Overview

Brief Summary

Biology

On the rocky shores of the Galapagos Islands, six to ten Galapagos fur seals may occupy an area of about 100 square metres (7). Grouping together in this manner may be largely due to the rarity of suitable rocky sites, but it also has the benefit of females being less vulnerable to predation or harassment when in large groups (8). Breeding males establish larger territories, around 200 square metres, which encompass a number of females (7). The breeding season lasts from mid-August to mid-November (5), when the cooler temperatures mean less heat stress and a greater availability of prey (7). A peak of births occurs in the last week of September or the first week of October (5), when females give birth to a single pup that has been carried for eight to twelve months (3). For the first five to ten days, the mother will stay with her newborn, but after this period, she alternates one to three days of feeding at sea with one to two days ashore with the pup. The pup is nursed for two to three years, sometimes even longer (7). Just eight days after giving birth, the female mates (7). Being a polygynous mammal, one male may mate with between six and sixteen females within his territory (8). The rough terrain and large size of the male's territory means that it can be difficult to successfully defend all the females within the area, and a rival male may sometimes invade and mate with a female (7). Defending a territory with threats and fighting can be tiring work, so the male can often be seen cooling off in the sea at midday (7). Although all females mate shortly after giving birth, only a small percentage will give birth the following year if they are still feeding a pup. If a pup is born to a female that is still feeding a pup from the previous year, the newborn often starves, or is occasionally killed by the older sibling (7). Females mature at three to four years of age, while males become territorial breeding bulls between seven and ten years old (2). While the Galapagos fur seal is capable of diving to much greater depths, it mainly undertakes short dives to between 10 and 50 metres (2) (3), where it feeds on a variety of fish and small squid (2) (5).
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Description

The scientific name of this marine mammal, Arctocephalus, comes from Greek words that mean 'bear headed' (3), and with its short, pointed muzzle, little button-like nose and fairly large eyes (5), the Galapagos fur seal does indeed bear a resemblance to its land-dwelling, carnivorous ancestors (3). The coat of this fur seal varies from dark brown to dark grey, with light-tipped, longer guard hairs giving a grizzled appearance (3) (6). Male Galapagos fur seals also have a mane of slightly longer hairs, from the top of their head to their shoulders (5). Both the muzzle and the fur on the undersides is paler (3), with females and subadults having a pale greyish-tan chest and rusty-tan belly (5), and the skin on the flippers is blackish (6). Galapagos fur seal pups have a blackish-brown coat, sometimes with greyish or whitish margins around the mouth and nose (5).
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Distribution

As suggested by the common name, Galapagos fur seals (Arctocephalus galapagoensis) are found primarily on the shores of, and in the waters immediately surrounding, the Galapagos Islands. During the breeding season, populations are observed in the northern and western parts of the Galapagos Islands. Galapagos fur seals are non-migratory. (Clark, 1979; Nowak, 1999)

Biogeographic Regions: neotropical (Native ); pacific ocean (Native )

Other Geographic Terms: island endemic

  • Clark, T. 1979. Mammals in the seas: Pinniped species summaries and report on sirenians. Rome, Italy: Food and Agriculture Organization of the United Nations.
  • Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: The Johns Hopkins University Press.
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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.
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Range

Endemic to the Galapagos Islands (3), where it is widely distributed. The main colonies occur on the western islands of the archipelago, with Isla Fernandina and Isla Isabela holding the largest populations (2).
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Physical Description

Morphology

Male Galapagos fur seals are on average 154 cm in length and weigh 64 kg, while females are 120 cm in length and weigh 27 kg, making Arctocephalus galapagoensis the smallest otariid. The fur of Arctocephalus galapagoensis is a light tan on the stomach and around the mouth and ears. The rest of the fur is colored gray-brown (Nowak, 1999). During lactation and perinatal fasting, female Galapagos fur seals lose about 1.68% of body mass per day and have a metabolic rate 1.1 times higher than the expected metabolic rate according to the Kleiber curve of energetics (Costa and Trillmich, 1988; Trillmich and Kooyman, 2001).

