Hooded seals are generally found from 47° to 80° N latitude. They occur along the eastern coast of North America north of Maine. Hooded seals also reach the western tip of Europe, along the coast of Norway. They are mainly concentrated around Bear Island, Norway, Iceland, and northeast Greenland. In rare cases they have been found in Siberia.

Biogeographic Regions: nearctic (Native ); arctic ocean (Native ); atlantic ocean (Native )

Other Geographic Terms: holarctic

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Usual distribution limited to arctic and subarctic North Atlantic, from Newfoundland to southern Greenland, Svalbard, and Novaya Zemlya (Russia); occasionally south to Portugal and Florida, with additional erratic occurrences far from usual range. Whelping areas include Gulf of St. Lawrence, the "Front" off southeastern Labrador, middle of Davis Strait, and West Ice near Jan Mayen Island (a few pups have been born on the coasts of Norway and Maine). Summer molting areas are in Denmark Strait off southeastern Greenland and on the pack ice of the Greenland Sea north of Jan Mayen Island (Reeves et al. 1992). Occurrences in the northern Gulf of Maine region increased greatly during the 1990s (McAlpine et al. 1999).

Hooded seals have blue-gray pelage with black spots over the body. The front of the face is black and this coloration extends posteriorly to just behind the eyes. Their limbs are rather small in proportion to their body, but are powerful nonetheless, making these seals excellent swimmers and divers. Hooded seals exhibit marked sexual dimorphism. Males are slightly longer than females, and reach 2.5 m in length; females average 2.2 m. The more significant difference between the sexes is weight. Males weigh up to 300 kg while females only weigh up to 160 kg. Also unique to males is the inflatable hood and nasal septum.

Hooded seals get their name from the inflatable “hood” on the top of the heads of males. The hood is not present until males are about 4 years old. When the hood is deflated, it hangs down over the upper lip. Males inflate this red, balloon-like nasal septum until it protrudes out of one nostril. Males use this nasal sac for aggressive display and also to get the attention of females.

Hooded seals have many characteristics that differentiate them from other phocids. They have the largest nostrils in the family. The skull is short with a wide snout. They also have a palate that projects posteriorly further than any other seal. One-third of the nasal bone extends beyond the edge of the maxilla. Their incisor formula is unique, with two upper and one lower incisor. The teeth are small and the tooth row is narrow. The dental formula is I 2/1, C 1/1, PC 5/5. Hooded seals have light and dark bands of cementum in the canines that can be used to determine age.

At birth the coloring of young is silver on the dorsal side, without spots, and blue-gray on the ventral side, which accounts for their nickname ”bluebacks.” Young are 90 to 105 cm in length when born and average 20 kg. Around age 1, differences between males and females can be observed; males begin growing larger in weight and length.

Range mass: 160 to 300 kg.

Range length: 2.2 to 2.5 m.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; ornamentation

Length: 250 cm

Weight: 40000 grams

• Terrestrial
• Marine

Hooded seals are found in coastal areas of Atlantic and Arctic Oceans. They are successful divers that spend much of their time in the water. They usually dive to a depth of 600 m but can go as deep as 1000 m. When they are on land they usually occur in areas with significant ice cover or made up of ice packs. They migrate annually in order to stay in areas where there is drifting pack ice.

Range depth: 100 to 1000 m.

Average depth: 600 m.

Habitat Regions: polar ; terrestrial ; saltwater or marine

Terrestrial Biomes: icecap

Aquatic Biomes: coastal

Habitat Type: Marine

Comments: Pelagic; normally in deep water or hauled out on heavy drift ice (Reeves and Ling 1981). Rarely on land or shore-fast ice except in Gulf of St. Lawrence (Kovacs and Lavigne 1986). Pups are born usually at center of large ice floe (Reeves and Ling 1981), in traditional breeding areas. Pupping habitat generally is transient and unstable.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

After breeding, populations in eastern Canada migrate north and reach western Greenland by late spring. Within a few weeks many migrate southward, later joining large molting assemblies east of Greenland in July and August. (Katona et al. 1983).

