Also known as the common seal, the harbor seal (Phoca vitulina) is a “true seal” in that it has small flippers and can only move on land by flopping its body. Harbor seals live along the coastlines of most every continent in the Northern Hemisphere and have been spotted as far south as Florida, and as far north as the Arctic Circle. The most widely distributed of all seals, there is an estimated population of 500,000 harbor seals worldwide.
Harbor seals are around six feet in length, and can weigh anywhere from 120 to 370lbs, with males noticeably larger than females. As they are true seals, harbor seals have no visible ear flaps but rather have an ear canal behind each eye. Each seal has a different pattern of spots, and they may vary in color depending on their habitat.
Harbor seals received their name because they usually do not venture very far away from the coast. Although they are capable of diving to over 1,500 feet and being underwater for up to 40 minutes, harbor seals prefer to stick to shallower waters and can even be found upstream in large rivers from time to time. They spend about half their time in the water and spend the remainder of their day “hauled-out”, which is another term for resting on shore. The seals will usually choose a rocky coastline, sandy beach or ice-pack for their haul-out site depending on their geographical location. Harbor seals are social animals and usually rest in groups, but they do not congregate in groups as large as most other types of seals.
The harbor seal is a carnivore and feeds on a variety of fish, octopus, squid, shrimp, crabs and mollusks, all depending on the prey native to its environment. Harbor seals have also been known to feed on seabirds. Although carnivorous and quite large, Harbor seals pose no threat to humans. While very capable swimmers, when hauled-out on land Harbor seals are very vulnerable and will often rush back into the water if approached by a human.
Female harbor seals give birth to one pup every year, with the birthing season varying by climate. The pups are fully developed and able to swim within a few hours of birth, but will depend on their mother’s milk for the first three to four weeks of life. After weaning, the female seal will mate again almost immediately to continue the annual birth cycle. The lifespan of a harbor seal is between 20-35 years, with females usually living 10 years longer than males.
Once heavily hunted by people, the harbor seal is a protected animal in almost every nation now and their population has been on the rebound. However, urbanization of coastline remains a threat to these animals. In order to rest and molt, harbor seals need to spend a lot of time out of the water, and if a human presence is detected they will often not haul out. If construction occurs at or near a usual haul out spot, the seals will often abandon it permanently, which could threaten their population.
HARBOR SEAL FACTS
- In San Francisco Bay, some harbor seals are partially or fully red in color.
- Harbor seals can often be spotted playing in both New York Harbor and Boston Harbor.
The Marine Mammal Center