Ladoga Ringed Seals (Ладожская нерпа; Pusa hispida ladogensis), are a subspecies of the Ringed Seal (Pusa hispida) which are found entirely in Lake Ladoga in northwestern Russia. The subspecies evolved during the last ice age, about 11,000 years ago. As the glaciers retreated and water levels changed, the Baltic Ringed Seal (including Ladoga seals) was trapped in freshwater lakes and separated from the Arctic Ringed Seal.
It is related to the even smaller population of Saimaa Ringed Seals in Lake Saimaa, a lake that flows into Ladoga through the Vuoksi River.
The adult Ladoga seal grows to about 150 cm in length and weighs approximately 60-70 kg. Pups
are approximately 50-60 cm at birth and weigh approximately 4-5 kg. There are 4 variations of coats. 47% of Ladoga seals have a dark brown coat with lighter ring shaped patterns, 29% have a dark brown coat with lighter vein-like patterns and 17% have a light brown coat with a dark dorsal belt as well as faint rings and spots. The coats of the remaining 7% are not described by Popov. Annual molting takes place from April through June.
Females reach maturity at the age of 4–5 and males at the age of 6–7. Pups are delivered in February through March, with weaning taking place after 1.5–2 months. A normal lifespan is about 30–35 years.
Current population is at about 2,000–3,000, down from approximately 20,000 at the beginning of the 20th century due to over-hunting (hunting of the seals was banned entirely in 1980, but some illegal poaching
still occurs). The species' primary threats include entanglement in fisheries netting, industrialization
in the areas surrounding lake Ladoga, fuel spills from water vessels and the disturbance of their warm-weather sunning places by human recreational activities. The Ladoga seal is listed as an Appendix II species under the Bern Convention
and also included in the Russian Red Data Book