Mammal Species of the World
Ribbon seal (Histriophoca fasciata)
The seal has large eyes, a long, flexible neck, small, widely-spaced teeth and a relatively short rostrum. It can grow about 1.5-1.7 m long, weighing 70-95 kg in both sexes.
This seasonally ice-bound species is found in the western and central Arctic and Subarctic regions of the North Pacific, notably in the Bering, Chukchi and Okhotsk seas, from Hokkaido and the northern Sea of Japan north and offshore to the East Siberian Sea in the Russian Federation to the western Beaufort Sea and south to the Alaska Peninsula and Aleutian Islands. In late winter and spring, it hauls out on pack ice and ice floes in pairs or small groups to breed, moult and give birth at the ice front, 100-200 km offshore, near the contiental shelf and away from the edge of floes. It stays there until early summer. It prefers areas of 60-80% moderately thick ice coverage, preferring broken pack ice over solid ice sheets and highly concentrated pack ice and shore fast ice. It can only open and maintain access holes in ice up to approximately 15 cm thick. It does not haul-out on land unless moribund. In summer and autumn, it lives in open water, but some move north as the ice recedes with warmer temperatures; it almost never comes to land during this time. In two cases ribbon seals have been found as far south as Seattle, Washington and Morro Bay, California. Seals from the Bering Sea population may summer in the Chukchi Sea and those from the Sea of Okhotsk, which has no ribbon seals by mid-July, may move into the southern Bering Sea.
The seal is solitary for much of its life and forms no herds, but scattered individuals may assemble on favorable ice floes. Biologists believe it has extensive social interactions underwater. It is rarely seen on land. It maintains access holes in ice up to @ 15 cm thick, and can often be seen in the middle of large floes. It can move rapidly on ice, using slashing side-to-side motions and running, rather than caterpillaring. It extends its neck to peer at sources of disturbance, but shows little concern for approaching people or vessels. The seal makes seasonal migrations, sometimes over 200 km, north and south with the receding and advancing ice edge.
The adult feeds almost exclusively on pelagic creatures: shrimps, fish such as pollocks, eelpouts, capelins and cods and cephalopods such as squid and octopus. Ribbon seals eat primarily fish, taking fish species depending on their relative abundance in the area. Ribbon seals also eat squid, shrimp, and crabs. Young seals eat euphausiids after weaning. At a year old, they switch to feed mainly on shrimp and other crustaceans for a year. Two-year-olds take up the adult diet. The seal dives to depths of up to 200 m to find food. Predators of the seal include the orca, Pacific and Arctic sleeper sharks and polar bear.
The mating system is probably polygynous, where mating occurs from April to early May, at about the same time as weaning. Adult females become pregnant once a year; the annual pregnancy rate is 85%. Gestation lasts 9 months after 2-3 months of delayed implantation, probably to assure the presence of ice at the time of birth. Females usually give birth to one pup on ice floes in April or May, generally far offshore (except when ice edge is near St. Matthew and St. Lawrence islands). They prefer moderately thick, clean, white, broken pack ice over solid ice sheets and ice with sediment or algae. The newborn pup is 0.9m long and weighs 9-10kg. It is fed for 3-4 weeks on its mother's milk, while its weight double. As soon as the pups are weaned, they leave their mothers and the adults will mate again. The pups spend a lot of time practicing diving and learning how to move on the ice, where they remain for a few more weeks, during which it moults its dense white fur and its colour changes to blue-grey on the back and sides and silvery or greyish beneath. It loses a drastic amount of weight. After this period, it can dive and hunt by itself. First year mortality is 44%. The typical design shows at the age of four years. Females becomes sexually mature at 2-5 years; many do not produce a pup until 4-5 years old; thereafter, almost all adult females give birth annually. Males become sexually mature at 3-6 years. Mortality during the first four years of life is nearly 58%. The generation time is @ 10 years. The seal may live for 20-31years in the wild.
The ribbon seal is the only living species in Histriophoca, but a possible fossil species, H. alekseevi, has been described from the Miocene of Moldova. Some other authors place Histriophoca, Pagophilus and Pusa in the genus Phoca. A cladistic analysis of mitochondrial DNA data yielded three clades among northern seals: Phoca-Pusa-Halichoerus, Cystophora-Pagophilus and Erignathus. Each clade may be regarded as a tribe of the subfamily Phocinae. As Cystophora is the closest relative of Pagophilus, the latter cannot be regarded as congeneric with Phoca; their differences justify placing them in separate genera. Mouchaty et al found a close phylogenetic relationship between the cytochrome b gene of Pagophilus groenlandicus and Histriophoca fasciata.
