Harbor Seal

Common Name: Harbor Seal

Class: Mammalia

Order: Pinnipedia

Family: Phocidae

Genus: Phoca

Species: Phoca vitulina

 

 

Harbor Seal Taxonomy/Description

Harbor seals belong to the Mammalian Order Pinnipedia, in the family Phocidae.  Other members of Phocidae include elephant seals, gray seals, and monk seals.  Phocids are referred to as true seals.  They are distinguished from other pinnipeds by their inability to support their body using their hind limbs.  The harbor seal's scientific name, Phoca vitulina, means "calf-like seal".

Harbor seals are easily identified by the spotted coloring on their fur and their dog-like  faces.  There are five subspecies of harbor seal, separated geographically.  They have short thick fur, can grow to be up to 6.5ft in length, weighing up to 375lbs.  The average lifespan for a harbor seal is 25-30 years.  Coloration and patterns vary from individual to individual from a dark background with light rings to light colored sides and belly with dark blotches or spots.

Harbor Seal Habitat/Diet

Harbor seals are found all along both coasts of North America.  They live along the shores in the north Atlantic and Pacific oceans.  On the Pacific they range from Alaska to Mexico.  Northern European coasts and northern Canadian and American coasts  They tend to occupy the shallow waters along shorelines and do not characteristically move very far out into sea.  Harbor seals are occasionally found in rivers and lakes.

Harbor seals eat squid, clams, octopus, fish and crustaceans.  They do not chew their food, instead tearing it to chunks and swallowing it whole.  They are hunted by killer whales, polar bears, sharks, Steller's sea lions, walruses, eagles, coyotes, and humans.

Harbor Seal Behavior/Reproduction

Harbor seals live in small groups but are hunt alone.  Harbor seals dive to depths of 400ft for time periods of 20 minutes when hunting.  They do not make long migrations.  Winter and summer movements are not very clear, but more information is becoming  available as researchers tag and study current populations.  Newborn pups are able to swim almost immediately after birth. Sexual maturity is at 3-7 years.  Females mate soon after delivery.  Delayed implantation causes the egg to implant 11 weeks later.

Harbor seals and other true  seals swim by powerful sideways movements of their hindquarters. Their short front flippers are used mainly for steering through the water and for grooming themselves.  Their broadly webbed flippers are less useful on land and cannot support their weight.  The movement of a harbor seal scooting along on its belly on land is similar to the movements of an inchworm.

Harbor seals spend half their time in the sea. They tend to spend part of each day hauled out on land where they warm themselves in the sun.  Harbor seals haul out onto to land to rest, dry out, regulate their body temperature, give birth, nurse their pups, and molt.  They arch their bodies so that the maximum amount of their skin is exposed to the drying effects of the air.

Harbor Seal Conservation

The number of Harbor Seals that inhabit the Pacific coast of North America has greatly declined in recent decades.  Pollutants and human waste collect near the shore where harbor seals live.  Thus, the overall threat to these animals derives from the ever growing human population.  As more and more people inhabit the earth, they occupy more coastal areas and deprive these seals from shorelines that  they have inhabited for millions of years.  Still this species is not critically endangered and there is plenty of reason to hope.  While on the Pacific coast, we were lucky enough to study the major haul-out site of the largest remaining population of breeding harbor seals.  This was at Limantour Beach in Point Reyes National Sea Shore.  

There is a big conflict between seals and commercial fisheries.  The seals damage the nets, and other fishing gear often harms seals.  Another big threat to seals is water pollution.  The presence of domesticate dogs on beaches transmits canine distemper to seals. Humans also cause  problems by "helping" seal pups that are “stranded”. The mothers of such pups are actually out hunting.  Although motivation to help Marine Mammals is a positive, ignorance of Marine Mammal behavior is very negative, and everyone should strive to expand their knowledge and understanding of Marine Mammal conservation.

 

Content provided by Canisius College students under the direction of Michael Noonan, PhD.