Ringed seal, ringed seal, akiba. Ringed seal Habitats of the ringed seal
The ringed seal is a native inhabitant of the harsh Arctic region. It belongs to the family of true seals and lives in almost all waters of the Arctic Ocean. This animal can be found near the Kola Peninsula and in the Bering Strait. Nerpa feels comfortable in the White Sea, in coastal waters Novaya Zemlya and on the gloomy shores of Franz Josef Land. She is painfully familiar with the waters near Severnaya Zemlya, New Siberian Islands, but here central regions She does not favor the Barents Sea. There are no drifting ice dear to her heart, on which she is far from short life and lives.
The seal has perfectly adapted near the northern coast of Norway, and Svalbard is as desirable for it as the Côte d'Azur is for a person. The western shores of Greenland are also included in the zone of its interests. The same can be said about the Canadian Arctic Archipelago, and even about Hudson Bay. To top it off, we can add that she settled in the waters of Newfoundland and the Gulf of St. Lawrence. This is not surprising, since the number of ringed seals is quite decent. According to the most conservative estimates, Arctic waters There are at least 3 million of them. If we take the Baltic Sea, the Sea of Okhotsk, Lake Ladoga, and other regions remote from the Arctic, then the value will already tend to 4 million.
The ringed seal living in the Arctic cannot boast of large forms. The length of her body rarely reaches one and a half meters. Basically, it grows up to 1.35-1.4 meters. Grows up to 10 years. The weight is 70 kg. Females are slightly smaller than males. This beast has an excellent sense of smell, perfect sharp hearing and excellent eyesight. The body of the seal is thick and therefore visually seems short. The head is small relative to the total length, the muzzle is as if flattened, and there is almost no neck - it is so short and thick.
The coat of the animal is short, hard. The color of the skin is quite peculiar. The back is dark or almost black. This background is diluted with light rings. Thanks to them, the seal got its name - ringed. Her belly is light. Often you can meet animals with a yellowish peritoneum. There are no rings on the belly and flippers.
Reproduction and lifespan
Sexual maturity in females occurs when they reach 4 years of age. Males mature later. They become capable of mating at the age of 5 to 7 years. The love period of the ringed seal begins in April and ends in May. The latent period of pregnancy lasts 3 months. The full gestation period, together with the latent one, lasts 11 months.
In March-April, one cub is born. He's pretty big. The length of his body is 0.6 meters, weight reaches 4 kg. The body of the newborn is covered with thick white fur. In such a beautiful outfit, the baby flaunts no more than a month and a half. The fur gradually turns gray, dark rings begin to appear on it. After 6 weeks, the snow-white handsome turns into an ordinary ringed seal and for the first time leaves the den where he was born. During this time, he grows by as much as 10 cm and doubles his weight.
To the birth and rearing of their offspring ringed seal carefully prepared. If she gives birth in the ice of the coastal solder, then she builds several shelters for herself among the hummocks. In each such shelter, she makes a hole in the ice. It leads straight into the water, and the female gets into all her shelters from the water, that is, she practically does not appear on the surface.
These shelters are very quickly covered with snow and it is almost impossible for an outsider to find them among a snow coat and ice. In one of their shelters, the seal gives birth. She feeds the cub with milk for almost two months. All this time, the baby does not leave the den, while the female herself constantly goes hunting.
If a ringed seal gives birth on a drifting ice floe, then it makes only one shelter for itself in the ice. The reason is that she simply has nowhere to roam. Up to a hundred pregnant seals sometimes gather on an ice floating craft. So the animals live in rather cramped conditions. On the coast, the situation is quite different. There is space and breadth, so pregnant females can be located at a very decent distance from each other and build up to a dozen shelters for themselves. The life expectancy of these amazing animals is an average of 40 years.
Behavior and nutrition
These animals usually live alone. Groups are very, very rare. Moreover, such groups are never bound by strong ties and disintegrate very quickly. Together, seals come together mainly in the summer. This time of the year, they like to while away in coastal waters and arrange temporary rookeries on pebble-covered shores. On such beds, 30 and 50 heads can gather, and there are even whole clusters of several hundred. autumn most of animal moves to drifting ice floes and floats on them to a distant sea distance.
