Caspian seal

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 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.

Caspian seal
Stamps of Turkmenistan, 1993 - Caspian seals (Phoca caspica) adult with young
Illustrated on Stamps of Turkmenistan, 1993
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Clade: Pinnipedia
Family: Phocidae
Genus: Pusa
Species:
P. caspica
Binomial name
Pusa caspica
(Gmelin, 1788)
Caspian Seal area
Caspian seal range
Synonyms
Phoca caspica

Description

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.

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.[3]

Caspian seals are shallow divers, with diving depths typically reaching 50 m (160 ft) and lasting about a minute, although deeper and longer dives have been recorded, with at least one individual seen at depths in excess of 165 m (540 ft).[4] They are gregarious, spending most of their time in large colonies.

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.

Diet

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. delicate caspia, Gobiidae, Rutilus rutilus caspicus, Atherina mochon pontica, and Lucioperca 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]

Behavior

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]

Reproduction

Male and female Caspian seals are monogamous. Among breeding seals, a lack of fighting for a mates 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. 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]

Threats

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.[11]

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.[12]

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.

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.[13]

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.[14]

Canine distemper virus

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.[15]

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.[15]

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.[15]

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.”[16]

See also

References

  1. ^ Härkönen, T. (2008). "'Pusa caspica'". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature. Retrieved 29 January 2009.
  2. ^ a b Wilson, Susan; Eybatov, Tariel; Amano, Masao; Jepson, Paul; Goodman, Simon (2 July 2014). "The Role of Canine Distemper Virus and Persistent Organic Pollutants in Mortality Patterns of Caspian Seals (Pusa caspica)". PLoS ONE. 9 (7): e99265. doi:10.1371/journal.pone.0099265. PMC 4079250. PMID 24987857.
  3. ^ Endo, H.; Sakata, S.; Arai, T.; Miyazaki, N. (April 2001). "The Muscles of Mastication in the Caspian Seal (Phoca caspica)". Anatomia, Histologia, Embryologia: Journal of Veterinary Medicine. 31 (5): 262–265. doi:10.1046/j.1439-0264.2002.00372.x.
  4. ^ "Seal@ 167m".
  5. ^ Khuraskin, L; Pochotoyeva, N (November 1997). "Status of the Caspian Seal Population". Caspian Environment Program: 86–94.
  6. ^ Grimeks, B (1990). Grimeks Encyclopedia of Mammals (Second ed.). New Jersey: McGraw-Hill. pp. 220–238.
  7. ^ Ikemoto, T; Kunito, T; Watanabe, I; Yasunaga, G; Baba, N; Miyazaki, N; Petrov, E. A.; Tanabe, S (2004). "Comparison of trace element accumulation in Baikal seals (Pusa sibirica), Caspian seals (Pusa caspica) and northern fur seals (Callorhinus ursinus)". Environmental Pollution. 127 (1): 83–97. doi:10.1016/s0269-7491(03)00251-3. PMID 14553998.
  8. ^ a b Reeves, R; Stewart, B; Clapham, P; Powell, J (2002). Guide to Marine Mammals of the World. New York: Chanticlear Press.
  9. ^ Easley-Appleyard, Bonnie (2006). "Pusa Caspica Caspian Seal". Animal Diversity Web. Retrieved 23 October 2014.
  10. ^ Hogan, Michael C, ed. (22 July 2010). "Caspian Seal". The Encyclopedia of Earth. Retrieved 24 October 2014.
  11. ^ Harkonen, Tero; Jüssi, Mart; Baimukanov, Mirgaly; Bignert, Anders; Dmitrieva, Lilia; Kasimbekov, Yesbol; Verevkin, Mikhail; Wilson, Susan; Goodman, Simon J. (Jul 2008). "Pup Production and Breeding Distribution of the Caspian Seal (Phoca caspica) in Relation to Human Impacts". AMBIO: A Journal of the Human Environment. 37 (5): 356–361. doi:10.1579/07-r-345.1.
  12. ^ 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. Moscow: Nauka. p. 5669.
  13. ^ Anan, Y.; Kunito, T.; Ikemoto, T.; Kubota, R.; Watanabe, I.; Tanabe, S.; Miyazaki, N.; Petrov, E.A. (March 2002). "Elevated Concentrations of Trace Elements in Caspian Seals (Phoca caspica) Found Stranded During the Mass Mortality Events in 2000". Archives of Environmental Contamination and Toxicology. 42 (3): 354–362. doi:10.1007/s00244-001-0004-7.
  14. ^ Dmitrieva, Lilia; Kondakov, Andrey; Oleynikov, Eugeny; Kydyrmanov, Aidyn; Karamendin, Kobey; Kasimbekov, Yesbol; Baimunkanov, Mirgaliy; Wilson, Susan; Goodman, Simon (26 June 2013). "Assessment of Caspian Seal By-Catch in an Illegal Fishery Using an Interview-Based Approach". PLoS ONE. 8 (6): 1–6. doi:10.1371/journal.pone.0067074. PMC 3694144. PMID 23840590.
  15. ^ a b c Kennedy, Seamus; Kuiken, Thijs; Jepson, Paul; Deaville, Robert; Forsyth, Morag; Barrett, Tom; van de Bilt, Marco; Osterhaus, Albert; Eybatov, Tariel; Callan, Duck; Kydyrmanov, Aidyn; Mitrofanov, Igor; Wilson, Susan (1 November 2000). "Mass Die-Off of Caspian Seals by Canine Distemper Virus". Emerging Infectious Diseases. 6 (6): 637–639. doi:10.3201/eid0606.000613. PMC 2640919. PMID 11076723.
  16. ^ Kuiken, T.; Kennedy, S.; Barrett, T.; Van de Bilt, M.W.G.; Borgsteede, F.H.; Brew, S.D.; Codd, G.A.; Duck, C.; Deaville, R.; Eybatov, T.; Forsyth, M.A.; Foster, G.; Jepson, P.D.; Kydyrmanov, A.; Mitrofanov, I.; Ward, C.J.; Wilson, S.; Osterhaus, A.D.M.E. (1 May 2006). "The 2000 Canine Distemper Epidemic in Caspian Seals (Phoca caspica): Pathology and Analysis of Contributory Factors". Veterinary Pathology. 43 (3): 321–338. doi:10.1354/vp.43-3-321. PMID 16672579.

