THE NORTHERN FUR SEAL

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Circular 169

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Breeding grounds of the northern fur seals: Robben
Island (Kaihyoto or Tyuleniy Island) off Sakhalin; the
Commander Islands (Bering Island and Medny or Copper
Island) at the Soviet end of the Aleutian chain; and
the Pribilof Islands — St. Paul Island, St. George Island,
Otter Island, Walrus Island, and Sea Lion Rock.

UNITED STATES DEPARTMENT OF THE INTERIOR

Stewart L. Udall, Secretary

James K, Carr, Under Secretary

Frank P. Briggs, Assistant Secretary for Fish and Wildlife

FISH AND WILDLIFE SERVICE. Clarence F. Pautzke, Commissioner

Bureau of commercial Fisheries, Donald L. McKernan, Director

THE NORTHERN FUR SEAL

by

Ralph C. Baker, Ford Wilke
and C. Howard Baltzo

Circular 169

Washington, D. C.
September 1963

Created in 1849, the Department of the Interior —
America's Department of Natural Resources — is concerned
with the management, conservation, and development of
the Nation's water, fish, wildHfe, mineral, forest, and park
and recreational resources. It also has major responsibilities
for Indian and Territorial affairs.

As the Nation's principal conservation agency, the
Department works to assure that nonrenewable resources
are developed and used wisely, that park and recreational
resources are conserved for the future, and that renewable
resources make their full contribution to the progress, pros-
perity, and security of the United States — now and in
the future.

CONTENTS

Page

Early history of fur sealing 1-3

Distribution and movement of seals 3-7

Food 8

Physical characteristics 8-9

Reproduction 10-11

Mortality and disease 11-12

Population 13

Management 13-16

Research 17

Sealing activity on the Pribilof Islands 17-18

Processing and sale of fur seal skins 18-19

THE NORTHERN FUR SEAL

by Ralph C. Baker, Ford Wilke,
and C. Howard Baltzo

Early History of Fur Sealing

Over 220 years ago Georg Wilhelm Steller drew
up the first scientific description of the fur seal
when he survived the wreck of the vessel com-
manded by Vitus Bering off what is now called
Bering Island in the Commander Islands.

Forty-two years later Gerassim Pribilof, nav-
igator in the service of Imperial Russia, joined
the search for other breeding grounds of the
North Pacific fur seals. Each spring the seals
were seen to swim northward through the passes
of the Aleutian Islands and disappear into the
fog and mist of Bering Sea. In 1786, 3 years
after his search began, Pribilof came upon the
islands that now bear his name and found fur
seals along the beaches in seemingly uncountable
numbers. Almost immediately the teeming rook-
eries began to yield sealskins for the fur markets
of the world, at about the time the 13 colonies
on the Atlantic coast of North America were
forming a new nation.

Two years before the discovery of the Pribilof
Islands, adventurous skippers from New England
and Europe had discovered commercial possibil-
ities in the great herds of fur seals in the South
Sea Islands. The first experimental cargo of
13,000 pelts from the Southern Hemisphere
appears to have been taken at the Falkland Islands

Authors note. — Ralph C. Baker, Assistant Director for
Resource Development, Bureau of Commercial Fisheries, U. S.
Fish and Wildlife Service, Washington 25, D.C. ; Ford Wilke,
Wildlije Research Biologist, and C. Howard Baltzo, Program
Director, Pribilof Fur Seal Program, Bureau of Commercial
Fisheries, U. S. Fish and Wildlife Service, Seattle, Wash.

in 1784 by the crew of the American vessel
States from Boston.

In the 50 years that followed, the fur seal rook-
eries on Mas-a-Fuero, Juan Fernandez, the South
Shetlands, Prince Edward, the Antipodes, and
countless other islands were destroyed as fast
as they were discovered. Literally millions of
pelts were taken to the Canton market to trade
for tea, silks, and other products of China. The
huge populations of fur seals south of the
equator were rapidly decimated. Some herds
survived, however, and are still found off the
coasts of South Africa, South America, Australia,
New Zealand, the Galapagos Islands, and some
of the subantarctic islands.

The exploitation of the Alaska herd at first
followed the same destructive pattern as that pur-
sued by sealers in the southern seas. Twice dur-
ing the Russian administration the herd on the
Pribilof Islands was threatened by annihilation:
first, through failure to restrict the numbers of
seals killed, and later by failure to adequately
protect the females. The killing of females finally
was forbidden by Russia after 1834, and the
herd began to increase. The Russians are said
to have taken more than IVz million pelts be-
tween the time of the discovery of the islands
and the sale of Alaska to the United States in
1867.

