Callorhinus ursinus

At the start of the breeding season, males begin arriving at their traditional sites about a month ahead of the females and start competing for breeding territories (4). These fights can be extremely violent, with each mature bull aiming to slash an opponent's neck with his sharp canine teeth. Only the largest and heaviest bulls can hope to claim the title of 'beachmaster'; the smaller younger males, who have no chance of competing with the fully-grown animals, occupy the fringes of the breeding territories (3). The females arrive in mid-June and give birth to the pups, conceived the year before, some two days after their arrival. Within a week of the birth, the females will mate again (4). Males compete to secure as many females as he can within his harem, although it is thought that females are influenced by the presence of other females and the characteristics of the territory rather than the mere size and power of the male (2). The beachmasters will continue to squabble and fight over females right through the breeding season, usually because these colonies are crowded, and wandering females sometimes stray into another male's territory (3). Occasionally, younger males will attempt to steal a mating with a female and, if spotted by one of the beachmasters, he will be chased off (2). In order to ensure that his females are not claimed by another male, bull northern fur seals do not feed throughout the breeding period and may eventually loose 20% of their body weight (4). Mothers suckle their pups for up to 10 days before returning to feed at sea, usually during the night. She will stay at sea from between four and ten days feeding, returning to feed her pup for one or two days. She will do this for four months before leaving her youngster and migrating south, usually in late October (4). Fur seals feed on a variety of prey, including squid and pollack (4) and have also been recorded taking seabirds (2). The fertilised egg within the female fur seal undergoes a four month period of delayed implantation. This ensures that that the developing pup will be born at the right time the following year when the animals return to their breeding grounds. The pups will spend as long as 22 months at sea before returning to the beach where they were born (4). Fur seals mature between the ages of three and six, but males will probably not begin to breed for an additional three years (2). The principal natural predators of fur seals are orca (killer whales), great white sharks and the much larger Steller sea lion Eumetopias jubatus. On land, pups can fall prey to foxes (4).

"Northern fur seals breed on islands near Russia, Alaska, and California, but not necessarily on the island where they were born—females tagged as pups have been found breeding on other islands. The seals range widely in the North Pacific, some swimming as far south as the US-Mexican border, and in the western Pacific, as far south as southern Japan. Females and their offspring tend to travel farther than males, who usually stay in Alaskan waters in the non-breeding season. Population numbers in some areas plummeted in the late 20th century, for a variety of reasons. From 1956-1968, 300,000 females were killed annually for their fur. Fisheries take millions of tons of fish—the seals' food—every year, and many seals died when they were trapped in tough, plastic, 30-mile-long fishing nets."

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Northern fur seals belong to the family known as eared seals, more commonly called sea lions. They differ from the true seals in having small external earflaps and hind flippers that can be turned to face forwards. Together with strong front flippers, this gives them extra mobility on land and an adult fur seal can move extremely fast across the beach if it has to. They also use their front flippers for swimming, whereas true seals use their hind flippers (3). Sea lions show a considerable size difference between the sexes. A bull northern fur seal is a big heavy animal, over two metres in length and weighing as much as 270 kg. Their fur varies in colour, ranging from reddish to black, and they have thick necks and a mane (2). The females (cows) are much smaller, less than a metre and a half in length and weighing a fifth as much as the bulls (2). Their colouring differs, too, having a silvery-grey back, with reddish-brown at the front and a whitish-grey patch on the chest (4). Young seal pups are black with paler markings around the nose and mouth (2).

Northern Fur Seals are a widely-distributed pelagic species in the waters of the North Pacific Ocean and the adjacent Bering Sea, Sea of Okhotsk and Sea of Japan. They range from Northern Baja California, Mexico north and offshore across the North Pacific to Northern Honshu, Japan. The southern limit of their distribution at sea is approximately 35° N. Vagrants reach the Yellow Sea in the west and eastern Beaufort Sea in the Arctic. The vast majority of the population breeds on the Pribilof Islands, with substantial numbers on the Commander Islands as well. Still other sites are used, including San Miguel Island in California, Bogoslof Island in the Bering Sea, and Robben Island off Sakhalin Island in Russia. Many animals, especially juveniles, migrate from the Bering Sea south to southern California or the waters off Japan, to spend the winter feeding.

