Arctocephalus galapagoensis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CARNIVORA OTARIIDAE

Scientific Name: Arctocephalus galapagoensis
Species Authority: Heller, 1904
Common Name(s):
English Galápagos Fur Seal, Galapagos Islands Fur Seal
Spanish Lobo de dos pelos de Galápagos, Lobo fino de Galapágos, Oso Marino de las Galápagos
French Arctocéphale des Galapagos
Synonym(s):
Arctocephalus australis subspecies galapagoensis Heller, 1904
Arctophoca australis subspecies galapagoensis (Heller, 1904)
Arctophoca galapagoensis (Heller, 1904)
Taxonomic Notes: 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 better be called by its former name A. a. galapagoensis (Wolf et al. unpubl. data).

Assessment Information [top]

Red List Category & Criteria: Endangered A2a ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group)
Reviewer(s): Kovacs, K. & Lowry, L. (Pinniped Red List Authority)
Justification:
Due to its limited distribution, fluctuating (not stable) population size, and marked decline in the last 30 years (in excess of 50%) the Galápagos Fur Seal should be classified as Endangered.

IUCN Evaluation of the Galápagos Fur Seal, Arctocephalus (australis) galapagoensis
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.

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 perhaps 5-6 years of age and a maximum longevity of approximately 20 years, the average age of reproducing individuals should be around 10 years. A population reduction of 50% has been estimated for Galápagos Fur Seals over the past 30 years. This meets the criterion for Vulnerable.

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.

A population reduction of Galápagos Fur Seals has occurred during the past 30 years. 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. This meets the criteria for Endangered.

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.

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.

A population reduction of around 50% of Galápagos Fur Seals has been estimated over the past 30 years.

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 Galápagos Fur Seals is approximately > 138,000 km².

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

The AOO of Galápagos Fur Seals is > 120,000 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.

C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000

The current abundance of Galápagos Fur Seals is roughly known, but is estimated to be about 15,000-20,000.

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.

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

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 for Galápagos Fur Seals.

Listing recommendation : Estimates of Galápagos Fur Seal abundance in 1977-1978 suggested a total population size of about 30,000-40,000. Current abundance is estimated to be around 10,000-15,000. The seals are protected within a National Park and the cause of the decline is unclear. Galápagos Fur Seals qualify for listing as Endangered under IUCN criterion A2(a).
History:
1996 Vulnerable (Baillie and Groombridge 1996)
1996 Vulnerable
1982 Out of Danger (Thornback and Jenkins 1982)

Geographic Range [top]

Range Description:Galápagos Fur Seals are observed throughout the Galápagos Archipelago. Lactating females make trips of relatively short duration, suggesting they do not go far from their colonies. 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 and pups have been reported to be born on the coast of mainland Ecuador, but these reports have not been confirmed.
Countries:
Native:
Ecuador (Galápagos)
FAO Marine Fishing Areas:
Native:
Pacific – southeast
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: A census conducted in 1978 yielded an estimate of 30,000-40,000 animals (Trillmich 1987). However, there was high mortality, especially of pups and yearlings during the 1982-1983 El Niño, and the amount of recovery since this time is unknown. The population appears to be fluctuating and population size is thought to be diminished markedly compared to the seventies (Alava and Salazar 2006), and current abundance is estimated to be around 10,000-15,000 animals. Methodological differences might exist in survey methods, but the suggestion of a decline in excess of 50% over this period is very concerning.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Galápagos Fur Seals are the smallest and the least sexually dimorphic otariid species. Adult males are 1.1-1.3 times longer and 2-2.3 times heavier than adult females. Galápagos Fur Seals are small and compact, and adult males are stocky in build. Pups are blackish brown, sometimes with grayish to whitish margins around the mouth and nose. Pups molt this natal coat for one that resembles that of the adult female.

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 27.3 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. Galápagos Fur Seals mature at an age of about 5 years, from which time females usually produce one pup a year but usually 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. 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.

