is the single species of the genus Callorhinus. Size
and weights of this species are remarkably different depending
on sex. Fully mature males have a head and body length of 213
cm and weights from 181-272 kg. Mature females are about 142
cm long and weigh between 42-50 kg. Coloration of adult males
is dark gray to brown above, grayish shoulders and foreneck
and a short mane. The underparts and flippers are reddish brown.
Adult females and immature males are grayish brown above, reddish
brown underparts and a pale area on the chest. There is a heavy
underfur in both sexes and the pelage stops at an abrupt line
at the wrist on the flippers.
Northern Fur Seals eat a mixture of pelagic fish and squid.
C. ursinus spends most of its life at sea, coming ashore
primarily to breed. This accounts for 60-70 days per year and
occur on a few tiny islands found within the vast oceanic range
of the Northern fur seal. The greatest migratory distances traveled
by any pinniped are traveled by C. ursinus. Depending
on sex and age, the Northern fur seal leaves its breeding island
at various times. In the northern part of its range in the Pribilof
Islands, C. ursinus migrates to wintering areas in the
Aleutian Islands and on to the Gulf of Alaska. While at sea,
Northern Fur Seals are active mainly at night and morning and
evening hours, sleeping on one side during the middle of the
day. Activity at the rookeries, however, continues around the
clock. C. ursinus is an excellent swimmer and diver,
traveling as fast as 24km/hr for short distances.
Females make their first trip from the birthing grounds about
7 days after delivering their young. These feeding trips can
last from 4-9 days and are punctuated by trips back to the rookery
to nurse their babies for 2 days. Males may remain at the rookery
during breeding season for up to 2 months living on fat reserves.
In the Pribilofs, the breeding season begins in early June,
when the males arrive at the Islands. When the females arrive
in mid June, they congregate in groups of between 1-100, more
often an average of 40 are present. There is no harem formation,
though, and males have no control over the movements of the
females. No social bonds other than those between mother and
suckling young seem to be formed. About 2 days after the females
arrive on shore they give birth. Mating takes place 6 days later
and the blastocyst enters the uterus where implantation is delayed
for 3.5-4 months. Gestation is about 11.75 months. There is
usually a single offspring, born between June 20 and July 20.
Rarely, but more frequently recorded in C. ursinus than
any other otariid, twins are born. Average sizes of babies at
birth are 66 cm long and 5.4 kg. for males and 63 cm long and
4.5 kg for females. Newborns have a coarse black coat which
they shed at about 8 weeks. The new coat is steel gray above
and creamy white below. Though they are capable of swimming
at birth, the pups remain at the rookery for about a month.
They are weaned after 3-4 months and there is no apparent contact
between mother and young thereafter. Sexual maturity in females
is reached at 3-7 years, and they are able to give birth once
a year until about age 23. Sexual maturity in males is achieved
at 5-6 years of age, but they cannot maintain a breeding territory
until 10-12 years of age.
of their thick underfur, C. ursinus' pelt is one of the
most valuable of any pinniped. Because of this, the Pribilof
Island population was over hunted. Harvesting restrictions were
implemented from 1835 to 1867, allowing only immature males
to be taken. After the purchase of Alaska by the United States,
the restrictions were lifted and the population suffered greatly.
The species is still in crisis today.
are found in the North Pacific coastal regions in Canada, China
(vagrant to Shangdong), Japan, Mexico (coasts of Baja California),
Russia (Okhotsk and Bering Seas, Commander and Pribilof Isls),
USA (Alaska, Washington, Oregon, S California).