The Red List Category is "Data Deficient". Young ribbon seals resemble young harp seals and were hunted for their fur. Adults are vulnerable, due to a lack of caution on the ice, but are harder to catch than harp seals, which live in groups. Some adults drown in commercial salmon and bottom-set gill nets in the Bering Sea and North Pacific. Soviet commercial harvesting for pelts, meat and oil, in the Bering Sea in the 1950s-60s led to a population decline, probably from about 80,000-90,000 to around 60,000. The Bering Sea population probably declined soon after commercial hunting began in 1961. The average age of harvested animals declined from 9.8 years in 1961, to 6.9 in 1962, and 4.9 in 1963, while the number of ribbon seals killed per day dropped regardless of hunting conditions. After the harvest was limited, abundance of the species quickly recovered. Russia stopped large scale commercial harvesting of ribbon seals in 1994. A reduced harvest resulted in a population increase. Current shore-based harvests in the Russian Far East are at very low levels and not likely to be a threat to the population. Very few seals are taken yearly; some are taken for subsistence purposes by native peoples. Other potential threats include industrial offshore development and overharvesting of prey species. The seal will probably be badly impacted by reductions in the extent and seasonal coverage of sea ice, due to climate change and rapid reduction of sea ice habitat essential for pupping and moulting. If global warming continues, the population will probably decline by at least 30% within next 30 years , which will qualify the species for listing as vulnerable. In the USA, ribbon seals are protected under the Marine Mammal Protection Act. In 2008 the US government considered adding ribbon seals to the endangered species list, but decided that sea ice critical to the seals; survival will not be endangered by global warming and declined to list the species, which became a U.S. National Marine Fisheries Service Species of Concern.
Ribbon seals (Histriophoca fasciata) are native to Arctic regions, occurring throughout icy waters of the northern Pacific Ocean and southern Arctic Ocean. Three populations of ribbon seals currently exist: two in the Sea of Okhotsk and one in the Bering Sea.
Ribbon seals most frequently inhabit the Bering Sea and the Sea of Okhotsk. Both are located near southern Russia, just north of Korea and Japan. The southern-most limit of the ribbon seal range extends as far south as the Aleutian Islands, a chain of volcanic islands located just west of the Alaska Peninsula. The northern-most portion of their range extends to the Chukchi Sea, between Alaska and Siberia. Ribbon seals have been reported as far west as the Beaufort Sea, just beyond the limits of Alaska. Solitary ribbon seals also have been observed along the coast of California.
Little is known about the extent of ribbon seal migration. During the breeding season, ribbon seals sometimes migrate to southern portions of the Chukchi Sea. They also are seen frequently in northern portions of the Bering Sea.
Biogeographic Regions: arctic ocean (Native ); pacific ocean (Native )
Other Geographic Terms: holarctic
- Berta, A., J. Sumich, K. Kovacs. 2006. Marine Mammals Evolutionary Biology. San Diego, California: Academic Press.
- Burns, J. 1970. Remarks on the distribution and natural history oh phagophilic pinnipeds in the Bering and Chuckchi seas. Journal of Mammology, 51/3: 445-454.
- MacDonald, S., J. Cook. 2009. Recent Mammals of Alaska. Fairfield, AK: University of Alaska Press.
- Macdonald, D. 2006. Seals, sea lions, and walruses. Pp. 520-544 in D Macdonald, ed. The Princeton Encyclopedia of Mammals, Vol. 1, 1 Edition. Princeton, NJ: Princeton University Press.
- National Oceanic and Atmospheric Administration. Status Review of the Ribbon Seal (Histriophoca fasciata). NMFS-AFSC-191. The Northwest Fisheries Science Center: U.S. Department of Commerce. 2008.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Mainly pack ice from Hokkaido and the Sea of Okhotsk to northern Alaska and the Aleutian Islands; from late winter to early summer concentrated in ice-covered parts of the Chukchi, Bering, and Okhotsk seas and adjacent straits and bays (Nowak 1991). Most common in the Bering and Okhotsk seas; apparently relatively few summer in the Chukchi Sea (Reeves et al. 1992). Okhotsk Sea population may move into the Bering Sea for the summer.
