|Caspian seal range|
The Caspian seal (Pusa 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 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. 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.
It is so-far unclear as to how these seals became isolated in the landlocked Caspian Sea. One of the most widely known hypotheses argues that the seals reached the Caspian during the Quaternary period from the north when continental ice sheets melted, and are descended from the ringed seal.
Adults are approximately 1.5 metres (4.9 ft) in length and weigh around 86 kilograms (190 lb); males are generally larger and bulkier. Their dental formula is I 3/2, R 1/1, PC 6/5.
Caspian seals are shallow divers, with diving depths typically reaching 50 meters and lasting about a minute, although deeper and longer depths have been recorded, with at least one individual seen at depths in excess of 165m. They are gregarious, spending most of their time in large colonies.
After an 11 month gestation period, the single pups are born in January and February. Similar to other ringed seals, these pups are born with white pelage and weigh about 5 kilograms. Their white coat is molted at around three weeks to a month. Sexual maturity is reached at 5 years for females, and about 6 or 7 years for males.
Prey and predators
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. Due to the increasing industrial development in the surrounding region, pollutants and pesticides have entered the Caspian and caused significant habitat problems, weakened immune systems and contributed to disease outbreaks.
In a three-week period in February 1978, wolves were responsible for the wanton killing of numerous seals near Astrakhan. Between 17 and 40% of the seals in the area were estimated to have been killed, but not eaten.
Since the late 1990s, there have been several cases of many Caspian seals dying due to canine distemper virus.
A century ago there were an estimated 1.5 million seals; by the 1980s, there were about 400,000.
- Härkönen, T. (2008). Pusa caspica. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 January 2009.
- [URL=http://s641.photobucket.com/user/1972rainman/media/Other/image_zps2a610382.jpg.html][IMG]http://i641.photobucket.com/albums/uu131/1972rainman/Other/image_zps2a610382.jpg[/IMG][/URL "Seal@ 167m."].
- Rumyantsev, V. D.; Khuraskin, L. S. (1978). "New data on the mortality of the Caspian seal due to wolves". In P. A. Panteleev et al.,. Page 187 in Congress of the All-Union Theriological Society, 2nd. ZR 116 (19). Moscow: Nauka. p. 5669.
- Caspian seal factsheet at pinnipeds.org
- "Caspian Seal under threat of extinction", Baztab newspaper. Persian article.