Northern fur seals migrate from the North Pacific Ocean in the winter to the Bering Sea in the summer. Northern fur seal populations occur along the coast of California (down to San Diego), Alaska, Russia, and Japan.

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

Bering Sea, North Pacific, Sea of Okhotsk

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Transient

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Breeding range is mostly the eastern and western Bering Sea and Sea of Okhotsk; also the vicinity of San Miguel Island, California. Primary breeding sites are the Pribilof Islands (St. Paul and St. George) in the eastern Bering Sea and the Commander Islands in the western Bering Sea; smaller breeding rookeries are on Robben Island in the Sea of Okhotsk, on the Kuril Islands north of Japan, on Bogoslof Island in the eastern Aleutians, and on San Miguel Island (Adams Cove, Castle Rock) in southern California (Reeves et al. 1992). A few haul out seasonally on Southeast Farallon Island and (rarely) on San Nicolas Island, California (Reeves et al. 1992). In winter, the species ranges south to the Honshu coast, Japan, to California, and occasionally the Mexican coast in the eastern Pacific. Adult females range farther south in winter than do males, about which little is known regarding nonbreeding distribution (perhaps remain near the Aleutians).

Northern fur seals range over most of the northern Pacific Ocean, as far south as southern California in the east and to central Japan in the west. Northwards, their range extends to the Bering Sea, north of the Aleutian Islands, and the Sea of Okhotsk, west of the Kamchatka peninsular (4). Their main breeding grounds are on the Pribilof Islands of St. George and St. Paul in the southern Bering Sea. They also breed on a number of other islands scattered throughout their range, principally the central Kuril Islands and Tyuleniy Island in the Sea of Okhotsk, the Commander Islands off the coast of Alaska, Bogoslof Island in the Aleutians and San Miguel Island off the coast of California (4).

Northern fur seals are extremely sexually dimorphic. Male and female northern fur seals vary both in size and color. Adult females are smaller than males, measuring about 142 cm and weighing 43-50 kg, and are usually gray or brown. Adult males tend to be reddish in coloration or black, measure 213 cm, and weigh between 181 and 272 kg. Northern fur seal pups have black pelage. Additional characteristics include vibrissae, which are white on the adult and black on the pup. Pups usually have lighter markings on the nose and underside. Adults, especially males, have a mane, which is similar to the mantle of some squirrels. The adults have small noses, thick underfur,and long pinnae. The fur on the front flippers stops at the wrist.

Range mass: 43 to 272 kg.

Average mass: 147.50 kg.

Average length: 142-213 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes colored or patterned differently; ornamentation

Weight: 270000 grams

Sexual Dimorphism: Males are much larger than females.

Length:
Average: up to 2.1 m males; 1.2-1.5 m females

Weight:
Range: 136-279 kg males; 30-50 kg females

Habitat and Ecology

Systems

• Terrestrial
• Marine

Northern fur seals spend the majority of their lives in the cool water of the North Pacific Ocean. During the reproductive season northern fur seals arrive at island breeding grounds. Male northern fur seals remain on land. Females will remain on land during mating but will re-enter the ocean to hunt while nursing a pup.

Range depth: 207 (low) m.

Average depth: 175 m.

Habitat Regions: temperate ; saltwater or marine

Aquatic Biomes: pelagic ; coastal

Depth range based on 2073 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1685 samples.

Environmental ranges
  Depth range (m): 0 - 0
  Temperature range (°C): 3.487 - 16.999
  Nitrate (umol/L): 0.116 - 11.410
  Salinity (PPS): 30.381 - 33.496
  Oxygen (ml/l): 5.554 - 7.600
  Phosphate (umol/l): 0.330 - 1.408
  Silicate (umol/l): 1.436 - 30.351

Graphical representation

Temperature range (°C): 3.487 - 16.999

Nitrate (umol/L): 0.116 - 11.410

Salinity (PPS): 30.381 - 33.496

Oxygen (ml/l): 5.554 - 7.600

Phosphate (umol/l): 0.330 - 1.408

Silicate (umol/l): 1.436 - 30.351
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Habitat Type: Marine

Comments: Open ocean and coastal waters. Rocky shores during breeding season.

