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Gray Seal (Halichoerus grypus)

Status | Species Description | Habitat | Distribution | Population Trends | Threats | Conservation Efforts | Regulatory Overview | Taxonomy | Key Documents | More Info

Status

MMPA - Gray seals, like all marine mammals, are protected under the MMPA.

Species Description

Weight:
550-880 pounds (250-400 kg)
Length:
7.5-10 feet (2-3 m)
Appearance:
Pups are born with white fur, then females have a silver-grey coat with scattered dark spots and males have a dark gray coat with silver gray spots; males also have a long arched nose
Lifespan:
25-35 years
Diet:
fish, crustaceans, squid, octopus
Behavior:
gather in large groups to mate, with males competing with each other for access to females

Gray seals are part of the "true seal" family, Phocidae. True seals lack external ear flaps and have short forelimbs that result in limited locomotion on land. Gray seals are sexually "dimorphic" with males reaching up to 10 ft (3 m) in length and 880 lbs (400 kg) and females reaching up to 7.5 ft (2.3 m) in length and 550 lbs (250 kg). Gray seal coloration varies by geographic region and sex of the animal. Females live up to 35 years, while males live up to 25 years in the wild.

Gray seals gather in large groups to mate, with males competing with each other for access to females. Land breeding gray seals are often "polygynous"; one male potentially mates with up to 10 females in a given breeding season. However, gray seals that breed on ice are thought to be primarily monogamous. The gestation period for gray seals is 11.5 months, which includes a 3 month delay in implantation of the fertilized egg. Pups in the eastern Atlantic Ocean are born September-November while pups in the western Atlantic Ocean are born January-February. At birth, pups weigh approximately 35 lbs (16 kg) and fatten quickly (by 2.5-3 pounds per day in the first 3 weeks) on rich milk from their mothers. Pups are born with creamy white fur that is shed after the first 3 weeks of life. After this period, coat patterns differ between the sexes with females having a silver-grey coat with scattered dark spots and males having a dark gray coat with silver gray spots. Males can also be distinguished from females by their long-arched "roman" nose. The male nose is the basis for its Latin name, Halichoerus grypus, which means "hooked-nose sea pig."

Gray seals are opportunistic feeders that consume between 4-6% of their body weight per day. Food sources include fish, crustaceans, squid, octopus, and even seabirds on occasion. Smaller fish are generally consumed underwater while bigger fish are brought up to the surface to be broken into smaller pieces using the seals' "prehensile" front flippers and mouth. Gray seals can dive to great depths to capture food, with recorded dives as deep as 1,560 feet (475 m). "Social feeding" is often practiced by gray seals, which helps to prevent prey escaping capture. With excellent vision and hearing, this species is a formidable hunter. In open waters, gray seals rest in a vertical position similar to a floating bottle, where the animal keeps only its head and neck above water. Some sharks and killer whales have been known to prey on gray seals.

Habitat

Gray seals are generally found in coastal waters. In their cold water habitat, these animals use blubber to maintain necessary body temperatures. On land, they inhabit rocky coasts and islands, sandbars, and ice shelves and icebergs. During mating, pupping, and molting, they gather into large groups. At sea they are usually found alone or in small dispersed groups. When hunting, gray seals use the entire water column--from the water's surface to the sea floor. Gray seals share their habitat with many organisms and are often found in the same areas as harbor seals.

Distribution

Gray seals are divided into three somewhat isolated stocks:

Breeding seals are found across the North Atlantic in coastal areas from Massachusetts to the Baltic Sea. Young seals often disperse widely, sometimes going over 1,000 miles (1,610 km) from their natal grounds. For example, young seals born in the eastern United States and Canada are sometimes seen in New Jersey waters.

Population Trends

The most recent stock assessment reports with population estimates are available on our website.

Threats

Gray seals are legally killed by fishermen and are harvested for subsistence, predator control, and commercial purposes in some areas outside of U.S. waters.

A morbillivirus known as phocine distemper virus (PDV) is widespread but does not appear to cause much mortality in gray seals, in marked contrast to PDV impact on harbor seals.

Conservation Efforts

Gray seals in U.S. waters are protected under the Marine Mammal Protection Act (MMPA).

Regulatory Overview

Gray seals in U.S. waters are protected under the Marine Mammal Protection Act (MMPA).

Taxonomy

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Phocidae
Genus: Halichoerus
Species: grypus

Key Documents

(All documents are in PDF format.)

Title Federal Register Date
Stock Assessment Reports n/a various

More Information

Updated: January 15, 2015