Immediately after the purchase of Alaska by
the United States, a number of independent com-
panies began sealing operations on the Pribilof

Islands, taking about 300,000 skins the first
season. An Act of Congress on 27 July 1868
prohibited the killing of fur seals, and on 3
March 1869 the islands were set aside by the U.S.
Government as a special reservation for the pro-
tection of the animals. A year later the U.S.
Treasury Department was authorized to lease ex-
clusive rights to take seals on the islands, with
the stipulation that no females were to be taken.
Further legislation in 1874 authorized the Sec-
retary of the Treasury to establish catch quotas
and open seasons for the lessee.

Under the first 20-year lease, beginning in 1870,
the Alaska Commercial Company took 1,977,377
sealskins. A second 20-year lease, to the North
American Commercial Company, produced only
342,651 sealskins for the period ending in 1909.

The leasing system was discontinued in 1910, and
since then the Alaska fur seal herd has been
under the management of the Federal Govern-
ment, first by the Secretary of Commerce through
the former Bureau of Fisheries and now by the
Secretary of the Interior through the Bureau of
Commercial Fisheries of the U.S. Fish and Wild-
life Service.

Fur seals are vulnerable to capture while at
sea as well as on land. Pelagic sealing, or taking
of fur seals at sea, began to develop on a com-
mercial scale about 1879. As practiced exten-
sively by American, Canadian, and Japanese seal-
ers in the North Pacific, pelagic sealing resulted
in the indiscriminate killing of the seals, without
regard to age or sex. The pelagic take of seal-
skins reached a peak of 61,838 in 1894.

"Fur seals sporting around the baidar — Natives of St. Paul lightering off the bundled sealskins to the
ship from the Village Cove." A sketch by Henry W. Elliott, who visited the Pribilofs for the Treasury De-
partment and the Smithsonian Institution in 1872, shortly after purchase of the islands from Russia. The
baidar, or bidarrah, was made of sea lion skins, canvas-covered bidarrahs are still used in ship-to-shore
ferrying.

Almost a million skins were taken on the high
seas from 1879 to 1909, and many of the seals
shot or speared in the open sea were not re-
covered. Because females comprised 60 to 80
percent of the pelagic catch, the effect on the
Alaska herd was disastrous. In 1912, when the
first complete census was taken, 215,900 seals
were counted or estimated. Although scientists
believe this estimate was too low, a severe reduction
in the Pribilof herd had undoubtedly taken place,
and the two smaller herds off the Asian coast
were faced with extinction.

After extended diplomatic negotiations and a
long series of ineffectual bilateral agreements, the
United States, Great Britain, Japan, and Russia
concluded a Convention on 7 July 1911, for the
protection of the fur seals of the North Pacific.
Pelagic sealing was prohibited except by abor-
igines using primitive weapons. Each country
owning fur seal rookeries agreed to share 30 per-
cent of its annual take of sealskins — Canada and
Japan each to receive 15 percent of the sealskins
from the Pribilof Islands and 15 percent of those
from the Commander Islands; and Canada,
Russia, and the United States each to re-
ceive 10 percent of the pelts from Robben
Island.

The Convention of 1911 provided for the first
time a sound basis for the management of the
North Pacific fur seals. It remained in force
for 30 years, until terminated by Japan on 23
October 1941. From 1942 to 1957 the Pribilof
herd was protected by a provisional agreement
between Canada and the United States, which
reserved to Canada 20 percent of the skins taken
each summer on the Pribilof Islands.

On 9 February 1957, a new interim North
Pacific Fur Seal Convention was concluded by
Canada, Japan, the Union of Soviet Socialist
Republics, and the United States, similar in form
to the 1911 Convention. The present Convention
provides in principle that Canada and Japan
each shall receive 15 percent of the sealskins
taken commercially by the United States and by
the U.S.S.R.

Under international protection and a rational
management program, the Alaska fur seal herd
has increased from the low point of about 216,-
000 animals in 1912 to its present level of over
1% million animals. From 1940 to 1962 the
herd has sustained an average yield of 62,300
male sealskins. Since 1956, the annual kill of
female seals has averaged 32,300.

Distribution and Movements of Seals

The northern fur seal, an abundant and widely
ranging mammal, is seldom observed alive except
by fishermen and seamen working offshore or
by visitors to the Alaskan and Asian islands
where the seals breed. Every winter beach-
combers find fur seal carcasses, mostly pups of
the previous summer, on beaches from the Alaska
Peninsula south to northern Oregon. Few young
seals migrate south of Oregon in winter.

Originally the fur seals that breed on the Pri-
bilof Islands, on the Commander Islands, and on

Robben Island and some of the Kurile Islands'
were described as three separate species because
of supposed differences in color and in shape
of head and neck. They have since been found
to be indistinguishable by physical appearance
and measurements; their wintering grounds over-
lap; and tagged seals, especially young males,
are regularly found in small numbers on rookery
islands other than where born. Therefore, the
fur seals of the North Pacific are now considered
to belong to a single species, Callorhinus ursinus.