The behaviour of the Galápagos Fur Seal has been extensively studied. They occasionally occur on nearly all of the islands in the Archipelago, and 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 the rocks. Galápagos Fur Seals have a fairly long pupping and breeding season, lasting from mid-August to mid-November. The peak of pupping shifts little from year to year and usually occurs between the last week of September and the first week of October.

Colonies are located close to foraging areas and the average length 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). Most foraging occurs at night and the mean depth of foraging dives is 26 m with duration of less than 2 minutes. The maximum dive depth recorded is 115 m, and the longest duration is 5 minutes. Pups are visited around 300 times before weaning, with attendance periods lasting 0.5-1.3 days. Weaning occurs at 18-36 months, with most pups being weaned in their third year. Pups born prior to the weaning of an older sibling rarely survive, with most starving to death and a small percentage being killed by the older pup. Females will allow multiple pups to nurse but this rarely lasts long enough for the youngest pup to get strong enough to survive. In exceptional cases offspring were allowed to nurse when they were 4-5 years old.

In the water, particularly near haul-outs, Galápagos fur seals raft in postures typical of many of the southern fur seal species. There is no evidence for 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 omastrephids. A variety of fish species are also taken mostly myctophids and bathylagids. They feed mostly at night, possibly exploiting vertically migrating species when they come closer to the surface.

Predators of Galápagos fur seals include sharks and killer whales. On land feral dogs on Isabela Island decimated colonies on the south-western end of the island, killing pups and adults.
Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): Similar to all southern fur seals there was a severe population decline 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. El Niño events dramatically elevate mortality rates of all age classes and cause population declines; this is due to the dramatic declines in productivity around the Archipelago during these events.

Tourism in the Galápagos, which is an Ecuadorian National Park, is heavy but regulated, and fur seals are protected. Episodes of entanglement in local net fisheries have been reported and are thought to be increasing over the last years. Feral dogs on Isabela Island which killed fur seals of all ages have been exterminated. This problem could erupt again if other feral dogs find their way to colony sites. The most serious threat at present is transmission of diseases from dogs to pinnipeds.

Like all fur seals, Galápagos Fur Seals are vulnerable to oil spills because of their dependence on their thick pelage for thermoregulation. Although there is limited large vessel traffic in the Galápagos Archipelago, 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.

Galápagos Fur Seals have experienced declines from El Niño-caused ocean warming and associated reduced marine productivity (Trillmich and Dellinger 1991) estimated of up to 80% (Salazar 2002; Alava and Salazar 2006), but the exact extent of population reduction is not clear. Therefore, although the effects of global climate change on this species and its habitat are uncertain at this time, it is possible that any change related disruption of present day ocean currents, levels of marine productivity, or increased air temperatures at haul out sites would adversely affect this species.

Despite their population size, the Galápagos Fur Seal population will always be vulnerable to a variety of threats because of the species' restricted distribution to a relatively small Archipelago of islands.

Conservation Actions [top]

Conservation Actions: 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. It is listed on CITES Appendix II.

Bibliography [top]

Alava, J. J. and Salazar, S. 2006. Status and conservation of Otariids in Ecuador and the Galápagos Islands. In: A. W. Trites, S. K. Atkinson, D. P. DeMaster, L. W. Fritz, T. S. Gelatt, L. D. Rea and K. M. Wynne (eds), Sea Lions of the World, pp. 495-520. Fairbanks: Alaska Sea Grant College Program, Alaska, USA.

Arnold, W. and Trillmich, F. 1985. Time budget in Galapagos fur seal pups: the influence of the mother?s presence and absence on pup activity and play. Behavior 92: 302-321.

Arnould, J. P. Y. 2002. Southern fur seals Arctocephalus spp. In: W. F. Perrin, B. Wursig and J. G. M. Thiewissen (eds), Encyclopedia of Marine Mammals, pp. 1146-1151. Academic Press, New York, USA.

Bonner, W. N. 1981. Southern fur seals Arctocephalus (Geoffroy Saint-Hilaire and Cuvier, 1826). In: S. H. Ridgway and R. Harrison (eds), Handbook of marine mammals, Volume 1: The walrus, sea lions, fur seals and sea otter, pp. 161-208. Academic Press.

