Fur seals are sea lions not seals. They have forward-pointing back limbs, which allows them to get around on land, and have soft dense fur next to their skin. Coarse guard hairs provide a dense outer coat. Males remain in polar regions the year round but females migrate to warmer climates to give birth to their young. One of the main that distinguished sea lions and fur seals is that the latter has thick underfur.
The Fur seals thick layer of fur grows underneath coarse protective hair. But this hair does little to keep them warm when they dive deep in the water. To keep warm in deep seawater and on land seals and sea lions need blubber. Sea lions and fur seals have relatively thin layers of blubber but have more hair.
Fur seals were once extensively hunted for their furs. The fur is waterproof and very warm for the seals on land and at in surface waters. Their fur loses it warmth when the animal dives because under great pressure the water squeezes out the relatively warm air between the hairs.
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Southern Fur Seals
Southern fur seals include seven distinct species, of all of which live south of the Equator except the Guadalupe fur seal, The South African and Australian are the largest. The primary thing that differentiates them is geography, although some breed on the beaches in the. same island groups of the southern oceans.
Antarctic fur seal Fur Seal Species: Common name (Scientific name), Subspecies, Numbers
Antarctic fur seal (Arctocephalus gazella), 700,000-1,000,000
Galápagos fur seal (Arctocephalus galapagoensis), Endangered, 10,000
Guadalupe fur seal (Arctocephalus townsendi), 10,000
New Zealand fur Seal (Arctocephalus forsteri), 100,000
Subantarctic fur seal (Arctocephalus tropicalis), 200,000.
Brown fur seal (Arctocephalus pusillus), 1,060,000: Subspecies: Cape fur seal (A. p. pusillus), 1,000,000; Tasmanian fur seal (A. p. doriferus), 60,000
South American fur seal (Arctocephalus australis), 99,000
Unnamed Peruvian fur seal,10,500
Falkland Island fur seal (A. a. gracilis), unrecognized by IUCN, 109,500
Juan Fernández fur seal (Arctocephalus philippii), 16,000. They are found only on the Pacific Coast of South America, more specifically on the Juan Fernández Islands and the Desventuradas Islands.
South American Fur Seals
South American fur seals (Scientific name: Arctocephalus australis) inhabit rocky shores along the coasts of Uruguay, Argentina, Chile and Peru. They are most numerous on the Atlantic side of South America and can be found on Uruguay islands and the Falkland Islands. Secluded places with few human disturbances and are safer for breeding. South American fur seals are found as far north as central Peru. They have been sighted as far off as 600 kilometers from the coast. [Source: Amelia DelGreco, Animal Diversity Web (ADW) /=]
South American fur seals spend approximately equal time on land and at sea. When they dive they typically do so to depths of 40 to 170 meters (130 to 560 feet). Breeding periods are spent on the shores of Peru, Argentina, Uruguay and the Falkland islands. When its not the breeding season, they are usually in the ocean. When on land, they prefer rocky areas to shield them from the sun. They are able to move quite easily on land and are able to climb steep slopes. In the wild, these fur seals live between 12 and 30 years.
South American fur seals are nocturnal hunters. They feed on anchovies, shrimp, lobster, squid and krill. Where they live plays a big part in what they eat. In Peru and Uruguay they feed primarily on anchovies. Those living closer to Brazil shores hunt for shrimp. Those in Chile favor krill, particularly lobster krill. Fur seals can dive up to 170 meters and can stay underwater for seven minutes per dive. If the females are caring for young on shore, they will spend a couple days at sea, then come back for a few days to care for their pup.