Range mass: 27 to 64 kg.

Range length: 120 to 154 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

  • Costa, D., F. Trillmich. 1988. Mass Changes and Metabolism during the Perinatal Fast: A Comparison between Antarctic (Arctocephalus gazella) and Galápagos Fur Seals (Arctocephalus galapagoensis). Physiological Zoology, 61: 160-169.
  • Trillmich, F., G. Kooyman. 2001. Field metabolic rate of lactating female Galápagos fur seals (Arctocephalusgalapagoensis): the influence of offspring age and environment. Comparative Biochemistry and Physiology, 129: 741-749.
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Ecology

Habitat

Galapagos fur seals are found in the Galapagos Archipelago, a group of islands located about 1000 km off of the coast of Ecuador, which have been formed by a multitude of volcanic eruptions. The Galapagos Islands are almost directly on the equator and are characterized by two seasons: a cool season (August to November) and a warm season (December to July). Being near the equator, average sea temperatures are relatively high; they range from an average of 22 degrees Centigrade during the cool season to 25 degrees Centigrade during the warm season. To escape high temperatures, Galapagos fur seals frequently take shelter in the shade of boulders, in caves, and under lava ledges. (Limberger et al., 1986) When Galapagos fur seals venture out into the deep waters of the Pacific Ocean they swim in the waters of the Humboldt Current and make dives of typically less than 30 meters (Nowak, 1999).

Habitat Regions: tropical ; saltwater or marine

Aquatic Biomes: coastal

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

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
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Depth range based on 104 specimens in 1 taxon.
Water temperature and chemistry ranges based on 70 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 22.429 - 24.724
  Nitrate (umol/L): 2.793 - 6.059
  Salinity (PPS): 34.053 - 34.713
  Oxygen (ml/l): 4.635 - 4.758
  Phosphate (umol/l): 0.523 - 0.797
  Silicate (umol/l): 3.577 - 5.767

Graphical representation

Temperature range (°C): 22.429 - 24.724

Nitrate (umol/L): 2.793 - 6.059

Salinity (PPS): 34.053 - 34.713

Oxygen (ml/l): 4.635 - 4.758

Phosphate (umol/l): 0.523 - 0.797

Silicate (umol/l): 3.577 - 5.767
 
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When ashore, the Galapagos fur seal prefers rocky areas where it can seek shelter from the sun under ledges and between large boulders (5).
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Trophic Strategy

Galapagos fur seals eat fish and various cephalopods off the coast of the Galapagos. Foraging occurs at night, when prey migrate closer to the surface of the water and to a depth where seals can reach them (Nowak, 1999; Horning and Trillmich, 1997).  Foraging behavior in Arctocephalus galapagoensis is influenced by the lunar cycle. Foraging trips are much longer during the new moon than during the full moon (Nowak, 1999; Trillmich and Mohren, 1984). Foraging behavior is greatly affected by the tropical storm El Nino. During the El Nino of 1982 the population of Galapagos fur seals was substantially reduced. About 30% of adults and almost all seals under the age of 4 did not survive. El Nino cycles are thought to be responsible for the Galapagos fur seals’ long lactation periods (Nowak, 1999, Limberger and Trillmich, 1985). Pups are weaned between 2 and 3 years of age and are mostly dependent upon their mother before this time (Horning and Trillmich, 1997).

Animal Foods: fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

  • Trillmich, F., W. Mohren. 1981. Effects of the lunar cycle on the Galápagos fur seal, Arctocephalus galapagoensis. Oecologia, 48: 85-92.
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Associations

The role of Galapagos fur seals in the ecosystem has not been studied as of yet.

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Occasionally, Galapagos fur seals are preyed on by killer whales (Orcinus orca) and sharks, but more frequently, Galapagos fur seals are threatened by feral dogs living on the islands that they inhabit (Nowak, 1999; Merlen, 2000; Riedman, 1990).

