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 the other environmental toxicants analyzed (Cd, Pb, PCB) are comparatively low .

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Oganochlorine compounds in blubber samples of the ringed seal (Phoca hispida saimensis, P. h. ladogensis, and P. h. hispida) were analyzed in order to estimate the state of pollution in three different water areas in Northeast Europe, namely, Lake Saimaa in Finland, Lake Ladoga, and the White Sea in Russia. Geographic differences in concentrations and in relative concentrations of tri‐ and tetrachlorocymenes, hexachlorobenzene, α‐HCH, β‐HCH, ‐γ‐HCH (Lindane), seven polychlorinated bi‐phenyl (PCB) congeners, and p,p′‐DDT and its metabolites in ringed seals were compared. Concentrations of chlorinated hydrocarbons varied between the water areas. The highest concentrations were found in Saimaa ringed seals, followed by Ladoga ringed seals, and the lowest concentrations were detected in ringed seals from the White Sea. Extractable organic halogen (EOX) concentrations in blubber were also analyzed. The concentrations showed a geographic trend similar to those for the individual compounds identified. In Lakes Ladoga and Saimaa, the concentrations of EOX and chlorinated hydrocarbons in the blubber were dependent on the age and sex of the seals, but no such relationship was observed in samples from the White Sea.

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