Arctocephalus townsendi

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CARNIVORA OTARIIDAE

Scientific Name: Arctocephalus townsendi
Species Authority: Merriam, 1897
Common Name(s):
English Guadalupe Fur Seal, Lower Californian Fur Seal
French Arctocéphale de Guadalupe, Otarie à fourrure d'Amérique
Spanish Oso Marino de Guadalupe
Taxonomic Notes: Sealers harvesting fur seals in California and Mexico did not distinguish between Northern and Guadalupe Fur Seals in their harvest records, which makes it difficult to reconstruct former ranges. Skull morphology and genetics suggests that the closest relative of A. townsendi is A. philippii, which explains why the Guadalupe Fur Seal was formerly considered a subspecies of this latter species.

Assessment Information [top]

Red List Category & Criteria: Near Threatened 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:
The reduction of this species took place more than three generations (30 years) ago, and its population is now increasing. It is restricted to a single location during the breeding season, but there are no immediately obvious threats that seem likely to drive it to Critically Endangered or even Extinct in a very short time period; it is, however, close to meeting criterion D2 for Vulnerable, and so it is listed as Near Threatened.
History:
1996 Vulnerable
1994 Vulnerable (Groombridge 1994)
1990 Vulnerable (IUCN 1990)
1988 Vulnerable (IUCN Conservation Monitoring Centre 1988)
1986 Vulnerable (IUCN Conservation Monitoring Centre 1986)
1982 Vulnerable (Thornback and Jenkins 1982)

Geographic Range [top]

Range Description:The distribution of the Guadalupe Fur Seal has been expanding in recent years. The majority of the population, with around 12-15 thousand individuals, is centred on Guadalupe Island, where nearly all pups are born. In 1997 a small colony was discovered at the San Benitos Islands, southwest of Guadalupe Island, near the Baja California coast; this site was a former rookery. A census in 2007 recorded a population of 1,566 animals and the first pups on San Benitos. A pup was also born on San Miguel Island in the Channel Islands in 1997. Guadalupe Fur Seals have been reported on other southern California islands, and the Farallon Islands off northern California with increasing regularity since the 1980s. They have been sighted in the Sea of Cortez, and as far south as 17°39'N at Zihuatanejo Guerrero, Mexico. The distribution at sea is poorly known, but records from a few satellite-tracked adult females suggest they travel several hundred kilometres during feeding trips.
Countries:
Native:
Mexico (Guadalupe I.); United States
FAO Marine Fishing Areas:
Native:
Pacific – eastern central
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: Since the 1950s, the species has recovered from an estimated population of 200-500 animals to an estimated level of 15-17 thousands at present, and is growing at about 13.7% per year.
Population Trend: Increasing

Habitat and Ecology [top]

Habitat and Ecology: Guadalupe Fur Seal are sexually dimorphic, with males 1.5-2 times longer and approximately 3–4 times heavier than adult females. Adult males may reach 2 m. Two adult males that were measured were approximately 1.8 and 1.9 m in length. The 1.9 m male was estimated to weigh 160-170 kg. Adult females average 1.2 m and reach approximately 1.4 m, and weigh 40-50 kg. Pups are estimated to be 50–60 cm long, weigh around 6 kg at birth and are weaned when 9-11 months.

Guadalupe Fur Seals are polygynous, with males establishing territories that are occupied by an average of six females. Pups are born from mid-June to August with a median birth date of 21 June. Male tenure on territories lasts at least as long as 31 days. Males defend territories with vocalizations, displays, and mutual displays with neighbouring bulls. Fighting between males is rare once territories are established. Females select only male territories that provide cover and shade from the sun and all territories occupied by females are fronted by water and include tidal pools. Adult females enter the water daily, presumably for cooling, while otherwise “ashore” attending their pups. Most animals breed in small caves, grottos, and cliff and boulder areas on the rugged east coast of volcanic Guadalupe Island. A small breeding colony was discovered on the east side of the easternmost parts of the San Benitos Islands in 1997, and it appears to be growing annually. During the breeding season of 2007, Guadalupe Fur Seals were seen on the three islands of San Benito.

Females returning to the rookery for the first time usually arrive at night or early in the morning. Estrous occurs 5-10 days after a female gives birth, and females can leave for their first foraging trip right after mating, or stay on the colony for another few days before departing. Foraging and attendance patterns are not well-known but the limited information indicates that females may travel from 700 to 4,000 km during feeding trips lasting from 4 to 24 days. Pups are weaned at 9–11 months, and females with pups can be seen on or around the island throughout the winter and into the spring.

