Physical Description

  • Small, round marine mammals covered in fur, with short, doglike snouts and long whiskers.
  • Spotted coats of white, silver, gray, black, dark brown, or reddish color.
  • Adults reach a length of 5-6 feet, and weight up to 300 pounds.
  • No external ear flaps, unlike sea lions. Instead just an external hole.
  • Small flippers, so must move on land by flopping along on their bellies.
  • Males are slightly larger than females.


  • North of the equator in both Atlantic and Pacific Oceans.
  • From Northern Japan, across to Alaska, down to Baja California, Mexico.
  • All along the Atlantic coast, from Georgia around to Spain.


  • Nearshore coastal waters.
  • Rocky islands, sandy beaches, mudflats, bays, and estuaries.
  • They are often seen sunbathing at the Children’s Pool beach in La Jolla.


  • Harbor seals reach maturity at 3-7 years old.
  • They mate in the winter and pups are born in the spring and summer, depending on location.
  • Females are pregnant for ten months.
  • Harbor seal pups weigh 24 pounds and can swim at birth.
  • Mothers raise their pups in large groups, called nurseries, to protect them from predators.
  • They are nursed for 4-6 weeks on milk that is 50% fat.


  • Sole, flounder, sculpin, hake, cod, herring, octopus, squid.


  • Killer whales, sharks, bears, coyotes, foxes, large birds, and Steller sea lions.
  • Sea otters can drown harbor seal pups.

Interesting Facts

  • A harbor seal pup can already swim at birth but will ride on its mom’s back when tired. Pups also make a bleating noise that sounds like “maaaa.”.
  • Harbor seals can dive up to 1,500 feet for 40 minutes at a time, although they normally dive more shallowly for 3-7 minutes..
  • Harbor seals normally live in small numbers, but can live in groups of up to 500 seals.. 
  • Harbor seals can sleep underwater!

Sources: Marine Mammal Center; NOAA Fisheries; Alaska Fisheries Science Center

Photo: Howard Hall