Halichoerus grypus
gray seal

The grey seal (Halichoerus grypus) occurs in temperate and subarctic waters on both sides of the North Atlantic ocean resulting in three distinct populations. The western Atlantic population is found in the Canadian maritime provinces located from Cape Chidley on the Labrador coast to Nova Scotia. Grey seals located on the southwestern coasts of Iceland, on the Faeroe Islands and the British Isles comprise the eastern Atlantic population. In addition, the eastern Atlantic population extends further onto the coasts of Norway, northwestern Russia, and even French, Dutch, Gernman and Portugal coasts. The third population is found in the Baltic Sea.

The habitat of the grey seal differs among each individual group of seals. Some are found along rocky continental coasts, while others are comfortable on isolated islands. There are also many grey seal populations around that haul out on icebergs and ice shelves.

At birth, grey seal pups weigh approximately 16 kg and have long, creamy white fur which is shed after the first three weeks of life. They fatten quickly on the rich milk from their mothers, and by moulting age have nearly quadrupled in body mass. At this time the young seals show coat patterns which differentiate the sexes. The female grey seal is silver-grey in colour, with small scattered dark spots, while the males are a dark grey with silver grey spots. The three populations of grey seals differ in exact colorings (grey, brown, silver), however the patterns are similar among the individual sexes -- female grey seals have dark spots on a lighter background while the males have a lighter spotting on a dark background fur, but both sexes in the three populations have a relatively dark back and lighter belly.

In addition to coat markings, the nose of a grey seal can distinguish a male from a female. The male grey seal has a long-arched roman nose which is the basis for its Latin name, Halichoerus grypus, meaning the hooked-nose sea pig. The shoulders of the male are massive with the overall bulk supplemented by a buildup of scar tissue from fighting during breeding seasons. The average adult male reaches his maximum size of 2.2 meters long and 220 kg at 11 years of age. The female is smaller and does not attain full size until approximately 15 years of age, reaching an average weight of 150 kg and length of 1.8 meters (measured from nose to tail). She has a more narrow, short nose and a straight profile to the dorsal surface of the head.

Their lifespan ranges from 15 to 25 years, with the oldest recorded wild female grey seal living to be 46 years of age.

Grey seals forage underwater and spend the remainder of their time on the coastlines. They are non-migratory creatures yet disperse widely after breeding season.

Halichoerus grypus is an opportunistic feeder consuming between four and six percent of its body weight in one feeding per day. The diet consists of a large variety of fish and the occasional crustaceans and mollusks. According to King, at least 29 different species of fish have been recorded as being eaten by these seals. Fish taken include nearly any species found at pelagic and midwater levels as well as bottom dwelling fish at depths of seventy or more meters.

The feeding methods of the grey seal vary among populations, however they are most often social feeders. Social feeding reduces the opportunity for the prey to escape thereby increasing the feeding efficiency. When small fish are caught by the seal, they are usually consumed underwater and are swallowed whole. However, when large fish are captured, they are brought to the surface and held in the prehensile front flippers. The fish head is then bitten off and discarded, while the remainder of the fish is broken into small pieces able to be swallowed.

These seals are also hosts for a parasitic roundworm called cod worm (Pseudoterranova decipiens), that infects cod and other commercially harvested fish.

Grey seals are widely believed by commercial fisherman to be a pest. They may remove fish from nets, become tangled in nets, damage traps, and feed on farmed fish. These seals are also hosts for a parasitic roundworm called codworm (Pseudoterranova decipiens), that infects cod and other commercially harvested fish.

There is some dispute about the large-scale impacts of grey seals on the Atlantic fisheries, but they are at least occasionally a problem in local situations.

In the past, grey seal pups were killed and harvested on a large commercial scale for their skins. There have been no recent large-scale hunts.

The grey seal species as a whole is under no special conservation status. In fact, many countries allow either monitored or unlimited hunting of the seals. For nearly a decade, from 1982 until 1993, Norway, Iceland and Canada offered bounties and local culls for the grey seal. Many fisherman believe that this species competes with them for fish, and seals damage nets and traps. Recently the species has been given great legal protection in Europe, and fewer culls are being authorized.

The Baltic Sea population of this species is much smaller than the two Atlantic population, probably due to hunting and pollution of its habitat. It has greater legal protection.

Pollution in the Baltic Sea has led to the declining population of the grey seal. The most dramatic increase in DDT and PCB levels in the Baltic occurred after 1955. Research conducted by Zakharov and Yablokov on skulls of grey seals investigated the notion that these increased pollutants result in skull asymmetry. Their study investigated whether morphological changes could be found in the grey seal population born during the major pollution episode that occurred after 1960. They studied skulls taken from seals born before 1940 and after 1960. It was shown that the pollution group had sharply increased levels of asymmetry in almost all characters analyzed. The findings indicate a dramatic change in the development stability of the Baltic grey seal during the period of heavy pollution after 1960, which could attribute to the rapid decline of the species (Zakharov 1990).