(DRAFT) - Taxonomy
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
TAXONOMY
NAME - seal, northern fur
OTHER COMMON NAMES - northern fur seal
ELEMENT CODE -
CATEGORY - Marine Mammals
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - ,
ORDER AND SUBORDER - ,
FAMILY AND SUBFAMILY - ,
GENUS AND SUBGENUS - Callorhinus,
SPECIES AND SSP - ursinus,
SCIENTIFIC NAME - Callorhinus ursinus
AUTHORITY -
TAXONOMY REFERENCES - 231 and 232
COMMENTS ON TAXONOMY -
Appendix A. of reference 232 is in preparation and will contain Alaska
native language names of the species.
Taxonomy - 1 (DRAFT) - Status
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
STATUS
Coded Status
Marine Mammal
Depleted
Furbearer
Existing, FMP exists
Subsistence
See Comments
REFERENCES FOR STATUS - 195 and 232
COMMENTS ON STATUS -
HISTORY OF LEGAL STATUS
Northern fur seals were previously managed by the United States Department
of Commerce, National Oceanic and Atmosphere Administration (NOAA), under
conditions of the Marine Mammal Protection Act (1972) and the North Pacific
Fur Seal Convention (1957). The National Marine Fisheries Service (NMFS)
oversaw the commercial harvest on the Pribilof Islands. The pelts were
distributed to the signators of the 1957 treaty *232*.
From 1957 through 1984, a commercial harvest of fur seals on the Pribilof
Islands was conducted by the United States under the authority of the
Interim Convention on Conservation of Fur Seals. When the U.S. Senate did
not ratify the protocol that would have extended the Convention, NOAA
determined that a commercial harvest could not take place under existing
domestic law *195*.
CURRENT LEGAL STATUS
The National Marine Fisheries Service (NMFS) has designated the Pribilof
Island population of North Pacific fur seals as depleted under the MMPA.
This action is required when a species or population stock falls below its
optimum sustainable population (OSP). Since the current Pribilof Island
population of North Pacific fur seals is below 50 percent of the population
levels observed in the 1940s and early 1950s, it is below its OSP and, by
definition, depleted. The designation became effective June 18, 1988 *195*.
Status - 1 (DRAFT) - Distribution
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
HABITAT - AQUATIC
TERRESTRIAL
REFERENCES FOR HABITAT - 232
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine RS.
Marine RS.
REFERENCES FOR NWI - 232
COMMENTS ON HABITAT ASSOCIATIONS -
TERRESTRIAL HABITAT
The terrestrial habitat of the northern fur seal is confined to rookeries
and haulout areas, mostly on the Pribilof Islands *232*.
Fur seals use rocky outcroppings along shorelines with exposed beach areas.
The strongly pelagic nature of fur seals suggests that protection from the
elements may not be important except for newborn pups and injured or sick
subadults and adults *232*.
REPRODUCTIVE HABITAT
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population *232*.
Habitat Associations - 1 (DRAFT) - Food Habits
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 232
LIFESTAGE FOOD FOOD PART
General Squid, Octopus See Comments
General Fish See Comments
General Osteichthyes See Comments
General Clupeiformes See Comments
General Salmoniformes See Comments
General Gadiformes See Comments
General Perciformes See Comments
Important Squid, Octopus See Comments
Important Fish See Comments
REFERENCES FOR GENERAL FOOD - 232
REFERENCES FOR IMPORTANT FOOD - 232
COMMENTS ON FOOD -
FOOD SPECIES USED
Fur seals feed almost exclusively on fish and squids, the latter being more
important in the Bering Sea than in the Gulf of Alaska *232*.
Gulf of Alaska:
Nearshore (shallower than 200 m), they primarily feed on herring (Clupea
harengus) during February/March; capelin (Mallotus villosus) during
March-July; and sand lance (Ammodytes hexapterus) during May-July.
Offshore (deeper than 200 m), they preimarily feed on rockfish
(Scorpaenidae); Salmonidae; and squid (Berryteuthis magister, Gonatopsis
borealis, Loligo opalescens). Fur seals also eat walleye pollock, Octopoda,
and gadids *232*.
Bering Sea:
The primary food of fur seals are capelin, sand lance, and Atka mackerel
(Pleurogrammus monopterygius) in early summer; capelin, Salmonidae,
herring, and walleye pollock (Theragra chalcogramma) in mid-to-late summer;
squid in deeper water (Berryteuthis) in early summer; and Gonatopsis in
mid-to-late summer. They also eat sablefish (Anoplopoma fibria), deep sea
smelts (Bathylagidae), sandfish (Trichodon trichodon), and tomcod
(Microgadus promimus) *232*.
FEEDING LOCATIONS
During the breeding season, nursing females feed in a 160 km radius from the
Pribilof Islands. Adult males do not feed while on the rookery *232.
