Cystophora cristata (Erxleben, 1777)

Russell A. Mittermeier & Don E. Wilson, 2014, Phocidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 120-183 : 175-176

10.

Hooded Seal

Cystophora cristata

French: Phoque a capuchon / German: Klappmtitze / Spanish: Foca de casco

Other common names: Bladdernose Seal, Crested Seal

Taxonomy. Phoca cristata Erxleben, 1777 ,

“Habitat in Groenlandia australiori et Newfoundland” (= S Greenland and Newfoundland).

Three distinct breeding stocks of C. cristata are often recognized, but molecular and morphological analyses suggest a single panmictic population. Monotypic.

Distribution. N Atlantic Ocean at high latitudes, from NE Canada (Davis Strait S to Gulf of Saint Lawrence) to Greenland, Iceland, Jan Mayen, and Svalbard; seasonally, distribution extended N into the Arctic Ocean and S into the North Sea in the NE Atlantic Ocean.

Descriptive notes. Total length 250-270 cm (males) and 200-220 cm (females); weight c.300 kg (males) and ¢.200 kg (females). Newborns are c.100 cm in length and weigh c.25 kg. Male Hooded Seals are longer and heavier than females, and exceptionally large males can weigh 400 kg. Hooded Seals are relatively large phocids, with a gray to silver pelage covered by dark splotches and spots; front and rear flippers are generally darker. Nose of a male Hooded Sealis larger than that of a female and can be inflated, especially in the breeding season during threat displays with other males. It starts to develop during puberty when males are about four years old. There is also a reddish membrane septum that internally separates left and right nostrils; adult males can expanded and extruded it through one of the nostrils to form an external balloon—also part of threat displays during the breeding season.

Habitat. Dispersed throughout deep water of the North Atlantic Ocean off eastern Canada and south-western and south-eastern Greenland. Hooded Seals sparsely aggregate on seasonal pack ice in the North Atlantic Ocean to breed in late winter and early spring and to molt in spring and early summer.

Food and Feeding. Diets of Hooded Seals are poorly known because they are pelagic for most of the year. Some prey includes Greenland halibut (Reinhardtius hippoglossoides), capelin ( Mallotus villosus), Arctic cod ( Boreogadus saida and Arctogadus glacialis) redfish (Sebastes spp.), Atlantic herring ( Clupea harengus), sand lance ( Ammodytidae ), crustaceans, squid, and octopus. They feed in areas of deep ocean water and at depths of 200 m or more. At greater depths—up to more than 1000 m—they presumably feed on benthopelagic and mesopelagic squid and fish.

Breeding. Hooded Seals are born from March through early April and are weaned after a brief four days of nursing on milk with ¢.60% fat. Females mate just after their offspring are weaned, and non-parturient females are presumably estrous and mate in early to mid-March. Adult male Hooded Seals compete with each other for the opportunity to mate with estrous females, sometimes by physical combat but usually with visual and vocal threat displays. They appear to be promiscuous and search for other receptive females as soon as they have mated with one, although they might sometimes be polygynous in areas where several females give birth relatively close together. The fertilized egg grows briefly and then remains free-floating for c.16 weeks when it attaches to the uterine wall and fetal development continues. About one-half of all females are sexually mature at c.3 years old and give birth the following year. About 90% of sexually mature females give birth each year. Males are sexually mature at 4-6 years old but not socially mature and able to compete for mates for a few years after that. Hooded Seals live 25-35 years.

Activity patterns. When Hooded Seals are not on ice to breed or molt, they appear to be constantly diving and foraging. Dives average 13-15 minutes, with the longest lasting ¢.60 minutes for males and ¢.40 minutes for females. Hooded Seals dive to average depths of ¢.260 m. Adult females appear to dive and forage c.70 m deeper than adult males when foraging in the same areas. Deepest dives recorded have been c.1600 m.

Movements, Home range and Social organization. Although Hooded Seals aggregate in large areas offast ice (ice fastened to land), they are mostly solitary or in groups of two (female and her single offspring) to three (female, her offspring, and a transient adult male). They also appear to travel and forage independently over large areas when not hauled out on ice to breed and molt. Hooded Seals are known to wander and have been seen south to the coast of Florida (USA) and the Iberian Peninsula, to eastern Arctic Russia, and the Beaufort Sea. One Hooded Seal appeared near San Diego, California (USA), in 1990.

Status and Conservation. Classified as Vulnerable on The IUCN Red List because the breeding stock in the north-eastern North Atlantic Ocean has declined by 85-90% in the past 40-60 years, and despite protective measures, it continues to decline. Norwegian, Greenlandic, Canadian, and Russian sealers have long harvested Hooded Seals, when they are on ice to breed and molt, for meat, oil from blubber, and skins, especially those of young. Off Greenland and Canada, hunting of Hooded Seals was often associated with harvest of Harp Seals ( Pagophilus groenlandicus ) and Greenland sharks (Somniosus macrocephalus). In the early 1900s, total annual commercial harvests were as high as 62,000 Hooded Seals in several areas. They are still harvested in some areas, although in substantially lower numbers of several thousand or less. Overall, the eastern stock of Hooded Seals declined from ¢.500,000 individuals to just ¢.70,000 individuals in the past few decades, and causes of this decline are unknown. Dependence of Hooded Seals on pack ice and their relatively restricted distribution suggest that climate change could cause further decline in their abundance. Conservation concern for the Hooded Seal dates back to the 1870s, and numerous international management plans, agreements, treaties, and harvest quotas, have been put in place. For example, Denmark has protected molting Hooded Seals in the Denmark Strait since 1961, harvesting has been banned in the Gulf of Saint Lawrence since 1972, and the European Commission banned importation of seal products.

Bibliography. Andersen et al. (2013), Bajzak et al. (2009), Boehme et al. (2012), Boness et al. (1988), Coltman et al. (2007), Folkow & Blix (1999), Folkow et al. (2010), Haug et al. (2007), Kovacs (1990, 2008a, 2009b), Kovacs & Lavigne (1986), Kovacs, Lydersen, Hammill & Lavigne (1996), Lavigne & Kovacs (1988), Reijnders etal. (1993), Wiig (1985), Wiig & Lie (1984).

Figures

5. Leopard Seal (Hydrurga leptonyx), 6. Weddell Seal (Leptonychotes weddelli), 7. Crabeater Seal (Lobodon carcinophaga), 8. Ross Seal (Ommatophoca rossu), 9. Bearded Seal (Erignathus barbatus), 10. Hooded Seal (Cystophora cristata)

Distribution. N Atlantic Ocean at high latitudes, from NE Canada (Davis Strait S to Gulf of Saint Lawrence) to Greenland, Iceland, Jan Mayen, and Svalbard; seasonally, distribution extended N into the Arctic Ocean and S into the North Sea in the NE Atlantic Ocean.