Guadalupe Fur Seal

Perception Channels: tactile ; chemical

The Guadalupe fur seal was nearly hunted to extinction in the 1880's, with the known population numbering only 7 individuals in 1892. Other than two males sold to the San Diego Zoo in 1928, only one other GFS was sighted until 1954. Guadalupe Island was declared a seal sanctuary by the Mexican government in 1975. The Guadalupe fur seal was first placed on the "threatened" list in the US on March 11, 1967. By 1984 there were 1,600 seals in the Guadalupe Island population, including around 650 new pups. Current estimates place the population number at >7,000 individuals. Despite the bottlenecks of the late 1800's, there still remains a high level of genetic variability in the population. The population of Guadalupe fur seals is growing at the rate of 11.5% per annum.

(Bernardi et al. 1998; Seal Conservation Society, 2001; USFWS 2001; Whitaker 1997; Wickens & York 1997)

US Federal List: threatened

CITES: appendix i

IUCN Red List of Threatened Species: near threatened

Prehistorically, A. townsendi may have been hunted by Chumash Indians at San Miguel Island and other Channel Islands in California. The seal produces a rich, dense fur that was highly prized up until recent times, with the species nearly driven to extinction by seal hunters in the 1880's. In 1892, only seven individuals were known to exist. The population has rebounded, and the trade in the fur of Guadalupe fur seals is prohibited.

(Melin & DeLong 1999; Whitaker 1997)

The Guadalupe fur seal plays the role of predator in the shoreline communities it inhabits.

(Whitaker 1997)

Guadalupe fur seals eat a variety of fish, including lantern fish, mackerel, and fish in the muctophid family. Squid also constitute a major part of their diet. In all cases, the seals swim out to sea and dive for their prey items. During the breeding season, females make 2 to 6 day forging trips to sea, coming onshore in between each trip in order to suckle their pups.

Anchovy otoliths (bony concretions formed in the ears of fish) have been found the the digestive tracts of Guadalupe fur seals, but they are believed to be remains left from feeding of the seals by fishermen.

(Hanni et al. 1997; Seal Conservation Society 2001; Whitaker, 1997)

Animal Foods: fish; mollusks

Primary Diet: carnivore (Piscivore , Molluscivore )

The northernmost border of the range of A. townsendi is the Channel Islands, CA. The southern range border is Cedros Island, Baja California, Mexico. The only current breeding area is on Guadalupe Island, 290 km west of Baja California. The Guadalupe fur seal is the rarest of the fur seals, and it is also the only species of Arctocephalus found in the Northern Hemisphere. They have also been sighted as far south as Puerto Gurrero, near the Mexico/Guatemala border, as far north as the Point Reyes National Seashore in California, and possibly in the Gulf of California. It is possible that the true range of the species is underestimated due to the rarity of sightings.

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

Guadalupe fur seals only live on rocky coasts and in the caves found along these shores. They can dive to an average maximum depth of 17m for an average of 2.5 minutes.

Range elevation: 0 (high) m.

Range depth: onshore to 17 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: coastal

The fur of Guadalupe fur seals is brownish gray dorsally, with a silvery and yellowish-gray "mane" on the nape of the neck. Their snouts are pointed, with a rust-orange color on the sides.

This species has great sexual dimorphism. Adult males usually weigh about 124 kg, and may get up to 160 kg, females weigh about 50 kg, rarely over 55. Males grow up to 1.9 m long, females to 1.4 m.

(Whitaker 1997; Wickens & York 1997)

Range mass: 50 to 160 kg.

Range length: 1.9 (high) m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Guadalupe fur seals have a polygynous breeding system, which involves a male seal with a territory (a bull) defending both his terriory and the females in his harem. The harem numbers between 4 to 12 females, each of which typically have one pup that they nurse.