The ringed seal is an excellent swimmer and diver. A depth of 50 meters is not the limit for her, she can safely stay under water for 20 minutes. To replenish the supply of air, the beast needs only a couple of seconds. Such physical abilities favorably affect hunting. The animal feeds mainly on fish. He gives preference to polar cod, but does not refuse navaga, capelin. Herring is also present on the seal menu. The animal feeds on crustaceans. Shrimps and black eyes are common food for him. The beast does not disdain zooplankton either. All this is present in abundance in the seas of the Arctic Ocean, so the issue of food for seals is never acute.
Enemies
With the exception of a man who destroys the ringed seal for fur, fat and meat, this animal has enough enemies among the predators of the Arctic. Here in the first place is the polar bear. The clubfoot loves to wait for its prey near the opening. As soon as the animal's nose emerges from the water to replenish its air supply, the bear's paw delivers a powerful blow to its head. The predator pulls the stunned seal onto the ice, finishes it off and eats it. Great danger Arctic foxes are also represented. They have excellent sense of smell, speed and agility. They are excellent hunters and it is very difficult to avoid their sharp teeth.
Killer whales also make their bloody contribution to the unseemly deed. These mighty predators swim under a drifting ice floe, on which seals cluster, and hit it with their huge and heavy bodies. The ice floe is tilting or overturning. Unfortunate animals find themselves in the water and immediately fall into wide-open toothy mouths. Walruses also pose a danger to seals. Among them come across very aggressive individuals, with big hunt eating these well-fed animals.
♦ ♦ ♦Ringed seal, akiba or ringed seal (lat. Phoca hispida) - the closest relative harbor seal, which is more common than others in the Arctic: according to the most conservative estimates, there are about 4 million heads in the world. The seal got its name due to the pattern on its coat, which consists of a large number light rings on a dark background.
The average weight of an adult ringed seal can reach 100 kg with a body length of up to 1.4 m. Males are slightly larger than females. Akiba has excellent eyesight, hearing and sense of smell, which help the animal find food for itself and hide from predators in time. The body of the seal is short and thick, the head is small, the muzzle is slightly flattened, but the neck is so shortened and thick that it seems as if it does not exist at all. 
Depending on the habitat, four subspecies of the ringed seal are distinguished:
On the drifting ice floes of the Arctic Ocean one can meet the White Sea ringed seal (P. h. hispida), which is considered the most common seal in its geographical area.
In the coldest regions Baltic Sea the Baltic ringed seal (P. h. botnica) lives. She liked the coasts of Switzerland, Estonia, Finland and Russia. From time to time she gets to Germany. This is the largest subspecies of the ringed seal.
The Ladoga ringed seal (P. h. ladogensis) settled in the freshwater Lake Ladoga. She got here about 11 thousand years ago, when the last glacial period. At that time, a huge glacier retreated, and the previous water level changed, which did not give the seal the opportunity to return to the waters of the Arctic Ocean. Today, the number of this subspecies is only 2-3 thousand individuals, which is ten times less than it was at the beginning of the last century. The Ladoga seal is included in the Red Book of the Russian Federation, hunting for it has been prohibited since 1980, but this does not interfere with poachers in the least.
Finally, the Saimaa ringed seal (P. h. saimensis) settled in the freshwater lake Saimaa. She has been living here for more than 8 thousand years, but in recent times is in danger of extinction. In total, there are 310 Saimaa seals, of which no more than 70 individuals are capable of fertilizing females. 
Ringed seals do not like noisy companies, so they never form colonies. Most often they stay alone, although sometimes they gather in small groups, which, however, are not very stable. All year round they spend in the sea, for which their body is very well adapted. 
At the age of four, females become sexually mature. Males are capable of procreation from 5-7 years. In April-May, the mating period begins in ringed seals, the pregnancy lasts 11 months, including a three-month latent stage. 
March-April next year females give birth to one large cub, whose body length reaches 50-60 cm and weighs about 4 kg. All of it is covered with beautiful white thick fur, which lasts only a month and a half, giving way to ordinary gray wool, through which you can see the rings characteristic of the species. The future mother carefully prepares for the birth of a new member of the seal society: she builds herself a reliable shelter among the snow hummocks, the entrance to which is under water, so that the newborn becomes inaccessible to predators. For about two months, the baby lives in his house, eating mother's milk. At the same time, the female goes hunting every day. The life expectancy of ringed seals is about 40 years.
Ringed seal, or Akiba (Pusa hispida), is covered with coarse blackish-brown fur with numerous irregularly shaped white rings. The body length of an adult male is up to 1.8 m.
