Published online by Cambridge University Press: 05 December 2011
Grey seals (Halichoerus grypus) and common seals (Phoca vitulina) both occur in Orcadian waters. In previous centuries they formed an important resource for both domestic use and export.
Annual grey seal pup production has more than doubled since 1964. Productivity on individual islands is influenced by human activity. Total population size is estimated to have risen from around 10,000 in 1964 to around 20,000 in 1982 despite a management policy of culling originally intended to stop population growth. Grey seals tagged in Orkney have been recovered around most parts of the North Sea, Norway, the Faeroes and south to Ireland.
Considerably less is known about the biology of common seals in Orkney. A boat survey in 1979 counted 2653 adults and 420 pups.