During the spring migration, Portlock Banks, Fairweather Ground, and
Albatross Banks appear to be important feeding grounds *232*.
During the fall migration, feeding areas off the eastern Aleutian passes are
used heavily *232*.
FACTORS LIMITING AVAILABILITY OF FOOD
Many prey species move to deeper water during daylight *232*.
FEEDING BEHAVIOR
Food Habits - 1 (DRAFT) - Food Habits
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
Fur seals swallow whole fish smaller than 25 cm while underwater. This size
prey constitutes most of their diet *232*.
Fur seals feed on Mallotus, Clupea, Ammodytes, squid, and Salmonidae
primarily at night and dawn. They feed on Theragra primarily during the
day and on Pleurogrammus monopterygius during the night or morning. In
general, they feed mostly during the night *232*.
Fur seals often make repeated dives of less than five minutes duration to
the same depth *232*.
NUTRITIONAL REQUIREMENTS
In water of 5 degrees C, subadult and adult fur seals require 12 to 13.5% of
their body weight/day in fish. There is an inverse correlation between
water temperature and food consumption in the normal range of the Bering
Sea/Gulf of Alaska water temperatures *232*.
COMMENTS ON ADULT FOOD -
During the breeding season, nursing females feed in a 160 km radius from the
Pribilof Islands. Adult males do not feed while on the rookery *232.
Food Habits - 2 (DRAFT) - Environment Associations
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Water Temperature: Between 15-21 degrees C
G Water Temperature: Below 15 degrees C
G Water Temperature: Specified in Comments
G Water Depth Preference: Specified in Comments
G Terrestrial Features: Rock outcrops
G Terrestrial Features: Specified in Comments
G Coastal Features: Rocky offshore islands
G Coastal Features: Rocky beaches
G Coastal Features: Specified in Comments
G Human Association: Specified in Comments
BA Terrestrial Features: Rock outcrops
BA Terrestrial Features: Specified in Comments
BA Coastal Features: Rocky offshore islands
BA Coastal Features: Rocky beaches
BA Coastal Features: Specified in Comments
BA Human Association: Specified in Comments
J Terrestrial Features: Rock outcrops
J Terrestrial Features: Specified in Comments
J Coastal Features: Rocky offshore islands
J Coastal Features: Rocky beaches
J Coastal Features: Specified in Comments
J Human Association: Specified in Comments
FJ Coastal Features: Rocky offshore islands
FJ Coastal Features: Rocky beaches
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR BREEDING ADULT ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR JUVENILE ENVIRONMENTAL ASSOC_ - 232
REFERENCES FOR FEEDING JUVENILE ENVIRONMENTAL ASSOC_ - 232
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
WATER TEMPERATURE
Although found in water from -1 to 15 degrees C, fur seals are most
abundant where temperatures range between 8 and 12 degrees C, which may be
in response to food availability rather than reflecting a temperature
preference *232*.
Environment Associations - 1 (DRAFT) - Environment Associations
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
WATER DEPTH
No direct information has been found. However, fur seals in the Bering Sea
are generally distributed within or at the edge of the continental shelf
and slope. They may descend to 100 m when feeding, and they have been
recorded diving to 190 m *232*.
TERRESTRIAL HABITAT
The terrestrial habitat of the northern fur seal is confined to rookeries
and haulout areas, mostly on the Pribilof Islands *232*.
HUMAN ASSOCIATIONS
A summary of possible impacts from human-related activites includes the
following:
- Pollution of water and/or food supply
- Disturbance of rookeries/abandonment of pups
- Reduction of food supply
- Destruction of rookery sites
- Oiling of fur
- Mortality from fishing gear
REPRODUCTIVE HABITAT
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population *232*. For
the duration of lactation, females alternate several days of feeding at sea
with two-day suckling visits to her pups on the rookery *232*.
COMMENTS ON BREEDING ADULT ENVIRONMENTAL ASSOC_ -
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population *232*. For
the duration of lactation, females alternate several days of feeding at sea
with two-day suckling visits to her pups on the rookery *232*.
COMMENTS ON JUVENILE ENVIRONMENTAL ASSOC_ -
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population *232*. For
the duration of lactation, females alternate several days of feeding at sea
with two-day suckling visits to her pups on the rookery *232*.
COMMENTS ON FEEDING JUVENILE ENVIRONMENTAL ASSOC_ -
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population *232*. For
the duration of lactation, females alternate several days of feeding at sea
with two-day suckling visits to her pups on the rookery *232*.
Environment Associations - 2 (DRAFT) - Life History
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
LIFE HISTORY
PREDATION
Major predators are sharks and killer whales (Orcinus orca), which cannot
utilize terrestrial habitat, and northern sea lions (Eumetopias jubatus).
It has been noted that killer whales are not common near the Pribilof
Islands despite the concentration of fur seals there *232*.