It is the only one of all seals that builds a nest for its young. In March or April, when the ice begins to break, the female makes a hole in a snowdrift with a tunnel leading to an air vent and water. Newborns (sometimes twins) are covered with snow-white soft wool (belka stage), which after a month is replaced by a darker one.
The ringed seal appears to be the farthest northerly of all mammals; she spends most of the year in ice-covered bays and fiords. In autumn, as the water freezes, the animal does not migrate south, but makes holes in the ice, to which it regularly swims up to breathe and rest. Sometimes this leads to a sad result, since a hunter with a harpoon or polar bear. Usually, the seal spends 8–9 minutes under water, but if necessary, it can stay there for up to 20 minutes. Ascending, she manages to stock up on air for the next dive in 45 seconds.
The ringed seal is distributed circumpolarly in the Arctic Ocean, reaching south to Labrador and the Bering Sea.
There are four subspecies of the ringed seal: Ringed seal (Phoca hispida hispida); Baltic ringed seal (Phoca hispida botnica); Ladoga seal (Phoca hispida ladogensis); Seal of Lake Saimaa in Finland (Phoca hispida saimensis)
Species: Pusa hispida Schreber = Ringed seal, ringed seal, akiba
Status: In Russia, the ringed seal is an object of fishing. It is not a CITES object. Only the Ladoga subspecies is listed in the Red Book of Russia (category 3).
Currently in Russia industrial production there is no ringed seal. Several hundred heads are harvested annually by the population of coastal areas for their own needs.
The heyday of industrial production of the species in our country falls on the 1950-60s. when annually it reached tens of thousands of individuals (for example, in 1962, 13,570 seals were caught in the Barents and White Seas alone).
Appearance, weight: An adult animal on average reaches 1.0-1.2 m in length and 50-80 kg in weight. A newborn cub is 0.6 m long and about 4 kg in weight. Newborn cubs have white juvenile fur, which after 4-6 weeks changes to gray with dark rings, for which the animal got its name.
Life cycle: The ringed seal is a typical pagophilic species, i.e. her life cycle closely related to the ice cover. Ringed seals become sexually mature at the age of 5-7 years. Mating occurs in January-March. Pregnancy lasts 11 months. In February-March, the female gives birth to one cub, which she feeds for 5-7 weeks. The molt takes place in the summer. Life expectancy - up to 40 years.
From the moment of formation of the ice cover, a pregnant female arranges a ancestral den in the ice. The lair is a shelter among the hummocks, connected to the water by a manhole in the ice. By the time of whelping, the lair is completely covered with snow and has no access to the surface. During the winter, the female maintains about a dozen such shelters under the snow for rest and breathing and gives birth to a calf in one of them. For 5-7 weeks, the cub is in the den and does not go into the water.
Distribution: The ringed seal is distributed in all Arctic seas, as well as in the Barents and Okhotsk. The Baltic Sea and Lake Ladoga are inhabited by independent subspecies (Baltic and Ladoga seals). The distribution of the species largely depends on the ice cover of the reservoirs on which these seals breed. It is believed that extended migrations are not typical for the species, and local movements depend on the availability of food and changes in ice conditions.
Population: Ringed seal is one of the most numerous kinds marine mammals. It is extremely difficult to determine the number of seals, as well as other marine mammals. All assessments that exist today are to a large extent expert in nature.
According to a rough expert estimate, the number of the species in the world is 1.2 million.
Nutrition: The basis of the diet of the ringed seal is different kinds fish, zooplankton. The predominance of one or another species in the diet depends on the season and the habitat of the ringed seal. In each particular area of habitat, the diet of seals can include 10-15 different species, with an absolute predominance of 2-4 of them. The maximum body length of ringed seal victims does not exceed 20 cm. In the Arctic seas great importance has polar cod (Boreogadus saida).
Arctic cod (Boreogadus saida) is one of the most abundant fish in the Arctic seas. The most important food source for more big fish, marine mammals and birds.
Threats: As with other marine mammals, ringed seals are currently greatest danger represents the pollution of the world's oceans. In addition, the premature destruction of the ice cover due to abnormally warm winter weather or icebreaking vessels can lead to the death of a large proportion of newborn pups. http://www.2mn.org/ru/mammals/species/ringed.htm#life
Seals are a genus from the seal family. Sometimes seals are included in the genus of common seals. There are 3 species in the genus seals.
