A reader who enjoys taking in the Thames during his lunch hour is intrigued by the number of seals he sees. ADRIAN KWINTNER found out that seal colonies often congregate on the Thames estuary after riding tidal waves from the North Sea ...

BENEFITS assessor Martin Hawkins, from Belvedere, who read my column about fish in the River Thames, wants to know why he keeps spotting seals.

Mr Hawkins works at Erith Town Hall so has ample time to take in the Thames during his lunch break and bond with the wildlife.

No doubt, this beats dealing with angry benefits claimants.

While on his lunchtime expeditions over the past few months, Mr Hawkins has spotted lonely seals on the Thames foreshore playing in the mud and swimming in and out of a life-belt.

Moving beyond the cute factor of this week's column, what are these seals doing in the River Thames?

Colonies of about 50 seals congregate in the Thames Estuary on sand banks such as at Herne Bay, Margate, after riding tidal waves from the North Sea.

The Herne Bay seals are common seals but there are also grey seals in the Thames. Members of both species occasionally roam up-river to places such as Erith.

Alan Knight, chairman of British Divers Marine Life Rescue, told me the Thames was providing quite a nice life for seals, porpoises and dolphins because there are plenty of fish varieties on which to feed, but no waves. Common seals are more properly called harbour seals because there are now just 36,000 of them in Great Britain, mostly in Scotland, compared to 124,000 grey seals.

More than 18,000 of Great Britain's harbour seals died in 1988 from phocine distemper virus.

Alan said seals have now almost completely lost their immunity to the virus and believes seals in England could be hit again in around three weeks.

The virus recently destroyed 600 seals in Scandinavia.

July 12, 2002 10:00