We invite to keep learning about marine species, especially about the grey seals or Halichoerus grypus, in scientific terms.
They are probably the rarest seal species in the world, with around 40% of the population of gray seals inhabiting the coldest waters of the United Kingdom.
Table Of Content
Grey Seals: Main Characteristics
Grey seals are part of the «true seal” family, so they have short fins which they employ to displace in a caterpillar-like movement on land. These phocids have no external ears which is also a distinctive feature of the true seals. Their heads have a characteristic straight shape and their nostrils are somewhat separated. Female grey sales reach around two meters long in lenght and weigh about 200 kilograms.
The males of this species are a little larger and their length reaches even three meters and weigh around 300 kilograms. Females have silver-grey fur with scattered dark spots, while males have dark gray fur with silvery grey spots.
Males also have longer noses than females and in fact this is the origin of their name Halichoerus grypus, «sea hook nose pig «.
The grey seal calves have white fur known as Lanugo. This white coat helps to absorb sunlight and traps the heat to keep the puppies warm.
Let´s meet them better
Grey Seals: Habitat and Distribution
This species inhabits the coastal or continental platform of the North Atlantic temperate zones. Gray seals usually move on exposed reefs or undisturbed island beaches.
They are distributed in Europe’s Atlantic area from the ScandinNorth Atlanticavian Peninsula to the north of France and also on the east coast of Canada and the north of the United States. In addition, there are other colonies in the Baltic Sea and Iceland.
In the United Kingdom and Ireland, grey seal reproduce in several colonies around the Coasts.
In the western North Atlantic, they are widely distributed in the coastal waters of Canada and as far south as New Jersey in the United States.
In Canada, they are usually seen in areas like the Gulf of San Lorenzo, Newfoundland and Quebec. The largest colony in the world is in Sable Island. In the United States it is found all year round in Maine and Massachusetts, and a little less frequently in the Mid-Atlantic States.
During winter months, grey seals can be seen on the rocks, islands and lowlands not far from the coast, occasionally arriving ashore to rest.
Grey Seals: Life Span and Reproduction.
Grey seals live from 25 to 35 years old and gather in large groups for mating. Males reproducing on the ground can mate with many different females in a single breeding season. Pregnancy lasts around 11 months and they have a single puppy each time. The birhting season depends on where they live.
Females in the eastern Atlantic Ocean give birth from September to November, while those in the western Atlantic Ocean give birth from December to February. Females in the Baltic usually give birth in March
These seals dig areas and find places to prepare for the birth of their offspring which breastfeed with their milk of 50% fatty Content. This allows seals to grow quickly, although they don´t enter the water for about a month when their fur develops waterproof features.
Until then, they depend on their mother for food supply and care. Weaning is carried out at around three weeks of age.
It is not uncommon for females to reproduce again immediately after they have weaned their puppy. This is one of the reasons why females do not live as much as males.
It certainly costs their bodies to carry a puppy during eleven months, breastfeed, and then start again without any recovery period. Many males are at least 8 years old before they can successfully mate. That’s because of fierce competition between them. Only the strongest males are able to reproduce with the females.
Here we go again
Gray Seals: Behavior and Alimentation Habits
Gray seals gather in large groups during mating, breeding and molting seasons. During the rest of the year, they usually find themselves alone or in small groups. Only its head and neck are observable when resting in open water. They can submerge up to 475 meters deep for one hour.
They eat 4 to 6 percent of their body weight in food each day, but do not eat during the mating, breeding and moulting seasons. Moreover, they are effective hunters due to their very accurate senses of vision and hearing. They often hunt in groups, which makes it easier for them to catch their prey. Their diet is made up mainly of fish, crustaceans, squid, octopus and, sometimes, even seabirds.
The Grey Seals’ Main Threats
As any marine species, grey seals face many threats which we list below.
Grey seals may become entangled in equipment and/or fishing nets and other types of marine debris. They can be entangled in many different types of equipment, including gillnets, trawl nets, purse seines or dams.
Once entangled, seals may choke if they can´t reach their breathing surface, or they can drag and swim with the equipment while traveling long distances. This situation usually generates fatigue and decreases their ability to feed.
Pollutants enter the oceanic waters from many sources, including oil and gas extraction, wastewater discharges, urban runoff, and other industrial processes.
Once in the environment, these substances rise in the food chain and accumulate in predators near the top of the food chain, such as gray seals. These contaminants accumulate in their bodies´ layers of fats, threatening their immune and reproductive systems.
The blows of unnoticed boats can injure or kill the grey seals. They are vulnerable to boat collisions and the risk is much higher in some coastal areas with heavy boat traffic.