The harbor seal (Phoca vitulina) is a coastal pinniped widely distributed in coastal areas of the Northern Hemisphere, with resident populations established along Japanese coasts. Its streamlined body and the accumulation of oxygen in muscles and blood give it high diving ability; recorded dives reach depths of about 480 m and durations up to 35 minutes. Its diet is broad, preying on fish, cephalopods, crustaceans, and others. Reproduction is seasonal; after a gestation of about 10 months that includes delayed implantation, a single pup is born. Its conservation status is Least Concern, with threats including bycatch in fishing gear and harmful substances.