The Common Seal (Phoca vitulina), also known as the Harbor (or Harbour) Seal, is a true seal found along temperate and Arctic marine coastlines of the Northern hemisphere. They are found in coastal waters of the northern Atlantic and Pacific Oceans as well as those of the Baltic and North Seas, making them the most wide-ranging of the pinnipeds (walruses, eared seals, and true seals).
Common seals are brown, tan, or gray, with distinctive V-shaped nostrils. An adult can attain a length of 1.85 meters (6.1 ft) and a mass of 132 kilograms (290 lb). Females outlive males (30–35 years versus 20–25 years). Common seals stick to familiar resting spots, generally rocky areas where land predators can’t reach them, near a steady supply of fish to eat. Males fight over mates underwater. Females mate with the strongest males, then bear single pups, which they care for alone. Pups are able to swim and dive within hours of birth, and they grow quickly on their mothers’ milk. A fatty tissue called blubber keeps them warm.
Their global population is 400,000 to 500,000, and subspecies in certain habitats are threatened. Seal hunting, once a common practice, is now mostly illegal.
With an estimated 400,000 to 500,000 individuals, the population is not threatened as a whole; most subspecies are secure in numbers with the Greenland, Hokkaidō and Baltic Sea populations being exceptions. Local populations have been reduced or eliminated through outbreaks of disease and conflict with humans, both unintentionally and intentionally. While it is legal to kill seals which are perceived to threaten fisheries in the United Kingdom, Norway and Canada, commercial hunting is illegal; the seals are also taken in subsistence hunting and accidentally as bycatch in fishing nets. In the United States stricter protection applies, and it is illegal to kill any seals or any marine mammals, as they fall under the Marine Mammal Protection Act. On the East Coast of the United States their numbers seem to be increasing quite steadily as they are reclaiming parts of their range, and have been seen as far south as Florida.
Female Common Seals have a life span of 30–35 years while male lifespans are usually 20-25. Scientists have suggested that this is due to stresses male seals are subjected to during breeding seasons.
(From Wikipedia, June 18th, 2010)
This species is gregarious; on land it forms groups to breed, rest and moult that are generally small but may number up to 1,000 individuals (5). Common seals feed mainly on a variety of fish, but squids, whelks, crabs and mussels are also taken. Juveniles feed on shrimps before progressing to the adult diet (2). When feeding, common seals travel up to 50 kilometres from haul-out sites to feed and may stay out at sea for days. They can dive for up to 10 minutes, and reach depths of 50 metres or more (3). With regards to breeding, there is apparently no social organisation, but females often give birth in small groups (7). Females give birth to a single pup at the end of June to early July (8). The pups weigh 11 to 12 kilograms at birth and are able to swim and crawl almost immediately (2). Pups are nursed for about four weeks, after which they may disperse over long distances (5). Around the time that the pup is weaned, females become receptive and copulation occurs. Males frequently engage in underwater displays and fights around this time and can lose up to 25 percent of their body weight (5).
(From EOL via ARKive, June 18th, 2010)