1 Pribilof Islands are U. S. territory; Commander, Robben,
and Kurile Islands are under the administration of the U.S.S.R,

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In late June this 9-year-old bull fur seal Is approaching the age when he
will compete actively for territory on a rookery. Probably the territory
he seeks will be near the spot where he was born.

Except as stragglers, few fur seals range north
of the Pribilof Islands. They migrate south to
the Channel Islands off Santa Barbara, Calif. In
the west they range from the vicinity of the Com-
mander Islands to the seas southwest of Kinkazan
Peninsula on northern Honshu and into the Sea
of Japan.

Fur seals breed on the following islands: St.
Paul and St. George Islands and Sea Lion Rock
of the Pribilof group in Alaska; Copper and
Bering Islands of the Commander group off

Kamchatka; Robben Island, off Sakhalin; Kot-
ikovaya Rock and Srednevoya Island in the Kurile
Chain of Islands. Seals were also reported by
the Soviet Institute of Oceanology to be
on the Kurile Islands, Paramushir and Urup,
but no pups were seen. Fur seals of the

Kurile Islands were thought to be exterminated
by sealers in the 1890's; however, in 1955 and
1956, investigations revealed their presence once
again, in small numbers. About 80 percent of
the northern fur seals are from the Pribilof
Islands.

From preliminary research on the intermixing
of seals from American and Asian islands, scien-
tists believe that a third or more of the seals
found off the coast of Japan in winter and spring
come from the Pribilof Islands. The proportion
of the eastern Pacific seals that originated on
Asian islands has not yet been estimated. Only 1
Soviet-tagged seal was taken on the Pribilof
Islands before 1960, but 8 were found in 1961
and 21 in 1962. More may be expected from
the enlarged tagging program begun on Soviet
islands in 1958.

Unless sick or injured, fur seals rarely land
from the time they leave their rookery islands in
the fall until they return the following spring,
summer, or fall. The one known exception is
Samalga Island near the west end of Umnak
Island where seals, apparently males, have been
observed hauled out on a reef. A living pup was
born on the Washington coast in early July 1959.
Such an occurrence is extremely rare. During
some winters, adult females enter West Crawfish
Inlet near Sitka, Alaska, to feed on herring to
within one-half mile of shore.

Seals are usually seen 10 to 90 miles offshore
and are frequently most abundant between 30
and 70 miles. Most people living along coastal
areas of the western United States, particularly
California, are unaware that many thousands of
fur seals feed and rest for several winter months
on the nearby ocean.

The top speed of fur seals in water is not accur-
ately known. For short distances they can keep
ahead of a ship moving at 10 to 15 miles per
hour. They can be overtaken if chased persist-
ently by a ship with a speed of only 9 miles per
hour.

On the ocean surface the seals are often seen
asleep, floating on their side or back, with all
four flippers folded or with one or more idly
stretched into the air. On the island rookeries,
activity continues unabated day and night.

In the open ocean seals may occur singly or
in small groups. Food will often attract con-

centrations of from 6 to 20 seals. Several such
groups may be in view at one time. A loose
grouping of up to 100 has been observed. The
density of seals on wintering grounds is extremely
variable, ranging from none to over 70 per square
mile.

A wide range of surface water temperatures
is found where seals occur, ranging from 30°
up to 59" F. They are found in greatest abund-
ance in waters with surface temperature of from
47° to 54 F. What seems to be a preference
for water of certain temperature may actually
be a response to available food.

Bull seals winter principally in Alaska waters.
They have been seen most frequently in the Gulf
of Alaska. They begin landing at their breeding
rookeries on the Pribilof Islands in late April
and appear in increasing numbers until the middle
of June.

The oldest bulls arrive first, and others follow
in order of age. The oldest and earliest females
appear in June. Occasional yearlings have ap-
peared ashore as early as August, but most of
them land in October and early November and
may remain only 2 or 3 weeks before going to
sea again. More male than female yearlings
come ashore. Only a small proportion of the
yearlings come ashore at all.

During autumn, most of the animals ashore
appear to prefer areas farther up from the beaches
than during the summer. The main exodus of
seals from their breeding grounds takes place
during November even while some yearlings may
be still arriving.

Three- and four-year-old males, which make
up the bulk of the commercial kill, arrive in late
June, July, and early August. The midpoint
for 4-year-old male arrivals is 13-18 July and
for 3-year-old arrivals 20-28 July. The midpoint
for 4-year-oId female arrivals is more than a
month later. Three-year-old females arrive still
later, and 2-year-old females are found mixed with
yearling males in October and early November.