Mating System: polygynous

Male Guadalupe fur seals are territorial, like other fur seals. They defend harems that number an average of 6.2 breeding females for each territorial bull. Males will defend their territory for 35 to 122 days. Unlike most other seal species, the males of A. townsendi occasionally observe their harems from the water. Female Guadalupe fur seals mate 7-10 days after giving birth to a pup conceived the previous year (post-partum estrus). Females lactate for an average of 9-11 months; how this related to the actual length of time before weaning is unclear.

(Whitaker, 1997; Wickens & York, 1997)

Breeding season: 15 June - 22 July

Average number of offspring: 1.

Average gestation period: approximately 12 months.

Average weaning age: most likely 11 months.

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

Parental Investment: female parental care

Like other fur seals, Guadalupe fur seals are territorial, with adult males fighting to form territories, and then endeavouring to accumulate females into their territories (5). Females start arriving at the breeding sites from mid-June to July or August, and give birth to a pup conceived the previous season within days of their arrival (5). About seven to ten days after giving birth the mother mates and then leaves to feed at sea (5). For the next eight to eleven months before the pup is weaned (5), the female will spend alternate periods of nine to thirteen days feeding at sea and nursing periods of five to six days back on land (7). Their search for prey may take them up to 500 kilometres away from their breeding sites and most of their dives are down to a depth of 50 metres (8). The Guadalupe fur seal diet is quite specialized on squid (95 percent) but also includes a few fishes (5) (9).

In 1975, the Isla de Guadalupe was declared a sanctuary by the Mexican government and the Guadalupe fur seal is now fully protected under Mexican law (2). The species is also protected in the U.S. portion of its range by Californian law and is listed on Appendix I of CITES, prohibiting any international trade (3). Thankfully, these measures have produced a dramatic rise in numbers, and the future looks a little brighter for the world's rarest fur seal (10).

The Guadalupe fur seal was once considered extinct, after being decimated by poaching for its dense, luxurious underfur (2). Remarkably, the species was rediscovered in 1954 with just 14 individuals remaining and, despite a tremendous recovery, it still remains the rarest of all fur seal species (2) (4). In males, the thick, dense coat is dark, greyish-brown to greyish-black. Much of the head and back of the neck may appear yellowish, and a silvery to yellowish-grey mane of long, coarse hair exists on the nape of the thick, muscular neck (2) (5). Females are similarly coloured dark, greyish-brown to greyish-black, but often appear paler, creamy-grey on the underside of the neck and chest. Guadalupe fur seals have elongated, pointy snouts with whitish-cream whiskers, and the male has a large and bulbous nose (2).

When ashore, Guadalupe fur seals live and breed in rocky habitats, such as volcanic caves and grottos (2).

The Guadalupe fur seal used to have a much wider distribution, but for most of the 20th century breeding was restricted to only one island; Isla de Guadalupe, off the coast of Baja California, Mexico (4). In 1997 a group of Guadalupe fur seals was observed in Islas San Benito, 165 miles south west of Isla Guadalupe (6). In 2006 and 2007 the first pups were seen in San Benito, and the species has spread out all around the San Benito Archipelago. Non-breeding seals range as far north as the Farallon Islands and Sonoma County, California, and south into the Gulf of California (5).

Classified as Near Threatened (NT) on the IUCN Red List (1), and listed on Appendix I of CITES (3).

Prized for their luxurious underfur, Guadalupe seals were hunted to near extinction in the 19th century (2) (10). Following its rediscovery in 1954, when just 14 individuals were found, the species has experienced a remarkable recovery, with population numbers having rebounded to a far healthier 7,348 by the early 1990s (10). Nevertheless, some Guadalupe seals may still be killed through entanglement in drift and set gillnets and individuals, particularly juvenile females, have been found stranded with injuries caused by entanglement in marine debris. In addition, El Niño and Hurricane Darby were responsible for 33 percent pup mortality in 1992, but it is not known how the population was affected by the 1997 to 1998 El Niño event (7).