Because their movements on lands are clumsy, they seldom venture far from the water, where they take refuge at the first sign of danger. They can remain underwater for as long as 20 minutes. Unlike other pinnipeds , harbor seals make little noise. Occasionally, they will slap the surface of the water with their flippers, producing a loud noise that can be heard for some distance. They are considered non-migratory.
Sexual maturity occurs in females when three or four years old and in males at five years.
Mating usually takes place in September, and after a gestation period of slightly more than nine months, a single pup is born. The young are usually born on a reef or sandbar and are able to swim almost immediately. Weaning occurs within four to six weeks. The harbor seals feed on fish, molluscs, squid, and octopus found along the shore and in bays and estuaries Conservation Status Harbor seals are protected in U.S. coastal waters by the Marine Mammal Protection Act. During summer 2000, the installation of a SealCam will provides 24-hour viewing of the La Jolla Harbor seals.