Although northern fur seals spend most of the year at sea in the cold northern waters of the Pacific Ocean (2), their breeding grounds are on rocky coastlines close to the edge of the continental slope (4).

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Males arrive in breeding areas in late May and early June, migrate south to winter range from early August to early October. Females and young migrate south beginning in October (e.g., see Ragen et al. 1995 for information on migration from St. Paul Island south through the Aleutian Islands), gone from Bering Sea by late November; begin returning north to rookeries in March (Reeves et al. 1992). San Miguel Island population probably stays in California waters all year.

Northern fur seals are described as opportunistic feeders. The main components of the diet are fish and squid. Occasionally northern fur seals will feed on birds. The diet is mainly dependent on the availability of prey due to season and location.

Foods eaten include: pollack, herring, lantern fish, cod, rockfish, squid, loons and petrels.

Animal Foods: birds; fish; mollusks

Primary Diet: carnivore (Piscivore )

Comments: Feeds mostly on small schooling fishes and squids, including a wide variety of species in both groups. Occasionally eats birds. Feeds mostly at night. Adult males fast 1-2 months during breeding season. In the Pribilof Islands, lactating females forage usually within 160 km of rookery, occasionally up to 430 km away; feeding dives average about 68 m, sometimes exceed 200 m (Reeves et al. 1992).

Because of their feeding habits, these seals play an important role in food webs, affecting the population of prey fishes. They also may have an effect on predator populations.

Since the main predators of northern fur seals are marine mammals, the main strategy of escape is to emerge onto land.

Known Predators:

• great white sharks (Carcharodon carcharias)
• killer whales (Orcinus orca)
• stellar sea lions (Eumetopias jubatus)

Callorhinus ursinus is prey of:
Carcharodon carcharias
Orcinus orca
Eumetopias jubatus

This list may not be complete but is based on published studies.

Callorhinus ursinus preys on:
Actinopterygii
Mollusca
Aves

This list may not be complete but is based on published studies.

10,000 to >1,000,000 individuals

Comments: Total population was estimated at 1.75 million in 1976, with nearly 900,000 in the Pribilofs and 256,000 in the Commander Islands. The Pribilof herd totaled about 2.5 million in the late 1950s; total population in 1983 was estimated at about 1.2 million (NMFS, Federal Register, 15 March 1996); in 2002, population estimate was 888,120 (NMFS 2003). San Miguel Island, California, population was about 10,500 in the mid-1990s (Barlow et al., cited by NMFS, Federal Register, 15 March 1996). Nearly 1,400 pups were born at the two San Miguel Island rookeries in 1988 (Reeves et al. 1992) and 2,634 in 1994 (Barlow et al.).

Solitary or slightly gregarious at sea.

Large sharks, killer whales, and northern sea lions are the primary predators. Mortality rate is nearly 50% in first year; natural mortality averages 10-20% per year for 2-3-year-olds, 10-11% for mature females, and 32-38% for adult males (Reeves et al. 1992).

Some movement occurs among rookeries; immigrants from the Pribilof, Commander, and Robben islands contributed to growth of the San Miguel Island colony, and recent repopulation of the Kuril Islands evidently resulted from immigration of seals from western and eastern Bering Sea rookeries (Reeves et al. 1992).

Vocal communication is important twice during the lifetime of a northern fur seal. Vocalizations are crucial to the mother and pup relationship. While the mother and pup are on the mating island the mother frequently returns to the ocean to hunt. When the mother returns vocalizations are used to find the young. If the young becomes lost the mother is able to locate her young by distinctive individual vocalizations. This type of vocalization is described as being loud, repetitive, and low or deep. Once the mother and pup have located each other the mother uses scent to verify the pup is her young.

Verbal communication also becomes important when males are competing for territory. Males will bark at each other during competition.

These animals are also reported to use scent marks.

