San Franciso’s Pier 39 sea lions suddenly vanished after earthquake commemoration

Latest update, Feb. 26th 2010: The thousands of California sea lions gathered at the Oregon Sea Lion Caves have left there in a massive exodus. The population at Pier 39 in S.F. is increasing. Details and summary in my latest post.

Update Januray 9th 2010: A powerful 6.5 magnitude earthquake hit Northern CA today. Details in this post.

Original post starts here:

All 1,500 sea lions disappeared almost overnight….               what does it mean?

CBS 5 in San Francisco just ran this story about the the bizarre disappearance of all 1500 of the city’s longtime resident sea lion population from Pier 39.

Dec 29, 2009 12:21 am US/Pacific

Sea Lions Mysteriously Disappear From Pier 39

Reporting
Joe Vazquez

Source: Wikimedia Commons (Click to enlarge)

Following a record sized herd, hundreds of sea lions have suddenly disappeared from San Francisco’s Pier 39 and have been gone for a month.

“It really was practically overnight,” said Sheila Chandor who said she has never seen anything like it in her 24 years as Harbor Master of Pier 39.

Chandor said the sea lions will occasionally leave en masse to follow feeding and mating patterns, but they always leave a large contingent behind.

“This is completely upside down,” said Chandor. “Usually, in the summer, the majority of the herd will go out for the mating season and leave at the most about 40 of the smaller ones behind. And in the winter – this time of year – we get the biggest sized herd. So this is incredibly unusual.”

More than 1,500 sea lions inhabited Pier 39 around the third week of November, setting a new record, Chandor said. But they took off around Thanksgiving without a clue as to where they were going.

Shelbi Stoudt with the Marine Mammal Center in Sausalito, an organization that routinely rescues sea lions, said the sea lions may have migrated off the coast to follow a food source. But Stoudt stressed there is no scientific evidence indicating where the sea lions may have gone…..

I got a chill while listening to the video at the CBS 5 site when it was mentioned that hundreds of the sea lions first showed up at the location after the 1989 Loma Prieta Earthquake that rocked San Francisco during the World Series on October 17 of that year. The sea lions were understandably in a very disoriented state when they mysteriously appeared at Pier 39.

Since the California sea lion lifespan is believed to extend up to 25 years, it is possible that some of the current population are survivors of the 1989 earthquake trauma. Did they sense something a month ago that reminded them of conditions prior to that event?

Here is the 2003 National Geographic article exploring reports by observers of animals sensing impending earthquakes.

After Peru’s 8.0 earthquake in 2007, most of the sea lions were noted missing from a population that lived near the epicenter, yet only two were found dead, leading scientists to consider the possibility that the missing sea lions had migrated out of the area.

We just don’t know why the Pier 39 sea lions suddenly fled San Francisco 30 days ago, but in mid-October the city held a week long event called “The Big Rumble” that commemorated the 20 year anniversary of the Loma Prieta Earthquake with a series of events designed to connect the community with preparedness resources.

Oct. 17, 1989, a three-story building collapsed and burned in the Marina District after the quake. Vince Maggiora/San Francisco Chronicle

And they partied a little, too.  Those events included entertainment by My First Earthquake, an indie rock foursome from San Francisco. At their first band practice back in August of 2006, Rebecca, the singer, experienced her first earthquake according to The Big Rumble website.

Perhaps California sea lions can suffer Post Traumatic Stress Disorder since we now know non-human primates used in research can suffer the disorder. Or perhaps the sea lions just realized that the city had healed enough to no longer require the diversion of their comically obnoxious presence. Another possibility is that the  the recession has negatively impacted the amount of treats given to the sea lions by tourists. The population may have just gone off in search of a better food supply.   (More recent information here.)

Here’s a fun holiday video by My First Earthquake recommended by the Big Rumble site.

UPDATE January 20, 2010:

Here is a Pier 39 Marina live camera and the sea lion floats still look desolate except for a small group on one float.

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