Caspian Seal
(Phoca caspica)
| Distribution and Numbers Referred to by some scientists as Pusa caspica, the Caspian seal is found only in the Caspian Sea, a landlocked sea bordered by Russia, Azerbaijan, Iran, Turkmenistan and Kazakhstan. The species inhabits most regions of the Caspian Sea on a seasonal basis, depending on the availability of food and the annual life cycle of the seals. Although probably linked to the ringed seal, Phoca hispida, the origin of the species remains unsolved. From an estimated population size of over 1,000,000 in the early 1900s, the population at the end of the 1980s was estimated to be no more than 360,000 - 400,000. However it is extremely likely that the population is now considerably lower than this. |
Photo: Pavel Prosyanov, KaspNIRH |
| Status The Caspian seal is listed as Vulnerable on the IUCN Red List. Caspian seals have been intensively hunted since the 19th century. The annual kill averaged about 160,000 from 1933-1940. Restrictions on killing were introduced from the 1940s, although killing apparently continued to average about 50,000 - 60,000 per year until 1970, after which the annual kill on the northern ice was limited to 20,000 - 25,000 whitecoat and moulted pups. There has been very little monitoring of the hunt since the break-up of the Soviet Union but recent quota figures were 12,400 pups for Russian sealers and 12,600 pups for sealers in Kazakhstan, Turkmenistan and Azerbaijan. Illegal killing and poaching of Caspian seals is known to occur, particularly as a result of economic hardship caused by the break-up of the Soviet Union, but the extent of this problem is unknown. Predation by wolves and occasionally by sea eagles may also sometimes contribute to pup mortality on the ice. |
| In April-June 2000 several thousand Caspian seals were found dead and dying along the Kazakhstan coast in the northeast Caspian Sea, further south in Turkmenistan, and also along the northwest and west Caspian Sea coasts of Russia and Azerbaijan. Reports of an increased mortality rate were still being received as late as August 2000. Analysis has indicated that the primary cause of the mass mortality was canine distemper virus. Although the source of the virus is currently unknown, it was the same strain of canine distemper virus previously found in a seal that died during another mass mortality event that peaked in Azerbaijan in the spring of 1997. In November 2000 Russian ecologists again reported finding seals dying "en masse" along the Caspian Sea shoreline. Strange regular-shaped injuries were found on many of the dead seals' bodies that may have been related to the mortality in some way. At the same time a number of dead seals were also reported along the Caspian Sea shoreline in the northern Iranian provinces of Gilan and Mozandaran. |
| The population is facing severe problems due to heavy pollution of the Caspian Sea by pesticides and industrial pollutants. Seals that died in Azerbaijan in 1997 were found to have extraordinarily high levels of DDT in their tissues. It has been suggested that the apparent persistence of distemper-related high mortality in the species may have been exacerbated by the weakening of the seals' immune systems due to the high levels of DDT compounds and other pollutants found. Sub-acute distemper itself also compromises the immune systems of infected seals. Heavy parasitic infestation of Caspian seals has been noted and this could also be a result of weakened immunity due either to organochlorine contamination, sub-acute distemper infection, or both. The high mortality of Caspian seals appears to have been a chronic condition over at least the past 20 years or so, large numbers of dead seals being washed up on the Apsheron peninsula of Azerbaijan, particularly in spring and autumn, and sick and dying seals noted in the northern Caspian Sea in the summer, particularly near the Ural and Volga delta regions. |
| Pollution in the Caspian Sea is also affecting the reproductive success of females, the proportion of barren females being as high as 64-70% in the late 1980s and more than 70% in the late 1990s. By 1986 the number of breeding females on the northern ice had dropped to 50,000 - 60,000 and may have dropped even further since then. |
Photo: Pavel Prosyanov, KaspNIRH |
Intensive commercial fishing by man of some of the prey species of the Caspian seal may have a serious effect on the seals' available food resources. Kilkas (Clupeonella sp.) account for about 50% of the total fish biomass in the Caspian Sea and at least 70% of the seals' diet. Kilka fishing has intensified in recent years by means of new mechanised techniques. Severe emaciation of Caspian seals was repeatedly noted during the 1997 and 2000 investigations of dead and dying seals. This could be a result of infected seals losing weight over a long period, but it could also be due to some seals having difficulty in finding food. Many seals are also killed by becoming entangled in fishing nets and some are injured by shipping. In December 2000 the northern Iranian province of Gilan announced that it had commissioned a special marine patrol force to supervise fishing practices in an effort to prevent harm to the seals. |
| In conclusion, although the present population status of the Caspian
seal is not known, and the species may possibly still number over 100,000, it must be
assumed that the species cannot withstand indefinitely the combined and persistent effects
of continued hunting, disease, low fertility, fisheries bycatch and possible decrease of
prey abundance. If these pressures on the species are not reduced then the Caspian seal is
expected to become endangered. |
| Lifestyle Most Caspian seals gather together in large colonies on the ice of the northern Caspian Sea from late January until the end of April in order to pup, nurse, mate and moult. A relatively small breeding colony is also located further south on the offshore islands of Turkmenistan, principally Ogurchinsky Island. Pupping takes place from late January to late February and pups are born with a white woolly coat. This white coat is moulted at 3 weeks of age and is eventually replaced by the adult coat which is greyish-yellow on the back, light grey on the front and sides, and covered with irregular brown or black camouflage markings. Pups are nursed for 4-5 weeks. Mature males enter the breeding grounds when the pups are about two weeks old and mating takes place from late February to mid-March. |
| Moulting takes place after breeding. Most of the
ice-breeding seals migrate after the moult to the central and southern Caspian sea to feed
and form colonies from May to September. A limited number of seals stay in the north
during the summer to feed, but there are reports that many of these seals may be sick or
dying. The seals migrate northwards again in October - November, most of the population gathering in large colonies on sand skerries in the northeastern Caspian Sea. Some seals however spend the winter in central and southern parts. In addition to feeding on kilka, the Caspian seal diet also includes silverside, roach, pike perch, asp and gobies as well as some crustaceans. |
Photo: Pavel Prosyanov, KaspNIRH |
| Statistics Adult male and female Caspian seals weigh an average of 50-60kg (maximum 86kg), and measure 1.3-1.5m in length, females slightly smaller than males. Pups are normally born weighing about 5kg and measuring 64-79cm in length. Both males and females become sexually mature at 8 years of age. Caspian seals can live up to about 50 years of age. |