South American fur seals are hunted by the South American sea lions, orcas, sharks, and humans. Other threats them include climate change and overfishing. These seals were hunted from 1515 to 1979 in Uruguay and Chile for their fur to make clothes skin to make leather and oil to light lanterns. They are no longer hunted commercially, but are still often poached, often for king crab bait. In 1997 the seals were harmed by an oil spill that covered about 5,000 square kilometers. An estimated 6,000 seals were killed. During El Nino years, food becomes scarce for the seals on the Pacific side of South America. An El Nino In Peru 2012, wiped out 80 percent of the females and pups. In Uruguay, the population is healthy and growing. South American fur seals are not endangered. They are designated as a species of least concern on the International Union for Conservation of Nature (IUCN) Red List and have no special status on Trade in Endangered Species (CITES).
South American Fur Seal Physical Characteristics
South American fur seals range in length from 1.4 to 1.9 meters (4.6 to 6.2 feet) and range in weight from 40 to 200 kilograms (90 to 440 pounds). Sexual dimorphism (differences between males and females) is significant. Males are much larger than females. Sexes are colored and patterned differently These seals are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them). [Source: Amelia DelGreco, Animal Diversity Web (ADW) /=]
Males can get up to three times larger than females. Females can reach up to 1.4 meters (4.6 feet) in length, whereas males can reach up to 1.9 meters 6.2 feet). Females weighing 50 kilograms (110 pounds) are considered large, but males can get up to 200 kilograms (440 pounds). Female seals are either dark brown or a dark gray on their backs, lighter in color on the nottom of their bodies. Male coloration is similar but can be darker. Juvenile males begin to have guard hairs around their face, from the top of their heads to about the shoulder area. When they become adults, the mane of guard hair is frosted with lighter gray coloring.
Adult seals have a stockier body than other fur seals and have a longer snout. The fins are also longer and narrower than other fur seals. South American fur seals have 20 upper teeth and 16 lower teeth. They have long front flippers to help them move around on the rocky shores. The fins of other fur seal tend to be more paddle like than those of South American fur seals.
South American Fur Seal Behavior and Communication
South American fur seals are nocturnal (active at night), motile (move around as opposed to being stationary), sedentary (remain in the same area), social (associates with others of its species; forms social groups), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). In terms of home range, male seals compete for territory during breeding season along the shore. The most dominate male tend to have larger territories. [Source: Amelia DelGreco, Animal Diversity Web (ADW) /=]
South American fur seals live together in rookeries along the shore. They often fish in groups and fur seals do move around. They spend most of their time in the water swimming, diving and searching for food. During the breeding season they live on land. Seals pick areas to breed that are rocky and provide shade. Males compete physically for territories and females . Each male competes for an area, and the most dominate males generally obtains the largest and best positioned area.
South American fur seals communicate with vision, touch and sound and sense using vision, touch, sound and chemicals usually detected with smell. They employ several vocalizations. noises. Mothers and their pup have a special calls that are individual to each pair. Studies indicate that pups only recognize their mother's voice. When a mother returns to her rookery after foraging in the ocean for a couple days, she needs to be able to find her pup among the crowd.
South American Fur Seal Mating and Reproduction
South American fur seals: 1) are viviparous, meaning they give birth to live young that developed in the body of the mother; 2) engage in delayed implantation (a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months); and 3) employ in embryonic diapause (temporary suspension of development of the embryo).[Source: Amelia DelGreco, Animal Diversity Web (ADW) /=]
South American fur seals breed once a year shortly after the females give birth. The breeding season is between October and December. The number of offspring is one. The gestation period ranges from eight to 12 months.On average females reach sexual maturity at age three years. On average males reach sexual maturity at seven years.
South American fur seals are polygynous (males having more than one female as a mate at one time). Males fights and compete for certain areas along the shore between October and December to establish territories for themselves and females in their harem. Dominant males claim the most females and the largest territory. The ratio of male to female South American fur seals is greater than that of any other mammal, implying that each male has more females on average than any other polygynous mammal. Seven to ten days after giving birth, the female will mate with a male. Embryonic diapause (temporary suspension of development of the embryo) lasts between three and four months.
South American Fur Seal Parenting and Offspring
fur seal pupSouth American fur seal young are precocial. This means they are relatively well-developed when born. Parental care is provided by females. During the pre-birth and pre-weaning stages provisioning and protecting is done by females.
