|Western Atlantic Harbour Seal Common Names: Harbour Seal
Pup, Irving Nature park, Saint John, NB
There is more than one Harbour Seal
Commonly called the Harbour Seal, the species Phoca vitulina is subdivided into the following 4 subspecies:
common name : Eastern Atlantic Harbour Seal
subspecies : P. v. vitulina (Linnaeus, 1758)
- found through Iceland, the British Iles & Ireland. Form Norway up to Finmark & the Barents Sea, the Southern Baltic, the Wadden Sea and the North coasts of Denmark, Germany and the Netherlands.
common name : Insular Seal
subspecies : P. v. stejnegeri (Allen, 1902)
- found on the Pacific Islands, ranging from Hokkaido Japan to the Commander Islands.
common name : Pacific Harbour Seal
- found from the Cedros Island of California, northward along the Pacific coasts of the United States, Canada and Alaska and as well, the Aleutian and Pribilof Islands.
common name : Western Atlantic Harbour Seal
subspecies : P. v. concolor (DeKay, 1842)
Phoca vitulina concolor is the harbour seal which one would find when exploring our New Brunswick coastal waters and is distributed through several areas the western Atlantic ocean. Additionally, the harbour seals living in the freshwater lakes in Ungava Canada are occasionally assigned a separate subspecies Phoca vitulina mellonae (Doutt, 1942), commonly called the Ungava seal. However, it is not universally used as a subspecies and is therefore most often included in subspecies P. v. concolor. The same will be done when referring to the Western Atlantic harbour seal in this report.
The body length of males ranges from 150 – 180 cm, from 120 – 150 cm in females and ranges 70 – 90 cm for pups at birth. The body weight of males ranges from 55 – 105 kg , from 45 – 87 kg in females and ranges 9 – 11 kg for pups at birth. Characteristic of P. v. concolor is a coat colour that is variable between grey to brown/grey and is spotted with black spots.
Important to understand when describing the characteristic behaviours of the harbour seal (and most seals in general) is the term ‘haul-out’. This is the activity whereby seals, just before the tide lowers, will find ledges located just below the sea surface. They stay on these ledges and when the tide goes out the seals are raised, or are exposed rather, out of the water, commonly referred to as being ‘hauled-out’.
It is suggested that this has several functions such as for sun bathing (warming up), rest, to look for mates, or it has also been proposed that this indicates to others that the area is safe (see article #2 in the Reference section).
When finding and observing P. v. concolor one does not always readily know the distribution of their food sources in order to use prey distribution as a means of locating. Since seals spend most of their time in the water they are not often visible to land viewers. Observing where haul-out sites are located along with local tide times is one of the best means for finding and observing the seals.
The global distribution of the Western Atlantic harbour seal is as the name suggests. They spread from Maine north to the Canadian Arctic, then west to the Hudson Bay and are as well found in Greenland. Their range in Canada includes New Brunswick, Nova Scotia, Newfoundland, Labrador and the Baffin Island. The distribution and population size of P. v. concolor specifically in New Brunswick, however, is know only slightly. An ariel count performed along the New Brunswick coast form Sept. – Dec. 1998, during the one of the two seasonal highs (the other high being in May) depicted roughly the population size to be 1041 animals (Ophelia, 1998). However, this is a rough estimate of the population size since this is only a maximum count of the seals during their peak population in New Brunswick and includes only hauled-out individuals (those visible). Similarly, the migratory patterns are not known with any certainty except that they are reported to migrate locally between New Brunswick and Maine according to the breeding seasons. There are no periods of torpor or hibernation.
Habitat requirements of P. v. concolor are most importantly plentiful fish stalks and varied coastal areas good for haul out purposes. The seals spend much of their time in the water. They are adapted with blubber layers for the cold ocean waters of the subtropical Atlantic and Pacific latitudes. They feed and mate in these waters as well. However, coastal areas of flat and smooth surfaces are equally as important. The seals need these areas for giving birth and then pupping the young until their bodies are ready for the cold oceans. Also for the important activities of sun bathing, resting and mate searching. These areas should ideally be flat and smooth so that seals, which have little manoeuverability on land, can readily access the sea.
P. v. concolor feeding is mainly, but not exclusively, on local fish such as cod, herring and flounder. Additional to their relatively large fish diet, crabs, mussels and squid are often eaten and they can dive to the bottom for invertebrates. It is believed that the population parameters and life history patterns of P. v. concolor are similar to those of the Eastern Atlantic Harbour Seal, P. v. vitulina, which has been more extensively studied. Females become mature at approximately age 3. Pregnancy rate is on average 87%. Gestation lasts 10.5 – 11 months. Lactation lasts 4 – 6 weeks. Females live approximately 35 years and males 25. Phoca vitulina is aquatically mating but must leave the water to give birth. The pups then remain on land until they have built up enough blubber to insulate them in the cold Atlantic water. The pupping season is seen in early July for the New Brunswick P. v. concolor and the mating season is seen in mid to late summer. It has been observed in male harbour seals that “prior to the mating season they occupy large and variable ranges”. Then close to the mating season (ie. August to September for P. v. concolor) the “males decreased their mean range size” (see article #1 in Reference section).
The harbour seal is warm blooded and breaths oxygen. Its flippers are actually modified arms and legs since it evolved on land. And although Phoca vitulina can not manoeuver easily on land (it can only really wiggle on its belly) they are highly specialized swimmers. Able to perform deep or shallow dives for up to 15 min without surfacing for air. This allows them to broaden their diets and food range. As well, diving is taken advantage of in mate searching and predator escape. Seals are able to perform these deep dives because their metabolisms change, their heart rates slow and they can conserve oxygen by cutting off blood flow to the extremities. Deep dives are believed to be associated with foraging while shallow dives are believed to be associated with mating (for further information, see article #3 in reference section).
There here is little known also about competition and predation of P. v. concolor. It is likely, however, that there is competition between P. v. concolor and seals which overlap in habitat range or niche requirements. Such seals are likely; the Grey Seal (Halichoerus grypus), the Ringed Seal (Phoca hispida), the Harp Seal (Phoca groenlandica) and Hooded Seal (Cystophora cristata). Known predators include polar bears & killer whales, as well pups have an added risk of being preyed on by foxes and large birds. Probably the most significant and detrimental interaction that P. v. concolor is involved in is with humans, or more specifically, commercial fisheries, for fish stalks. As well, there have been reports of seals damaging fishing gear. Exploitation of Phoca vitulina in the United states and Canada is none commercially, the species is protected. However, they are taken in subsistence hunts. In the Atlantic region the numbers of P. v. concolor lost this way are consistently quite low. Between the years of 1993 and 1998, a total of 216 harbour seals were lost in subsistence hunts. Also, all 216 seals that were lost this way were taken in the Newfoundland region.
The IUCN status of P. v. concolor is insufficiently known.