The ringed seal is found in temperate and cold waters of the Pacific and Atlantic Oceans and in the Arctic Ocean; in Russia lives in all northern seas, and also in the Bering and Okhotsk seas. The Caspian seal, or the Caspian seal, lives in the Caspian Sea. Baikal seal, or Baikal seal inhabits Lake Baikal.
The uniqueness of the Baikal seal lies in the fact that it the only mammal that lives on Baikal. Belongs to the seal family. A rather large mammal, the body length reaches up to 140 cm, and the weight reaches a full 90 kg. Males are always larger and heavier than females. Even a newborn cub is particularly weighty; at birth, it weighs about 3 kilograms.
Appearance and behavior
The color is rather monotonous light gray on the back, closer to the belly, the transition to yellow begins. Such, dull at first glance, coloring perfectly masks the seal. In nature, she does not natural enemies, the only one who hunts her is a man.
The skin of the seal is considered the warmest and most practical, so the fishermen catch this animal. The indigenous inhabitants of Transbaikalia are happy to use the meat of the hunted seal for food.
The seal has very powerful paws crowned with strong nails, which allows it to winter period tear apart a thin piece of ice in order to breathe oxygen. The constant presence under water at dusk has formed a certain device of the eyes, they are rather convex, which allows the seal to easily get its own food. The seal can be under water for up to an hour, holding its breath for this period, it is an amazing swimmer, thanks to the increased concentration of hemoglobin, it can dive up to 300 meters deep.
Her habitat habitats - water depths, despite its impressive dimensions, it is very maneuverable and dexterous in water, under water it can reach speeds of up to 25 km / h. But, like all seals, it is completely clumsy on land, in moments of danger, being on the shore, it can go to the races, which looks pretty funny.
Nutrition
The favorite food of the seal is the small and large golomyanka, long-winged goby, yellow-winged goby, sandy sculpin. Golomyankas occupy the main stage in the nutrition of seals. The seal eats from 3 to 5 kg of fish per day. And it takes 2-3 hours to digest food in the stomach.
reproduction
Females after 4 years of life are ready for mating and reproduction, but males are a little behind and mature a couple of years later. mating season For seals it lasts from the end of March to the end of April. At this time, the males make every effort to invite the female to the ice to mate. And if successful, a small seal will be born in 11 months. A natural feature is the delay in pregnancy for 2-3 months, that is, the fertilized egg may be in the fading stage, and only after this period, the female's pregnancy will begin to develop.
It is the female who takes care of the place of the future birth for her cubs, usually this is a lair in the snow, since the cubs appear in winter. After the birth of the baby, the seal mother will feed him with milk for 3 months. Baby seals are born completely dependent on their mother, their skin is colored in White color. During the feeding period, the mother will only go fishing for her own food, the female spends the rest of the time with the babies. When she is in the lair, the temperature there rises to +5, although outside it the temperature can drop to -15.
The ringed seal is so named for the light rings with a dark frame that make up the pattern of its coat. Adults reach a size of 135 cm and a weight of 70 kg.
Dimensions and appearance
The ringed seal is one of the smallest. The body length of an adult seal is up to 150 cm, total weight usually does not exceed 50-60 kg. The body is relatively short and thick. The neck is short, the head is small, the muzzle is shortened. Vibrissae are flattened with wavy edges. The hairline of adult animals, as in other species, is short, hard, with a predominance of awns.
Adult coloration varies widely. Characterized by the presence of a large number of light rings scattered throughout the body. The general background of the coloration of the dorsal side of the body is dark, sometimes almost black, the ventral side is light, yellowish. There are no light rings on the flippers. Males and females are colored the same.
Habitat
The ringed seal is an inhabitant of the arctic and subarctic waters of the Atlantic and Pacific Oceans where it is ubiquitous. It lives mainly in coastal shallow water areas. It also inhabits the Baltic Sea, lakes Ladoga and Saimaa.
In Russia, the seal is distributed from the Murmansk coast to the Bering Strait, including the White Sea, the waters of Novaya Zemlya, Franz Josef Land, Severnaya Zemlya, and the New Siberian Islands. On the Far East ringed seal is called akiba. In the Bering Sea, it lives along the western (where it descends to the south almost to Cape Lopatka in Kamchatka) and eastern (up to Bristol Bay) coasts, including the waters of the Commander and Aleutian Islands. In the Sea of Okhotsk, it inhabits the entire coastal part, including numerous bays, as well as the coast of Eastern Sakhalin, the Sakhalin Bay and the Tatar Strait. Reaches the shores of the island of Hokkaido.