Communication Channels: acoustic

Other Communication Modes: scent marks

Perception Channels: acoustic

Comments: Feeds mostly at night. Active day and night in breeding aggregations.

Gestation is approximately one year. After the pup is born nursing will last for 4 months. Both males and females of the species reach sexual maturity between the ages of 3-6 years.

(Insley 2000)

Actual lifespans of up to 26 years have been measured, although it is thought that the actual maximum may be around 30 years of age.

Range lifespan
Status: wild: 26 (high) years.

Typical lifespan
Status: wild: 30 (high) years.

Observations: After fertilization, implantation is delayed for 3.5 to 4 months, making the total gestation period to be approximately 11.75 months (Ronald Nowak 2003). In the wild, females have been estimated to live more than 30 years (http://www.demogr.mpg.de/longevityrecords), which is possible but unverified. Their longevity in captivity has not been studied in detail but one wild born specimen was about 25.1 years old when it died in captivity (Richard Weigl 2005).

Northern fur seals are polygynous. Males compete for territories and successful males can mate with many females.

Males arrive at the mating island prior to the females, at which time they begin to claim a mating territory. The mating islands in the Pribilofs, St. George and St. Paul,the southern California island San Miguel, and additional islands in the Bering Sea are the most common mating grounds.

Non-mating males will also travel to the island and usually end up on a territory on the outer edge. Non-mating males learn from their experiences until they reach mating age and are able to successfully compete with other males.

When females arrive it is believed that they choose a mate not based on the male's appearance, but the specific characteristics of the mating territory and possibly the presence of other females.

Males will participate in aggressive, but usually not lethal, behavior with other males. Females are more likely than males to be injured during the mating selection process. Occasionally, two males with fight over a female if she attempts to leave a mating territory, which could result in a tug of war. While males are sparing they will make attempts not to injure any pups in the area.

Mating System: polygynous

Northern fur seals are extremely polygamous. In some cases a single male may mate with up to 50 females during one breeding season. However, more typical is 15 to 20 females. The number of females a male mates with is dependent on the number of available females and the male’s ability to control a mating territory.

The female arrives at the mating island, gives birth to a pup which is a result of the prior year's mating, then mates. Mating occurs during summer. The fertilized egg undergoes delayed implantation. After the blastocyst stage occurs, development halts for approximately four months. Implantantion of the embryo occurs four months after fertilization.

Gestation lasts for approximately one year. Pups are born between June and July, and remain on land for 60-70 days. Peak pupping season is mid-June to mid-July, and peak mating occurs just after this, from late-June to late July.

Females typically become sexually mature between 3 and 6 years of age. Males reach sexually maturity between the same ages, but typically will not participate in mating until three years later.

The same group of males and females tends to return to the same mating island every year. However, male pups born on a particular island will go to a different island when they reach reproductive age. This can be considered dispersal of males.

Breeding interval: Northern fur seals breed annually.

Breeding season: Mating occur in summer, with the peak of mating falling in late June through mid-July.

Average number of offspring: 1.

Range gestation period: 11 to 12 months.

Average weaning age: 4 months.

Range age at sexual or reproductive maturity (female): 3 to 6 years.

Range age at sexual or reproductive maturity (male): 3 to 6 years.

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

Average birth mass: 5281 g.

Average number of offspring: 1.3.

Pups are born unable to swim or to move around much. Females care for their pups. They nurse the pups, providing milk to sustain them. During the nursing period, the mother makes feeding trips to the ocean. She may leave her pup for four to nine days! The mother returns to land to nurse the pup for about two days between feeding trips. Weaning occurs between three and four months of age, and is apparently begun by the pup. After the pup is weaned, there are no long-term social bonds in this species.

Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Protecting: Female)

Females arrive at rookery mainly in June, with some arriving as late as early August. Pups are born 2-3 days after pregnant females arrive. Pupping peaks about July 15, usually ends about August 1. Mating occurs 4-7 days after single pup is born. In the Pribilofs, pups are weaned in October and November, about 125 days after birth; young go to sea soon afterward. Females sexually mature usually at 4-5 years, few males breed before they are 8-9 years old. In a given year, about 57% of adult females give birth. Few males breed in more than 2 seasons. Maximum longevity about 26 years. Male territory may contain from less than 10 to about 100 females.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 6 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 6
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Vulnerable

Harvesting of the seal for its coat almost led to the species extinction in the mid 1700s. At the time of the Alaskan Treaty provisions where put into place in order to maintain population sizes. The treaty stated that only juvenile male seals, found on land, could be killed.

