Caspian Seal
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.
Distribution
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.
Geography
Climate zones
Habits and Lifestyle
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.
Diet and Nutrition
Caspian seals are mostly piscivorous, meaning that they feed on a range of small fish, in particular kilka, and also crustaceans such as shrimp.
Mating Habits
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.
Population
Population threats
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.
Population number
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.
Ecological niche
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.
Fun Facts for Kids
- Seals have blubber under their skin, a thick layer of fat that keeps them warm in the icy water.
- Seals have more blood than other animals, and since blood cells carry oxygen, seals are able to dive for longer than other animals.
- Seals can hold their breath for 2 hours, the longest in the animal world.
- On diving, seals decrease their heart rate from 50-80%.
- Seals’ very sensitive whiskers help them detect vibrations from their prey under water.
- Seals may have evolved from otter- or bear-like ancestors which lived on land.