Summer on a typical
fur seal rookery —
Kitovi Rookery on St.
Paul Island. Char-
acteristically, the fur
seals return each
summer to the rook-
eries where they were
born. In May and
June come the harem
bulls or beachmas-
ters, later the females.

13 JUNE. — By mid-June most of the harem bulls have estab-
lished stations and await the arrival of the females.

\

28 JUNE. — By late June, the first females arrive, and harems
begin to form.

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The pups are born
soonafterthefemales
come ashore. The
pups grow stronger,
they wander over the
rookery and eventu-
ally gather in groups
or pods, while their
mothers spend much
time at sea searching
for food.

3 AUGUST. — In late July or early August the harems begin
to break up.

/

8 JULY. — In early July the harem groups remain closely knit.

Food

Fur seals feed particularly on small, schooling
fish such as anchovy, capelin, and herring but
will feed on whatever species are available. Squid
is a mainstay of their diet almost everywhere.
Anchovy, hake, squid, saury, and rockfish are
principal food items off California and Oregon.
Off Washington, herring, rockfish, and anchovy
are leading foods. Herring and walleye pollock
are important food items off Southeastern Alaska.
Capelin and sand lance are part of the seals' diet
in the Gulf of Alaska, the Aleutian Island passes,
and the Bering Sea. Salmon occurred in 28 of
the 1,829 stomachs containing food, collected in

1958 and 1959, in the northeast Pacific. Twelve
of the 28 salmon-containing stomachs were from
seals taken in Alaska. Forty-eight species of fish
and 8 species of squid were found in seal stomachs
collected off North America from 1958 to 1961. In
the same period 24 species of fish and 9 species of
squid were identified from seals in the western Pa-
cific where lantern fishes are a very important food.

At sea, seals feed primarily at night because
some of the important food species rise to the
upper water layers during darkness. Where food
is available during the day, seals feed then also.

Physical Characteristics

Compared with other seals and sea lions, the
fur seal has unusually large flippers. The large
flipper area is useful for cooling, especially on
land, since dense fur effectively insulates other
parts of the body. The fur, which contains over
300,000 hairs per square inch, is so impermeable
to water that the skin remains dry even when
the seal rubs or scratches itself in the water.
Molt is incomplete because part of the hairs re-
main fixed in the skin more than one year. Body
temperature is about 100° F. Overheating from
unusual exertion or sunshine when on land causes
obvious discomfort. Body temperatures above
107' F. result in heat prostration and usually
death.

The eyes are relatively large and capable of
gathering enough light for night activity. The
nostrils can be closed and the external ears are
small, tightly rolled cylinders with a narrow, waxy
orifice that prevents the entrance of water. A

fish or squid held by the 36 teeth has no chance
of escape. The lower incisors fit into a notch
in the upper incisors and the upper molar and
premolar teeth interlock with the lower, making a
highly efficient bite.

The question "How much does a fur seal
weigh?" has many answers. A 10-to 12-pound
pup eventually becomes either a mature female
weighing 95 to 110 pounds or a bull weighing
from 400 to over 600 pounds. Three-year-old
males as selected for the commercial kill average
62 pounds, and 4-year-old males 78 pounds. The
size difference between male and female is appar-
ent even before birth. In early May unborn
males are about an inch longer and V2 pound
heavier than females. At birth an average male
is 26 inches long and a female an inch shorter.
A large adult female measures 56 inches from
the tip of its nose to tip of tail and a bull 84
inches.

While at sea the females and young males are
gray in color. After a few days ashore they turn
yellow-brown from staining by the mud and ex-
crement on the rookeries. Although cleaned
somewhat during trips to sea, unstained pelage
is not restored until molt occurs. Pups are black

when born but assume a gray pelage in Sep-
tember. Males over 6 years old are predominantly
brownish-black, but they vary greatly and may
also be dark gray and reddish brown. An adult
male develops a short bushy mane on his shoulders
and neck.

The pelage of fur seals effectively prevents the animals from becoming wet. The photograph dem-
onstrates the water repellent nature of the underfur in a section freshly cut from a yearling seal. Mag-
nification is 4 times.

Reproduction

Motivated by a strong homing instinct, bulls
usually return to the rookery of their birth to
establish a territory which they will defend,
whether or not they are joined by females. A
female seal or group of seals occupying a terri-
tory is called a harem. Harems vary in size from
1 to over 100 females; the average is about 40.
Location determines the size of a bull's territory
and his harem and the rapidity with which he
will acquire females. Generally, locations near
the water attract the most females but there are
many exceptions. Locations that appear almost
identical to the human eye either may be crowded
with seals or completely unused. Females seek
a location rather than cL specific male. The most
vigorous efforts of a bull are not sufficient to
retain a female that is determined to leave.

On the Pribilof Islands in 1962, 12,674 harem
bulls were counted in addition to 11,759 bulls
without harems.

