation, the population recovered substantially during the 20th century. In 1977-1978 the first systematic census efforts were conducted; 9,785 fur seals were counted and total abundance was estimated as 30,000 taking into account lunar stage and time of day when counts were made (Trillmich 1987). This would represent about 20,000 mature individuals. In November 2001, 2,733 fur seals were counted at haulouts and rookeries in the Galápagos Islands (Alava and Salazar 2006). By correcting for the probability that animals could be seen at a distance, total abundance was estimated to be 6,000-8,000. This would correspond to 4,000-5,300 mature individuals. Analysis methods differed somewhat, but comparisons of these two estimates indicate a reduction of 74-80% over a period of 23 years (2.3 generations). Alava and Salazar (2006) also showed information on counts made at specific rookeries in 1977, 1978, and 2001. If the average numbers of individuals counted per site in 1977 (345.5) and 1978 (395.6) are compared to 2001 (79.2) this suggests a reduction in abundance of 77-80%. The population seems to have recovered somewhat since 2001, at least on the western side of Fernandina Island (Trillmich, pers. obs). The current abundance of Galápagos Fur Seals has not been assessed reliably since 2001, so recent and current trends in abundance are unknown. Abundance has been roughly estimated at 15,000 total or about 10,000 mature individuals in recent years; a reduction of 50% from 1977/78. While this includes a period slightly longer than the best estimate of three generations (i.e., 35 years rather than 30 years), there is no evidence that abundance has changed in recent years and it is precautionary to assume that the 50% reduction applies to the last three generations.

The reasons for the reduction are not clearly understood, but may lie mostly in population effects of the 1982/83 and 1997/98 El Niño events (Trillmich and Limberger 1985, Trillmich and Dellinger 1991, Alava and Salazar 2006). The population has been exposed to recurrent El Niño events for thousands of years, and at present it is unclear whether the population is strongly fluctuating or declining.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:10000Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Galápagos Fur Seals are the smallest and the least sexually dimorphic of the otariid species. Adult males are 1.1-1.3 times longer and 2.0-2.3 times heavier than adult females. They are small and compact, and adult males are stocky in build. Pups are blackish brown. Pups moult this natal coat for one that resembles that of the adult female when about 4-6 months old.

The few adult males measured to date have been 1.5-1.6 m and weighed 60-68 kg. Adult females have curvilinear lengths of 1.1-1.3 m and an average weight of about 27-28 kg, with a maximum of 33 kg. Pups are 3.4 kg at birth and an average of 11.3 kg when they are 12 months old (Trillmich 1987). Galápagos Fur Seals are believed to mature at an age of about 5 years, from which time females usually produce one pup a year, but successfully rear a pup only every other year, for most of the rest of their lives.

Males do not become physically mature and large enough to compete for a territory that will be used by females until they are considerably older than the average age of maturity of females, but exact data are missing. Males hold territories that average 200 m², which is large compared to the average size of territories held by of other otariid males; this is particularly notable given the Galápagos Fur Seal's small size.

Galápagos Fur Seals occasionally occur on nearly all of the islands in the Archipelago. They prefer to haul-out on rocky coasts with large boulders and ledges that provide shade and the opportunity to rest in crevices and spaces between rocks. They have a pupping and breeding season that on Fernandina lasts from mid-August to mid-November. The peak of pupping on Fernandina shifts little from year to year and usually occurs between the last week of September and the first week of October. Pupping on other islands may occur at different times (Trillmich pers. obs.), but no systematic data are presently available.

Colonies are located close to pelagic foraging areas and the average duration of female trips is the shortest for a fur seal with a mean trip length of 1.5 days in the cold season (May to November and up to 4 days in the warm season (December to April) (Trillmich and Kooyman 2001, Jeglinski et al. 2013, Villegas-Amtmann et al. 2013). Foraging occurs pelagically, almost exclusively at night and, around Fernandina, 10 to 70 km off the coast. The mean depth of foraging dives is 26-32 m with duration of less than 2 minutes (Horning and Trillmich 1999, Jeglinski et al. 2013). The maximum dive depth recorded is 115 m, and the longest duration is 5.7 minutes. Mothers visit their pups around 300 times before weaning, with attendance periods lasting 0.5-1.3 days. Weaning occurs at 12-36 months, with the exact age at weaning depending on marine productivity. Pups born prior to the weaning of an older sibling rarely survive, with most starving to death because they are being outcompeted by the older pup while a few are directly killed by the older sibling (Trillmich and Wolf 2008). Females will allow multiple pups to nurse but this rarely lasts long enough for the youngest pup to survive. In exceptional cases offspring were allowed to nurse when they were 4-5 years old.

