Caspian seals live in the temperate region of the Caspian Sea on islands or fast ice sheets. This landlocked, saltwater sea is 100 ft (30.84 m) below sea level and at latitudes of 37 to 47 degrees north. Caspian seals can also be found in estuaries. The mouths of the Volga and Ural rivers are the most popular of these estuaries.
During winter months Caspian seals live in the north on ice caps. There, females give birth and nurse their young. A small portion of the population breeds farther south in the winter on islands such as Ogurchinsky, near the Turkmenistan coastline. These breeding areas tend to be in protected places like pressure ridges away from the wind and predators. Unlike their closest relatives, ringed seals (Pusa hispida), Caspian seals do not give birth in lairs (holes in snow drifts); this is said to maybe be an adaptation to ice that is not as stable as Arctic ice. During the spring and summer months, Caspian seals migrate south to live on sand banks or rocky areas, usually on islands and usually not on the main coastline. The southern part of the Caspian Sea has deeper water where seals may dive up to 50 meters.
Average elevation: -30.84 m.
Range depth: 50 (high) m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: coastal
Other Habitat Features: estuarine
Besides humans, the two other predators of Caspian seals are sea eagles and wolves. Sea eagles snatch up newborn pups soon after they are born, during lactation their mortality rate is around 22%. In the northern part of the Caspian Sea, wolves will kill seals lying out on islands.
Known Predators:
When Caspian seals are born, they have a coat called a lanugo, made up of long white to silver gray fur. The lanugo helps keep pups warm until they develop blubber. Newborn pups are between 64 to 79 cm in length and weigh about 5 kg when born. After 2 to 3 weeks, the lanugo begins to shed and is replaced by dark gray hair; this process takes 6 to 8 weeks. It's possible that, when pups are weaned at a younger age, they may become smaller adults.
Adult Caspian seals are one of the smallest pinnipeds in the “true seal” family (Phocidae). Adult Caspian seals vary in size and appearance. Males grow to 1.5 meters in length, which is slightly larger than females, who reach 1.4 meters. Both males and females have grayish-yellow to dark gray fur coats with a lighter underbelly. Males tend to be darker with dark spots over the entire body, whereas females are lighter in color with lighter spots on the back and not on the belly. The spots of Caspian seals can also be encircled by light colored rings. Both males and females have relatively short flippers with moderate sized claws on their fore flippers and shorter, narrower claws on their hind flippers. Adult Caspian seals have a dental formula of I 3/2, R 1/1, and PC 6/5.
The closest relatives of Caspian seals are ringed seals (Pusa hispida), the skulls of both are similar morphologically. However, unlike those of Caspian seals, the bodies of ringed seals are covered with light rings against a dark background. Both species are similar in size and have a relatively long narrow snout. These two species do not inhabit the same areas, being separated by 1600 km.
Range mass: 50 to 86 kg.
Average mass: 55 kg.
Range length: 1.4 to 1.8 m.
Average length: 1.45 m.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently
In the wild, Caspian seals live to be on average about 35 years old; however, some have been recorded to live 50 years. Males have relatively short lives, around 26 years. Caspian seals are not usually found in captivity except for a few zoos in Russia. There is no evidence of their life span in captivity.
Range lifespan
Status: wild: 26 to 50 years.
Average lifespan
Status: wild: 35 years.
Pusa caspica, Caspian seals, are one of the most numerous and widespread of northern pinnipeds. They are only found in the world’s largest inland body of saltwater, the Caspian Sea, which is located in a small part of the Paleartic region, between the countries of Russia, Azerbaijan, Iran, Turkmenistan, and Kazakhastan. Caspian seals migrate to different parts of the Caspian Sea during different seasons, however they never leave the landlocked Caspian Sea. From May to September most Caspian seals live in the southern part of the Caspian Sea. In autumn, they migrate north to the ice sheets for the birth of their newborn pups and breeding season.
There are various ideas to explain how Caspian seals began inhabiting the Caspian Sea. One theory is that they are direct descendants of ringed seals (Pusa hispida). During the Quaternary period, when there were glacier ice sheets, ringed seals migrated south. When the ice retreated seals were left isolated in the Caspian Sea. Others argue that Caspian seals originally occupied an inland area of the Paratethys Sea during the Miocene and Pliocene epochs. Other researchers argue that ringed seals are derived from Caspian seals and eventually migrated north to the Arctic.