FOOD SPECIES USED
Fur seals feed almost exclusively on fish and squids, the latter being more
important in the Bering Sea than in the Gulf of Alaska *232*.
Gulf of Alaska:
Nearshore (shallower than 200 m), they primarily feed on herring (Clupea
harengus) during February/March; capelin (Mallotus villosus) during
March-July; and sand lance (Ammodytes hexapterus) during May-July.
Offshore (deeper than 200 m), they preimarily feed on rockfish
(Scorpaenidae); Salmonidae; and squid (Berryteuthis magister, Gonatopsis
borealis, Loligo opalescens). Fur seals also eat walleye pollock, Octopoda,
and gadids *232*.
Bering Sea:
The primary food of fur seals are capelin, sand lance, and Atka mackerel
(Pleurogrammus monopterygius) in early summer; capelin, Salmonidae,
herring, and walleye pollock (Theragra chalcogramma) in mid-to-late summer;
squid in deeper water (Berryteuthis) in early summer; and Gonatopsis in
mid-to-late summer. They also eat sablefish (Anoplopoma fibria), deep sea
smelts (Bathylagidae), sandfish (Trichodon trichodon), and tomcod
(Microgadus promimus) *232*.
FEEDING LOCATIONS
During the breeding season, nursing females feed in a 160 km radius from the
Pribilof Islands. Adult males do not feed while on the rookery *232.
During the spring migration, Portlock Banks, Fairweather Ground, and
Albatross Banks appear to be important feeding grounds *232*.
During the fall migration, feeding areas off the eastern Aleutian passes are
used heavily *232*.
FACTORS LIMITING AVAILABILITY OF FOOD
Many prey species move to deeper water during daylight *232*.
FEEDING BEHAVIOR
Fur seals swallow whole fish smaller than 25 cm while underwater. This size
prey constitutes most of their diet *232*.
Fur seals feed on Mallotus, Clupea, Ammodytes, squid, and Salmonidae
primarily at night and dawn. They feed on Theragra primarily during the
day and on Pleurogrammus monopterygius during the night or morning. In
general, they feed mostly during the night *232*.
Fur seals often make repeated dives of less than five minutes duration to
the same depth *232*.
NUTRITIONAL REQUIREMENTS
In water of 5 degrees C, subadult and adult fur seals require 12 to 13.5% of
their body weight/day in fish. There is an inverse correlation between
water temperature and food consumption in the normal range of the Bering
Life History - 1 (DRAFT) - Life History
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
Sea/Gulf of Alaska water temperatures *232*.
REPRODUCTION
Breeding takes place on terrestrial rookeries. The rocky beaches on the
Pribilof Islands support 75 to 80% of the world's population. Males are
capable of spermatogenesis over the entire summer (mid June to Mid August).
For females, ovulation follows parturition by 6 to 10 days. Behavioral
estrus begins at the same time and terminates at first copulation or 48
hours after onset. The female will not become behaviorally receptive again
that year. Parturition occurs from early June to early August. Lactation
continues three to four months following parturition *232*.
Sexually mature males establish territories upon arrival at the rookery in
May in a descending order of age. Dominant bulls maintain territories
closest to the beach front and exclude other males but do not actively herd
or interfere with the females' movements. Males remain full-time on
females' territories until August.
The receptive female selects a territorial male, and copulation occurs soon
therafter. The female begins feeding excursions seven days postpartum. For
the duration of lactation, females alternate several days of feeding at sea
(usually within 160 km) with two-day suckling visits to her pups on the
rookery *232*.
Fur seals breed annually. The gestation period is one year. However, there
is a four-month delayed implantation *232*.
MATURATION
Males become mature at five to six years. However, they are not
behaviorally mature (i.e., able to maintain territory) until 8 to 12 years.
They become reproductively senescent by age 15, possibly due to the stress
associated with maintaining territories. Females are sexually mature at
four to seven years. They are reproductively active until 23 years. They
are, however, most active between 8 and 16 years *232*.
FECUNDITY
Estimates of the pregnancy rate vary from 60% for all females to 93% for
ages 7 to 17. Pup survival to the first year is 40 to 50% for males.
No information is available for female pup mortality. Females have a single
pup *232*.
MORTALITY
Pup mortality:
Total pup mortality on the rookery varies from 5 to 20%. Pup losses on the
rookery have been reported as follows: emaciation, 34%; disease and
parasitism, principally hookworm, Uncinaria, 59%; trauma (e.g., trampling,
injury from males), 3%. At sea, storms, predation by sea lions (3 to 6% in
1975), sharks, and killer whales are the principal causes of pup mortality.
Total pup mortality estimates range from 38 to 72% *232*.
Adult mortality:
The total mortality up to and including age-class three may be up to 85% in
some years. However, mortality to older age classes is "very low" *232*.