In the water, particularly near haulouts, Galápagos Fur Seals raft in postures typical of many of the southern fur seal species. There is no evidence of migration, and they do not seem to spend prolonged periods of time at sea, except for males immediately before the period of territory tenure.

Galápagos Fur Seals consume a variety of small squids including Onychoteuthis banksi, and a number of species of ommastrephids (Clarke and Trillmich 1980). A variety of fish species are also taken, mostly myctophids and bathylagids (Dellinger and Trillmich 1999). They feed almost exclusively at night, exploiting vertically migrating species when they come closer to the surface. Predators of Galápagos Fur Seals include sharks and killer whales.
Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):8-11.7,10
Movement patterns:Not a Migrant
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: Whalers and sealers harvested Galápagos Fur Seals indiscriminately during the 19th century and there were few left by 1900. The population recovered substantially during the 20th century. Galápagos Fur Seals were protected under Ecuadorian law in the 1930s, and since 1959 with the establishment of the Galápagos National Park, by the Administration of the Park. Currently there is no direct use or trade.

Threats [top]

Major Threat(s): Similar to all southern fur seals there was a severe reduction of Galápagos Fur Seals as a result of 19th century exploitation by sealers and whalers. The species was near extinction early in the 20th century and has since recovered. Hunting was prohibited (but not necessarily stopped) in 1934, and additional protection was provided in 1959 when more than 80% of the Galápagos archipelago was declared a National Park (Trillmich 1987).
El Niño events dramatically elevate mortality rates of all age classes, but primarily of juveniles, and cause population declines; this is due to the dramatic decline in productivity around the archipelago during these events (Trillmich and Limberger 1985). Oceanographers differ in their predictions of how the frequency and intensity of El Niño events may change with climate warming. Cai et al. (2014) suggest that the total number of El Niño events will decrease slightly, but the total number of extreme events will double as global warming continues. In contrast, Santoso et al. (2013) predict a doubling of the frequency of El Niño events with global warming. In the historical long-term perspective offered by Cobb et al. (2013) the frequency of El Niño during the last 50 years is unusually high, but still within the range of variability observed over the last 7,000 years. The most likely projection seems to be that El Niño events will be more frequent, and perhaps stronger, in the immediate future. In their review of otariid extinctions, Gerber and Hilborn (2001) conclude that for species subject to El Niño impacts, "the concern about species recovery should focus on changes in frequency of El Niño events".

Tourism in the Galápagos, which is an Ecuadorian National Park, is heavy and increasing, but regulated, and Fur Seals are fully protected. Episodes of entanglement in local net fisheries have been reported and are thought to be increasing over the last years (Alava and Salazar 2006). An increasing number of fast travelling fiberglass boats with strong outboard engines could occasionally cause mortality through collisions with Fur Seals resting at sea. Feral dogs on Isabela Island, which had killed Fur Seals of all ages, have been exterminated. This problem could occur again if other feral dogs find their way to colony sites.

Like all fur seals, Galápagos Fur Seals are vulnerable to oil spills because of their dependence on thick pelage for thermoregulation. Although there is limited large vessel traffic in the Galápagos archipelago, particularly in the areas of greatest fur seal abundance, numerous small and medium sized vessels operate in the area that could release moderate quantities of oils, fuels, and lubricants if involved in a marine accident. The level of contamination with pollutants is at present not alarming, but needs to be monitored (Alava et al. 2011). Infectious diseases occur commonly in pinnipeds and may have substantial impacts on their populations.

Galápagos Fur Seals have experienced up to 80% declines from El Niño-caused ocean warming (Salazar 2002, Alava and Salazar 2006) and associated reduced marine productivity (Trillmich and Dellinger 1991), but this estimate is most likely too high as it did not take into account increased time at sea during warm water periods. Therefore, although the effects of global climate change on this species and its habitat are uncertain at this time, it is possible that any climate change-related disruption of present day ocean currents would adversely affect this species through reduced levels of marine productivity.

The Galápagos Fur Seal population will always be vulnerable to a variety of threats because of the species' restricted breeding distribution to a relatively small part of an archipelago of islands.

Conservation Actions [top]

Conservation Actions: Galápagos Fur Seals were protected under Ecuadorian law in the 1930s, and since 1959 with the establishment of the Galápagos National Park, by the Administration of the Park. The waters around the islands are also protected by a 40 nautical mile no fishing zone. Tourism is regulated and most visitors are escorted by a trained Park Naturalist. The species is listed on CITES Appendix II.

Citation: Trillmich, F. 2015. Arctocephalus galapagoensis. The IUCN Red List of Threatened Species 2015: e.T2057A45223722. . Downloaded on 25 September 2018.
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