The respiratory system of ribbon seals is unique, they lack lobes in the lungs. These lobes, common in other species, create multiple lung sections divided by thin walls of tissue. Ribbon seals have well-developed air sacs, believed to help with buoyancy and production of sounds. These air sacs do not form until maturation and are considerably smaller in females than in males.
Like other pinnipeds, ribbon seals have cylindrical bodies with limbs modified for swimming. Newborn ribbon seals are white. Body color changes gradually with maturity, with adult males becoming reddish-brown until they molt or shed. After molting, the male coat changes to black. Females are usually lighter than males. Ribbon seals are easily distinguished from other phocids by their unique white bands over their bodies. Markings begin to appear as early as 12 weeks old, although they usually are not distinct until after the seal molts. Each ribbon seal has four white bands, creating a pronounced black and white pattern. One band is around the neck, one around each of the fore-flippers, and one around the lower back before the hind-flippers. The size and exact location of each band varies from seal to seal. These markings are usually more distinct in males than in females.
Three developmental stages are recognized in ribbon seals. Newborns typically range in body length from 73 to 98 cm, with a weight of 6 to 10 kg. Juveniles have a body length of 128 to 134 cm, with a weight of 40 to 50 kg. At about 2 to 3 years old, ribbon seals are considered adults, with a body size of roughly 145 to 155 cm and weight of 55 to 70 kg. Over the next few years, ribbon seals continue to grow and can reach a maximum length of 165 to 175 cm and weight of 72 to 90 kg. This increase is due to continuing development and additional accumulation of blubber, as well as changes after reproduction.
Another distinguishing feature of ribbon seals is a higher percentage of body weight attributable to vital organ volume. Major organs contribute to body weight as follows: 22% liver, 17% lungs, 8% heart, 7% diaphragm, and 2.7% kidneys. This is believed to help increase their diving and swimming abilities.
Range mass: 6 to 90 kg.
Range length: 73 to 175 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
- Renouf, D. 1991. Behaviour of Pinnipeds. University Press, Cambridge: Chapman and Hall.
- Roest, A. 1964. A ribbon seal from California. Journal of Mammalogy, 45/3: 416-420.
Length: 150 cm
Weight: 90000 grams
Size in North America
Range: 1.6-1.7 m
Range: 70-80 kg
Differs from other northern phocids by the unique color pattern and in having a relatively longer and more flexible neck, a shorter rostrum, and more widely spaced teeth (Nowak 1991).
Habitat and Ecology
Ribbon seals are solitary for much of their lives. Pups are born on ice floes from early April to early May. Clean, white, broken pack ice is preferred over solid ice sheets and ice with sediment or algae. Ribbon seals maintain access holes in ice up to approximately 15 cm thick, and can often be seen in the middle of large floes. Ribbon seals are able to move rapidly on ice, using slashing side-to-side motions. They also extend their necks to peer at sources of disturbance, but are fairly approachable by boat. They are rarely encountered, because of the remote and inhospitable nature of their habitat.
Diet varies by area and age of the seal. Ribbon seals in the Okhotsk and Bering seas are known to take 35 different species of fish and invertebrates (Frost and Lowry 1980, Bukhtiyarov 1986). Young ribbon seals feed on euphausiids after weaning and until about age one when they switch to feed predominantly on shrimp for a year. As two-year-olds they take up the adult diet, which includes a variety of fishes, squids, and octopuses. Bukhtiyarov (1986) has determined that diet biomass of ribbon seals in the Sea of Okhotsk contains 69% of pollock, while in the Bering Sea 67% was squid and octopuses.
Females are mature when they are 2-4 years old and males when they are 3-5 years (Burns 1981). The annual pregnancy rate of adult females is 85%. Gestation lasts 9 months after 2-2.5 months of delayed implantation. Ribbon seals may live up to 26-27 yrs. First year mortality is 44% and the annual mortality rate for older age classes averages 11%.
Histriophoca fasciata is an Arctic marine mammal that spends the majority of its life in cold waters. Ribbon seals prefer deeper waters, where sea ice is less solid and occurs in smaller pieces rather than large, contiguous masses. In these areas it is relatively easy to break holes in the ice to enter the water while also maintaining access to haul out areas.
Ribbon seals prefer to remain near food sources, rather than traveling long distances to locate prey. Areas with broken ice chunks support constantly circulating water, which helps to create a stable food source. Ribbon seals can dive to depths of 600 m to obtain food.
Ribbon seals are found in the Okhotsk Sea, a region that is typically 80 to 90% covered with ice. It is believed that ribbon seals use this area for breeding. Breeding rookeries help reduce predation by larger marine mammals, as many lack the ability to pull themselves onto the thick ice.
