Animal Facts Common Seal

The Common Seal, or Phoca vitulina, is more commonly known as the harbor seal. It is a true seal that is found all along the coasts of the northern hemisphere and the arctic coastlines. They have a wide range extending all the way from the Atlantic to the Pacific Ocean and from the Baltic to the North Sea. This makes them the most widely ranged pinniped in the world. Their estimated population worldwide is between 400,000 and 500,000.

There are five subspecies of the common seal. First there is the Western Atlantic Common Seal that are only found on the eastern shore of North America. The Ungava seal is located in eastern Canada, usually in freshwater areas. The Pacific common seal is the resident of the western coasts of North America. Insular seals are found in eastern Asia. And the Eastern Atlantic common seal is found all over Europe and western Asia, they are among the most populous species of seal in the world.

Common seals are tan, gray, and brown in color. Every individual seal will also have a unique pattern of light or dark spots which can be used to identify individuals from a group. Generally they have a lighter colored belly though not significantly lighter. They are most recognizable for their V-shaped nostrils which set them apart from other seals and pinnipeds. They can grow to be around 6 feet long and weigh on average 290 pounds. Females usually are smaller than their male counterparts and are usually in the range of 120-200 pounds. Males can weigh up to 370 pounds though this size is rare and under 300 pounds is much more typical.

These seals are very picky about the spots in which they decide to rest and are reluctant to leave that spot and create a new habitat elsewhere. Because of this it is not unusual for them to spend a few days at sea searching for food or swim into large freshwater rivers for the same purpose, then return to the same resting spot they just left. Their resting areas are usually on the coast and can be either the rocky beaches of New England or the sandy beaches of Los Angeles. Their most typical congregating place is in harbors and on docks, which has led to both their names of common seal and harbor seal. Though this is their typical habitat they have been known to make resting places in estuaries to prey on the fish there as well. 

Common seals prey on many different marine animals and their primary diet will vary based on their range and location as well as what is available. Their primary food is fish like flatfish, sea bass, herring, mackerel, cod, and anchovy. Though at times they will also feed on shrimp, squid, and crabs. Although this is not common there have been recorded attacks and feedings on seabirds as well.

Most species of seals tend to create large groups and the common seal is the same although their groups are generally not as large since they are a more gregarious animal than other seal species. Unless they are actively hunting and feeding the seals will haul themselves out of the water and onto a land-based resting place. These seals generally do not stray too far offshore and prefer to stay near the coast whenever possible. 

Not a lot is known about the mating and breeding of the common seal. They are believed to be polygamous animals and it is known that courting and mating both take place underwater. Males will congregate underwater, turn on their backs, and make vocalizations in order to attract the females attention and interest in breeding. Gestation lasts for nine months and females will give birth to one pup per year. The pups are born on shore but the timing of the births will vary based on the seal’s location, February for lower latitiudes and July in the subarctic. The mother of the pup provides all of the care and lactation usually lasts for around 4-6 weeks. During this period the pups will often double their weight and start developing a fatty layer of blubber. Pups are born very well-developed and are capable of swimming within a few hours of birth. Females will generally mate again as soon as the pup is weaned in order to produce another pup the following year.

One of the times when common seals spend the most time on shore is during their molting or shedding their fur. This usually happens after breeding and is a very vital time for the seals. This molting period can be interrupted by the presence of humans who disturb the seals and this can be detrimental to the life cycle of the seals. The onset of the molting season depends on the age and sex of the animal. Yearling pups will start to molt first and generally the adult males will be the last to molt. These seals can be shy and don’t like to leave the water if there are too many humans present, so for this reason human development needs to be carefully monitored in known resting places of common seals in order for there to be a minimal impact on their populations. Some populations of common seals seem to have overcome this aversion to people and so you will find particular populations in California of common seals resting comfortably within feet of popular tourist areas.