Clark, T. W. 1979. Galapagos Fur Seal. Mammals in the Seas, Vol. II: pinniped species summaries and report on sirenians, pp. 31-33. FAO Fisheries.

de Anda, H. 1985. Habitos Alimenticios del Lobo Marino de Califomia (Zalophus californianus) en Las Islas Los Coronados B.C., de Noviembre 1983 a Octubre 1984. Tesis de Licenciatura en Ciencias Marinas., Univ. Auton.

Dellinger, T. and Trillmich, F. 1999. Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation. Canadian Journal of Zoology 77: 1204-1216.

Horning, M. and Trillmich, F. 1999. Lunar cycles in diel prey migrations exert a stronger effect on the diving of juveniles than adult Galápagos fur seals. Proceedings of the Royal Society of London B Biological Sciences 266: 1127-1132.

IUCN. 2008. 2008 IUCN Red List of Threatened Species. Available at: http://www.iucnredlist.org. (Accessed: 5 October 2008).

Limberger, D., Trillmich, F., Biebach, H. and Stevenson, R. B. 1986. Temperature regulation and microhabitat choice by free-ranging Galapagos fur seal pups (Arctocephalus galapagoensis). Oecologia 69: 53-59.

Mace, G. M. and Balmford, A. 2000. Patterns and processes in contemporary mammalian extinction. In: A. Entwhistle and N. Dunstone (eds), Priorities for the Conservation of Mammalian Biodiversity, pp. 27-52. Cambridge University Press, Cambridge, UK.

Repenning, C. A., Peterson, R. S. and Hubbs, C. L. 1971. Contributions to the systematics of the southern fur seals, with particular reference to the Juan Fernandez and Guadalupe species. American Geophysical Union, Antarctic Research Series 18: 1-34.

Salazar, S. 2002. Lobo marino y lobo peletero. In: E. Danulat and G. J. Edgar (eds), Reserva Marina de Galapagos. Linea Base de la Biodiversidad, pp. 267-290. Fundacion Charles Darwin / Servicio Parque Nacional Galapagos, Santa Cruz, Ecuador.

Scott, P. 1965. Section XIII. Preliminary List of Rare Mammals and Birds. The Launching of a New Ark. First Report of the President and Trustees of the World Wildlife Fund. An International Foundation for saving the world's wildlife and wild places 1961-1964, pp. 15-207. Collins, London, UK.

Thornback, J. and Jenkins, M. 1982. The IUCN Mammal Red Data Book. Part 1: Threatened mammalian taxa of the Americas and the Australasian zoogeographic region (excluding Cetacea). IUCN, Gland, Switzerland.

Trillmich, F. 1986. Attendance behavior of Galapagos fur seals. In: R. L. Gentry and G. L. Kooyman (eds), Fur seals: Maternal strategies on land and at sea, pp. 168-185. Princeton University Press, Princeton, NJ, USA.

Trillmich, F. 1987. Galapagos fur seal, Arctocephalus galapagoensis. In: J. P. Croxall and R. L. Gentry (eds), Status, biology, and ecology of fur seals, pp. 23-27. NOAA Technical Report.

Trillmich, F. and Dellinger, T. 1991. The effects of El Niño on Galápagos pinnipeds. In: F. Trillmich and K. A. Ono (eds), Pinnipeds and El Niño: responses to environmental stress, pp. 66-74. Springer Verlag, Heidelberg, Germany.

Trillmich, F. and Kooyman, G. L. 2001. Field metabolic rate of lactating female Galápagos fur seals (Arctocephalus galapagoensis): the influence of offspring age and environment. Comparitive Biochemistry and Physiology 129(A): 741-749.

Trillmich, F. and Ono, K. O. 1991. Pinnipeds and El Niño: Responses to environmental stress. Springer, Berlin, Germany.

Wolf, J. B. W., Tautz, D. and Trillmich, F. 2007. Galapagos and Californian sea lions are separate species: genetic analysis of the genus Zalophus and its implications for conservation management. Frontiers Zoology 4: doi:10.1186/1742-9994-4-20.


Citation: Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group) 2008. Arctocephalus galapagoensis. In: The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 22 September 2014.
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