Age determinations have been made for seals
up to 26 years of age. Tagged seals 21 years old
were recovered in 1962. The maximum life span
is believed to be about 30 years. Most fur seals
have their first pups when 4 to 6 years of age.
Few bear young after age 18 or 19. Some 70
percent of the adult females in the Pribilof herd
in any one year bear young.

A large proportion of the fur seal pups are
born during the first three weeks of July. Females
give birth to one pup usually a day after first
coming ashore on the rookery. Five days later
they are impregnated, usually in a single mating,

and sometime in the following week make a trip
to sea to feed. Feeding excursions may last 5
to 14 days, but average 8 days. Females nurse
only their own offspring, which they recognize
by a combination of location, sound, and smell.
The pup must obtain enough of the rich milk,
containing about 45 percent fat, to survive be-
tween the widely spaced feedings. During the
nursing period the pup's stomach occupies most
of the body cavity. A well-fed pup in September
resembles a football with flippers! No food other
than milk is taken by the pup before it leaves
the island in the fall at weaned age of 3 or 4
months. By the time the young are ready to
leave the rookery in November, the larger ones
weigh over 30 pounds. Nursing ends abruptly
when the female leaves the islands to migrate
southward. The pups must then begin finding
their own food in the form of fish and squids.
After several months at sea they may not have
gained or may even have lost weight, but their
contours are more nearly those of an adult.

A much-repeated fallacy is that young fur
seals are taught to swim. The pups can swim
from the moment of their birth, and none ever
receives lessons from its mother. At first they
swim rather awkwardly with head high out of
the water but soon gain in skill and endurance.

During the first day or two after birth of her
pup the female will attempt to protect it and will
sometimes carry it in her mouth. Thereafter,
the female flees from an intruder without making
any attempt to protect her pup. A pup that
falls into a crevice in rocks dies because the
mother will not retrieve it.

10

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Fur seal pups sleeping on the sand near Tolstoi Rookery, St. Paul Island,
in late July. These pups, which are less than a month old, are resting during
one of the 5- to 14-day intervals between nursings.

Mortality and Disease

When the Pribilof herd was small, about 2
percent of the pups died on land; now from
10 to 15 percent are dead before the autumn
migration. In each of recent years, from 40,000
to over 100,000 have died on the Pribilof Islands.
More than half perish from the effects of hook-
worm infection. Starvation, physical injuries,
congenital defects, and bacterial infections also
kill many. No epizootic diseases have been ident-
ified, although the sudden death of several hund-
red seals on the Commander Islands in 1958 and
off St. George Island in 1962 places suspicion on
a disease or food toxin.

Hookworms occur in the tissues of seals of all
ages. The parasites are apparently able to pen-
etrate the skin, at least on bare surfaces such
as the flippers. Pups are infected through
nursing, and the parasite attaches principally to
the small intestine. Bloodsucking by the worm
causes severe anemia. By fall, the intestinal in-
fection disappears, but hookworms are retained
in the blubber, mammary tissue, and perhaps
other tissues. There is no evidence that adult
worms from the intestines move into the blubber.
Larval worms that penetrate the skin hatch from
eggs passing from the intestine of pups. Reasons

11

for variation in mortality on land from year to
year are not clear, but possibly variation is related
to the effect of weather on the number and in-
fectivity of hookworm larvae. High mortality of
pups on land is correlated with low survival to
age 3 even though mortality on land may be only
20 percent of the total loss. This suggests that
pups surviving a severe hookworm attack are left
in a weakened condition and are unable to with-
stand the rigors of ocean life.

Little is known about the causes of death at sea.

The killer whale and great white shark are known
predators of seals. Parasites probably also kill
seals. Evidence in the form of emaciated young
seals that drift ashore in winter suggests that in-
adequate food and violent weather are the greatest
hazards during the first year at sea. At this time
the pups make a sudden transition from nursing
to finding their own food in the cold, stormy,
winter ocean. Many perish. As high as 85
percent of some year classes may be lost by the
time they are 3 years old.

Each year a few brown, yellow, almost white, or piebald seal pups are born. Light col-
ored adults are occasionally seen but true albinos rarely survive.

12

Population

When the Convention of 1911 first gave inter-
national protection to fur seals, the Pribilof herd
numbered about 200,000 and could be counted
with reasonable success. After 1924, only bulls
were counted because crowding and constant inter-
change of animals on the rookeries made a mean-
ingful count impossible. Until 1948, the size of
the herd was estimated annually on the basis of
calculated geometric rates of increase established
just after the turn of the century. The calculated
and actual increase corresponded well until the
mid-1930's, but by 1947 the method was discon-
tinued because there was then no basis for cal-
culating the increase rate, with useful accuracy,
for a population that was near the peak of the
growth potential. The estimate of the number of
pups born in 1957 was 770,000. The total Pribi-
lof herd exceeds 1,500,000. The population on
all other North Pacific islands (Commanders,
Robben, Kuriles) is about 250,000 in late summer.
The herds on these islands have rates of increase
that are similar to the rate demonstrated by the
herd on the Pribilof Islands in the 1920's when

it was growing rapidly. Seals on the western Paci-
fic islands have a better survival of pups and
higher reproduction rates among young females.
The change in growth rate as these herds mature
will be followed with interest by students of animal
population dynamics.