Knowledge of activities and behaviour at sea, away from Guadalupe Island, are limited to a handful of records. At sea, they appear to be mostly solitary. In recent years they have been reported in small numbers throughout the summer in waters off Southern California and northern Baja California by long range sport fishing boats pursuing albacore. Observations of animals in captivity suggest that they spend a considerable amount of time grooming while floating at the surface. They often rest at the surface in the characteristic southern fur seal, head-down posture. They also float with one or more flippers extended out of the water. When travelling rapidly, they have been observed to “porpoise.”

Prey preference and foraging activity are poorly known. Feeding habits based on scat analysis at San Benito Islands indicated that 95% of the prey items were squid species dominated by the market squid (Loligo opalescens) which made up 65% of the identifiable prey. Stomach contents retrieved from stranded animals included a variety of squid, bony fishes, and crustaceans, including vertically-migrating species.

Killer whales and sharks, particularly Great White Sharks which are regularly seen at Guadalupe Island in the summer, are undoubtedly predators of Guadalupe Fur Seals, although there is no evidence in the literature to support this assumption. A wound on a male from a Cookie-cutter Shark bite has been reported.
Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): Guadalupe Fur Seals have a long and mostly unfortunate history of association with humans. Hunted to the brink of extinction by the late 19th century, they were not reported again until 1926. Following this “rediscovery” all animals that could be found were taken and once again the species was thought to be extinct. Guadalupe Fur Seals were suspected to have survived, because of scattered unconfirmed reports in the 1930s, and were rediscovered once again with the sighting of a bull on San Nicholas Island in Southern California in 1949. An expedition to Guadalupe Island in 1954 confirmed the survival of the species.

Although the Guadalupe Fur Seal population is steadily growing, the species is still at risk because the total population remains low and nearly all pup production occurs at only one island. Also, since the species passed through a genetic bottleneck and probably recovered from a very small number of individuals, there may be a lack of genetic diversity within the surviving population (Weber et al. 2004).

The feeding ground of the species occupies the region around Guadalupe and San Benito Islands and the lower part of the California Current. This region is influenced by human population centres with contaminant runoff, extensive oil tanker traffic and offshore oil extraction activity from southern California. Like all fur seals, Guadalupe Fur Seals are vulnerable to oil spills because of their dependence on their thick pelage for thermoregulation. Guadalupe Fur Seals share most of their haulout and breeding sites with California Sea Lions, which have suffered from viral disease outbreaks in the past, and which could be a vector for transmission of diseases from terrestrial sources to Guadalupe Fur Seals, because of their extensive use of coastal areas.

No conflicts with commercial fisheries are known to exist at the present time, although gillnet and set-net fisheries probably take some animals, as is probably also the case for entanglement in marine debris. There is a possibility of negative interactions between Guadalupe Fur Seals and lobster fishermen when the seals occupy inshore areas to breed and out, particularly if the population continues to increase.

Conservation Actions [top]

Conservation Actions: It is listed on CITES Appendix I. The Guadalupe Fur Seal and its habitat are protected by the Mexican government and tourist visits to breeding islands are regulated and very limited. In the United States the species is protected by the Marine Mammal Protection Act and the Fish and Game Code of the State of California. The Guadalupe Fur Seal was listed as Threatened under the U.S. Endangered Species Act in 1985, which automatically brought the species the status of Depleted under the Marine Mammal Protection Act to the species.

Bibliography [top]

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Aurioles-Gamboa, D. and Camacho-Ríos, F. J. 2006. Diet and feeding overlap of two otariids, Zalophus californianus and Arctocephalus townsendi: Implications to survive environmental uncertainty. Aquatic Mammals 33(3): 315-326.

Aurioles-Gamboa, D., Henandez-Camacho, C. J. and Rodriguez-Krebs, E. 1999. Notes on the southernmost records of the Guadalupe fur seal, Arctocephalus townsendi, in Mexico. Marine Mammal Science 15: 581-583.

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Citation: Aurioles, D. & Trillmich, F. (IUCN SSC Pinniped Specialist Group) 2008. Arctocephalus townsendi. In: The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 25 July 2014.
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