Histriophoca fasciata

Geographic Range

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 arctic ocean
  • native native
• pacific ocean pacific ocean
  • native native

• Other Geographic Terms
• holarctic holarctic

Habitat

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.

• Habitat Regions
• temperate temperate
• polar polar
• saltwater or marine saltwater or marine

• Terrestrial Biomes
• icecap

• Aquatic Biomes
• pelagic pelagic
• coastal coastal

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful

Reproduction

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 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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous
• delayed implantation 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 altricial
• female parental care 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

Lifespan/Longevity

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.

Behavior

Ribbon seals are diurnal, when they forage for food. Ribbon seals generally occur in small groups. The majority of their time is spent in the water foraging and migrating between breeding areas and areas of lighter sea ice. During the breeding season, ribbon seals of all ages, genders, and sizes are found together. Breeding and molting season overlap, both happening during the spring ice breakup. Adult seals come to the ice in order to breed while juveniles use the ice as a site for molting.

Ribbon seal females leave their pups alone for extended periods of time, unlike most true seals . A probable reason for this behavior is their relative lack of predators. This is because they rear their pups on thinning ice, which creates a barrier for many predators.

When ribbon seals feel there may be a threat, they scan the area visually for a much longer period than other pinnipeds. Poor eyesight out of water is believed to be the reason for this extended scanning. When on the ice, they use their fore-flippers to dig in and propel them forward.

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• social social

Home Range

There is little known about home range size in ribbon seals.

Communication and Perception

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 acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• echolocation echolocation
• chemical chemical

Food Habits

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.

• Primary Diet
• carnivore carnivore
  • piscivore piscivore
  • eats non-insect arthropods
  • molluscivore molluscivore

• Animal Foods
• fish
• mollusks
• aquatic crustaceans

Predation

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.

Ecosystem Roles

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

Economic Importance for Humans: Positive

Ribbon seals do not provide known sources of economic benefit to humans, although sport hunting was common in the past.

Economic Importance for Humans: Negative

There are no known adverse effects of Histriophoca fasciata on humans.

Conservation Status

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".

Additional Links

Encyclopedia of Life

Contributors

Ben Berry (author), Radford University, Kelsey Townsend (author), Radford University, Christine Small (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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Fedoseev, G. 2002. Ribbon seal ( Histriophoca fasciata ). Pp. 1027-1033 in Encyclopedia of Marine Mammals , Vol. 1, 1 Edition. San Diego, CA: Academic Press.

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Macdonald, D. 2006. Seals, sea lions, and walruses. Pp. 520-544 in The Princeton Encyclopedia of Mammals , Vol. 1, 1 Edition. Princeton, NJ: Princeton University 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.

Renouf, D. 1991. Behaviour of Pinnipeds . University Press, Cambridge: Chapman and Hall.

Richardson, J., C. Greene, C. Malme, D. Thomson. 1995. Marine Mammals and Noise . San Diego, California: Academic Press.

Roest, A. 1964. A ribbon seal from California. Journal of Mammalogy , 45/3: 416-420.

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.

Watkins, W., G. Ray. 1977. Underwater sounds from ribbon seal, Phoco (Histriophoca) fasciata . Fishery Bulletin , 75/2: 450-453.

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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.