Satisfactory management requires some mea-
sure of changes in various segments of the popu-
lation. These include number of pups born,
survival of year classes, number of bulls, preg-
nancy rates, and extent of mortality at various
ages. Marking of seals for management pur-
poses began in 1912. Since 1947 tagging has been
used as a means of estimating the population.
Over 500,000 seal pups were tagged between 1947
and 1962. The current rate of tagging is 50,000
per year. By combining ( 1 ) information from
tag recoveries, (2) age classification of the kill
through tooth growth- ring counts, (3) pregnancy
rates, and (4) pup mortality counts, annual est-
imates of the number of pups born are statistically
calculated.

Management

Fur seal habits are such that a program of
wise utilization is readily devised. The success
of such a program, however, depends on inter-
national cooperation because the seals live much
of the time outside territorial waters. In Alaska,
fur seals come ashore only on the Pribilof Islands,
always about the same date each year. Because
seals are highly polygynous and the sexes are born
in equal numbers, it is possible to take many males
without adversely affecting the productivity of
the herd. The young males, whose pelts are
most valuable, habitually haul out on the islands
apart froni the breeding animals in the harems,
so that little difficulty is experienced in obtaining
them.

Harvesting of the seals is limited for the most
part to the 3- and 4-year-old males. In 1918,
age-length relationships were established by the
U. S. Government from measurements taken of
seals of known age, branded as pups in 1912.
Until recently this age-length relation has served
as the basis for estimating the age of animals
to be utilized commercially. The kills are now
classified into age categories by counting the an-
nular ridges on a 10-percent sample of canine
teeth. Also the range of lengths within ages
is more fully understood through extensive recent
measurements of tagged seals.

From 1911 to 1917, seals were killed only for

13

the residents of the Pribilof Islands to use as food.
Commercial kiUing for skins was resumed in 1918
after the 6-year cessation. From 1918 to 1922,
harvests of seals were high in relation to pop-
ulation size because of the accumulation of males.
The kill declined after these were removed, but
thereafter steadily increased until 1940. From
1940 to 1955, it averaged about 66,000 males
annually. Since then, male production has varied
from a high of 96,000 in 1956 to a low of 30,000
in 1959. Part of the difference between these
extremes resulted from an extended season in 1956
which made available a larger proportion of the
3-year-old class, but recent fluctuations are caused
primarily by variations in year class survival.

In the management of the fur seal herd, the
Federal Government has adhered to a policy of
taking pelts from seals considered surplus to
breeding requirements. From 1923 to 1932, a
minimum yearly breeding reserve of several
thousand bachelors was provided by marking them
with a brand or by shearing a patch of fur, then
permitting them to return to the sea. This pre-
caution may not have been necessary, but it in-
sured that the number of males escaping the kill
would be adequate.

From 1932 to 1955, a sufficient breeding stock
was assured by limiting the killing season each
year to a selected period from about the middle
of June to the end of July. Only the male seals
41 to 45 inches long were taken as they appeared
in the daily drives on the islands during the
sealing season. From one-half to two-thirds of
the animals in this group are 3 years old, and
most of the rem.ainder are 4 years old; a small
number of 2- and 5-year-old males are included.
The proportion of 3- and 4-year-old animals
taken depends on the relative survival of year
classes.

In recent years the sealing season has been
adjusted to the number of young males that are
available and to some extent to the age and size
of seals that are wanted. Early seasons produce a

larger proportion of 4-year-old seals and later
seasons a larger proportion of 3-year-old seals,
since they arrive in order of age. Currently,
the season for male seals begins on 2 July and
ends on 5 August. Close cropping of 3-year-old
seals during a late season leaves relatively few
4-year-old males to be taken early in the following
year. Forecasts of year class strength made be-
fore the 3-year-old seals appear in the kill are
still inaccurate. Therefore, exact advance plan-
ning for harvests of a given size is not possible.

The number of males that have been escaping
the kill is considered to be more than adequate.
As a result, the upper size limit of harvestable
male seals has been increased recently. This
change permits closer cropping by taking animals
that would have been rejected solely because of
size under the former limit even though they
had skins of good quality. It also compensates
for the change in the method of measuring length.
Length is now measured from nose to tip of tail
rather than from nose to base of tail.

