Common seal
Phoca vitulina
The common or harbour seal is the UK’s most widespread seal. They vary in colour, ranging from black, brown, grey or tan with darker patches, with each individual having unique markings. They have a relatively large head with a short body and flippers. They are opportunistic feeders and hunt fish, molluscs and crustaceans. They rarely travel more than 20km from the shore and haul out in order to rest, give birth or suckle pups on rocky shores, mud flats, sandy beaches and intertidal sand and mud flats.
The species is widely distributed, inhabiting the waters of the north Atlantic and north Pacific oceans. In Britain they mostly haul out on the Scottish coasts and the east coast of England and the Wash. The species is not threatened. However, in 1988 over 17,000 common seals died in the North Sea from an outbreak of phocine distemper, with about 3,000 deaths on British Coasts. Seals are at the top of the marine food chain, so tend to accumulate pollutants such as heavy metals and PCBs (polychlorinated biphenyls), which can reduce their breeding success.
Seals have lived at the mouth of the River Tees for hundreds of years. Two hundred years ago the estimated population at Seal Sands was 1,000. Numbers rapidly declined in the nineteenth century and by the 1930’s none were recorded despite extensive surveys. This local extinction was probably the result of disturbance by shipping and loss of haul out sites by dredging as well as pollution plus culling by salmon fishermen. Seals started to return to the Tees Estuary in the mid 1980s after improvements in water quality and a reduction in shipping. There are now small but successful breeding populations at Seal Sands, Greatham Creek and Billingham Beck.
