Perhaps it's a wildlife reunion to celebrate the quake's 20th anniversary next month.
Regardless of the reason, the people who do the counting say they have never counted this high before. Last Friday, there were 1,585 sea lions hanging out at the pier.
The experts at the Marine Mammal Center say they don't know what is behind the increase, but that they are hunting for clues.
Record Number of Sea Lions Flock to Pier 39
The influx of animals is being called an anomaly. "Usually during this time of the year, we typically have only a few smaller sea lions on the docks, as the larger males head south to mate," Pier 39 Harbor Master Sheila Chandor said.
In response, officials will add more docks to accommodate the herd.
The record number of adult sea lions follows a record number of yearlings earlier this summer. At the time that was blamed on an ocean upwelling pattern that shifted the animal's source of food.
"Now, the older sea lions that are out there are seeking food wherever they can find it," Marine Mammal Center director Jeff Boehm said, "and the current run of anchovies has a lot of them hanging out in some areas in greater numbers than we’ve grown used to."
Experts say they have responded to nearly 1,500 animals in need of rescue so far this year. That's nearly triple the average.
And this might not be the end of the sea lion saga of 2009. If El Nino conditions continue at the equator, the Marine Mammal workers say they are sure to be for a buy rescue season come this winter.