By Mark Nabong
Geographic Range
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. (Aurioles-Gamboa and Hernandez-Camacho, April 1999; Seal Conservation Society, 2001)
Biogeographic Regions:
nearctic 
(native ); pacific ocean (native ).
Habitat
( to 55.76 ft)
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. (Seal Conservation Society, 2001; Whitaker, 1997)
These animals are found in the following types of habitat:
temperate ; tropical ; saltwater or marine .
Aquatic Biomes:
coastal .
Physical Description
(110 to 352 lbs)
(6.23 ft)
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)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: male larger.
Reproduction
15 June - 22 July
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 systems:
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)
Key reproductive features:
seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual .
Behavior
Mother seals use olfactory clues to find their pups after foraging trips.
The seals are not migratory, but a male and his females will occasionally diperse to new areas.
(Whitaker 1997; Wickens & York 1997)
Key behaviors:
motile ; territorial ; social .
Food Habits
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)
Primary Diet:
carnivore (piscivore , molluscivore ).
Animal Foods:
fish; mollusks.
Ecosystem Roles
The Guadalupe fur seal plays the role of predator in the shoreline communities it inhabits.
(Whitaker 1997)
Economic Importance for Humans: Positive
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)
Conservation Status
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)
For More Information
Find Arctocephalus townsendi information at
Contributors
Mark Nabong (author), University of Michigan.
Kate Teeter (editor), University of Michigan.