Newborns weigh between 3.5 and 5.5 kilograms (7.7 and 13 pounds) and measure 60 to 65 centimeters (2 to 2.2 feet) in length. When they are first born, pups are black. As they grow and molt they become lighter. They molt three to four months after birth. [Source: Amelia DelGreco, Animal Diversity Web (ADW) /=]
Females give birth during per breeding season. Pups are weaned between six and 12 months. They may nurse for up to three years. In this extreme case, mothers nurse two pups at the same time. Males reach sexual maturity around the age of seven, but many of them don’t actually mate until they are eight years of age. This may be the result of competition required to earn territory and females.
Female seals give birth and feed pups until they are able to feed on their own. After pups are born mothers alternates between days in the water foraging for food and days on land caring for their young. Often times, the survival of the pup relies on how crowded the shoreline is with seals. When the mother is gone foraging, if the shore is too crowded, the young pup can get trampled by other female seals or get lost and starve. El Nino years often result in a lack of prey fish for the mothers to catch and the many pups die of starvation.
Guadalupe Fur Seals
Guadalupe fur seals (Scientific name: Arctocephalus townsendi) live in the waters off southern California and the Pacific coast of Mexico. During the breeding season, they are found in coastal rocky habitats and caves. Little is known about their whereabouts during the non-breeding season. Females weigh around 50 kilograms (110 pounds) and are about 1.5 meters (five feet long). Males weigh about 180 kilograms (400 pounds0 and are 2.2 meters (seven feet) long. Their lifespan is about 20 years. [Source: NOAA]
The breeding grounds of Guadalupe fur seals are almost entirely on Guadalupe Island, off the Pacific coast of Mexico. There are small populations off Baja California on San Benito Archipelago and off southern California at San Miguel Island. Guadalupe fur seals generally do not migrate, although they have been documented traveling great distances from their breeding grounds. They are only species of southern fur seals that occurs north of the equator. From archeological findings Guadalupe fur seals were historically found as far north as the northwest Washington coast.
Threats include entanglement and incidental hooking on (longlines) in commercial and recreational fishing gear, oil spills, coastal development and military activities Commercial sealers heavily hunted Guadalupe fur seals in the 1700s to the 1800s until they were thought to be extinct in the early 1900s. Dr. Hubbs and Dr. Bartholomew from the University of California rediscovered them breeding in a cave on Guadalupe Island in 1954.
The Guadalupe fur seal population has continued to increase from the small remnant group on Guadalupe Island due to protection by the Mexican Government. Guadalupe fur seals are listed as threatened under the Endangered Species Act and depleted under the Marine Mammal Protection Act. The Guadalupe fur seal population has been growing steadily since 1955.Based on surveys conducted between 2008 and 2010 there are approximately 20,000 of these fur seals.
Guadalupe Fur Seal Characteristics, Behavior, Feeding and Reproduction
Guadalupe fur seals have narrow, flat heads with pointed, narrow, long snouts. Their fore-flippers are broad, with some hair, reaching past their wrists and forming a "V" on the foreflipper. Their coloration is dark brown. Adult males have tan or yellow hairs on the back of the mane. Adult males are considerably longer and larger-bodied than adult females. [Source: NOAA]
Guadalupe fur seals are generally solitary, are thought to be non-social animals when at sea. They primarily feed at night on coastal and pelagic squid, and small pelagic fish (such as, mackerel,sardine, and lanternfish) by diving to average depths of 30 meters (65 feet) with maximum depths of about 76 meters (250 feet), They rest in the water with their heads below water and their hind-flippers jutting out. NOAA]
Guadalupe fur seals' breeding season extends from June through August. Adult males return to the colonies during early June. They set up territories that they defend through aggression and vocalizations when challenged or threatened by other males. Breeding Guadalupe males are polygamous and may mate with up to 12 females during a single breeding season. Adult females arrive to the colonies in early June, giving birth a few days later. Pups are born from early June through early July, with a peak in late. Pups are born from early June through early July, with a peak in late June. An adult female will mate about a week after giving birth to her pup. Weaning occurs around nine months.
