The hooded seal (Cystophora cristata) is a large phocid that is silver-grey in colour with irregular black spots covering most of the body; the face is often completely black. The most distinctive physical feature of hooded seals is the prominent nasal ornament borne by adult males. When relaxed the nasal appendage hangs as a loose, wrinkled sac over the front of males’ noses. During the breeding season (in March) males inflate this sac to display to females and to other males, forming a tight, bi-lobed "hood" that covers the front of the face and the top of the head. This structure is the source of the species common name.
Adult males are about 2.5 metres long and weigh an average of 300 kg. Adult females are considerably smaller than males, measuring 2.2 m in length and weighing an average of 200 kg.
Hooded seal pups are approximately one metre long when they are born and they weigh about 25 kg. They are blue on their backs and silver-grey on their bellies. This distinctive "blue-back" pelage is maintained for about two years.
The most distinctive physical feature of hooded seals is the prominent nasal ornament borne by adult males. When relaxed the nasal appendage hangs as a loose, wrinkled sac over the front of males’ noses. During the breeding season (in March) males inflate this sac to display to females and to other males, forming a tight, bi-lobed "hood" that covers the front of the face and the top of the head. This structure is the source of the species common name. Males also have the ability to inflate the nasal septum, which when expanded, protrudes through one nostril as a big membranous pink-red balloon.
Hooded seals are a migratory species, with a range that encompasses a large sector of the North Atlantic. They follow an annual cycle of movement that keeps them in association with drifting pack ice. They breed during the spring in three traditional areas – off the east coast of Canada, in the Davis Strait, and in theWest Ice (between Greenland and Jan Mayen). During the summer and autumn hooded seals disperse broadly, preferring the outer edges of packice areas.
Hooded seals can be seen during the spring, summer and autumn in Svalbard waters, in fjords or in more open water areas – wherever there is pack ice.
The global population of hooded seals is in the order of half a million animals. The actual number of hooded seals that visit Svalbard waters likely varies dramatically according to annual ice conditions but numbers are not known.
Hooded seals are solitary animals outside the breeding and moulting seasons. They are deep divers that feed on Greenland halibut, a variety of redfish species, squid, and a variety of pelagic fish species including herring, capelin and Atlantic cod. During the autumn their diet in some areas can also include smaller prey such as prawns and polar cod.
Life history and reproduction
Hooded seals give birth in a highly synchronous fashion at each birthing site, in late February or early March on free-floating annual pack ice.
This species is notable for having the shortest mammalian lactation period. Mothers remain with their pups for only four days. During this time pups drink more than 10 litres of milk per day and more than double their birth mass, gaining weight at a rate of up to seven kg per day. Hooded seals have the fattest milk documented to date among mammals; it can contain up to 70 % fat. Pups are weaned at 50–60 kg.
Males attend females serially, with successful combatants achieving a degree of polygamy. Females reach sexual maturity at an age of three; males are a little bit older when they mature.
Hooded seals live to be 25–30 years of age.
Management status and monitoring
Hooded seals have been commercially exploited for centuries. At various points in times hunts have originated from Norway, Russia, Denmark-Greenland, Great Britain and Canada. In years of high harvest up to 150,000 animals have been taken in the North Atlantic.
Documented population declines resulted in the introduction of quotas in the early 1970s. Norway and Russia have a bilateral agreement for setting quotas for harvesting hooded seals in the North-East Atlantic. Commercial harvesting of hooded seals is managed internationally under the International Commission for Northwest Atlantic Fisheries with Canada, Norway and Denmark- Greenland as voting members. Subsistence harvesting of hooded seals also takes place in Canada and Greenland.
Hooded seals are protected in Svalbard.