External links

Asiatic linsang

The Asiatic linsang (Prionodon) is a genus comprising two species native to Southeast Asia: the banded linsang (Prionodon linsang) and the spotted linsang (Prionodon pardicolor). Prionodon is considered a sister taxon of the Felidae.

Baikal seal

The Baikal seal, Lake Baikal seal or nerpa (Pusa sibirica), is a species of earless seal endemic to Lake Baikal in Siberia, Russia. Like the Caspian seal, it is related to the Arctic ringed seal. The Baikal seal is one of the smallest true seals and the only exclusively freshwater pinniped species. A subpopulation of inland harbour seals living in the Hudson's Bay region of Quebec, Canada (lac de loups marins harbour seals), the Saimaa ringed seal (a ringed seal subspecies) and the Ladoga seal (a ringed seal subspecies) are found in fresh water, but these are part of species that also have marine populations.The most recent population estimates are 80,000 to 100,000 animals, roughly equaling the expected carrying capacity of the lake. At present, the species is not considered threatened, despite hunting (both legal and illegal) and pollution of the lake.

Baku Archipelago

The Baku Archipelago is a group of coastal islands close to Baku, Azerbaijan. The waters surrounding the islands are shallow.

Bycatch

Bycatch, in the fishing industry, is a fish or other marine species that is caught unintentionally while catching certain target species and target sizes of fish, crabs etc. Bycatch is either of a different species, the wrong sex, or is undersized or juvenile individuals of the target species. The term "bycatch" is also sometimes used for untargeted catch in other forms of animal harvesting or collecting.

In 1997, the Organisation for Economic Co-operation and Development (OECD) defined bycatch as "total fishing mortality, excluding that accounted directly by the retained catch of target species". Bycatch contributes to fishery decline and is a mechanism of overfishing for unintentional catch.The average annual bycatch rate of pinnipeds and cetaceans in the U.S. from 1990 to 1999 was estimated at 6215 animals with a standard error of 448.The fisherman bycatch issue originated due to the "mortality of dolphins in tuna nets in the 1960s".There are at least four different ways the word "bycatch" is used in fisheries:

Catch which is retained and sold but which is not the target species for the fishery

Species/sizes/sexes of fish which fishermen discard

Non-target fish, whether retained and sold or discarded

Unwanted invertebrate species, such as echinoderms and non-commercial crustaceans, and various vulnerable species groups, including seabirds, sea turtles, marine mammals and elasmobranchs (sharks and their relatives).Additionally, the term "deliberate bycatch" is used to refer to bycatch as a source of illegal wildlife trade (IWT) in several areas throughout world.

Earless seal

The earless seals, phocids or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae . They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal.

Ferret-badger

Ferret-badgers are the five species of the genus Melogale, which is the only genus of the monotypic mustelid subfamily Helictidinae.

Bornean ferret-badger (Melogale everetti)

Chinese ferret-badger (Melogale moschata)

Javan ferret-badger (Melogale orientalis)

Burmese ferret-badger (Melogale personata)

Vietnam ferret-badger (Melogale cucphuongensis)

Lutrogale

Lutrogale is a genus of otters, with only one extant species—the smooth-coated otter.

Mephitis (genus)

The genus Mephitis is one of several genera of skunks, which has two species and a North American distribution.

Mustelinae

Mustelinae is a subfamily of family Mustelidae, which includes weasels, ferrets amd minks.It was formerly defined in a paraphyletic manner to also include wolverines, martens, and many other mustelids, to the exclusion of the otters (Lutrinae).

Nyctereutes

Nyctereutes is an Old World genus of the family Canidae, consisting of just one living species, the raccoon dog of East Asia. Nyctereutes appeared about 9.0 million years ago (Mya), with all but one species becoming extinct before the Pleistocene.

