Animal Diversity Web

Ge­o­graphic Range

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. ("Seal Con­ser­va­tion So­ci­ety", 2001; Ridg­way and Har­ri­son, 1981; Wikipedia, 2006)

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. (Ridg­way and Har­ri­son, 1981; Wikipedia, 2006)

• Biogeographic Regions
• palearctic
  • native

Habi­tat

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. ("Seal Con­ser­va­tion So­ci­ety", 2001; "UNEP World Con­ser­va­tion", 2004; Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

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. ("UNEP World Con­ser­va­tion", 2004; Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

• Habitat Regions
• temperate
• saltwater or marine

• Aquatic Biomes
• coastal

• Other Habitat Features
• estuarine

• Average elevation

  -30.84 m

  -101.18 ft

• Range depth

  50 (high) m

  164.04 (high) ft

Phys­i­cal De­scrip­tion

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. ("Sci­ence and Con­ser­va­tion of Ice lov­ing Seals", 2002; Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

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. ("Caspian Seal", 1984; Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

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. (Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently

• Range mass

  50 to 86 kg

  110.13 to 189.43 lb

• Average mass

  55 kg

  121.15 lb

• Range length

  1.4 to 1.8 m

  4.59 to 5.91 ft

• Average length

  1.45 m

  4.76 ft

Re­pro­duc­tion

Both male and fe­male Caspian seals are monog­a­mous. There seems to be no fight­ing for a mate among breed­ing seals. (Nowak, 1964; Reeves, et al., 2002)

• 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. ("Phoca caspica", 1990; Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• viviparous
• delayed implantation
• post-partum estrous

• 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

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. (Reeves, et al., 2002; Ridg­way and Har­ri­son, 1981)

• Parental Investment
• precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

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. ("UNEP World Con­ser­va­tion", 2004; Reeves, et al., 2002)

• Range lifespan
  Status: wild

  26 to 50 years

• Average lifespan
  Status: wild

  35 years

Be­hav­ior

Caspian seals tend to live in large groups dur­ing the mat­ing sea­son in sum­mer and win­ter months. At other times of the year, these seals are soli­tary. There is lit­tle else known about their be­hav­ior. (Reeves, et al., 2002; Wikipedia, 2006)

Caspian seals are shal­low divers, typ­i­cally div­ing 50 me­ters 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. (Reeves, et al., 2002; Wikipedia, 2006)

• Key Behaviors
• natatorial
• diurnal
• motile
• migratory
• solitary

Home Range

Home range sizes are un­known. ("Caspian Seal", 1984)

Com­mu­ni­ca­tion and Per­cep­tion

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. (Reeves, et al., 2002)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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. ("Phoca caspica", 1990; "UNEP World Con­ser­va­tion", 2004; Reeves, et al., 2002; Wikipedia, 2006)

• Primary Diet
• carnivore
  • piscivore

• Animal Foods
• fish
• aquatic crustaceans

Pre­da­tion

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. (Reeves, et al., 2002)

• Known Predators

  • sea eagles (Haliaeetus leucoryphus)
  • wolves (Canis lupus)

Ecosys­tem Roles

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. ("Phoca caspica", 1990; Reeves, et al., 2002)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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. ("Seal Con­ser­va­tion So­ci­ety", 2001; "UNEP World Con­ser­va­tion", 2004; Nowak, 1964; Reeves, et al., 2002)

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. ("Seal Con­ser­va­tion So­ci­ety", 2001; Reeves, et al., 2002)

• Positive Impacts
• food
• body parts are source of valuable material
• ecotourism

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Caspian seals do not neg­a­tively af­fect hu­mans. They may take some fish, but these are not typ­i­cally fish that are eco­nom­i­cally im­por­tant.

Con­ser­va­tion Sta­tus

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. ("Sci­ence and Con­ser­va­tion of Ice lov­ing Seals", 2002; "UNEP World Con­ser­va­tion", 2004; Nowak, 1964)

• IUCN Red List

  Endangered
  More information

• IUCN Red List

  Endangered
  More information

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

Caspian seals were pre­vi­ously known by the sci­en­tific name Phoca caspica.

Con­trib­u­tors

Tanya Dewey (ed­i­tor), An­i­mal Di­ver­sity Web.

Bon­nie Easley-Ap­p­le­yard (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor, Phil Myers (ed­i­tor, in­struc­tor), Mu­seum of Zo­ol­ogy, Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

1984. Caspian Seal. Pp. 125 in D Mac­don­ald, ed. The En­cy­clo­pe­dia of Mam­mals, Vol. 2, 2 Edi­tion. New York: Equinox.​Ltd.

1990. Phoca caspica. Pp. 220-238 in B Grimeks, ed. Grimeks En­cy­clo­pe­dia of Mam­mals, Vol. 5, 2 Edi­tion. New Jer­sey: Mc­Graw-Hill.

2002. "Sci­ence and Con­ser­va­tion of Ice lov­ing Seals" (On-line). Caspian seal. Ac­cessed March 10, 2006 at http://​pagophilus.​org/​caspian.​html.

2001. "Seal Con­ser­va­tion So­ci­ety" (On-line). Caspian Seal. Ac­cessed March 10, 2006 at http://​www.​pinnipeds.​org/​species/​caspian.​htm.

2004. "UNEP World Con­ser­va­tion" (On-line). Ac­cessed March 10, 2006 at http://​www.​unep-wcmc.​org/​index.​html?​http://​www.​unep-wcmc.​org/​species/​data/​species_​sheets/​caspian.​htm~main.

An­der­son, H. 1969. The Bi­ol­ogy of Ma­rine Mam­mals. New York: Aca­d­e­mic Press.

Cassini, M. 1999. The evo­lu­tion of re­pro­duc­tive sys­tems in pin­nipeds. Be­hav­ioral Ecol­ogy, Vol­ume 10/ num­ber 5: 612-616.

Har­wood, J. 2001. MA­RINE MAM­MALS AND THEIR EN­VI­RON­MENT IN THE TWENTY-FIRST CEN­TURY. Jour­nal of Mam­mal­ogy, 82/3: 630–640..

Khuraskin, L., N. Za­kharova. 2002. "Phoca (Pusa) caspica" (On-line). Ac­cessed March 10, 2006 at http://​www.​caspianenvironment.​org/​biodb/​eng/​mammals/​Phoca%20(Pusa)%20­Caspica/main.​htm.

Ma­claren, I. 1966. Tax­on­omy of Har­bor Seals of the West­ern North Pa­cific. Jour­nal of Mam­mal­ogy, Vol 47/ Nu 3: 466-473.

Nowak, R. 1964. Walk­ers Mam­mals of the World. Lon­don: John Hop­kins Uni­ver­sity Press.

Reeves, R., B. Stew­art, P. Clapham, J. Pow­ell. 2002. Guide to Ma­rine Mam­mals of the World. New York: Chan­ti­clear Press.

Ridg­way, S., R. Har­ri­son. 1981. Hand­book of Ma­rine Mam­mals. San Diego: Aca­d­e­mic Press Lim­ited.

Wikipedia, T. 2006. "Wikipedia" (On-line). Ac­cessed March 19, 2006 at http://​en.​wikipedia.​org/​w/​index.​php?​title=Caspian_​Seal&​oldid=42880722.