Harbour Seal (Phoca vitulina)

 

Class:	Mammalia
Order:	Carnivora suborder: Pinnipedia
Family:	Phocidae
Size:	Length: 4 to 6 feet (1.22 to 1.8 m)
Weight:	110 to 375 pounds (50 to 170 kg)
Diet:	Fish, including squid, rockfish, herring, flounder, salmon and hake; crab and mussels
Distribution:	Coastal waters of northern oceans
Young:	1, usually every year
Animal Predators:	Killer whales, sharks, polar bears, walruses and Steller sea lions
IUCN Status:	No special status
Terms:	Male: Bull   Female: Cow  Young: Pup
Lifespan:	Up to 30+ years

 

Facts/Trivia:

·         The scientific name Phoca vitulina means “sea dog” and comes from their resemblance to cocker spaniels.

·         Harbour seals can swim upside-down and forward, but rarely swim backward.

·         They are also known as common seals, hair seals or spotted seals.

·         San Francisco Bay harbour seals are reddish in colour. 

·         The Exxon Valdez oil spill led to a 43 percent decline in the harbour seal population in the Gulf of Alaska.

 

Description

Harbour seals have a rounded, torpedo-shaped body with a relatively small head and small flippers. They are “true” or “earless” seals—true seals have no external earflaps and have small flippers, which means they flop along on their bellies to move across land. “Eared” seals have small external ears and strong enough flippers to lift their bodies off the ground to move. The foreflippers (pectoral flippers) are composed of five digits that are webbed together. Claws on the foreflippers are used for scratching, grooming and defence. The hind flippers also have five digits; however, the first and fifth digits are long and stout, while the middle digits are shorter and thinner. The hind flippers propel the seal forward by moving side to side. Their round body is covered by a coat made of thick, short hairs that range from nearly white with dark spots to black or dark brown with white rings. Harbour seals have a thick layer of blubber that insulates them. These seals have excellent hearing and their large, dark eyes provide excellent vision, especially in water. They are able to close both their ear openings and nostrils when submerged. Harbour seals have characteristic V-shaped nostrils. 

 

Habitat

Unlike most other seals, harbour seals are not usually found on ice, they mostly inhabit areas with sandy beaches, even in the northern-most areas of their range. They inhabit the coastal areas of both sides of the North Atlantic and North Pacific oceans, extending as far as Mexico. Harbour seals spend 50 percent of their time on land and 50 percent in water, even occasionally sleeping while in water. 

 

Feeding Habits

Harbour seals eat mostly fish, including squid, rockfish, herring, flounder, salmon and hake, swallowing the fish whole or tearing it into chunks first, but not chewing it. Most of their food is found in shallow water, but they are capable of diving as deep as 295 feet (90 metres), but usually stay submerged for no longer than 10 minutes. Harbour seals do not migrate, but will travel in search of food. 

 

Reproduction

Mating occurs in the water, several weeks after the current season’s pups are born. The female experiences delayed implantation of the fertilized egg for two to three months, so the pregnancy lasts 10 to 11 months. She gives birth to a single pup, weighing about 30 pounds (14 kg). Unlike harp seal pups, who are born with temporary white coats, harbour seals shed their white puppy coats before birth. The pups can swim right at birth, and are sometimes born in the water. A two-day-old pup may be able to stay underwater for up to two minutes. Mothers are very protective of their pups and touch them frequently with their noses. When on land, if a female senses danger, she takes her pup in her mouth and heads for water. A pup rides on its mother’s back when very young and when it is a bit older, the mother plays with the pup, letting it chase her in the water. Mothers occasionally leave their pups on a beach while hunting. The pups nurse for one minute every three to four hours and are weaned in four to six weeks, by which time their weight will have doubled. They are able to catch shrimp by that time, and the mother leaves the pup to fend for itself. 

 

Behaviour

Harbour seals are usually solitary—they hunt alone and when they haul out onto land, they will move away or slap their flippers if another seal comes too close. However, they can sometimes be found in groups numbering several hundred and fights are rare, except between males during mating season. They are shy animals and will flop back into the water if humans approach, but, being curious, they like to watch humans from a safe distance. Aggression is shown by growling, snorting, and head-thrusting, which is a sharp, rapid retraction of the neck. Vocalisation occurs only when they feel threatened. 

 

Conservation

Fishermen, who claimed these seals ate too many fish, killed harbour seals in large numbers in the 1960s. Scientists proved that overfishing, rather than seals, led to a decrease in fish. Public disapproval of the seal slaughter led them to become protected by law in many areas. The Lac des Loups Marins Harbour Seal is listed as Special Concern by Environment Canada. The subspecies Ungava Seal (Phoca vitulina mellonae) found in Canada and Greenland, is listed as Data Deficient on the IUCN Red List. 

 

Sources

http://animaldiversity.ummz.umich.edu/accounts/phoca/p._vitulina$narrative.html

http://www.speciesatrisk.gc.ca/Species/English/SearchDetail.cfm?SpeciesID=159

http://ourworld.compuserve.com/homepages/jaap/harbseal.htm

http://www.oceanoasis.org/fieldguide/phoc-vit.html

http://pinnipedlab.ucsc.edu/pinniped/phoc.html

http://www.pinnipeds.fsnet.co.uk/species/harbour.htm

http://www.vanaqua.org/Visitor_Information/AquaFacts/Harbour_Seals.htm

http://www.aquatic.uoguelph.ca/mammals/whales/accounts/harbour/harbour.htm

http://www.geocities.com/Yosemite/Rapids/7076/harborseal.html

Harbor Seal Wildlife Fact File, IM Pub, US