Biogeographic Regions: palearctic (Native )
Caspian seals are primarily piscivorous. They eat a variety of foods depending on season and availability. Clupeonella (kilka) is the most abundant food source in the Caspian Sea, accounting for 70% of their diet. When Caspian seals inhabit shallow waters in the northern part of the sea (autumn and winter months), they prey mostly on sculpins, gobies, and crustaceans. While in the southern part of the Caspian Sea (deep waters), during the summer months, they eat herring, roach, carp, sprat, and smelt. When Caspian seals live in estuaries, they eat large amounts of the freshwater species Sander lucioperca. Other prey include shrimp, crab, silversides, and asp.
Animal Foods: fish; aquatic crustaceans
Primary Diet: carnivore (Piscivore )
Caspian seals are the only mammal found in the Caspian Sea, and they are near the top of the food chain. They eat many different types of fish and crustaceans. If seal populations decrease, the number of fish may increase. Seal population density may also affect the numbers of their two predators, wolves and eagles.
For the past 200 years, humans living around the Caspian Sea have killed seals for their blubber and for the lanugo fur of newborn pups. Currently around 60,000 Caspian seal pups are caught annually for their fur. Some ecotourism is increasingly focusing on these animals, which involves taking ferries out to view them.
Hunting Caspian seals in the past has been intense. For example, between 1933 and 1940 an average of 160,000 seals were caught each year. In 1940, when the hunting of Caspian seals was first regulated, there was still an average of 50,000 to 60,000 caught each year. In 1970 restrictions were increased on the northern ice allowing only 20,000-25,000 pups to be killed. However, when the Soviet Union collapsed, these regulations were not enforced. In addition, the weak Soviet Union contributed to a large increase in illegal killing and poaching of Caspian seals.
Positive Impacts: food ; body parts are source of valuable material; ecotourism
Caspian seals do not negatively affect humans. They may take some fish, but these are not typically fish that are economically important.
According to International Union for the Conservation of Nature (IUCN) Red list of Threatened Animals, Caspian seals are identified as vulnerable. This is for several reasons: loss of food by commercial fishing, toxic pollution, habitat destruction, human disturbance, disease, and commercial exploitation. In addition to a few regulations limiting the amount of Caspian seals caught each year, adult females are also protected during the breeding season.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: endangered
Little is known about communication in Caspian seals. They are solitary in winter months, in summer months they make aggressive snorts or use flipper waving to tell other seals to keep their distance.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Caspian seals were previously known by the scientific name Phoca caspica.
Both male and female Caspian seals are monogamous. There seems to be no fighting for a mate among breeding seals.
Mating System: monogamous
In late autumn, Caspian seals migrate to the northern part of the Caspian Sea where the water is shallow and frozen. Caspian seals give birth in protected areas on ice sheets after a gestation period of about 11 months. There is no evidence to support this currently, but researchers believe that since there is a long gestation period, there is a delay in implantation of the egg. Annual pregnancy rates are normally between 40 to 70 percent, but are currently at an all time low of 30 percent. This maybe due to pollution. In late January to early February, each female seal gives birth to one pup. Female pups become sexually mature after 5 to 7 years, male pups become sexually mature after 6 to 7 years. Newborn pups are not fully grown for 8 to 10 years after they are born. Breeding begins a few weeks after the birth of last years’ pup, in late February to mid March. Breeding occurs after weaning of newborn pups but can begin while pups are still nursing. After the breeding season and molting in late April, the weather in the north starts to warm and the ice begins to melt. Caspian seals then migrate back to the southern part of the Caspian Sea. The southern part has deeper, colder waters where seals spend the summer months.
Breeding interval: Caspian seals breed once a year.
Breeding season: Breeding occurs from late February to March.
Range number of offspring: 1 to 1.
Range gestation period: 10 to 11 months.
Range weaning age: 1 to 1 months.
Range age at sexual or reproductive maturity (female): 5 to 7 years.
Range age at sexual or reproductive maturity (male): 6 to 7 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; delayed implantation ; post-partum estrous
There is no available information about the parental care of Caspian seals, except that newborn pups are weaned after 4 to 5 weeks of lactation. Given that Caspian seals are asocial there may be no collaboration with other seals in raising newborn pups. In their closest relatives, ringed seals, as well as other seal species, males leave females soon after mating and do not help raise the newborn pups. Females will leave newborn pups to forage for short periods of time.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
The Caspian seal (Pusa caspica, syn. Phoca caspica)[1] is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. It lives along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. In winter and cooler parts of the spring and autumn season, it populates the northern Caspian coastline. As the ice melts in the summer and warmer parts of the spring and autumn season, it also occurs in the deltas of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where the water is cooler due to greater depth.
