Here's your chance to walk the wak and talk the talk of the California sea lions!

Why are the sea lions here?
California sea lions (CSL) have always frequented the San Francisco Bay, especially during the winter months when herring spawn in the bay. The Marine Mammal Center's biologists believe that the CSLs have chosen to haul out at PIER 39's K dock because there's plenty of food nearby in the bay and ocean; their natural predators (white sharks and orcas) do not typically feed in the bay; and there is plenty of space. Also, the docks are easier to haul out on, more comfortable, and protected from storms than a rocky beach. As the tide goes in and out, the floating docks move up and down on the water, so the CSLs just keep sleeping rather then having to scramble up and down rocks with the tide!

Didn't there used to be boats at K dock?
Yes, when the first sea lions arrived, half of the dock was filled with boats and half was overnight guest docking. The boat owners were not too happy about having to avoid sea lions in order to reach their boats. Initially there was some discussion about how to get rid of the animals, but nothing was done. The PIER 39 Marina contacted the Center to guide their decisions. Ultimately, for the safety of the boat owners, it was decided to leave the dock to the sea lions. Boat owners who owned dock slips were relocated elsewhere in the PIER 39 Marina. The weight of the sea lions, often thousands of pounds, caused K dock to submerge, become waterlogged and eventually fall apart. PIER 39 initially built twelve 10' x 12' floats, which were placed between the fingers of K dock. In the summer of 1995, the original K dock was removed, as it was a hazard to boats. More floats were moved in to replace the dock.

Do the sea lions stay here all year?
Yes and no. From late summer (late July) to late spring (mid May), there are typically hundreds of sea lions hauled out here (ranging from 150 to 600+). In June and July, most of the sea lions head south to breeding grounds on the Channel Islands, but a handful to a few dozen have remained throughout the summer in recent years. In late July, non-breeding subadult males and juvenile females begin to migrate north again. Other breeding males travel north later. Some males migrate as far north as British Columbia, Canada, and Alaska.

Do you feed them or take care of them in any way?
It is illegal in the U.S. to feed, harm, or harass wild seals and sea lions, as well as all other marine mammals. PIER 39 Marina staff hose down the docks when needed (usually weekly during warm weather when there are lots of sea lions), so that the smell of the sea lions does not drive away the tourists and neighboring boat owners. To do this, they use a boat pulling a small raft equipped with a compressor that pumps bay water to be sprayed on the docks. Additionally, the Center monitors sick and injured animals, rescuing them when possible.

Can they get out?
Yes, they are wild animals that come and go as they please. They swim out into the Bay through the opening that the boats use at the north end of the pier.

Are the bigger animals the males?
Yes, but actually most of these animals are male. About 85-95% of all the CSLs at PIER 39 are males.

If these are mainly males, where are the females?
Most females typically live year-round at or near breeding grounds, which are primarily on the Channel Islands, off the coast of Santa Barbara, and on other islands south to Baja California and the Gulf of California in Mexico. Females have one pup each year. They stay with their new pup for about six to eight months, sometimes as long as a year. Sometimes, there are some non-breeding young females seen in the Bay Area and at PIER 39.

How old are the smallest ones?
The smallest sea lions are probably yearlings, weaned pups who are capable of foraging on their own (and who have probably been pushed away by mom who is ready to have another pup).

Why are some of them in groups and some of them alone?
Sea lions are very gregarious social animals, so groups of sea lions are normal. They are positive thigmotactic animals, because they prefer to rest in close bodily contact with other animals. However, it is not unusual to see animals hauled out alone. There could be no reason, or it could be a large male that no other sea lion has attempted to join, or a sick or injured animal that prefers to be alone.

Are they fighting?
At PIER 39 the CSLs often "argue" over a haul out spot, who got there first and who is going to stay. Much of the shoving and some biting we see is between young males playing, or practicing behaviors and skills that they will need in the future when they are breeding males. Most serious fighting occurs between males defending their breeding territories, which would not be seen at PIER 39. However, even there fighting is rare, as it wastes energy needed for mating and can result in injury or death. Most "fights" are decided by vocalizations, size, posturing, and neck and chest pushing.

How much time do they spend lying up on the docks compared to swimming around in the water?
It is not unusual for them to sleep 8 to 12 hours. Sea lions are binge feeders, eating all they can when food is plentiful, and then hauling out and resting for long periods of time.

Why do they stick their flippers up in the air?
Lifting up a flipper and flipper fanning are methods for cooling off (thermoregulation). Sea lion flippers have many capillaries that can be cooled off by the wind when they are sunbathing. Conversely, sticking a flipper out of the water helps to keep the sea lion warm (you lose more heat in water than in air).

How frequently do they eat, and how much each day?
CSLs eat when they are hungry and food is available. When it is available they binge feed, or eat all they can, because the fish could soon be gone. On average they may eat 3 to 15 or more pounds per day in the wild and may fast for several days at a time (please note this depends and varies based on age, sex, and time of year as well as the type of food they are eating). How long can CSLs stay under water before having to come up for air? Most dives are only a few minutes long, but CSLs can stay under water 10 to 15 minutes.



Credit:  The Marine Mammal Center