Current threats include loss of breeding habitat on islands.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: vulnerable

Canada

Rounded National Status Rank: N2M - Imperiled

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: Occurs in the North Pacific Ocean; declines have occurred in recent decades in the north, but California breeding population has increased; population decline in the Pribilof Islands in the 1980s apparently was due to harvests of females during the 1960s, increased mortality at sea (e.g., due to entanglement in debris such as discarded fishing nets), and perhaps reduced prey availability caused by increased commercial fishing; substantial numbers are killed in the high-seas squid driftnet fishery.

Vulnerable.

Classified as Vulnerable (VU A1b) on the IUCN Red List 2003 (1).

Population

Population Trend

Major Threats

Comments: Population decline in the Pribilof Islands in the 1980s apparently was due to harvests of females during the 1960s, increased mortality at sea (e.g., due to entanglement in debris such as discarded fishing nets), and perhaps reduced prey availability caused by increased commercial fishing in the North Pacific and Bering Sea. Substantial numbers are killed in the high-seas squid driftnet fishery between 40 and 50 degrees N latitude (Reeves et al. 1992). Until a new international fur seal treaty is established, this species remains vulnerable to renewed killing at sea.

The fur that protects the northern fur seal from the cold has led to the animals being hunted for centuries. Although early native peoples made little impact on their numbers, the 'discovery' of the species in the 18th century was followed by commercial hunting that nearly led to the seals' extinction by the end of the 19th century. In 1911 a treaty, the North Pacific Fur Seal Convention was signed by the USA, Japan, Russia and the UK (acting for the Dominion of Canada), limiting hunting to immature males on land and banning all sea hunts (4). Although serious commercial hunting of the northern fur seal has ended, the animals no longer enjoy the protection of the international treaty which lapsed in 1984. Neither is the animal currently protected under CITES (Convention on International Trade in Endangered Species) (5). There is still some hunting permitted under licence in Canadian waters by native peoples only (5), and a similar agreement exists for natives of the Aleutian Islands (4). But the main threats globally are now believed to be caused by entanglement in the nets of the Japanese squid fishing fleets and in the Bering Sea. Seals are also threatened by marine pollution such as plastic twine and waste packaging, as well as discarded trawl nets. The animals are very vulnerable to oil pollution and, with an increase in oil and gas exploration around several of their breeding grounds, there are fears that accidental oil spills and the inevitable industrial disturbance will affect seal populations (4).

Conservation Actions

The North Pacific Fur Seal Convention lapsed in 1984 after an extension was vetoed by the USA (5), but all commercial hunting has ceased at sea and only limited numbers are now taken under licence. It is believed the world population currently stands at about 1,350,000 animals, but with no current international agreement, some experts fear that commercial hunting could start again at some time in the future. There is also evidence that the El Niño event of 1997-8 affected the pup survival rate of the San Miguel Island breeding colony. A drop in the availability of fish led to 87% of young fur seals dying before they were weaned (4).

This species has often been accused of having a negative impact on fisheries. However, analysis of stomach contents indicate that northern fur seals do not feed on the same species that humans take. Most of the diet of these seals appears to be lanternfish, which are not harvested by people.

Negative Impacts: crop pest

Northern fur seals have been harvested mostly for their fur, but are also used as a food source.

Positive Impacts: food ; body parts are source of valuable material

Comments: Long history of commercial exploitation for pelts, both at sea and at breeding rookeries (see Reeves et al. 1992 for details). Commercial harvest on Pribilof Islands ended in the mid-1980s, but a relatively small subsistence harvest by Aleuts is allowed. Subsistence harvest by Aleut residents on Pribilof Islands in 1993 was 1518 seals on St. Paul Island and 319 seals on St. George Island (Federal Register, 1 November 1993).