Range depth: 600 (low) m.
Habitat Regions: temperate ; polar ; saltwater or marine
Terrestrial Biomes: icecap
Aquatic Biomes: pelagic ; coastal
- Fedoseev, G. 2002. Ribbon seal (Histriophoca fasciata). Pp. 1027-1033 in W Perrin, B Wursig, J Thewissen, eds. Encyclopedia of Marine Mammals, Vol. 1, 1 Edition. San Diego, CA: Academic Press.
- Mizuno, A., A. Wada, T. Ishinazaka, K. Hattori, Y. Watanabe, N. Ohtaishi. 2002. Distribution and abundance of spotted seals Phoca largha and ribbon seals Phoca fasciata in the southern Sea of Okhotsk. Ecological Research, 17: 79-96.
- Simpkins, M., L. Hiruki-Raring, G. Sheffield, J. Grebmeier, J. Bengtson. 2003. Habitat selection by ice-associated pinnipeds near St. Lawrence Island, Alaska in March 2001. Polar Biology, 26/9: 1-10.
Habitat Type: Marine
Comments: Associated with sea ice during late winter, spring, and early summer; prefers to haul out on moderately thick, clean ice, generally on ice floes well out to sea (Nowak 1991). Rarely hauls out on shore-fast ice and almost never on land. Gives birth on moderately thick, clean sea ice (Nowak 1991), generally far offshore (except when ice edge is near St. Matthew and St. Lawrence islands).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some 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.
At least some migrate northward and southward with the receding and advancing ice edge.
Ribbon seal food habits vary depending on their age, time of year, and location. Stomach contents are different during the spring months, when ribbon seals begin whelping. Females undergo a brief fasting during whelping and lactation in order to provide nutrition and protection to the pup. As juveniles, they feed primarily on shrimp and other small crustaceans. Adults eat different types of cephalopods, crustaceans, and fish. Primary diet components are walleye pollock (Theragra chalcogramma) and magistrate armhook squid (Berryteuthis magister). On average, ribbon seals consume 7.7 kg of food per day.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
- Dehn, L., G. Sheffield, E. Follmann, L. Duffy, D. Thomas, T. O'Hara. 2007. Feeding ecology of phocid seals and some walrus in the Alaskan and Canadian Arctic as deteremined by stomach contents and stable isotope analysis. Polar Biology, 30/2: 167-181.
Comments: Feeds opportunistically on crustaceans, fishes (important species include walleye pollock and arctic cod), and cephalopods. Food intake is reduced during spring molt.
Ribbon seals are potential prey for species such as polar bears and killer whales. Other species may use the abandoned ice rookeries of ribbon seals as shelter or for breeding.
Ecosystem Impact: creates habitat
A common predator of ribbon seals is humans (Homo sapiens). From 1956 to 1992, hunting of several species of seals that lived on ice was a popular sport. This drastically decreased population sizes of ribbon seals. Humans still hunt ribbon seals, but it is not as common as it once was. Polar bears (Ursus maritimus), walruses (Odobenus rosmarus), killer whales (Orcinus orca), and pacific sleeper sharks (Somniosus pacificus) also prey on ribbon seals. Ribbon seals have been found in their stomach contents. Polar bears and killer whales are the most likely predators of ribbon seals. Both share the same habitat as ribbon seals and are known to eat other seals. Killer whales are most likely the major predator because they are found throughout the entire ribbon seal range. The range of polar bears typically does not extend further south than St. Matthew Island, so they are less likely to prey on ribbon seals, especially during the spring months when the ribbon seals migrate south. Ribbon seals typically struggle when they are harassed less and often "play dead" until they are released.
- humans (Homo sapiens)
- polar bears (Ursus maritimus)
- walruses (Odobenus rosmarus)
- killer whales (Orcinus orca)
- Pacific sleeper sharks (Somniosus pacificus)
Usually solitary, though scattered individuals may assemble on favorable ice flows (Nowak 1991). Mortality during the first four years of life is nearly 58% (Reeves et al. 1992).
Life History and Behavior
Ribbon seals have long vibrissae that are sensitive to vibrations in the water and can be used to locate prey. They have well-developed hearing across a broad range of frequencies in water. It is believed that they use a system similar to echolocation for navigating through water and for catching prey. Ribbon seals also have well-developed auditory senses on land, although their hearing occurs across a narrower range of frequencies than in water. Two types of sounds have been recorded for ribbon seals. These sounds are believed to be used for communication with other ribbon seals, but there have been no studies to confirm this. Other pinnipeds make sounds to communicate during hunting or mating. Little research has been conducted on hearing in ribbon seals, but other pinnipeds have poor hearing in water because they are well adapted to spending large amounts of time on land. The water slows down sound waves, making their hearing poor.
