Current status of the Ladoga ringed seal Pusa hispida ladogensis (Nordquist, 1899)
Aerial survey using strip transects method was performed in April 2012, when majority of ringed seals were hauled out on ice during the moulting period. Adaptive distance sampling and stratification were used. The observed number of ringed seals in 25 transects (in total 2368 km) was 807. Calculations were performed using program DISTANCE. Basking population was estimated at 5211 (CV = 15.4 %) with 95 % confidence limits from 3769 to 7204. The mean density was estimated to be 0.38 seals/km2. There is indication that ringed seal numbers have increased approximately 2.6 times in the last 10 years. Refs 41. Figs 2. Tables 1.
Ladoga ringed seal, Ladoga lake, aerial survey, abundance estimation, population increase
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