Northern Fur Seals
Northern fur seals (Scientific name: Callorhinus ursinus) range over a large area from the Bering Sea in the east to the Japanese islands of Hokkaido and Honshu in the west. Also known as the Alaska or Proibilof fur seal, northern fur seals feed on fish and squid and hunt at night. They have very sensitive whiskers which they use to track prey. They in turn are fed on by sharks and killer whales. Sometimes pups are taken by foxes on land. There are around 650,000 of them. It was once estimated that there were more than a million of them.
Northern fur seals get their name from their fur, which looks black when wet but is brownish gray or reddish brown on males and silvery-gray with a white patch on females. Their hair is densely packed at 60,000 hairs per square centimeter, forming a waterproof coat and layer of insulation that allows the animal to thrive in cold water and deep sea environments. Their blood contains 3½ times the hemoglobin of humans.
Northern fur seals are members of the "eared seal" family (Otariidae). They spend most of the year in the ocean. Males can live up to 18 years, while females can live up to 27 years. Weaned pups typically spend nearly two years away before returning to their breeding colonies. Northern fur seals primarily use open ocean for foraging and rocky beaches for resting and reproduction. [Source: NOAA]
Northern fur seals often sleep in the open sea. They sleep unihemispherically, which means that one hemisphere of the brain sleeps while the other is awake. Dominant males form harems with 20 or 30 members and occasionally up to 100. They copulate with females for a month without eating and lose about 25 percent of their body weight. Sometimes females mate again within 48 hours of giving birth.
Northern fur seals have been hunted by Russians, Americans, Canadians and Japanese. for their fur and body parts which are regarded as having medicinal properties. One Japanese shogun ate fur seal extracts for strength. Hunting them is a matter of considerable controversy. Images of baby fur seals being clubbed
Northern Fur Seal Habitat, Migrations and Where They Are Found
Northern fur seals live in the north Pacific Ocean, with breeding grounds in Pribilofs and Commander islands and off the coast of California. There are estimated to 8,000 breeding pairs on San Miguel island, 628,000 in the Pribilofs and 442,000 at Russian rookeries. [Source: Canon advertisement]
Northern fur seals primarily inhabit two types of habitat: open ocean and rocky or sandy beaches on islands for resting, reproduction, and molting. They seals seasonally breed on six islands in the eastern North Pacific Ocean and Bering Sea in the United States — St. Paul, Bogoslof, St. George, Sea Lion Rock, San Miguel, and South Farallon. They also breed on the Commander Islands, Kuril Island, and Robben Island. The Pribilof Islands support the largest aggregation of northern fur seals, which breed on St. Paul, St. George, and Sea Lion Rock (about half of the world's northern fur seal population). Non-breeding northern fur seals haul-out on Walrus Island and Otter Island which are also part of the Pribilof Islands. [Source: NOAA]
Adult northern fur seals spend more than 300 days per year (about 80 percent of their time) at sea. During the summer and autumn they intermittently fast while on land and feed at sea. During the winter and spring they are pelagic, occupying the North Pacific Ocean as well as the Bering and Okhotsk Seas. In the open ocean, concentrations of northern fur seals may occur around oceanographic features — such as eddies, convergence-divergence zones, and frontal boundaries — because of the availability of prey in those places. In the winter, the southern boundary of the northern fur seal range extends across the Pacific Ocean, between southern California and Honshu Island, Japan, but they are found as far north as the Bering Sea.
