The Caspian seal (Pusa caspica or 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. They are found not only 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, these marine mammals populate the Northern Caspian. 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.
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.
The Caspian seal is found only in the Caspian Sea and is the only marine mammal that lives there. At the beginning of the 20th century, around 1 million of them were in existence. Being an iconic animal for that area, it is a key indicator of the health of this body of water, upon which thousands of people depend for their livelihoods. The population today has decreased by over 90% and this decline is continuing. The Caspian Sea is faced with many ecological changes and human pressures, so urgent conservation measures need to be put in place to prevent its disappearance, being a vital component of the Caspian’s ecosystem.
The Caspian seal is an endemic animal of the Caspian Sea. The seasonal migrations, which are prompted by ice formation, take place between the regions in the north, south and middle of the Sea. This sea is not connected to the oceans; its waters are weakly saline. Caspian seals use both the Sea’s shallow northern basin and its deeper waters in the middle and south, sometimes also entering the rivers feeding into the Sea. Births usually take place on the ice that forms in northern areas, although sand banks, sandy islands, and reefs can also be used for births and for hauling out.
These seals usually live in large groups at the time of the mating season in the summer and winter months. During the rest of the year, they are solitary. Between late spring and late autumn these animals are probably most of their time out at sea, feeding. Sometimes they will haul out on islands, forming dense groups, typically at the ends of sandbars or peninsulas. Here the ‘personal space’ maintained by each animal is different to that of the ice-breeding grounds, as on the beach seals rest very close to each other. These seals are shallow divers, usually diving 50 meters for around one minute, although they have been recorded diving deeper and longer. After diving to forage, they rest at the water’s surface. Little else is known about the communication and behavior of Caspian seals. In summer months they make aggressive snorts or wave their flippers to warn other seals to stay at a distance.
Caspian seals are carnivores (piscivores); they mainly feed on a range of small fish, in particular kilka, and also crustaceans such as shrimp.
Both male and female Caspian seals are monogamous, which means that one male mates with only one female. It seems there is no fighting over mates among breeding seals. They migrate in late autumn to the shallow and frozen water in the northern region of the Caspian Sea. After a gestation of about 11 months, females give birth on ice sheets in protected areas. Newborns are nursed for about a month, but do not go into the water until after the ice has begun to melt and their lanugo coat has molted. About a month after birthing, from late February to the middle of March, the breeding colony sees the arrival of males, and mating take place again, following which the adults molt, the ice breaks up, and the seals begin to disperse into deeper, cooler areas in the south to feed. Females reach maturity at 5 to 7 years, and males at 6 to 7 years.
The population of the Caspian seal was thought to be more than a million at the beginning of the 20th century, but has since suffered a dramatic decline of more than 90 percent as a result of certain human activities. Current deaths still greatly exceed the introduction of young into the population. The current main threats include: loss of food to commercial fishing, habitat destruction, toxic pollution, human disturbance, commercial exploitation and disease.
According to the IUCN Red List, the total Caspian seal population size is estimated to be from 104,000 to 168,000 individuals, including 68,000 reproductively mature individuals. Currently this species is classified as Endangered (EN) on the IUCN Red List.
Caspian seals, being the only mammal inhabiting the Caspian Sea, are at the height of the food chain. Their diet consists of a large range of fish and crustaceans. Fish populations may increase if seal populations decrease, and seal numbers may also affect the populations of wolves and eagles, their two predators.