It is thought that ribbon seals have poor vision on land because of their reactions to potential threats. They look for danger, but they scan the land area for longer periods of time than other pinnipeds. Ribbon seals allow human approach more often than other pinnipeds. They are believed to have well-developed vision in water.
Communication Channels: acoustic
Perception Channels: visual ; tactile ; acoustic ; echolocation ; chemical
- Richardson, J., C. Greene, C. Malme, D. Thomson. 1995. Marine Mammals and Noise. San Diego, California: Academic Press.
- Watkins, W., G. Ray. 1977. Underwater sounds from ribbon seal, Phoco (Histriophoca) fasciata. Fishery Bulletin, 75/2: 450-453.
Ribbon seals typically live for 25 to 30 years in the wild. Ribbon seal age can be determined roughly by examining the horn covers on the front claws and the layers found on the tip of the tusks. Little is known about the lifespan of ribbon seals in captivity.
Status: wild: 20 to 30 years.
- Weigl, R. 2005. Longevity of mammals in captivity. Stuttgart: Kleine Senckenberg-Reihe 48.
Lifespan, longevity, and ageing
Ribbon seals typically mate in rookeries established on sea ice. Like most true seals, ribbon seals are polygynous. Male ribbon seals use their air sac for vocalizations or phonation during mating, both to attract mates and to establish or defend territories.
Mating System: polygynous
Male ribbon seals reach reproductive maturity at approximately three to six years of age. Females typically mature earlier, between two to five years of age. Ribbon seals undergo delayed implantation for two to four months. This allows them to wait until sufficient sea ice is present for birthing. Breeding season usually begins in late May, with breeding centering around the annual breakup of ice each spring. Differences in ice conditions affect the duration of pup rearing and the size of individual pups.
Female ribbon seals have a gestation period of about 11 months, after which they give birth to a single pup, usually in April. It is rare for females to give birth to two pups. When this occurs, one usually does not survive. Females give birth and raise pups on packed ice. Pups average 73 to 98 cm long and 6 to 10 kg in body weight. Females nurse pups for four to six weeks, after which pups are weaned. Milk for the young is rich in proteins and fats which helps to rapidly increase the weight of the pup. After weaning, adults are able to mate again the following year.
Breeding interval: Ribbon seals breed once annually.
Breeding season: Ribbon seals breed from May to June.
Average number of offspring: 1.
Range gestation period: 10 to 11 months.
Average weaning age: 1 months.
Range age at sexual or reproductive maturity (female): 2 to 5 years.
Range age at sexual or reproductive maturity (male): 3 to 6 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation
Female ribbon seals expend considerable energy on parental care, particularly energy for feeding and defending pups from adult males and potential predators. During lactation, females undergo a short fasting period in which they do not leave their pup. After the nursing period, females help pups to become independent by teaching them to dive for food.
Parental Investment: altricial ; female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female)
- Atkinson, S. 1997. Reproductive biology of seals. Reviews of Reproduction, 2: 175-194.
- Fedoseev, G. 2002. Ribbon seal (Histriophoca fasciata). Pp. 1027-1033 in W Perrin, B Wursig, J Thewissen, eds. Encyclopedia of Marine Mammals, Vol. 1, 1 Edition. San Diego, CA: Academic Press.
- Macdonald, D. 2006. Seals, sea lions, and walruses. Pp. 520-544 in D Macdonald, ed. The Princeton Encyclopedia of Mammals, Vol. 1, 1 Edition. Princeton, NJ: Princeton University Press.
Apparently polygynous mating system. Mating occurs about the same time as weaning. Gestation, including a period of delayed implantation, lasts about 11 months. Births of single pups occur in April and early May (mainly early to mid-April). Young are weaned in 3-4 weeks, remain mostly on the ice for a few more weeks. Females becomes sexually mature at 2-4 years; many do not produce a pup until 4-5 years old; thereafter, almost all adult females give birth annually. Males are sexually mature at 3-5 years. Most probably do not live beyond 20 years.
Molecular Biology and Genetics
Barcode data: Phoca fasciata
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.