In the spring, most northern fur seals migrate north to breeding colonies in the Bering Sea. Territorial adult male northern fur seals leave their breeding colonies in August and are thought to spend most of their time in the Bering Sea and North Pacific Ocean along the Aleutian Islands. Pregnant adult females begin their winter migration in November and generally travel to either the central North Pacific Ocean or to offshore areas along the west coast of North America to feed. Some northern fur seals may spend all year in the waters around San Miguel Island, California.
Northern Fur Seal Physical Characteristics
Sexual dimorphism (differences between males and females) is very pronounced with Northern fur seals. Adult males are up to 370 percent larger than adult females. Adult Northern fur males reach a length of 2.1 meters (7 feet) and weigh up 275 kilograms (600 pounds). Females reach 1.5 meters (5 feet) and weigh up to 65 kilograms (140 pounds) Pups are 60 centimeters (two feet) long when they are born. Their lifespan is up to 18 years for males and 27 years for females.
Northern fur seals have a stocky body, small head, very short snout, and extremely dense fur (46,500 fibers/centimeters²) that ends at the wrist lines of their flippers. Their flippers are the longest in the Otariidae family. Their hind flippers can measure up to one-fourth of their total body length. Their fore flippers are incredibly strong allowing them to walk or run on all fours. They can outrun a human on slippery rocks and can climb nearly vertical cliffs. [Source: NOAA]
Adult males are dark brown to black, and adult females are dark gray or brown on their backs and light gray, silver, or cream on their throat, chest, and stomach.The adults also have white whiskers, known as vibrissae, while the juveniles and pups have black vibrissae. Pups are uniformly black until they molt when they are around three months old.
Northern Fur Seal Behavior and Feeding
Northern fur seals are a highly pelagic (open ocean), mostly solitary, nocturnal species. They seals often sleep in the open sea — unihemispherically, which means that one hemisphere of the brain sleeps while the other is awake. They are known to be aggressive on land, especially during breeding and mating season. Adult males forcefully defend their breeding territory site. Male to male aggression is most frequently used in defense of territories and consists of pushing and biting, sometimes to the death. Female to female aggression is frequent but mild (open mouth threat). Intense female to female aggression (biting and pushing) is rare. [Source: NOAA]
Northern fur seals feed on wide variety of fish and sea creatures and are able to sleep in the water on their back due to their extraordinary buoyancy. Only during the breeding season to they spend a lot of rime on land, when bulls aggressively defend territories of several square meters,
Northern fur seals are described as generalist or opportunistic foragers, consuming a wide variety of midwater shelf fish and squid species. Walleye pollock is the predominant prey of northern fur seals that forage over the Bering Sea shelf. They consume greater amounts of oceanic fish and squid species when they forage over the slope and in off-shelf waters. Other primary prey include Pacific sand lance, Pacific herring, Northern smoothtongue, Atka mackerel, and Pacific salmon. The northern fur seal diet differs depending on geographic area and time of year. Northern fur seal diet and tracking (telemetry) studies indicate they forage in colony-specific areas, while they use their preferred land sites for resting and reproduction.
Northern Fur Seal Reproduction
Northern fur seals are born in the water. They stay close to their mothers the first few days and after that explore and feed on their own, Dominant males form harems with 20 or 30 members and occasionally up to 100. They copulate with females for a month without eating and lose about 25 percent of their body weight. Sometimes females mate again within 48 hours of giving birth. [Source: NOAA]
Beginning in May, male seals start returning to the breeding islands. Older males, or bulls, arrive first to vie for prime breeding territories before the females arrive. A male’s ability to mate depends on several factors, such as body size, fighting ability, size and location of the chosen breeding territory, and skill at interacting with females. Because males do not leave the breeding territory to feed, their ability to fast is critical. Males remain on their territory an average of 50 days, losing 20 percent to 25 percent of their body mass. Breeding males are typically 10 or more years old and maintain females within their territories. A small number of the total adult males in a territory accomplish most of the breeding.
