Halichoerus grypus (Fabricius, 1791)
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publication ID |
https://doi.org/ 10.5281/zenodo.6607185 |
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DOI |
https://doi.org/10.5281/zenodo.6607255 |
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persistent identifier |
https://treatment.plazi.org/id/464F694F-FFA6-A85B-FFB2-D7FC93B9FD37 |
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treatment provided by |
Diego |
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scientific name |
Halichoerus grypus |
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Gray Seal
Halichoerus grypus View in CoL
French: Phoque gris / German: Kegelrobbe / Spanish: Foca gris
Other common names: Atlantic Seal, Horsehead
Taxonomy. Phoca grypus Fabricius, 1791 View in CoL .
No type locality given. Listed by V. B. Scheffer in 1958 as “Greenland.”
There are three populations isolated geographically. Some authors recognized two subspecies ( grypus in the western Atlantic Ocean and macrorhynchus in the eastern Atlantic Ocean), and the Baltic population was formerly referred to as the subspecies baltica; none of them are recognized here. Monotypic.
Distribution. N Atlantic in subarctic to temperate waters, from S Labrador to Gulf of Maine, including Gulf of Saint Lawrence in NE North America, also in Iceland, Faroe Is, Norway, NW Russia, Baltic Sea, British Is, and North Sea and Atlantic coasts S to NW France (Brittany). View Figure
Descriptive notes. Total length 195-230 cm (males) and 165-200 cm (females); weight 170-310 kg (males) and 100-190 kg (females). Newborns are 90-110 cm in length and weigh 11-20 kg. Gray Seals in the western Atlantic Ocean are significantly larger (males more than 400 kg and females more than 250 kg) than those in the eastern Atlantic Ocean. Adult Gray Seals are sexually dimorphic in body size and shape of heads and necks. Chests, necks, and shoulders of adult males are more massive than those of adult females, with many folds and wrinkles in skin and are heavily scarred from battles with other males during the breeding season. Nose of adult males is also longer and broader than that of adult females. Color of pelage varies substantially from black to brown to dark gray and even pale white, with darker blotches scattered dorsally and laterally and some ventrally. Adult females are generally lighter colored than males. Neonates have a silky white or yellow lanugo (fine,soft hair) that is molted at 2-3 weeks old into a lighter phase of the adult pelage.
Habitat. Coastal areas of the northern North Atlantic Ocean and Baltic Sea. Breeding rookeries of Gray Seals are on rocky coasts and sandy beaches, or in caves, usually on remote beaches and uninhabited islands. Gray Seals also uses fast ice (ice fastened to land) in the Baltic Sea and the Gulf of Saint Lawrence. Coastlines exposed to the open sea, intertidal flats, and estuaries are used to haul-out.
Food and Feeding. Gray Seals are shallow, short-duration divers, and most of their foraging activity is focused at or near the seafloor. Their diet can be diverse, but they mostly eat sand eel ( Ammodytes sp. ), which can make up 70% of the diet at some locations and in some seasons. Other prey includes squid, octopus, and fish such as Atlantic herring ( Clupea harengus ), Atlantic cod ( Gadus morhua ), capelin ( Mallotus villosus), Adantic wolffish (Anarhichas lupus), dab (Limanda limanda), North Atlantic flounder (Platichthys flessus), European plaice (Pleuronectes platessa), saithe ( Pollachius virens), whiting ( Merlangius merlangus ), and sole (Solea solea).
Breeding. Timing of breeding of Gray Seals varies among populations, but it generally occurs from September through early March, either on offshore islands and reefs or on sea ice. Females aggregate in large concentrations, give birth to single offspring, and then remain ashore fasting while they nurse their offspring for c¢.17-20 days. Adult male Gray Seals assemble at these sites and compete with each other, using visual and vocal threat behaviors to monopolize access to estrous females. Females mate, either on land or in the water, c.15 days after giving birth and then wean their offspring soon after that. Female Gray Seals are sexually mature at 3-5 years old and males at 4-8 years old, although most males are not socially mature and capable of breeding until they are about ten years old.
Activity patterns. Gray Seals spend most of their time after the breeding season in the water foraging, but they haul-out again to molt in April-June. Offspring are highly mobile and wander considerably in the North Atlantic Ocean during their first year of life. When foraging, Gray Seals dive to and forage near the seafloor at 60-100 m, occasionally to more than 300 m, and most dives last 4-10 minutes, although some can last as long as 30 minutes.
Movements, Home range and Social organization. During the non-breeding and nonmolting seasons, Gray Seals make regular foraging trips of one to several days or more to offshore sites within ¢.40 km of haul-outsites and often repeatedly visit the same sites to hunt. Gray Seals are polygynous, and sometimes, large aggregations of females occur at particular breeding sites, although they are not particularly social then or at any other time of the year. Vagrant Gray Seals are known from as far south as New Jersey (USA) in the western Atlantic Ocean and Portugal in the eastern Atlantic Ocean.
Status and Conservation. Classified as Least Concern on The [UCN Red List. A key population of Gray Seals occurs in eastern Canada and Nova Scotia, including Sable Island south to the Gulf of Maine and Cape Cod. There is another small population in the Baltic Sea, and larger ones around the British Isles, Iceland, and Finland. Gray Seals were hunted extensively throughout most of their distribution beginning in the late 1600s near Nova Scotia and then more intensively there and elsewhere for most of the 20" century. They were killed for bounties in several places to reduce perceived competition with commercial fisheries. Hunting is now regulated in most areas. Numbers of Gray Seals are actually increasing at most locations (e.g. continental Europe, British Isles, USA, and Sable Island in Canada), but they are declining in a few localities such as Iceland or the Gulf of Saint Lawrence in Canada. Recent estimates for births throughout their distribution are ¢.100,000 offspring, translating to global population of perhaps 400,000-500,000 individuals.
Bibliography. Hall & Thompson (2009), Hammond et al. (1994a, 1994b), Harwood & Greenwood (1985), Mansfield (1988), McConnell et al. (1999), Pomeroy et al. (1994), Scheffer (1958), Thompson & Harkénen (2008a), Wiig et al. (1990).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
