This is bizarre.

The blubbery sea lions at Pier 39, one of San Francisco’s smelliest and most famous tourist attractions, are gone. During the last week of November, they left the wooden docks on which they’ve spent the last 20 years and no one knows if they’ll be coming back.

“We have no idea where they moved on to or why,” said Shelbi Stoudt, who manages a team that helps stranded animals in the San Francisco Bay from the Marine Mammal Center in Sausalito, California.

The sea lions’ disappearance is as strange as their initial colonization of the pier about 20 years ago, in late 1989. They just started showing up one day and as their numbers increased, their traditional hang out, Seal Rocks, became less populated. There are all sorts of theories about why the pier became a favorite haul-out spot for the sea lions, but no one knows for sure why the animals’ behavior changed.

I’ve been out to Pier 39 a couple of times when I’ve been in San Francisco and I’ve always gotten a kick out of watching those sea lions play around. It’s a shame that they’ve decided to head out for new pastures.