More than a thousand sea lions used to occupy the area by San Francisco's Pier 39. But now all but a few have swum away leaving experts to puzzle over why they left. Photo: Nick Talbot
Thousands were still gathering in the area last year, as this photo taken by Paivi Drummond demonstrates. Photo taken in October 2009.
The sea lions became a popular tourist attraction with many international visitors. These sea lions were snapped basking in the warm April sunshine by Mike Gammie.
During their twenty year residence at Pier 39 the sea lions were allowed to laze around undisturbed, except perhaps by the occasional seagull. Photo: Gordon Kretschmer
All alone, but enjoying a peaceful nap in the August sunshine. Jen Crompton took this photo while on holiday in August 2008.
What did one sea lion say to the other? Photo: Mike Jarrett
Up close and personal, these sea lions were snapped by J Peaurt while on holiday in California in August 2007.
The scene at Pier 39 before the sea lions left. Photo: Gordon Kretschmer
Got an itch? Meri Tosh and her husband were on holiday in California when they went to visit the sea lions.
Before the exodus. Steve Johnston from England captured this picture of the Pier 39 sea lions while on holiday.
Jo Stranix could be forgiven for thinking the sea lions had all left sooner, she took this picture while on holiday in California in 2009.
Tim Wright took this photo in October 2009 when thousands of sea lions were still visiting the famous "Pier 39" area, but...
...by the time Peter Arnold arrived in December 2009 they had all vanished, leaving Peter and the experts wondering where they all were. Send your pictures to email@example.com. Terms and conditions www.bbc.co.uk/yourpics
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