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Download FASTA File
Statistics of barcoding coverage: Phoca fasciata
Public Records: 3
Specimens with Barcodes: 3
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
IUCN Evaluation of the Ribbon Seal, Histriophoca fasciata
Prepared by Pinniped Specialist Group
A. Population reduction Declines measured over the longer of 10 years or 3 generations
A1 CR > 90%; EN > 70%; VU > 50%
Al. Population reduction observed, estimated, inferred, or suspected in the past where the causes of the reduction are clearly reversible AND understood AND have ceased, based on and specifying any of the following:
(a) direct observation
(b) an index of abundance appropriate to the taxon
(c) a decline in area of occupancy (AOO), extent of occurrence (EOO) and/or habitat quality
(d) actual or potential levels of exploitation
(e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
The generation time of Ribbon Seals is probably about 10 years. The most recent population abundance estimate, based on aerial surveys conducted in 1979, was between 450,000 and 500,000 with an increasing trend. No reliable surveys have been conducted since 1979 and current abundance and trend are unknown. A decline in Ribbon Seals in the Bering Sea was observed in mid-late 1960s due to overharvesting. After reduction of harvest effort the population recovered rapidly. Large scale commercial harvests of ribbon seals in the Russian Far East ceased in 1994.
A2, A3 & A4 CR > 80%; EN > 50%; VU > 30%
A2. Population reduction observed, estimated, inferred, or suspected in the past where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under A1.
A population reduction of Ribbon Seals has not been observed, estimated, inferred, or suspected in the past 30 years.
A3. Population reduction projected or suspected to be met in the future (up to a maximum of 100 years) based on (b) to (e) under A1.
A population reduction of Ribbon Seal is suspected in the future due to global warming and rapid reduction of sea ice habitat essential for pupping and moulting. If global warming continues it is likely that the population of ribbon seals will decline by at least 30% within next 30 years which qualifies the species for listing as vulnerable under criterion A3c.
A4. An observed, estimated, inferred, projected or suspected population reduction (up to a maximum of 100 years) where the time period must include both the past and the future, and where the causes of reduction may not have ceased OR may not be understood OR may not be reversible, based on (a) to (e) under Al.
The cause of the Ribbon Seal decline in the 1960s-1970s was understood and reversible. No other population reduction of ribbon seal has been observed, estimated, inferred, or suspected in the past.
B. Geographic range in the form of either B1 (extent of occurrence) AND/OR B2 (area of occupancy)
B1. Extent of occurrence (EOO): CR < 100 km; EN < 5,000 km; VU < 20,000 km
The EOO of Ribbon Seal is > 20,000 km.
B2. Area of occupancy (AOO): CR < 10 km; EN < 500 km; VU < 2,000 km
The AOO of Ribbon Seal is > 2,000 km.
AND at least 2 of the following:
(a) Severely fragmented, OR number of locations: CR = 1; EN < 5; VU < 10
(b) Continuing decline in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) area, extent and/or quality of habitat; (iv) number of locations or subpopulations; (v) number of mature individuals.
(c) Extreme fluctuations in any of: (i) extent of occurrence; (ii) area of occupancy; (iii) number of locations or subpopulations; (iv) number of mature individuals.
C. Small population size and decline
Number of mature individuals: CR < 250; EN < 2,500; VU < 10,000
The number of mature ribbon seals is > 10,000.
AND either C1 or C2:
C1. An estimated continuing decline of at least: CR = 25% in 3 years or 1 generation; EN = 20% in 5 years or 2 generations; VU = 10% in 10 years or 3 generations (up to a max. of 100 years in future)
C2. A continuing decline AND (a) and/or (b):
(a i) Number of mature individuals in each subpopulation: CR < 50; EN < 250; VU < 1,000
(a ii) % individuals in one subpopulation: CR = 90100%; EN = 95100%; VU = 100%
(b) Extreme fluctuations in the number of mature individuals.
D. Very small or restricted population
Number of mature individuals: CR < 50; EN < 250; VU < 1,000 AND/OR restricted area of occupancy typically: AOO < 20 km or number of locations < 5
The number of mature Ribbon Seals is > 1,000. AOO is > 20 km and the number of locations is > 5.
E. Quantitative analysis
Indicating the probability of extinction in the wild to be: CR > 50% in 10 years or 3 generations (100 years max.); EN > 20% in 20 years or 5 generations (100 years max.); VU > 10% in 100 years
There has been no quantitative analysis conducted on probability of extinction of Ribbon Seals.