Known Predators:

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Life History and Behavior

Behavior

Galapagos fur seals make two separate vocalizations when foraging at night in the ocean. First, they make a lengthened growl, and secondly, they make a snap or knocking sound. The purpose of these vocalizations is not known, but they are thought to aid in foraging and are not thought to be a form of communication (Merlen, 2000). However, fur seals generally communicate with vocalizations and through visual displays.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic ; chemical

  • Merlen, G. 2000. Nocturnal Acoustic Location of the Galapagos Fur Seal (Arctocephalus galapagoenis). Marine Mammal Science, 16: 248-253.
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Life Expectancy

On average the lifespan of Galapagos fur seals is about 264 months, or 22 years (Ferguson and Higdon, 2006).

Average lifespan

Status: wild:
22 years.

Average lifespan

Sex: female

Status: wild:
22.0 years.

  • Ferguson, S., J. Higdon. 2006. How Seals Divide up the World: Environment, Life History, and Conservation. Oecologia, 150: 318-329.
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Lifespan, longevity, and ageing

Observations: There is a delayed implantation after fertilization (Ronald Nowak 2003). The actual embryonic development takes about 7 months, but the pregnancy usually lasts 1 year. In the wild, these animals have been estimated to live up to 22 years (http://www.demogr.mpg.de/longevityrecords). Their longevity in captivity has not been studied in detail and hence their maximum longevity could be underestimated.
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Reproduction

Galapagos fur seals are polygynous, meaning that a single male will seek and mate with multiple females. Males establish territories and defend groups of females, but due to environmental factors, they are not very efficient at protecting their females and other males are able to successfully mate on a rival male’s territory (Nowak, 1999). One adult male may mate with 6 to 10 females located within his territory. This is a relatively small number of mates compared to other otariids, but is in part due to the spatial distribution of females within the population (Riedman, 1990; Arnould, 2002). Adult males defend their territories without eating until the physical demands, nutritional needs, or heat becomes so great that they must enter the water. During the El Nino of 1982, adult territorial males were driven to near 100% mortality because the food supply did not provide sufficient energy to sustain the demands of territory defense (Trillmich and Limberger, 1985).

Mating System: polygynous

Galapagos fur seal breeding occurs once a year; the breeding season, August to November, coincides with the cool season in the Galapagos islands. Pregnancy can last about a year, but this may not be a good reflection of the duration of fetal development, because females are thought to undergo a process of delayed implantation (Nowak, 1999; Riedman, 1990). Females give birth to one pup at a time and can resume estrous 5 to 10 days after the birth of a pup or after they also resume foraging trips (Nowak, 1999; Riedman, 1990; Arnould, 2002). However, even though females can resume estrous shortly after giving birth, they often do not become pregnant if they have a pup that still requires milk as the major form of nourishment. The lactation period for adult females is relatively long compared to other otariids; pups are not weaned until they are between the ages of 2 and 3. This long lactation period has been linked to unstable environmental conditions caused by El Nino events (Trillmich and Limberger, 1985). The long lactation period causes sibling conflict if a mother gives birth to a second pup before the first is weaned. In many cases, either the older sibling will kill the younger or the younger sibling will starve to death (Nowak, 1999; Trillmich and Wolf, 2008).

Even though young Galapagos fur seals are not weaned until at least the age of 2, pups begin to make trips into the ocean at 6 months and begin to forage for themselves at 12 months. However, pups continue to rely on milk as a major form of nourishment until they are fully weaned and become independent, which typically occurs between the ages of 2 and 3 (Horning and Trillmich, 1997).

Females become sexually mature between 3 to 5 years of age. It takes males slightly longer to become sexually mature and large enough to defend territories, anywhere from 7 and 10 years (Reijnders et al., 1993; Nowak, 1999). At birth a male will typically weigh 3.8 kg, while a female will weigh 3.4 kg (Trillmich, 1986).

Breeding interval: Galapagos fur seals breed once yearly.

Breeding season: Galapagos fur seals breed from August to November.

Average number of offspring: 1.

Average gestation period: 11 to 12 months.

Range weaning age: 12 (low) months.

Average weaning age: 24-36 months.

Range time to independence: 2 to 3 years.

