IUCN STATUS (2010) - LEAST CONCERN
|Distribution and Numbers
Known locally as the nerpa and referred to as Pusa sibirica, the Baikal seal is found only in Russia's isolated Lake Baikal, a designated World Heritage Site and the world's deepest, oldest and most voluminous mass of freshwater. The Baikal seal, one of the world's smallest pinnipeds, is in fact the only pinniped species that lives solely in freshwater. Individuals are also sometimes found wandering up the rivers surrounding the Lake, one seal having been found 400km upstream. A scientific expedition in 2000 calculated that there were about 85,000 Baikal seals, of which 18,000 were pups born earlier in the year. It has however been estimated by one environmental group that 80% or more of the pups born in 2000 died from either natural causes or as a result of hunting.
Photo: Baikal Environmental Wave
|The origin of the species is still uncertain, although the most accepted theory suggests descent from the ringed seal Phoca hispida and that the species may have been isolated geographically for about 500,000 years.
There is concern at the recent decline in numbers of the Baikal seal, the total population having dropped from 104,000 when the last survey took place in 1994. The survey carried out in 2000 also concluded that the mortality rate among seal pups had risen two to threefold and that the seal population was rapidly ageing, resulting in a drastic decline in the number of seals capable of reproduction. It is thought that if the present rates and age-related nature of the mortality continue then the population will be at severe risk. The Baikal seal is currently listed as Least concern on the IUCN Red List.
|Various causes have been attributed to the decline in the Baikal seal population. Hunting of Baikal seals is still carried out in the spring, the official annual kill for 2000 being 3,500 seals, mostly pups, a reduction from the 1999 quota of 6,000 seals. This includes a large number that are killed for "scientific purposes", the 2000 quota for these purposes being 500 pups. These figures do not include seals that are wounded by hunters and which will eventually die, estimates of this "struck and lost" figure ranging as high in some cases as three seals wounded for each one killed. Almost any unprofessional hunter can currently buy a licence for 100 rubles and start hunting Baikal seals. It has been roughly estimated that up to 10,000 seals were killed in total each year in the years leading up to 2000. Products from the hunt include pelts, meat (much of which is used as food for animals on fur farms), souvenirs and seal oil for medicinal purposes. The hunting of young seals ("kumutkans") is thought to be the main factor that led to a change in the population structure and a decrease in the reproductive success of the species in the 1980s. As well as the official hunt there is an increasing problem with poaching caused by weakening enforcement and rising prices for the fur of young seals. Fur hats made from seal fur cost approximately 700 rubles each. Undocumented kill has been estimated at 20-40% of the official kill.
|It was reported in 1999 that the Pribaikalsky National Park was considering promoting the sport hunting of Baikal seals, among other wildlife, in order to generate income. The proposed price to tourists for shooting a Baikal seal was said to be about $US 1,400 under a "kill or a portion of your money back" scheme operated by the park rangers who know the seal's habits and haulout locations. The plans were severely criticised by local environmentalists who are calling for a ban on all hunting of the species, apart from subsistence purposes, and for the launch of a wide-scale anti-poaching campaign. The hunt for Baikal seals has an additional effect, the 2000 survey concluding that the growing hunt in the north and middle areas of Lake Baikal has been the main reason for a large migration of seals to the southern area. Weather conditions in the southern area of the lake have become less favourable for breeding in recent years, warmer springs causing the covers of many seal lairs to melt too early and to cave in. This causes an increased number of whitecoat seal pups to be left unprotected and subsequently to be killed by crows or to die through sharp changes in the weather.
Photo: Baikal Environmental Wave
|There is a serious problem of pollution in Lake Baikal, research showing that organochlorines and other chemical pollutants build up through the food web in the Lake and accumulate in the seals as top-level predators. These pollutants can cause disease, reproductive problems and lowered immunity in the seals. Identified sources of this pollution include the agricultural use of pesticides, including DDT, and the emissions and discharges of PCBs and dioxins from industrial activities in the towns around the Lake. Particularly heavy pollution has been found in the vicinity of the Baikalsk and Selenginsk Pulp and Paper Plants and the power plant at Sludianka.
|In 1987-1988 at least 5,000 Baikal seals died as a result of infection by a form of Canine Distemper Virus which is thought to have been transmitted to the seals from dogs or other land mammals. It has been suggested that the severity of this epizootic may have been partially caused by stress due to the high levels of persistent organic pollutants in the seals. In 1997 there was a mortality of dozens of Baikal seals near the Baikalsk Pulp and Paper Plant. In June 1999 a total of 78 dead seals were found washed ashore, some near the Irkutsk village of Utulik and the others near the Baikalsk Pulp and Paper Plant. In 2000 a number of dead seals were found on the Ushkany Islands, the species' last remaining constant haul-out site in the northeastern part of the Lake. In the same year several seals, which were captured in the north and placed in an aquarium at the Limnological Museum in Listvyanka, infected the existing seals there and caused the deaths of all the seals involved. No cause for any of these recent mortalities has yet been identified.
|Loss of shoreline habitat due to commercial development is also threatening the population, as is the disturbance of seals during their on-shore moult in mild years. This disturbance lengthens the overall time required to moult and thus has knock-on effects on the subsequent ability of the seals to feed. Ten thousand pups were lost as a result of such disturbance in 1981. Observations show that the Baikal seal population is strongly and easily influenced by any changes in the food chain so that a reduction, whether natural or caused by man, in one or more components of the food chain can adversely affect the species. Intensive fishing of some of the prey species of the Baikal seal may therefore cause problems. It is estimated that about 1,000 seals die each year as bycatch in fishing gear and nets.
Pupping takes place on the Lake Baikal ice from February to March, the pups being born in lairs that have been hollowed out on the fast ice. Baikal seals maintain breathing and haulout holes in the ice, adults usually maintaining one main hole and several auxiliary holes, juveniles usually only a solitary hole. Pups are born with a white woolly coat that is moulted after 6-8 weeks, still in the lair, to be replaced by a silvery grey coat. This coat is eventually replaced by the adult coat of a uniformly dark silvery grey back and a lighter yellowish grey front, rare individuals also having a spotted coat. Pups are nursed for 2-2.5 months but in the southern part of the lake the ice breaks up earlier causing weaning to occur prematurely and thus the pups to be smaller.
|Mating takes place in the water around the time that the pup is weaned. There is no evidence to date that the adult males form aquatic territories for breeding purposes. The seals usually moult on the ice in the late spring but in mild years the ice melts earlier and the seals are forced to complete their moult on shore. Individuals normally lead a solitary existence during winter. A radio-tagging study in 1990-91 showed that 1.5-2.5 year-old juvenile Baikal seals moved extensively in the Lake from September - May, covering between 400 and 1,600km. Baikal seals feed mainly on pelagic Comephorus and Cottocomephorus fish species, young seals having been observed feeding up to 100m in depth and performing a large number of short duration dives mostly under 10 minutes long. Brown bears sometimes kill seals near the shoreline.
Photo: Baikal Environmental Wave
Adult Baikal seals measure 1.2-1.4m in length and weigh 63-70kg, the males slightly larger than the females. Pups normally measure about 65cm in length and weigh about 4kg at birth. Females reach sexual maturity at 3-6 years of age, males at 4-7 years. Baikal seals have been known to dive for as long as 43 minutes. It has been estimated that adult males can live up to 52 years of age, females to 56 years.