Evidence suggests the seals are descended from Arctic ringed seals that reached the area from the north during an earlier part of the Quaternary period and became isolated in the landlocked Caspian Sea when continental ice sheets melted.
Adults are about 126–129 cm (50–51 in) in length. Males are longer than females at an early age, but females experience more rapid growth until they reach ten years of age. Males can grow gradually until they reach an age of about 30 or 40 years.[2] Adults weigh around 86 kg (190 lb); males are generally larger and bulkier. Their dental formula is 3.1.4.22.1.4.1.[3]
The skull structure of the Caspian seal suggests it is closely related to the Baikal seal. In addition, the morphological structures in both species suggest they are descended from the ringed seal which migrated from larger bodies of water around two million years ago.[4]
Caspian seals can be found not only along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. As the ice melts in the warmer season, they can be found on the mouths of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where cooler waters can be found due to greater depth.
In winter, and cooler parts of the spring and autumn season, these marine mammals populate the Northern Caspian. In the first days of April, spring migration to the southern part of the Caspian Sea begins with mature female seals and their pups, during this migration hungry seals eat the fish in the nets. Male mature seals stay in the northern Caspian Sea longer and wait until the moulting is completed. In summer, seals find empty places in the western part of Apsheron for resting. In the eastern part, the most crowded place used to be the Ogurchinskiy Island, but by 2001, fewer than 10 pups were recorded on Ogurchinsky, some of which were killed by people on the island.
Caspian seals are primarily piscivorous. They eat a variety of food depending on season and availability. A typical diet for Caspian seals found in the northern Caspian sea consists of crustaceans and various fish species, such as Clupeonella engrauliformis, C. grimmi, C. caspia, Gobiidae, Rutilus caspicus, Atherina boyeri, and Sander lucioperca. Caspian seal adults eat about 2–3 kg (4–7 lb) of fish a day and almost a metric ton of fish per year.[5]
In autumn and winter, Caspian seals prey mostly on sculpins, gobies, and crustaceans while inhabiting shallow waters in the northern part of the sea. During the summer, in the southern part of the Caspian Sea, they eat herring, roach, carp, sprat, and smelt. When Caspian seals live in estuaries, they eat large amounts of the freshwater species, Sander lucioperca. Other prey include shrimp, crab, and silversides.[6]
Being one of the top predators in the ecosystem, Caspian seals had hazardous chemicals found inside their bodies such as heavy metals, organochlorine compounds, and radionuclides.[7]
Caspian seals are shallow divers, typically diving 50 m (160 ft) for about one minute, although scientists have recorded Caspian seals diving deeper and for longer periods of time. After foraging during a dive, they rest at the surface of the water.[8]
In the summer and winter, during mating season, Caspian seals tend to live in large groups. At other times of the year, these seals are solitary. During the summer, however, they make aggressive snorts or use flipper waving to tell other seals to keep their distance. Little else is known about their behavior.[8]
Male and female Caspian seals are monogamous. Among breeding seals, a lack of fighting for a mate seems prevalent. In late autumn, Caspian seals travel to the northern part of the Caspian Sea where the water is shallow and frozen to give birth in secluded areas on ice sheets after a gestation period of 11 months. Normally, pregnancy rates are 40 to 70%, but are currently at an all-time low of 30%. In late January to early February, female seals give birth to one pup each. Similar to other ringed seals, these pups are born with white pelages and weigh about 5 kg (11 lb). Their white coats are molted at around three weeks to a month. Male pups become sexually mature after six to seven years, whereas female pups sexually mature after five to seven years. Newborn pups are not fully grown until 8 to 10 years after they are born.[9] Breeding begins a few weeks after the birth of last year's pup around late February to mid March. Breeding usually occurs after weaning of a newborn pup, but can begin while the pup is still nursing. Caspian seals migrate back to the southern part of the Caspian Sea after the breeding season and molting in late April because the north begins to warm with constant ice melting. The southern region of the Caspian Sea has deep, colder waters where the seals spend the summer months.[10]
Several recent cases of large numbers of Caspian seals dying due to canine distemper virus have been reported, in 1997, 2000 and 2001.[2] In April 2000, a mass die-off of Caspian seals was first reported near the mouth of the Ural River in Kazakhstan. It spread south to the Mangistau region, and by the end of May, more than 10,000 seals had died along the Kazakhstan coast. High death rates were also recorded in May and June along the Apsheron peninsula of Azerbaijan and the Turkmenistan coast.[11]