COMPETITION
Larga seals (Phoca largha) and ribbon seals (Phoca fasciata) feed on many of
the same species as fur seals. Larga seals are in the Pribilof area only
Life History - 2 (DRAFT) - Life History
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
during winter and early spring, when fur seals are absent, whereas ribbon
seals probably overlap northern fur seals in the southern Bering Sea during
summer. Marine birds such as kittiwakes (Rissa spp.), murres (Uria spp.),
horned puffin (Fratercula corniculata), and tufted puffin (Lunda cirrhata)
eat many of the same prey species as fur seals but mostly small sizes of
these species *232*.
HUMAN ASSOCIATIONS
A summary of possible impacts from human-related activites includes the
following:
- Pollution of water and/or food supply
- Disturbance of rookeries/abandonment of pups
- Reduction of food supply
- Destruction of rookery sites
- Oiling of fur
- Mortality from fishing gear
LIFE HISTORY CODES -
Foraging Strategy: Diving (aquatic)
Breeding/Spawning Season: June
Breeding/Spawning Season: July
Breeding/Spawning Season: August
Mating System (Single breeding season): Monogamy (mal
Gestation/Incubation Period: Greater than 8 months
Average Number of Offspring/Reproductive Effort: 1
Number of Broods/Litters (Reproductive Efforts) Per Ye
Periodicity: Active at night
REFERENCES FOR LIFE HISTORY- 232
Life History - 3 (DRAFT) - Management Practices
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Prohibiting harvest of species being described
Beneficial Restricting/regulating human use of habitats
Beneficial Restricting/regulating human disturbance of populations
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Maintaining unique or special habitat features [wetlands, caves,
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Other management practices [specified in comments]
Adverse Applying other toxicants
Adverse Other management practices [specified in comments]
Existing Prohibiting harvest of species being described
Existing Other management practices [specified in comments]
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 232
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 232
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 195
COMMENTS ON MANAGEMENT PRACTICES -
STATUS OF POPULATION
The Pribilof Island population of North Pacific fur seals has declined from
about 2.2 million in the 1950's to 800,000 today. The causes of the
decline remain under investigation *195*.
HUMAN ASSOCIATIONS
A summary of possible impacts from human-related activites includes the
following:
- Pollution of water and/or food supply
- Disturbance of rookeries/abandonment of pups
- Reduction of food supply
- Destruction of rookery sites
- Oiling of fur
- Mortality from fishing gear
CURRENT LEGAL STATUS AND RESTRICTIONS
The National Marine Fisheries Service (NMFS) has designated the Pribilof
Island population of North Pacific fur seals as depleted under the MMPA.
This action is required when a species or population stock falls below its
optimum sustainable population (OSP). Since the current Pribilof Island
population of North Pacific fur seals is below 50 percent of the population
levels observed in the 1940s and early 1950s, it is below its OSP and, by
definition, depleted. The designation became effective June 18, 1988 *195*.
Once a stock is designated as depleted, the MMPA requires additional
restrictions on taking and importation. Intentional takings are permitted
only for research, subsistence and handicraft purposes by Alaska Natives.
Small unintentional incidental takes resulting from other acitivites may be
allowed under certain circumstances *195*.
LIMITATIONS OF INFORMATION
Entanglements in nets and debris may be causing a decline in the population
size *232*.
Management Practices - 1 (DRAFT) - Management Practices
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
Large numbers of males are thought to winter in the Bering Sea north of
Unimak Pass. There have been no definitive surveys, however, because of
poor weather and light conditions.
RESEARCH
A major objective of NMFS' research is to identify and eliminate the causes
of the population's decline. In 1987, NMFS scientists conducted fur seal
research on the Pribilof Islands, Alaska, and on the Channel Islands,
California *195*.
Management Practices - 2 (DRAFT) - References
Species seal, northern fur
Species Id M120105
Date 26 AUG 96
References
195 * U.S. Department of Commerce. 1988. Marine Mammal
Protection Act of 1972 Annual Report. National Oceanic and
Atmospheric Administration (ed.):38.
231 * National Oceanographic Data Center. 1984. National
Oceanographic Data Center Taxonomic Code; Volume 2: Alphabetical
(Scientific Name Order) Listing. 2 (ed.). National Oceanographic
Data Center Washington, DC:374.
232 * State of Alaska Department of Fish, and Game. 1986. Alaska
Habitat Management Guide: Life Histories and Habitat
Requirements of Fish and Wildlife. (ed.). Alaska Department of
Fish and Game Juneau, Alaska:763.
276 * Harvey, James T., David L. Stein. 1986. The State of
Scientific Information Relating to the Biology and Ecology of
the Gorda Ridge Study Area, Northeast Pacific Ocean: Nekton.
(0-86-7) (ed.). Oregon Department of Geology and Mineral
Industries Portland, Oregon:131.
References - 1