The pier was originally for commercial shipping. Then it was redeveloped as a tourist attraction. There was an opening ceremony in 1978, at which then-mayor Dianne Feinstein wore a “discreet but attractive swimsuit because of a bet with the developer,” according to the New York Times of that era. (Sadly, I can't find a photo.)
In 1989, some small boat docks on the north side of the pier were vacant during repair work. Unexpectedly, sea lions started hauling out on these docks. They napped. They grunted. They barked.
Business owners and boat owners complained. Noisy! Stinky! Unsanitary! Bad for business. A permit was requested to scare them away by detonating explosive charges. Others objected to the request. The controversy made it into the newspapers. This alerted residents who didn't ordinarily go to Pier 39 about the easy-to-view sea lions. We rushed to the spot to view the pinnipeds (Zalophus californianus). It was a great angle, and the sea lions were very close, and delightfully blasé about being viewed.
Since we were there, we drank lemonade, bought left-handed scissors and gala hosiery, and were manifestly good for business. We made plans to bring our out-of-town visitors.
The permit request was hastily dropped. Pier 39 began promoting the sea lions.
Most of the sea lions leave in the summer, to catch breeding season in the Channel Islands, and return in the fall.
What are the sea lions doing here? Resting. It is said that the sea lions who hang out at Pier 39 used to hang out at Seal Rock, but moved for some reason. How mysterious. Why on earth would they do that? Why wouldn't a wild animal prefer to hang out in a wild place? Look how great Seal Rock is:
The two places aren't that far apart, but Seal Rock is outside the Bay, and Pier 39 is inside. It's speculated that there are fewer predators inside the Bay. Fewer predators makes it easier for scrumptious types to relax.
San Franciscans pay close attention to the doings of the sea lions. Earlier this year, almost all of them vanished from Pier 39 and there was much worry and much press coverage. Were they starving? Had a shark or a killer whale scared them away? Was that them up in Oregon?
Then they came back. There was much rejoicing, especially among the merchants.
Things don't seem normal among the sea lions this year. Mothers are giving birth to pups early, and in unusual places. Five were actually born at Pier 39.
El Nino may have something to do with it, or domoic acid, or declining fish stocks. The species isn't endangered, but it's not having a good year. If there's anything I can do to help, just say the word. And I know I speak for the small-business community when I say so.