I saw these sealions last year. I didn't know they'd been there for 20a but they had. The council was planning the 20a anniversary of their arrival for 15 Jan 2010, but they all left last November. The 'experts' don't know why. If it's global warming it would be nice to know, so why didn't they tag these mothers over the last 20 years so we know where they've gone?
The sea lions of San Francisco are almost as famous as the city's cable cars or even the Golden Gate bridge, says the BBC's Peter Bowes in Los Angeles.
Twenty years ago, for no apparent reason, the smelly, noisy animals took up residence in the docks at Pier 39.
Their numbers grew rapidly to about 1,700 animals, and they became a popular tourist attraction.
But then most of them disappeared.
Initially, marine experts were baffled.
One outlandish suggestion was that they were fleeing the bay because of an imminent earthquake, our correspondent says.
But now the sighting of large numbers of sea lions off the coast of Oregon may have solved the mystery.
Scientists says it is normal for the animals to move north in search of food during the winter but it is extremely unusual for them to migrate in such huge numbers.
The sea lions of San Francisco are almost as famous as the city's cable cars or even the Golden Gate bridge, says the BBC's Peter Bowes in Los Angeles.Twenty years ago, for no apparent reason, the smelly, noisy animals took up residence in the docks