Listing recommendation Ribbon Seals have an unknown mortality in salmon nets and bottom-set gill nets. This species is likely to be seriously, negatively impacted by reductions in the extent and seasonal coverage of sea ice throughout their range. However, it is not possible to evaluate the current situation for this species as the most recent estimates are almost two decades old. This species must be considered Data Deficient at this time.
- 1996Lower Risk/least concern (LR/lc)
- 1965Status inadequately known-survey required or data sought
There is little data on the current conservation status of H. fasciata. According to the IUCN Redlist, the most recent population study was conducted in the 1970s. At that time, research suggested that H. fasciata populations were declining. A 1979 study estimated the population size as 450,000 to 500,000 individuals. Since that time, Russia has mostly stopped large scale commercial hunting and, in the United States, they are protected by the Marine Mammal Protection Act. These legislative acts were enacted after the last population study, so it is generally believed that population sizes should have increased. Due to the lack of current data, the IUCN Red List notes the current conservation status as "Data Deficient".
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: data deficient
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
The Bering Sea population appears to have declined shortly after the beginning of commercial hunting in 1961. The average age of harvested animals declined from 9.8 years in 1961, to 6.9 in 1962, and 4.9 in 1963. During the same period, the number of ribbon seals killed per day dropped regardless of hunting conditions (Heptner 1976). After the harvest was limited, abundance of the species quickly recovered.
Interactions between ribbon seals and fisheries are not well documented. There were no mortalities recorded in required logbooks or by voluntary reports from 1990 to 1995 in fisheries monitored by the United States. Estimated mortality from 1999 to 2003 was 1 ribbon seal in the Bering Sea pollock trawl fishery, and 1 observed and 3 estimated mortalities in the Bering Sea/Aleutian Islands Pacific cod longline (Anglis and Outlaw, 2005). During seven years (1993-1999) of monitoring the offshore salmon gill net fishery in Russian Far East, accidental mortality of ribbon seal was estimated to be 1,079 individuals (154 per year), mostly juveniles (Burkanov and Nikulin 2001). Some mature animals die in a bottom gill net halibut fishery in the Sea of Okhotsk, but information is very limited.
Reduction in late winter and spring sea ice cover in the Sea of Okhotsk, or the central and southern Bering Sea could be problematic for ribbon seal reproduction as this species depends on the availability of offshore pack ice. Disruption or alteration of the patterns of Arctic primary productivity and abundance of key marine mammal prey species such as Arctic cod could also have detrimental effects on ice dependent seals (Tynan and DeMaster 1997). Pollock are an important spring ribbon seal food in the central and south central Bering Sea (Frost and Lowry 1980) and in the Sea of Okhotsk (Bukhtiyarov 1986). The effect of pollock harvesting on ribbon seals in the Bering Sea has not been examined, but competition with fisheries has been suggested as a possible limiting factor on population growth, or a threat that could result in declines (Reijnders 1993).
Comments: Some drown in commercial gill nets in the Bering Sea and North Pacific. Soviet commercial harvest in the Bering Sea in the 1960s resulted in a population decline there, probably from about 80,000-90,000 to around 60,000; later, a reduced harvest resulted in a population increase. In addition to commercial hunting from ships, potential threats include industrial offshore development and overharvesting of prey species (Reeves et al. 1992).
Relevance to Humans and Ecosystems
There are no known adverse effects of Histriophoca fasciata on humans.
Ribbon seals do not provide known sources of economic benefit to humans, although sport hunting was common in the past.
Comments: Due to remote habitat, not regularly hunted by native peoples (but small subsistence harvest continues). Seal's lack of caution on the ice makes it vulnerable to commercial pelagic sealers. In the 1960s, the annual Soviet catch averaged about 13,000 and the population began to decline; lower quotas later resulted in a population increase (Nowak 1991).
The ribbon seal (Histriophoca fasciata) is a medium-sized pinniped from the true seal family (Phocidae). A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is distinguished by its striking coloration, with two wide white strips and two circles against dark brown or black fur.
Adult seals are recognizable by their black skin, which carries four white markings: a strip around the neck, one around the tail and a circular marking on each body side, which encloses the front fins. The contrast is particularly strong with the males, while with females the difference in color between bright and dark portions is often less conspicuous. Newborn ribbon seal pups have white natal fur. After moulting their natal fur, their color changes to blue-grey on their backs and silvery beneath; after some years some portions become darker and others brighter, and only at the age of four years does the typical design show.