Clinical signs of infected seals included debilitation, muscle spasms, ocular and nasal exudation, and sneezing. Necropsies performed in June 2000 on eight Azerbaijan seals revealed microscopic lesions, including bronchointerstitial pneumonia, encephalitis, pancreatitis and lymphocytic depletion in lymphoid tissues. Similar lesions were also discovered on four seals from Kazakhstan. Morbillivirus antigen was also detected in multiple tissues, including lung, lymph nodes, spleen, brain, pancreas, liver, and epithelial tissue of the reproductive, urinary, and gastrointestinal tracts. Such tissue lesions are characteristic of distemper in both terrestrial and aquatic mammals.[11]
Tissues from 12 carcasses found in Kazakhstan, Azerbaijan, and Turkmenistan were examined for morbillivirus nucleic acid. Sequences from the examination showed that canine distemper virus, which is part of the genus Morbillivirus, was the primary cause of death. The sequences also proved that seals from widely separated regions of the Caspian Sea were infected by the same virus. This finding established spatial and temporal links between the seal deaths in these regions. The sequences were also identical to that of canine distemper virus found in the brain tissue of a seal that died in 1997 and showed no morbillivirus lesions. This suggests persistence of canine distemper virus in the Caspian seal population over a span of several years or repeated spillover from the same terrestrial reservoir.[11]
Another study in 2000 using 18 Caspian seal corpses found several concurrent bacterial infections that could have contributed to the illness of the affected seals. These include Bordetella bronchiseptica, Streptococcus phocae, Salmonella dublin, and S. choleraesuis. Corynebacterium caspium, a new bacterium, was identified in one of the seals, and poxvirus, Atopobacter phocae, Eimeria- and Sarcocystis-like organisms, and a Halarachne species were identified in Caspian seals for the first time. The study also asserts that the “unusually mild” winter that preceded the die-off in 2000 could have contributed to its cause “through increased ambient air pressure and accelerated disappearance of ice cover at the breeding areas in the northern Caspian Sea.”[12]
A century ago, their population was estimated at 1.5 million seals; in 2005, 104,000 remained, with an ongoing decline of 3–4% per year.[13] By 2022, the Caspian Environmental Protection Center estimated the population at 70,000.[14]
In a three-week period in February 1978, wolves were responsible for the killing of numerous seals near Astrakhan. An estimated 17 to 40% of the seals in the area were killed, but not eaten.[15]
Due to increased industrial production in the area, pollution has had an effect on the survival of the Caspian seal. From 1998 to 2000, the concentration of zinc and iron increased dramatically in the tissue of dead, diseased seals. This suggests these elements are causative agents in compromising the Caspian seal's immune system.[16]
Sea eagles are known to hunt these seals, which results in a high number of fatalities for the juveniles. They are also hunted by humans for subsistence and commerce. As of 2006, commercial icebreaker routes have passed through areas with high Caspian seal pup concentrations, which may contribute to loss of habitat.[17]
For threats related to migration, high density seal aggregations were recorded in November 2009 and 2010 CISS helicopter surveys in Kenderli Bay, but the integrity of seal habitat in Kenderli Bay is currently threatened by an imminent large-scale coastal resort development. This resort development can be a serious disturbance for seals. The local authorities have been advised about the need to preserve the seal habitats in the bay, but it is not yet clear what steps are planned to achieve this. According to the present study, Kosa Kenderli plays an important role for the seasonal migration of the Caspian seals and is recommended to be a protection area.
In December 2022, a substantial die-off was reported, with initial reports of 700 corpses later revised upwards to 2,500. The cause is unknown.[14]
The Caspian seal (Pusa caspica, syn. Phoca caspica) is one of the smallest members of the earless seal family and unique in that it is found exclusively in the brackish Caspian Sea. It lives along the shorelines, but also on the many rocky islands and floating blocks of ice that dot the Caspian Sea. In winter and cooler parts of the spring and autumn season, it populates the northern Caspian coastline. As the ice melts in the summer and warmer parts of the spring and autumn season, it also occurs in the deltas of the Volga and Ural Rivers, as well as the southern latitudes of the Caspian where the water is cooler due to greater depth.
Evidence suggests the seals are descended from Arctic ringed seals that reached the area from the north during an earlier part of the Quaternary period and became isolated in the landlocked Caspian Sea when continental ice sheets melted.