Adult males are counted annually during the peak of the breeding season as an index of the population size. They are categorized as territorial with females, territorial without females, or non-territorial. There is some turnover of territorial males in August, allowing non-territorial males to occupy sites abandoned by territorial males, but the vast majority of adult females have already mated at this point. Territorial males exclude juvenile males from the breeding areas.
Juveniles instead congregate on land in areas called "haulouts" during the summer breeding season. The haulouts can be located inland, typically behind the breeding areas, or adjacent to the breeding areas. The typical structure of northern fur seal terrestrial habitat consists of the core group of breeding males with females, idle males without females on the fringe of the core area, and non-territorial males and juvenile males on haulouts outside the breeding areas.
Females generally have their first pup at 5 to 6 years of age and are in their reproductive prime between the ages of 8 and 13. They are not selective in their choice of mate, but they do show an affinity for a specific breeding site. Females typically start returning to the breeding islands in late June and give birth to a single pup a few days after arriving on land. Mating occurs within 5.3 days of giving birth. Female northern fur seals undergo embryonic diapause, meaning the embryo does not immediately implant in the uterus but is delayed until after lactation, or weaning. Females suckle their pups for 5 to 6 days and then go to sea to forage for 3.5 to 9.8 days. Pups are nursed until weaning (about 4 months) and leave the breeding site before their their mothers to forage independently for the first time.
Threats to Northern Fur Seals
The greatest threat to northern fur seals has been human hunters. They were hunted aggressively in the early 20th century for their fur on land and at sea, and their numbers shrunk considerably. In 1911, the Fur Seal Treaty created an international prohibition on hunting fur seals at sea. In 1984, the United States ended commercial harvest of northern fur seals on the Pribilof Islands. They have come back strong since then and are not hunted so much but are sometimes affected by disease ad food-chain disturbances. [Source: NOAA]
Northern fur seals, like all marine mammals, are protected under the Marine Mammal Protection Act (MMPA). In 1988, the Pribilof-Islands-Eastern Pacific population was designated as a depleted stock under the Marine Mammal Protection Act (MMPA) because it had declined by more than 50 percent from its estimated population of 2.1 million seals in the 1950s. The 2017 abundance estimate for the eastern Pacific stock is 620,660 northern fur seals. The California Stock is significantly smaller than the eastern Pacific stock. It was estimated to have 14,050 northern fur seals in 2016.
The killer whale is a primary predator of northern fur seals, but Steller sea lions are also known to prey on northern fur seals. Sharks may also prey on them. Human-produced threats include changes in available food, entanglement in fishing gear, habitat degradation, illegal taking, oil spills, environmental changes, oil and gas exploration, human presence, disturbance by marine vessels or aircraft, chronic pollution, and illegal harvests.
Entanglement in Marine Debris and Lost or Abandoned Fishing Gear: Northern fur seals can become entangled in lost or abandoned fishing gear such as trawl webbing, packing bands and monofilament nets, or other marine debris, either swimming off with the gear attached or becoming anchored. Northern fur seals encounter marine debris during their winter and spring migrations when they spend most of their time in the North Pacific foraging in the transition zone and eddies. They also encounter marine debris in the Bering Sea during their travels to and from their rookeries. Once entangled, seals may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death.
Changes in Available Food Due to Commercial Fishing: The type of available prey, access to prey, and distribution of prey can change for a variety of reasons. For example, regional and local prey can change because of changes in climate, oceanography, and the overall complexity of the oceans ecosystem. In addition, cumulative and annual commercial fisheries may result in reduced availability of northern fur seal prey. Fishery interactions can include fisheries bycatch and indirect effects like competition for commercial fish species.
Environmental Contaminants can enter the ocean and subsequently affect the food chain of the northern fur seal. Contaminant studies on northern fur seals have shown exposure to various toxic substances and evidence of accumulation in various tissues. Contamination sources can include oil and gas development, industrial runoff, vessel discharge, microplastics, vessel grounding, and oil spills. These contaminants have the potential to affect the immune system of northern fur seals, leaving them more susceptible to disease.
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated June 2023