Tag loss in grey seals (Halichoerus grypus) and potential effects on population estimates

摘要: Cumulative tag loss among 4064 grey seal (Halichoerus grypus) pups observed on Sable Island was less than 1% during the first 5 months of life, 13% by end year, and continued to increase with age. seals aged 6 older over 40.0%. A double-tagging study indicated that pre-punching flippers, colour tags applied, application left or right flipper significantly affected loss. The addition a flag had no significant effect. comparison scientific observations commercial bounty return data casual observers probably missed double-tagged animals. Overlooked in single-tagging experiments result population overestimates. In experiments, overlooked correction factor overestimates underestimates. Age-specific factors should be used if estimates include more one age group.