Failure of the harem bulls and the male kill to
increase in number after 1940 caused biologists
to conclude by 1952 that the herd had reached,
or was near, its peak of development. One major
factor that precludes further possible growth of
the herd is the limited food supply available to
the nursing females in the summer and to the
pups during their first months at sea in the fall.
Estimates of the number of pups born, based on
tag recoveries, indicate that production is high
but that survival to age 3 is now much more
variable than when the herd was smaller and
growing rapidly. On the basis of experience
with other animal populations and on calcula-
tions of the relation of pups born to the return
of males at age 3, it is believed that the max-
imum sustainable yield can be achieved from,
a fur seal herd that produces about 500,000
pups annually. The adult female component
of the herd has been undergoing reduction
since 1956 in order to bring it to a level that
will produce this optimum number of pups.

14

This scene on Tolstoi Rookery, St. Paul Island, in late July illustrates the fact that after mid-July a large
part of the females that have a pup to nurse are feeding in the sea and therefore many more pups
than females are to be seen on the rookeries.

Female seals do not appear on rhe hauling
grounds or the margins of rookeries, where they
are available for driving without disturbing seals
on the breeding areas, until August. Most fe-
males, therefore, are not taken until after the
harvest of males is concluded. Females occurring
on hauling grounds are principally (1) young

animals, (2) those not pregnant during the pre-
vious year, or (3) those whose pups have died.
Female seals most numerous on hauling grounds in
middle and late August are from 3 to 6 years old.
Their skins are more valuable than those of older
animals because they have fewer scars and do not
lose fur on the belly in the course of fur processing.

15

Females can be roughly separated into three
age groups by the color of their whiskers. Dark-
whiskered females are rarely over 4 years old,
those with mixed dark and white whiskers are 4
to 6 years old, and those with white whiskers are
usually 7 years or older. Thus the commercially
valuable, young, female seals may be readily se-
lected because of a fortunate combination of lo-
cation, time, and physical appearance.

Future harvests of fur seals on the Pribilof
Islands will continue to be composed of both
sexes. Reproducing females range from 4 to
over 20 years of age. The abundance of any
age group depends upon its success at survival,
principally during the first year of life. It is

estimated that from 15,000 to 30,000 surplus fe-
males should be harvested annually when the herd
is reduced to the level of maximum sustained
yield. At this stage, females 3 to 6 years old are
preferred, both because they furnish the highest
quality skins and because they are most easily
available. Males only are taken by the U.S.S.R.
on Robben Island and the Commander Islands,
but females may be taken in the future if the
Asian herds regain their optimum size.

As knowledge of population dynamics accum-
ulates, the probability increases of successfully
forecasting year class survival and the resulting
harvest.

When hauled out on land, fur seals are easily cut off from the sea and driven to nearby fields. Because
of their insulating fur, they must be driven slowly and for moderate distances to avoid heat prostration.

^"^k

Research

On their respective islands the United States
and the U.S.S.R. carry on research programs
that emphasize population dynamics. Tagging,
tag recovery, kill records by age and sex, and
studies of mortality and reproduction are all
essential to understanding fur seal populations.
In addition, research on growth, pelage and other
anatomical features, behavior, and parasitism
and other infections are underway or completed.

Canada, Japan, the U.S.S.R., and the United
States cooperate in a widespread investigation of
the ocean life of fur seals. The distribution,
ocean abundance, food habits, and intermingling
of seals of different origins are studied.

Most of the investigations are of aid to man-
agement, certain broad principles of animal pop-
ulations are being tested, and zoological knowledge
of marine mammals is increased.

Sealing Activity on the Pribilof Islands

The harem or rookery areas and adjacent
hauling grounds of the bachelors and idle bulls
are situated at widely separated points along the
southern and eastern beaches of St. Paul Island
and along the northern and western shores of
St. George Island. Owing, in part at least, to
the high bluffs characteristic of St. George
Island, only about 20 percent of the herd fre-
quents the limited beach areas of that island.

The greater part of the herd congregates on
the low-lying beaches of St. Paul Island, 40 miles
to the north. A few thousand fur seals haul
out on Sea Lion Rock, off the southern tip of St.
Paul Island. For convenience in administration,
the hauling grounds are divided into five groups
on St. Paul Island and four on St. George Island.
On each island during the sealing season the
hauling grounds are worked in rotation.

The labor required in the taking of sealskins
and the year-round maintenance of two Govern-
ment stations on the islands is supplied by the
native Aleut inhabitants who are employees of
the Bureau of Commercial Fisheries. During the
summer season the local labor supply is supple-

mented by Aleut workmen from the Aleutian
Islands.