Native to East Asia, the raccoon dog has been intensively bred for fur in Europe and especially in Russia during the twentieth century. Specimens have escaped or have been introduced to increase production and formed populations in Eastern Europe. It is currently expanding rapidly in the rest of Europe, where its presence is undesirable because it is considered to be a harmful and invasive species.

Ogurja Ada

Ogurja Ada (sometimes also spelt "Ogurga") is the largest island in Turkmenistan and the longest in the Caspian Sea. Ogurja Island is also widely known by its Russian name Ogurchinskiy Island (Ostrov Ogurchinskiy).

Phoca

Phoca is a genus of the earless seals, within the family Phocidae. It now contains just two species, the common seal (or harbour seal) and the spotted seal (or largha seal). Several species formerly listed under this genus have been split into the genera Pusa, Pagophilus, and Histriophoca. Until recently, Phoca largha has been considered a subspecies of Phoca vitulina but now is considered its own species. For this reason, the fossil history of the genus is unclear, and it has formerly been used as wastebasket taxon for a number of fossils of uncertain affinity.

Pusa

Pusa is a genus of the earless seals, within the family Phocidae. The three species of this genus were split from the genus Phoca, and some sources still give Phoca as an acceptable synonym for Pusa.

The three species in this genus are found in Arctic and subarctic regions, as well as around the Caspian Sea. This includes these countries and regions: Russia, Scandinavia, Britain, Greenland, Canada, the United States, Iran, Azerbaijan, Kazakhstan, and Japan. Due to changing local environmental conditions, the ringed seals found in the Canadian region has varied patterns of growth. The northern Canadian ringed seals grow slowly to a larger size, while the southern seals grow quickly to a smaller size.

Only the Caspian seal is endangered.

Ringed seal

The ringed seal (Pusa hispida or Phoca hispida), also known as the jar seal, as netsik or nattiq by the Inuit and as Ньиэрпэ by the Yakut, is an earless seal (family: Phocidae) inhabiting the Arctic and sub-Arctic regions. The ringed seal is a relatively small seal, rarely greater than 1.5 m in length, with a distinctive patterning of dark spots surrounded by light grey rings, hence its common name. It is the most abundant and wide-ranging ice seal in the Northern Hemisphere: ranging throughout the Arctic Ocean, into the Bering Sea and Okhotsk Sea as far south as the northern coast of Japan in the Pacific, and throughout the North Atlantic coasts of Greenland and Scandinavia as far south as Newfoundland, and include two freshwater subspecies in northern Europe. Ringed seals are one of the primary prey of polar bears and killer whales, and have long been a component of the diet of indigenous people of the Arctic.

Tyuleniy Archipelago

The Tyuleniy Archipelago (Kazakh: Түлен аралдары Tülen Araldary, Russian: Тюленьи острова) is an island group in the north-eastern Caspian Sea off the Mangyshlak Bay west of the Mangyshlak Peninsula and about 13 kilometres (8.1 miles) northwest of the Tupkaragan Peninsula, 27 kilometres (17 miles) north of Bautino. Perhaps the most substantial group of islands in the Caspian, they were first accurately mapped by Fedor Ivanovich Soimonov who led the 1719 Caspian Expedition, studying the Caspian Sea from 1719 to 1727.Administratively, the Tyuleniy Archipelago belongs to the Mangystau Region of Kazakhstan. It was named "Tyuleniy" —meaning "seal"— after the currently endangered Caspian seal.

Türkmenbaşy Gulf

The Türkmenbaşy Gulf or Türkmenbaşy Bay (Russian: залив Туркменбашы Turkmen: Türkmenbaşy aýlagy) is a bay of the Caspian Sea in the coast of Turkmenistan.

With the Krasnovodsk Peninsula to the north and the Cheleken Peninsula to the south, the gulf extends westwards into the sea for 46 km and has an 18 km wide mouth. At its northwest corner are the Bala-Ishem salt marshes which mark the mouth of the dried-up Uzboy River. It became part of the Hazar Nature Reserve in 1968. Among the animals in the bay the Krasnovodsk herring (Alosa braschnikowi nirchi) and the Caspian seal deserve mention.

Wildlife of Iran

The wildlife of Iran has first been partly described by Hamdallah Mustawfi in the 14th century who only referred to animals. In the 18th and 19th centuries, Samuel Gottlieb Gmelin and Édouard Ménétries explored the Caspian Sea area and the Talysh Mountains to document Caspian fauna. Several naturalists followed in the 19th century, including Filippo de Filippi, William Thomas Blanford and Nikolai Zarudny who documented mammal, bird, reptile, amphibian and fish species.One of the most famous wildlife of Iran is the critically endangered Asiatic cheetah (Acinonyx jubatus venaticus), which today survives only in Iran.

Wildlife of Kazakhstan

The wildlife of Kazakhstan includes its flora and fauna, and their natural habitats.

Extant Carnivora species

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