Saimaa (Phoca hispida saimensis) and Ladoga (P. h. ladogensis) seals are subspecies of ringed seals that live in freshwater lakes. The founding populations for these two subspecies became separated from Arctic ringed seals (P. h. hispida) during the last ice age. The Saimaa seal population currently numbers approximately 200 seals with 36 - 40 pups born annually. The Ladoga seal population contains at least 5,000 seals. The weight of adult animals in Lake Saimaa is 45-100 kg (mean 62 kg) and in Lake Ladoga adults weigh 32-56 kg (mean 47 kg). The lanugo of Saimaa seals is grey. Normally pups in Lake Ladoga are born with white lanugo, although some pups have been found that have black hairs in the natal pelt. Adult Saimaa seal vary a lot in colour, ranging from dark to pale animals, but all colour morphs have regular ringed patterns on the pelt. Ladoga seals are usually quite dark, with irregular, light ringed patterns. Saimaa seals are usually found hauledout alone or in pairs along shorelines. Ladoga seals haul out in herds of up to 300 animals, and are very vocal when they are hauled out. The lairs of Saimaa seals are situated in snowdrifts adjacent to shorelines of islets, which are the only places where snow piles up in Lake Saimaa. Most Ladoga seal lairs are situated near hummocked or ridged ice along the shoreline of the lake, but some lairs are also found along the shorelines of islets in northern Lake Ladoga. Saimaa seals are an endangered population. The main threats to these seals are fisheries conducted using nets and destruction of breeding habitat. The Ladoga seal is vulnerable, and it also is threatened by fishing. Mercury in both lakes presents an anthropogenic risk factor, but present levels probably do not affect the breeding of either seal population.
. 1999. The diet of the Saimaa ringed seal Phoca hispida saimensis. Acta Theriologica 44: 443-450.The diet of the Saimaa ringed seal Phoca hispida saimensis Nordquist, 1899 was studied by the analysis of stomach contents and by feeding trials with a captive seal. Nine prey species were found in the stomachs, the most important being small schooling fish species: perch Perca fluviatilis, roach Rutilus rutilus, vendace Coregonus albula, smelt Osmerus eperlanus and ruff Acerina cernua. The importance of crustaceans in the diet of the ringed seal in Lake Saimaa is insignificant. Length of the intestinal tract of the Saimaa ringed seal is relatively shorter than those of marine ringed seals. In cafeteria tests on one captive seal the preferred fish species were vendace and smelt. The captive seal displayed clear seasonal variation in feeding activity. The consumption of fish was lowest in springtime and highest in autumn and winter.
Recent studies of Lake Ladoga ringed seal have included estimation of population size, studies on morphology and behaviour of this subspecies, and analyses of some environmental toxicants in the tissues of recovered carcasses. Compared with the Baltic ringed seal, and especially with the Saimaa seal, the population status of the Ladoga ringed seal is good. The population probably includes over 5000 animals. The body of the Ladoga seal is smaller than that of the Saimaa seal or the Baltic ringed seal; its pelage is darker and also craniometrically the Ladoga seal clearly differs from the other subspecies of ringed seal. During summer in Northern Ladoga, the Ladoga ringed seal forms haul-out herds of more than 50 animals. During haul-out in herds the Ladoga seal actively uses different vocalizations. Concentrations of mercury in the liver and kidney of the Ladoga seal are clearly elevated, but levels of thc other environmental toxicants analyzed (Cd, Pb, PCB) are comparatively low.
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