Irish waters are home to two different species of seal – the grey seal, and the common seal, which is also sometimes called the harbour seal.
WHERE CAN I FIND THEM?
Both species are distributed mainly around the western coast of Ireland but can also be found in the east in bays and offshore islands. Grey seals prefer offshore islands, going there to give birth to pups and to breed, while common seals can often be found closer to land, in inlets and estuaries.
Grey seals swim in the waters of many different countries with coasts on the North Atlantic, but they remain faithful to particular breeding and birthing sites. Common seals travel less than grey seals, but also have traditional breeding and birthing sites that they return to each year.
In Cork, good places to spot seals are in the west of the county, including Garinish Island, Baltimore, Clonakilty and Kinsale.
WHAT DO THEY LOOK LIKE?
Both species of seals are covered in a thick layer of blubber to keep them insulated against cold water, and also have a short layer of fur to keep them warm. On land, seals can be seen waving their flippers and tossing wet sand on themselves to stay cool!
You can separate the species by their body size. Common seals of both sexes reach up to 1.85m in length, while grey seal males (or “bulls”) can be over 3m in length. Female grey seals (or “cows”) reach about the same length as the common seal – so how else can we tell our seals apart?
The common seal has a rounded head, short snout, and a dipped “forehead” in profile. Its nostrils are oriented in a V-shape, though this might be difficult to see at a distance, or if the seal is flaring its nostrils. Grey seals have a longer snout, and a flatter head when seen in profile. Its nostrils are more parallel in orientation. Some people say that the common seal is cuter than the grey, with a distinctly “puppy-like” face and expression – what do you think?
Both seals also feature spots on their bodies – these will only be easily visible if the seal is on land (or “hauled out”). Common seals have many, smaller spots all over their bodies, while grey seals feature fewer, larger spots. When hauled out, the common seal often poses with its tail pointed up in the air, which the grey seal does not do often.
HOW DO THEY LIVE?
Common seals give birth in the summer months (around June/July mostly), and their pups are born ready to swim, having moulted their baby fur while in their mother’s womb! After one feeding, they are ready to hit the water, and stay with their mother’s for several weeks, feeding on their milk for around 4 – 6 weeks, and then learning how to hunt for themselves.
Grey seals, on the other hand, give birth to pups that must remain on land and shed their baby fur for around 3 weeks. Once they are weaned off their mother’s milk (at around 3 weeks old), they are ready to swim, and are left to their own devices to learn how to hunt – grey seal mortality is quite high for the inexperienced pups as a result.
Both species of seal are opportunistic hunters – they will eat just about anything that they can catch.
They use their sensitive whiskers to locate food in the water. Their diet includes shoaling fish such as mackerel and herring, but also crustaceans, squid, octopus, and sandeel.
Seals are preyed on by killer whales/orcas, sharks, and sea-lions (who are related to seals) – however, we have very few of these predators in Irish waters, so seals enjoy their spot at the top of the food web most of the time!
THREATS TO OUR SEALS
Outside of their natural predators, seals are most under threat from human-caused problems:
Overfishing: Ireland is one of the worst overfishers in the EU. In 2019, Ireland took 22% more fish than recommended by scientific evidence. By depleting our fish stocks and fishing unsustainably, we deprive seals of food, and harm the livelihoods of smaller-scale fisheries.
Plastics: Plastic waste in the ocean is becoming more and more of a problem, from microparticles of plastic ending up in the bodies of plankton, crustaceans and fish, to larger pieces of plastic being consumed by larger animals. Seals are not very picky about what they eat, and may mistake floating plastic items for food – these get stuck in their gut, with fatal consequences.
Disturbance and culls: Seals need time to rest, digest, breed, and give birth on land. When they are disturbed by humans, or dogs allowed to roam without a leash, mother seals may become distressed and abandon their pups. There have been calls to cull seals for their perceived impact on the success of fisheries. While it is illegal to harm or kill seals in Ireland under the Wildlife Act 1976, this did not stop the killing of 60 grey seals on the Blasket Islands in 2004.
- The Irish boy’s name Rónán means “little seal”! This may come from the legends of “selkies” or seal-women, who are mythical creatures similar to mermaids
- Seal milk is the fattiest in the animal kingdom, at 50% fat!
- Seals, sea-lions, and walruses are all part of a group called the pinnipeds – this group is related to bears and weasels!
- Seals get most of their water from the food they eat – seawater is far too salty for them to drink, and they concentrate salts that they do ingest into their urine.
- The grey seal’s Latin name is Halichoerus grypus, while the common seal’s is Phoca vitulina – Latin names might seem archaic, but they allow researchers from different countries with different common names for wildlife to identify species with no confusion.
Written by Tom Murphy