With Summer Ahead, Most Sea Lions Expected To Leave Pier 39

With Summer Ahead, Most Sea Lions Expected To Leave Pier 39Photo: Matt Kieffer/Flickr
Teresa Hammerl
Published on May 25, 2017

After the 1989 Loma Prieta earthquake, hundreds of California sea lions began flocking to Pier 39's K-Dock. But for the next few months, most of these creatures will embark on a mission that will leave the wharf a quieter (and less fragrant) place.

According to Pier 39, most of the animals will head south to breeding grounds near the Channel Islands in June and July. Females will already be pregnant at this time from the previous season, and many pups will be born in June on the islands located just off the Southern California coast.

Channel Islands National Park provides a natural habitat for breeding California sea lion populations, and also for northern fur seals, harbor seals and northern elephant seals.

Photo: TJH1976/Flickr

That doesn't mean that K-Dock will be completely empty in the upcoming weeks; in recent years, a few sea lions have chosen to stay. Because their behavior is unpredictable, visitors are advised to check out Pier 39's webcam before heading over.

Non-breeding sub-adult males and juvenile females will migrate back to the wharf at the end of July, while the breeding males follow later. In general, the majority of the sea lion population at Pier 39 is male. They reach up to 850 pounds, while females can weigh up to 220.

From late July to mid-May, anywhere from 150 to 600 sea lions can usually be once again observed sunbathing and barking at K-Dock.

Photo: Kai Lehmann/Flickr 

Biologists at The Marine Mammal Center believe that the sea lions have adopted this place because of the food opportunities nearby. Zalophus californianus like to eat sardines, anchovies or herring.

Additionally, predators like sharks and orcas usually don't make their way into San Francisco Bay, which keeps the sea lions better protected. It's worth noting that today, plastic can often be their biggest enemy.

In 1990, the number of sea lions grew to more than 300, reaching a record population of 1,701 in November 2009. That same year, they suddenly disappeared for three months. Experts believed that the sea lions, who can live for up to 25 years, ran out of food and went on to search for more.

When the pinnipeds first arrived, the docks at Pier 39 were still full of boats. Eventually, The Marine Mammal Center convinced boaters to relocate, and new floats were brought to K-Dock to carry the sea lion's weight.

When heading to Pier 39, keep in mind that sea lions are protected by the Marine Mammal Protection Act, which makes it unlawful to feed, touch or harass them. If you see marina staff getting closer, they might be hosing down the docks—the only way to manage the animals' pungent aroma on warm days.