Hooded seals eat a variety of marine prey, especially fish, such as redfish, herring, polar cod, and flounder. They also feed on octopus and shrimp. Some research indicates that during the winter and autumn hooded seals feed more on squid and switch to primarily fish in the summer, especially polar cod. Pups first begin feeding near the shore and eat mainly squid and crustaceans. When Arctic algae and phytoplankton bloom, their energy is transferred to fatty acids. These food sources are eaten by herbivores and make their way up the food chain to the top predators like the hooded seal. The fatty acids that begin at the bottom of the food chain are then stored in the blubber of the seals. This blubber is sustained throughout the autumn and winter and used as an energy resource in the summer during the molting and breeding season when fasting occurs.

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )

Comments: Eats redfish, Greenland turbot, octopus, squid, herring, capelin, shrimp, and mussels (Katona et al. 1983). Pelagic feeder; may dive deeply when feeding. Pups initially feed near ice edge on crustaceans and squid (Kovacs and Lavigne 1986).

Hooded seals often find themselves the host of parasitic worms, such as heartworms, Dipetalonema spirocauda. Often these parasites result in shortened lifespans. Hooded seals are predators of many fishes, such as polar cod, squid, and various crustaceans. They are preyed on by sharks, orcas, and polar bears.

Commensal/Parasitic Species:

• heartworms (Dipetalonema spirocauda)

In recent times, the major predators of hooded seals have been humans. The sealing industry began in the 18th century and these mammals were hunted for 150 years without any restrictive laws. More than 500,000 seals (hooded and harp seals) were caught per year between 1820 and 1860. At first, sealing was popular because there was a demand for oil and leather. After the 1940s, seals began to be hunted for their fur and one of the most prized species was the hooded seal, considered four times more valuable than other seals. A quota to limit hunting was introduced in 1971 and was set at 30,000.

Natural predators of hooded seals include sharks, polar bears, and killer whales. Polar bears mainly feed on harp and bearded seals but will hunt hooded seals when they are breeding on ice and are more visible, vulnerable targets.

Known Predators:

• polar bears (Ursus maritimus)
• Greenland sharks (Somniosus pacificus)
• killer whales (Orcinus orca)
• humans (Homo sapiens)

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: No exact figures.

10,000 to >1,000,000 individuals

Comments: Estimates range from 300,000 to 750,000 worldwide. In the late 1980s, 60,000 pups were born at the West Ice, suggesting a total population there of perhaps 250,000 seals one year old or older. Mid-1980s data indicate a population of about 300,000 (60,000 pups born annually) at the Front off Newfoundland. In 1990, more than 2000 pups were born in the Gulf of St. Lawrence. Davis Strait population was estimated at 18,600 pups and 93,000 seals one year old or older in the mid-1980s (Reeves et al. 1992).

Solitary throughout most of year. Polar bears sometimes kills large numbers of young.

Hooded seals are able to make vocalizations such as roars that can be heard easily on land. However, their most important form of communication is produced from the hood and septum. They are able to produce pulses ranging from 500 to 6 Hz, these sounds can be heard on land and in the water. They are often seen moving their inflated hood and nasal septum up and down, which can create sounds described as “pings” and “whooshes”. This method of communication can serve as male display for females but also serve as threats.

Communication Channels: visual ; acoustic

Perception Channels: visual ; acoustic

Comments: Intermittently active day/night.

The expected maximum lifespan of hooded seals is 35 years. In this sexually dimorphic species the differences in body size among males and females result in differences in longevity. In hooded seals males are larger and have shorter lifespans. The mortality rate of adults is 7 to 15% a year. One cause of death is known to be infections from the parasitic heartworm, Dipetalonema spirocauda. Before there were restrictions on hunting, humans were the main cause of death in hooded seals. Captive hooded seals have been reported to die from tuberculosis and cranial infections.

Typical lifespan

Status: wild: 35 (high) years.

During the short time that the mother is giving birth and nursing her pup, several males will be in close proximity to her in order to obtain mating rights. At this time many males will aggressively threaten each other using their inflated nasal sac and even push each other out of the breeding area. Males do not typically defend personal territories; they only defend the area where there is a receptive female. A successful male will then mate with the female in the water. Once returning to land he will search for another female. Mating occurs typically through April and June.