Range age at sexual or reproductive maturity (female): 3 to 5 years.

Range age at sexual or reproductive maturity (male): 7 to 10 minutes.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation

Average birth mass: 3500 g.

Average gestation period: 213 days.

Average number of offspring: 1.

Like most mammal species, female Arctocephalus galapagoensis make a substantial investment in their offspring. Weaning does not occur until pups are between 2 to 3 years of age. After the first 5 to 10 days of a pup’s life a mother will divide her time between foraging at sea and spending time with the offspring on shore (Nowak 1999). The extent to which males give direct parental care is not known; there is a possibility that males provide some indirect parental care through territorial defense during the mating season (Arnould, 2002; Riedman, 1990).

Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

  • Arnould, J. 2002. Southern fur seals: Arctocephalus spp.. Pp. 329-410; 726-1150 in W Perrin, B Würsig, J Thewissen, eds. Encyclopedia of Marine Mammals, Vol. 1, 1 Edition. London: Academic Press.
  • Horning, M., F. Trillmich. 1997. Ontogeny of Diving Behaviour in the Galapagos Fur Seal. Behaviour, 134: 1211-1257.
  • Nowak, R. 1999. Walker's Mammals of the World. Baltimore and London: The Johns Hopkins University Press.
  • Reijnders, P., S. Brasseur, J. van der Toorn, P. van der Wolf, I. Boyd, J. Harwood, D. Lavigne, L. Lowry. 1993. Seals, Fur Seals, Sea Lions, and Walrus: Status Survey and Conservation Action Plan. Gland, Switzerland: IUCN.
  • Riedman, M. 1990. The Pinnipeds: seals, sea lions and walruses. Berkeley and Los Angeles: University of California Press.
  • Trillmich, F. 1986. Maternal Investment and Sex-Allocation in the Galapagos fur Seal, Arctocephalus galapagoensis. Behavioral Ecology and Sociobiology, 19: 157-164.
  • Trillmich, F., D. Limberger. 1985. Drastic effects of El Nino on Galapagos pinnipeds.. Oecologia, 67: 19-22.
  • Trillmich, F., J. Wolf. 2008. Parent–offspring and sibling conflict in Galápagos fur seals and sea lion. Behavioral Ecology and Sociobiology, 62: 363-375.
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Conservation

Conservation Status

In the early 20th century, Galapagos fur seals were put under the protection of Ecuadorian law because they were hunted almost to extinction by sealers (Nowak, 1999).

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: endangered

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IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
A2a

Version
3.1

Year Assessed
2008

Assessor/s
Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group)

Reviewer/s
Kovacs, K. & Lowry, L. (Pinniped Red List Authority)

Contributor/s

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)
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Status

Classified as Endangered (EN) on the IUCN Red List (1) and listed on Appendix II of CITES (4).
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Population

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
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Threats

Major Threats
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.
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During the nineteenth century, the Galapagos fur seal was severely impacted by the large-scale commercial seal hunting that was rampant at the time (3) (7). By the early twentieth century, the Galapagos fur seal was believed to be extinct, until a small colony was discovered in 1932-33 (7). Since then, and following the end of extensive seal hunting (3), numbers have increased substantially (7), and the Galapagos fur seal is no longer exploited (2). Today, the spread of feral dogs on the Galapagos Islands may jeopardise the future of some of the fur seal colonies (2).
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Management

Conservation Actions

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.
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Conservation

The Galapagos fur seal is fully protected by the Galapagos National Park Service under Ecuadorean law (2). It will also benefit from the management of the Galapagos Islands and the surrounding waters as a national park and marine reserve (5) (9). As one of the first sites to be designated a Natural World Heritage Site (9), the recognition of the Galapagos' incredible and unique ecosystem will hopefully ensure the preservation of the islands' fauna and flora for generations to come.
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Relevance to Humans and Ecosystems

Benefits

There are no known adverse effects of Arctocephalus galapagoensis on humans. However, there may be a negative effect upon the fishing industry due to competition over fish species that Galapagos fur seals eat (DeMaster et al., 2001).