On a typical day in the sealing season, a crew
of 20 to 50 Aleut sealers proceeds in trucks from
the village to the hauling ground. Leaving their
trucks, the sealers cautiously work their way up-
wind along the beach between the bachelor seals
and the water. With the line of escape to the
sea cut off, it is an easy matter to surround several
hundred to several thousand seals and drive them
slowly inland a short distance to the grass-cov-
ered killing field. Two or three Aleut boys pro-
vide the only guard necessary to prevent a stam-
pede of the animals back to the beach and the
open sea.

The sealing crew is well-trained and clubbers
are adept at selecting animals of commercial size.
The work is efficiently organized and carefully
supervised. One small group of seals after an-
other is separated from the main group. Seals
judged to be less than 41 inches, or of poor
pelage quality are permitted to return to the
beach. Animals of the desired size are quickly
and humanely dispatched with a single blow on
the head from a hardwood pole.

17

Each sealskin is stripped from the carcass by
the Aleut sealers in a matter of seconds. The
day's collection of skins is transported by trucks
to the village processing plant. Here they are
thoroughly soaked in cold sea water, blubbered,
and brine-cured. Boric-acid powder is applied
to the skin side of each cured and drained pelt
to prevent bacterial action, and a small quantity
of salt is sprinkled over the skins as they are
packed in barrels for shipment to the mainland,
where they are held in cold storage until pro-
cessed.

On St. Paul Island from 1918 to 1961, most
of the carcasses and the blubber removed from

the skins were converted to meal and oil in a
byproducts plant operated by the Government.
About 350 tons of meal and 40,000 gallons of
oil were produced each season and sold to the
highest bidder at Seattle, Wash. The meal was
used as a protein supplement in animal feeds,
and oil was used in soap making and tanning.
On St. George Island the number of carcasses
has never been sufficient to justify a reduction
operation, but much of the blubber from that
island is salted and later cold pressed to extract
oil for tanning seal skins. The byproducts plant
operation became uneconomical after 1961 and
was discontinued. The use of seal meat to feed
mink is being tested.

Processing and Sale of Fur Seal Skins

The processing and sale of all Government-
owned skins is by a private company serving as
agent for the Government. About 100 different
operations by highly skilled workmen are in-
volved in converting Pribilof Island sealskins in-
to the beautiful, soft, supple furs sold to the
fur trade at semi-annual auctions.

The first major step in the processing of seal-
skins is the removal of the coarse guard hair that
overlies the dense, soft underfur. The pelts are
thoroughly washed and subjected to moist heat
to loosen the guard hair so it can be extracted
by scraping. After the unhairing process, the
pelts are tanned and dyed.

U. S. Government sealskins have been dyed
four shades of colors: (1) black, (2) a rich
dark brown, (3) a neutral brown with overtones
of bluish gray, and (4), a midnight gray with
highlights of silver and a subtle blue cast.
Closely sheared pelts that arc not unhaired are
being introduced onto the market in increasing
volume as a new type of garment fur.

Pelts of northern fur seal have consistently
brought the highest prices of all sealskins on
the world market. The world human population
is increasing rapidly but only moderate increases
in the production of seal skins can be expected,
a situation that should strengthen the market.

Six to eight sealskins are needed to make a full
coat. Pelts remain the property of the U. S.
Government until sold at public auction held
semi-annually by the contracting processor for
the Government.

Nearly 2 million sealskins from surplus males
have been taken by the Government since restor-
ation of the herd was begun 45 years ago. The
net profit to the Federal Treasury from the United
States share of these skins has exceeded $25
million. A portion of the receipts are made
available by Congress to the Bureau of Commer-
cial Fisheries to defray expenses of administering
the Pribilof Islands and the fur seal industry;
70% of the net proceeds are given to Alaska
under terms of its statehood Act.

18

The future of the Alaska fur seal herd seems
assured as long as the nations of the world
continue to work together in the solution of
problems peculiar to such migratory wildlife pop-
ulations. An epilogue for the Alaska fur seal
story is found in the words of Dr. G.C.L. Bertram,

English biologist, following his visit to the Pri-
bilof Islands: "One can give no higher praise
than sincerely to hope that planning and agree-
ment for the future may be as beneficent and ra-
tional as have been the administration and conser-
vation of the herd during the last forty years."

Skins that have been washed, cleaned of blubber, cured in a saturated salt solution, and drained
ore rubbed with salt and boric-acid powder, rolled, and tightly packed in barrels for shipment.

H,ISi """I Libnirv - S.riar.

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GPO 985-199

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The Pribilof Islands in Bering Sea are the homeland of the largest fur
seal herd in the world. Here the fur seals come ashore to bear their
young on the rocks and sands above tidewater. The story behind
the restoration and development of the Alaska fur seal herd is one
of adventure and international diplomacy. It is a heartening account
of cooperation among nations — an outstanding example of wildlife
conservation.

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