Mating System: polygynous

Females reach the age of sexual maturity between 2 and 9 years old and it is estimated that most females give birth to their first young at around 5 years of age. Males reach sexual maturity a little later around 4 to 6 years old but often do not mate until much later. Females give birth to one young at a time through March and April. The gestation period is 240 to 250 days. During this time the fetus - unlike those of other seals - sheds its lanugo (a covering of fine soft hair that is replaced thicker pelage) in the uterus. These young are precocial and at birth are able to move about and swim with ease. They are independent and left to fend for themselves immediately after they have been weaned.

Breeding interval: Hooded seals breed once a year.

Breeding season: Hooded seals breed from April to June.

Range number of offspring: 1 to 1.

Range gestation period: 240 to 250 days.

Range birth mass: 10 to 30 kg.

Range weaning age: 5 to 12 days.

Range age at sexual or reproductive maturity (female): 2 to 9 years.

Average age at sexual or reproductive maturity (female): 3.2 years.

Range age at sexual or reproductive maturity (male): 4 to 6 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average number of offspring: 1.

Hooded seals have the shortest nursing period of any mammal, from 5 to 12 days. The milk of the female is rich in fat, which makes up about 60 to 70% of its content and allows the pup to double in size during its short nursing period. During this same period, the mother loses 7 to 10 kg each day. Females are protective of their pup during their short weaning interval. They fight potential predators, including other seals and humans. Males do not invest energy in defending their young. Since young are precocial at birth and already able to crawl and swim, little is done to help raise them.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Single pup is born mid-March to mid-April (peak in second half of March). Breeds near end of lactation period, which lasts only about 4 days. In any given area, breeding season spans only 2-2.5 weeks. One to several males may be on ice floe with female and pup; these groupings are widely scattered (loose aggregations). Females sexually mature usually in 3-4 years; more than 90% of adult females are pregnant each year. Males sexually mature in 4-6 years but do not do much breeding until several years older. Few live beyond their late 20s. Polygynous mating system.

• 1996
  Lower Risk/least concern

Hooded seals were hunted in high numbers starting in the 18th century. The popularity of their pelts, especially of the “bluebacks”, which are pup pelts, resulted in a rapid decline of populations. After World War II the hunt for hoodeds seals increased, resulting in concern that they would become endangered. In 1958 laws were introduced, followed by quotas in 1971. Recent efforts include treaties and agreements, banning of hunting in areas such as the Gulf of St. Lawrence, and bans on importation of seal products. Despite these measures hooded seal populations are still on the decline for unknown reasons.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: vulnerable

Canada

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Widespread distribution in arctic and subarctic North Atlantic; relatively abundant (several hundred thousand individuals); relatively secure.

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Substantial numbers die in fishing gear off the coast of Norway. Other threats include over-exploitation and pollution by pesticides and heavy metals.

Biological Research Needs: Effects of parasites on survival.

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: Individuals protected in part by the Marine Mammal Protection Act.

Needs: Worldwide ban on hunting.

There are no negative effects of hooded seals on humans.

Hooded seals have played an important role in subsistence for the natives of Greenland and Canada who hunt these seals for a source of food. They have also provided valuable goods including leather, oil, and fur. However excessive demand of these goods have negatively impacted populations of hooded seals.

Positive Impacts: food ; body parts are source of valuable material

Comments: Long history of commercial exploitation; pups and adults hunted chiefly for pelts but also for meat and oil (Katona et al. 1983, Reeves et al. 1992). Harvests formerly were in the 10,000s; now greatly reduced due to EEC import ban (Reeves et al. 1992). Still harvested in summer by Greenlanders, for food for humans and dogs.

Comments: A cladistic analysis of mtDNA data yielded three clades among northern seals: Phoca-Pusa-Halichoerus, Cystophora-Pagophilus, and Erignathus (Perry et al. 1995). Each clade may be regarded as a tribe of the subfamily Phocinae. The magnitude of the differences among Phoca, Pusa, and Halichoerus was on the same order as that between species and subspecies within the genus Odocoileus. Because Cystophora is the closest relative of Pagophilus, the latter cannot be regarded as congeneric with Phoca; the differences between the two are great enough to justify placing them in separate genera (Perry et al. 1995).

Evidently there is substantial genetic mixing among populations in Newfoundland, Denmark Strait, and Jan Mayen (Reeves et al. 1992).