  • DeMaster, D., C. Fowler, S. Perry, M. Richlen. 2001. Predation and Competition: The Impact of Fisheries on Marine-Mammal Populations Over the Next One Hundred Years. Journal of Mammalogy, 82: 641-651.
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There is relatively little interaction between humans and Arctocephalus galapagoensis, but, in the early 20th century, the seals were hunted for fur. Today, Galapagos fur seals are one of the many endemic species of the Galapagos that bring tourism to the islands (Clark, 1979; de Groot, 1983; McElroy, 2003; Nowak, 1999).

Positive Impacts: ecotourism

  • McElroy, J. 2003. Tourism Development in Small Islands across the World. Geografiska Annaler. Series B, Human Geography, 85: 231-242.
  • de Groot, R. 1983. Tourism and conservation in the Galapagos Islands. Biological Conservation, 26: 291-300.
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Wikipedia

Galápagos fur seal

The Galápagos fur seal (Arctocephalus galapagoensis) breeds on the Galápagos Islands in the eastern Pacific, west of mainland Ecuador.

Description[edit]

Basking

Galápagos fur seals are the smallest of otariids. They have a grayish brown fur coat. The adult males of the species average 1.5 m (4 ft 11 in) in length and 64 kg (141 lb) in mass. The females average 1.2 m (3 ft 11 in) in length and 28 kg (62 lb) in mass. They spend more time out of the water than almost any other seal. On average, 70% of their time is spent on land. Most seal species spend 50% of their time on land and 50% in the water.

Range and habitat[edit]

The Galápagos fur seal is endemic to the Galápagos Islands, with a single colony in northern Peru, according to the Organisation for Research and Conservation of Aquatic Animals[citation needed]; they live on the rocky shores of the islands which tend to be on the west sides, leaving only to feed.

Reproduction[edit]

Galápagos fur seals live in large colonies on the rocky shores. These colonies are then divided into territories by the female seals during breeding season, which is mid-August to mid-November. Every mother seal claims a territory for herself and breeds her pup there.[2]

Maternal care[edit]

Galápagos fur seals have the lowest reproductive rate reported in seals, and it takes an unusually long time to raise seal pups to independence.[2] Females bear only one pup at a time, and she remains with her newborn for a week before leaving to feed. She then periodically returns to the pup and stays to suckle it for a few days before leaving on another hunting trip. Females recognize their own pups by smell and sound, and pups also learn to identify their mothers by the females’ “Pup Attraction Calls”.[3] Mother-pup recognition is crucial because females exclusively nurse their own pups, often violently rejecting strange pups that approach. Orphaned seal pups usually try to sneak up on sleeping or calling females to suckle, but stealing milk is not enough to sustain the pups, and they usually die within a month.[3]

Interbrood conflict[edit]

Fur seal pups rely on their mother’s milk for the first eighteen months, and weaning may be delayed for up to two or three years if conditions are poor. The result is that every year up to 23% of pups are born when an older sibling is still suckling.[4] Survival of the younger sibling greatly depends on the availability of resources. In years when there is abundant food, the mortality rate of second pups is as low as 5%, which is equivalent to the mortality rate of pups without siblings. In years when food is scarce, 80% of pups with suckling older siblings die within a month.[2] The younger sibling thus serves as an insurance in case the first sibling dies, and also provides extra reproductive value in case conditions prove better than expected. Such a bet-hedging strategy is particularly useful in Galapagos fur seals, since there is a great deal of maternal investment in raising a seal pup to independence in an environment that has great fluctuations in food.

