The harbor seal, a familiar sight along temperate and arctic coastlines, is the most common seal species, yet it remains modest in size compared to its relatives in the seal family. This marine mammal exhibits a fascinating variety of pelage, or fur, patterns that range from silver, light tan, or blue-grey adorned with dark spots to darker shades of black, brown, or grey highlighted with light rings.

The fur of the harbor seal is uniquely adapted to the marine environment in which it lives. It consists of a thick and short double-layer system: a coarse outer coat that sheds water and a fine undercoat that retains air to insulate the body. Additionally, the skin houses specialized glands that secrete oil further waterproofing the fur and ensuring the seal remains insulated even in cold waters. Beneath this protective fur lies a layer of thick fat, which is crucial in maintaining the seal’s body temperature, enabling it to thrive in the chilly waters of its habitat.

Harbor seals are carnivorous, with a diet encompassing a wide range of marine life. They primarily feast on fish, such as mackerel, cod, and herring, which provide them with the necessary nutrients for energy and survival. In addition, they are adept hunters of octopuses, squid, and various crustaceans, showcasing their versatility and adaptability in sourcing food. Interestingly, the diet of harbor seal pups is slightly different, with a preference for shrimp, which are perhaps easier for them to catch and digest at a young age.

Historically, the dietary habits of harbor seals placed them in direct competition with human fishermen. The seals’ penchant for the same types of fish that were commercially valuable to humans led to conflicts, as fishermen saw them as rivals, depleting the stocks of valuable catch. As a result, harbor seals were hunted extensively up until 1960, with their population suffering significant declines in certain areas. This hunting threatened the species’ survival and disrupted the delicate balance of the marine ecosystem.

Distribution

Country

Population est.

Status

Year

Comments

Pacific ocean

170,000

Official estimate

LC

2016

Eastern Pacific Harbor Seal

Atlantic Ocean

65,000

Official estimate

LC

2016

Eastern Atlantic Harbor Seal

Atlantic Ocean

60,000

Official estimate

LC

2016

Western Atlantic Harbor Seal

North Sea

2016

Baltic Sea

2016

Belgium

2016

Canada

2016

Denmark

2016

Finland

2016

France

2016

Germany

2016

Greenland

2016

Iceland

2016

Ireland

2016

Japan

2016

Mexico

2016

Netherlands

2016

Norway

2016

Portugal

2016

Seasonality Uncertain

Russia

2016

Spain

2016

Seasonality Uncertain

Svalbard

2016

Sweden

2016

United Kingdom

2016

United States

2016