The ribbon seal has a large inflatable air sac that is connected to the trachea and extends on the right side over the ribs. It is larger in males than in females, and it is thought that it is used to produce underwater vocalizations, perhaps for attracting a mate. The ribbon seal can grow about 1.6 m (5.2 ft) long, weighing 95 kg (209 lb) in both sexes.
The ribbon seal lives in the Arctic parts of the Pacific Ocean. During winter and spring, it hauls out on pack ice to breed, molt, and give birth. During this time, it is found at the ice front in the Bering and Okhotsk Seas. During the summer and autumn, the ribbon seal lives in open water, though some move north as the ice recedes with warmer temperatures. Little is known about its habit during this time, as it is so far from land and human observation. The ribbon seal almost never comes to land.
Thus far, there have been only two acknowledged instances where ribbon seals have been found as far south as Seattle, Washington and even further south at Morro Bay, California. There was nothing to suggest that illness was the cause of either seals appearance at either place, as both appeared to be healthy.
The diet of ribbon seal consists almost exclusively of pelagic creatures: fish like pollocks, eelpouts, the Arctic Cod and cephalopods such as squid and octopus; young seals eat crustaceans as well. The ribbon seal dives to depths of up to 200 m in search of food; it is solitary and forms no herds. Females reach sexual maturity at 2 to 5 years and males reach sexual maturity at 3 to 6 years, and an individual may reach twenty to twenty-five years of age. Mating takes place from late April to early May. Young animals are born on the ice in April and May. They are fed for four weeks on their mother's milk, then leave their mother. They remain on the ice for a few more weeks, in which they lose their dense white fur and lose a drastic amount of weight. After this period, they are able to dive and hunt by themselves.
Young ribbon seals look like young harp seals, and like these, they were hunted for their fur. Since they do not form herds, ribbon seals were more difficult to catch than harp seals. Since the Soviet Union limited the hunt on ribbon seals in 1969, their population has recovered. The current population is around 250,000.
In March 2008 the US government agreed to study Alaska's ribbon seal population and considered adding it to the endangered species list. However, in December 2008, the US government decided that sea ice critical to the seals' survival will not be endangered by global warming, and declined to list the species. Instead, it became a U.S. National Marine Fisheries Service Species of Concern. The US Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NMFS), has some concerns regarding status and threats of some species, for which insufficient information is available to list them under the US Endangered Species Act.
- Wozencraft, W. C. (2005). "Order Carnivora". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Burkanov, V. & Lowry, L. (2008). Histriophoca fasciata. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 January 2009.
- Berta, A. & Churchill, M. (2012). "Pinniped Taxonomy: evidence for species and subspecies". Mammal Review 42 (3): 207–234. doi:10.1111/j.1365-2907.2011.00193.x.
- Peter Saundry. 2010. Ribbon seal. Encyclopedia of Earth. C.Michael Hogan (Topic Editor). Cutler J. Cleveland, ed. National Council for Science and the Environment, Washington DC
- SCS: Ribbon Seal (Phoca fasciata)
- Rare sea creature appears on Seattle woman's dock.
- Govt: Ribbon seals not endangered. Associated Press. 23 December 2008
- Boveng, P.L. et al. (2008). Status Review of the Ribbon Seal (Histriophoca fasciata). Seattle, WA: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Alaska Fisheries Science Center.
Names and Taxonomy
Comments: Placed in the genus Histriophoca by Muizon (1982), Rice (1998), Baker et al. (2003), and some other authors, but regarded (with the nominal genera Pagophilus and PUSA) as a member of the genus Phocain other recent literature on pinnipeds (e.g., King 1983; Riedman 1990; Nowak 1991; Reeves et al. 1992; Wozencraft, in Wilson and Reeder 1993).
A cladistic analysis of mtDNA data yielded three clades among northern seals: Phoca-Pusa-Halichoerus, Cystophora-Pagophilus, and Erignathus (Perry et al. 1995). Each clade may be regarded as a tribe of the subfamily Phocinae. The magnitude of the differences among Phoca, Pusa, and Halichoerus was on the same order as that between species and subspecies within the genus Odocoileus. Because Cystophora is the closest relative of Pagophilus, the latter cannot be regarded as congeneric with Phoca; the differences between the two are great enough to justify placing them in separate genera (Perry et al. 1995).
Mouchaty et al. (1995) examined the cytochrome b gene and found a close phylogenetic relationship between Pagophilus groenlandicus and Histriophoca fasciata, consistent with earlier studies.