The harbor seal (Phoca vitulina) is also known as the common seal, and can be found in the coastal waters of the North Atlantic and North Pacific, as well as the Baltic and North Seas, being one of the most widely distributed of the pinnipeds (eared seals, true seals and walruses). There are 5 subspecies of Phoca vitulina.
They typically appear on barrier islands, although they can also be found on rocky shores. The coat is gray or light gray to black and mixed with a pattern of darker spots in various shades . The males measure 1.3 to 1.95 meters long and weigh about 100 kg. Females are slightly smaller and lighter.
The Harbor seals (such as seals and other marine mammals in general) have a thick layer of fat under the skin, which protects them from cold. The head is large relative to the body and has V shaped nostrils.
Unlike sea lions, seals do not have ears, and this is one of the features that most easily distinguishes these two groups of animals.
They are very well adapted for locomotion in water and move with difficulty on the ground, dragging their body on the ground with the aid of the fins. They are essentially sedentary, although the eating area is quite variable. When on ground, they gather in large groups, with about 1000 individuals.
The females of harbor seals live longer than males and have an estimated life span of 30 to 35 years, while the male life span is about 20 to 25 years. They are one of the favorite prey for orcas or killer whales and white sharks.
Harbor Seal - Diet
They feed on fish, squid and crustaceans. Juveniles will eat mainly crustaceans.
Harbor Seal - Reproduction
The courtship and mating takes place in water. Mating takes place after weaning of the offspring born in that year. The gestation period lasts from 10.5 to 11 months, including a period of 45 to 90 days of delayed implantation.
The time of birth varies with geographic location (these occur in February, March or April in California, in June or July, in Europe, North Pacific and North Atlantic Arctic region). The female gives birth to only a pup on land, which is nursed for about four to six weeks.
Once born, the offspring is already able to swim and dive. Most males reach sexual maturity at six years of age and females at three to five years of age.
Harbor Seal - Conservation status and main threats
The species is not globally threatened (according to the International Union for Conservation of Nature). Pollution is one of the a major threat factors, either directly (causing breathing problems) or indirectly (by causing the death of the fish that feed on).
However, protective measures were taken, so it is still relatively common. The once common practice of seal hunting or sealing, is now considered illegal in many countries within the harbor seal range.
Their global numbers reach 5 to 6 million, but some subspecies in certain areas are threatened.
Species: P. vitulina