Outside of our waters, the ringed seal lives off the coast of Northern Norway, Svalbard, eastern (up to 75 degrees N) and western coasts Greenland, in the northern part of the Gulf of St. Lawrence and near the island of Newfoundland. Inhabits almost the entire Canadian Arctic Archipelago, including Hudson Bay.
Migration in ringed seals is weakly expressed. Obviously, she comes the farthest to the north. She spends most of the year in ice-covered bays and fiords. In autumn, as the water freezes, the animal does not migrate south, but makes holes in the ice, to which it regularly swims up to breathe and rest. Usually, the seal spends 8-9 minutes under water, but if necessary, it may not rise to the surface for up to 20 minutes. It takes 45 seconds for a seal to stock up on a new portion of air.
reproduction
In the Okhotsk and Chukotsk, in the White and Barents Seas females bring offspring in the period from mid-March to mid-April, in the Baltic Sea and in Lake Ladoga - mainly in early March.
The cubs are born in a long, thick white coat, which is replaced, apparently, after 2 weeks. The length of the newborn is about 60 cm, weight up to 4 kg. Milk feeding lasts about one month. During this time, the body length of the cubs increases by approximately 10 cm, and the weight doubles. Then the growth rate slows down. By winter, the body weight of young seals reaches 12 kg, and its length is 80 cm or more. One-year-old seals have a body length of up to 84 cm, weight up to 14 kg.
The ringed seal is the only one of all seals that builds a nest for its young. In March or April, when the ice begins to break, the female makes a hole in a snowdrift with a tunnel leading to the water.
Females give birth to one baby pup. characteristic hallmark This species is that in many cases the cubs that have lost their mother do not die, but survive, but their growth is greatly slowed down, and as a result they remain dwarfs.
Ringed seal females reach sexual maturity in most cases at the age of 5-6 years, and the first offspring are brought at the age of 6-7 years. Males start breeding mainly at the age of 6-7 years. In ringed seals, growth stops at the age of 10 years.
The food of the ringed seal is based on two groups of animals - fish and crustaceans, and only those that form large accumulations in the upper layers of the water.
Appearance
The body length of the Caspian seal is up to 150 cm, and its average weight is 70 kg. The body is relatively thick with a short length. The neck is not long, but noticeable, the head is small. The edges of the flattened vibrissae are wavy.
The color of this seal in animals of different ages and different sexes is different. There is a large individual variation in coloration. Primarily upper surface the body has a darkish background, the ventral - light gray. On the sides, the transition of tones is gradual. Dark gray, brownish, sometimes almost black spots of various sizes and shapes are randomly scattered throughout the body. Spotting is more pronounced on the back than on the belly. Males are more brightly and contrastingly colored than females.
Habitat
The Caspian seal lives only in the Caspian Sea, where it is found everywhere from the Northern Caspian to the coast of Iran. The northern half of the sea is generally more populated than the southern.
The Caspian seal makes regular seasonal, although not long, migrations. During the winter months, almost the entire population is concentrated in the ice zone of the Northern Caspian. As the ice disappears, the animals move to the south and by the beginning of summer they are widely distributed over the waters of the Middle and South Caspian. Here they feed heavily, and in early autumn they begin to move again to the Northern Caspian.
Nutrition
The basis of the diet of the Caspian seal is made up of various types of gobies. The second place in nutrition is occupied by sprat. In even smaller quantities, these seals eat atherina, shrimps, and amphipods. From valuable commercial fish in their stomachs they sometimes find herring, eaten by them in certain periods of the year in small quantities. The composition of food during the year changes little.
reproduction
The period of puppies in the Caspian seal is shorter than in other species - from the middle of the last decade of January to the end of the first decade of February. The majority of females bring offspring during this period. Mating begins after the puppy and lasts from mid-February to early March. Reproduction and mating take place on the ice of the Northern Caspian.
The female brings, as a rule, one large cub up to 75 cm long, weighing 3-4 kg. It is covered with long silky almost white hair. The duration of milk feeding is about 1 month, and during this period the length of the cub increases to 85-90 cm, and body weight - more than 4 times.