The high level of resource uncertainty, late weaning, and potential overlap time of suckling young all lead to violent sibling rivalry and provide a good environment for studying parent-offspring conflict. From an offspring’s point of view, it would be most beneficial to continue suckling and receive more than its fair share of milk, but to the mother seal, it would pay to wean the older, more independent offspring in order to invest in the next pup.[4] Thus, studies show that 75% of mothers intervened, often aggressively, when the older sibling harassed the newborn pups. Mothers would bite or lift the older offspring roughly by its skin, which sometimes caused open wounds. Maternal aggression towards the older sibling diminishes with time after the second sibling’s birth. Even without direct aggression, older siblings may still indirectly harm their younger siblings by outcompeting them for milk. The older offspring usually suckles first and allows their younger sibling access to the mother only after it is satiated, resulting in very little milk left over for the younger pup. Thus, the younger siblings often die from starvation.[5]

During periods when there is very little prey, interbrood conflict increases. Galapagos fur seal population is drastically affected by El Nino, a period accompanied by high water temperatures and a deepening thermocline.[6] Food becomes scarce during El Nino, and thus older seals exhibit an intense aversion to weaning, causing the mother seal to neglect the younger sibling.

Feeding and predation[edit]

The Galápagos fur seal feeds primarily on fish and cephalopods. They feed relatively close to shore and near the surface, but have been seen at depths of 169 m (554 ft). They primarily feed at night because their prey is much easier to catch then.[7] During normal years, food is relatively plentiful. However, during an El Niño year, there can be fierce competition for food, and many young pups die during these years. The adult seals feed themselves before their young and during particularly rough El Niño years, most of the young seal populations will die.

The Galápagos fur seal has virtually no constant predators. Occasionally, sharks and orcas have been seen feeding on the seals, but this is very rare. Sharks and orcas are the main predator of most other seal species, but their migration paths do not usually pass the Galápagos.

Conservation[edit]

Galápagos fur seals have had a declining population since the 19th century. Thousands of these seals were killed for their fur in the 1800s by poachers. Starting in 1959, Ecuador established strict laws to protect these animals. The government of Ecuador declared the Galápagos Islands a national park, and since then no major poaching has occurred. Despite the laws, another tragic blow to their population occurred during the 1982–1983 El Niño weather event. Almost all of the seal pups died, and about 30% of the adult population was wiped out.

The population is relatively stable now and is on the rise. Since 1983 no major calamity has occurred to decrease their population significantly.[citation needed]

References[edit]

  1. ^ Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group) 2008. Arctocephalus galapagoensis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.
  2. ^ a b c Horning, M. and Trillmich, F. (1997). "Ontogeny of diving behaviour in the Galapagos fur seal". Behaviour 134 (15): 1211–1257. doi:10.1163/156853997X00133. 
  3. ^ a b Trillmich, Fritz (1981). "Mutual Mother-Pup Recognition in Galápagos Fur Seals and Sea Lions: Cues Used and Functional Significance". Behaviour 78 (1/2): 21–42. doi:10.1163/156853981X00248. 
  4. ^ a b Davies, N. and Krebs, J. and West, S. (2012). An Introduction to Behavioural Ecology (Fourth ed.). Wiley-Blackwell. ISBN 978-1-4443-3949-9. 
  5. ^ Trillmitch, Fritz. and Wolf, Jochen (2008). "Parent–offspring and Sibling Conflict in Galápagos Fur Seals and Sea Lions". Behavioral Ecology and Sociobiology 62 (3): 363–375. doi:10.1007/s00265-007-0423-1. 
  6. ^ Aurioles-Gamboa, D. and Schramm, Y. and Mesnick, S. (2004). "Galapagos Fur Seals, Arctocephalus Galapagoensis, in Mexico". Latin American Journal of Aquatic Mammals 3 (1): 77–80. doi:10.5597/lajam00051. 
  7. ^ Horning, M. and Trillmich, F. (1999). "Lunar Cycles in Diel Prey Migrations Exert a Stronger Effect on the Diving of Juveniles Than Adult Galapagos Fur Seals". Proceedings of the Royal Society B 266 (1424): 1127–1132. doi:10.1098/rspb.1999.0753. 

Further reading[edit]

  • MarineBio.(1999). Retrieved September 22, 2008, from http://marinebio.org/species.asp?id=293
  • Randall R. Reeves, Brent S. Stewart, Phillip J. Clapham and James A. Powell (2002). National Audubon Society Guide to Marine Mammals of the World. Alfred A. Knopf, Inc. ISBN 0375411410. 
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