Just last month, this pier 39 in San Francisco was encompassed with sea lions. They were piled 3 to 4 high. There were over 1500 calculated by the local nautical man of science.
It is amazing how they all decided to move on. All but about 40 left the dock.
It was like some one told them it was time to pull up stakes. They left in multitudes. But it is said to be extraordinary that the sea lions remained as long as they did.
They are most likely proceeding in the same direction their food source is traveling. Or departing in the yearly direction of the spawning groups that accumulate in the Channel Islands.
Pier 39 still does have an adequate amount of sea lions to keep the visitors pleased. They put on displays of diving and barking out for the tourist.
The larger group of sea lions that left could return at a later date. Most likely in the spring.