During the second and third decades of February, even during the lactation period, the cubs molt, replacing the children's white hairline. Shedding cubs are called sheepskin coats, and young animals that have completely replaced children's hair are called sivaris. The short hairline of the sivar has an almost monochromatic dark gray color on the back and a light gray (whitish) monochromatic color on the belly. As the animal grows, with each annual molt, the spotting of color appears brighter and brighter.
Females reach sexual maturity, apparently, at the age of 5, so that most of the females bear the first offspring at the age of 6 years. After that, most sexually mature females breeds annually.
The seals do not form large and dense accumulations on the ice. Females with cubs are usually located at some distance from one another. Preferably, they cub on strong ice floes, in which they make holes (holes) even at a time when the ice is thin. These holes do not freeze due to the constant use of their animals to go out onto the ice. Sometimes seals are forced to widen their eyes with the help of sharp claws on their front flippers.
During the molting after the breeding and mating period, when the ice area is reduced, the Caspian seals form relatively dense aggregations. Animals that did not have time to molt on the ice sometimes (in April) lie down in groups on shalygs (sand islands) in the northern part of the Caspian.
AT summer months Caspian seals stay in open water separately in a large area of the Middle and South Caspian, and in autumn (September-October) they gather in the north-eastern part of the sea, where they lie in dense groups (males and females different ages) on shalyga.
Author's workAuthor: Vasilyeva E. and Fedotova E., students of the 2nd grade of the GBOU Gymnasium No. 196
Head: Glikman Elena Vladimirovna
Review: Lyubov Anatolyevna Eremina, teacher of biology, chemistry and geography, MKOU "Selkovo basic comprehensive school"
Appearance
The Baltic ringed seal is a marine mammal that belongs to the genus of small seals. It is called differently ringed seal or akiba. Here is what is noted in Wiktionary about this seal: "In general, the ringed seal is much smaller than the common seal; but it has a thick layer of fat under the skin." It is this layer that prevents the seal from freezing, so some subspecies of the seal dare to swim far into the Arctic Ocean. The body color is dark gray with light streaks in the form of rings. Maybe that's why they call her a ringed seal? The front flippers are shorter than the back ones. Head with a short muzzle. The average weight of the animals is 80 kg, as in a tall adult male.
Spreading
An inhabitant of the arctic and subarctic waters of the Atlantic and Pacific oceans. It lives mainly in coastal shallow water areas. It also inhabits the Baltic Sea, about Lake Ladoga. In the northern seas of Russia, the seal is distributed from the Murmansk coast to the Bering Strait, including the White Sea, the waters of Novaya Zemlya, Franz Josef Land, Severnaya Zemlya, and the New Siberian Islands.
The Baltic ringed seal also lives in the Gulf of Finland and Riga.
Nutrition
In the Baltic Sea, seals mainly feed on sprat, Baltic herring, gobies, crustaceans, and rarely cod. During the day, the seal eats up to 8 kilograms of this food.
reproduction
Females give birth in the Baltic Sea - mainly in early March. Prior to that, she had been carrying her offspring for 11 months. The female brings one, occasionally two cubs, covered with thick and soft hair. The baby is creamy white in color, which is why it is called white pup. A newborn seal can independently go into the water and swim. Milk feeding of cubs lasts 3-4 weeks, after which they become independent. After 6-7 years, adult animals will be able to breed.
Security
In 1970, there were about 12.5 thousand Baltic ringed seals in the Gulf of Finland and Riga. Today, their numbers are decreasing. Previously, the number of these seals decreased due to the hunting of these marine animals. Now seals breed less and less often, because the waters of the bays where they live are polluted with industrial and agricultural waste.
in the waters former USSR since 1980, a ban on the extraction of the Baltic ringed seal has been introduced.
The image of the seal can be found on postage stamps and in art.
Gallery
Nerpa 1 001.jpg
Nerpa in the water
Nerpa-2-001.gif
Nerpa on dry land
Literature (sources)
- Airapetyants A.E., Verevkin M.V., Fokin I.M. Baltic ringed seal / Red Book of Nature of St. Petersburg. Rep. ed. G.A. Noskov. - St. Petersburg: ANO NPO "Professional", 2004. - 95-96 p.
- Atlas of marine mammals of the USSR. - City: "Food industry", 1980. - 39-40 p.
- Geptner V.G., Naumov N.P. Mammals of the Soviet Union. Volume 2, part 3. - City: Title, 1976. - 169-173 p.
- Ivanter E.V. Mammals. - Petrozavodsk: "Karelia", 1974. - 202 p.