Common seal

Common and Grey Seals

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Although I am lucky enough to live by the sea and watch seals regularly, it is always a treat to see them. Part of the attraction is their transformation from lumbering, blubbery creatures on land to svelte and graceful swimmers when they enter the water. They can also be extremely curious, which makes them easy to see at times. While you should never disturb a hauled-out seal by approaching it, if they spot you walking nearby when they are swimming, they will often come closer to check you out. So, let me introduce you to our common and grey seals.

Common Seals

We have two species of seal in the UK, grey seals and common seals (also called harbour seals). These can be quite difficult to tell apart, especially youngsters and females, but there are some handy things to look out for. Common seals are the smaller of the two and have a much shorter, ‘cuter’ face. Grey seal faces are much longer and look more dog-like in appearance. If you get a good look, nostril position is also a good aide. Common seals’ nostrils form a v shape in contrast to the parallel nostrils of greys. Common seals are also much more likely to raise their heads and tails when hauled out, forming a characteristic banana pose.

Common seals
The left hand seal is in a classic banana pose

Common seals are very variable in colour. They can be pale brown, dark brown, black or silvery grey. Each animal has its own unique combination of dark spots. They are most abundant around the Western and Northern Isles but also breed at a few locations along the east coast of Scotland and England. Despite their name, they are actually less common in the UK than grey seals with an estimated population of around 55,000. They have a bigger global distribution, though, living in the Pacific, Atlantic, Baltic and North Sea.

Common and grey seals: common seals
Common seals can be varied in colour and their nostrils form a v shape

Pups are born in the summer and can swim almost straight away. Like all pinniped young, they are able to grow extremely fast due to the high fat content of their mother’s milk. Once they are weaned, their diet consists of fish, crabs and shellfish.

Grey Seals

Grey seals are larger and bulkier than their UK relatives and their roman noses are particularly obvious on large males. They can show some colour variation between grey and brown, but they are usually grey and have a unique combination of dark blotches. Pups are born between September and December, earliest in the south west and progressively later clockwise round the UK. For the first two to three weeks of their lives, pups have dense white fur to make up for the fact blubber hasn’t yet formed to keep them warm. This means they can’t swim as soon as common seal young. The fur moults after weaning.

Grey seal
This grey seal’s roman nose is clear

Unlike common seals, grey seals live around much of the UK, but the biggest concentrations are on west and north coasts, especially Scotland. Globally, they are restricted to the North Atlantic and Baltic, and the UK is home to 40% of them. Due to overhunting for fur and oil in the nineteenth and early twentieth centuries, they almost became extinct in the UK, with numbers as low as 500 at one point. This led to the introduction of the Grey Seals Protection Act in 1914. This was the first piece of British legislation to protect any of our mammals. There are now approximately 120,000 grey seals around the UK.

Common and grey seals: grey seal
A large male grey seal

Threats to Our Seals

Despite protection in law, currently under the Conservation of Seals Act 1970, both UK seal species face a number of threats. As their numbers recovered from overhunting, grey seals came into increasing conflict with fishermen who accused them of threatening their livelihoods. As a result, between 1962 and 1983, there was an annual cull of grey seals. This ended after a public outcry, but it remained legal to kill seals if they were deemed to be impacting fish stocks and fish farms. The Scottish Government banned the killing of seals in 2020, but tensions between seals and fisheries remain. Seals are opportunists and the huge increase in the number of fish farms around Scottish coasts inevitably attracts seals, but the biggest problem for fisheries in the UK is our overfishing rather than seal predation.

Common seal

Some fishermen would like to see a return to annual culls

Common and grey seals have also been hit twice in the last 35 years by a disease affecting pinnipeds called Phocine Distemper Virus (PDV). There were large outbreaks in 1988 and 2003, killing thousands across European seas. Scientists are unsure what led to these outbreaks but theories about triggers range from reduced immunity caused by pollutants to climate change bringing the virus to new areas. Avian flu can also pass over to seals. As I write, a devastating outbreak is killing thousands of seabirds around the UK’s coasts and further afield. I can’t help but worry this will spread to our seals, as it has in the past.

Grey seal
Grey seals have been affected by avian flu in the past

Seals are very vulnerable to pollution. Because they are at the top of the food chain, pollutants in their prey become concentrated to the point where they are extremely toxic. Chemical pollutants wash into the sea and can lead to infertility and death in seals. They almost certainly also affect the immune system. This may have contributed to the PDV outbreaks mentioned above. The prevalence of microplastics in our seas is likewise a cause for concern, as is climate change which may affect food sources.

Perfect Pinnipeds

Like all seals, our two species are pinnipeds, a name which means ‘fin-footed’. This group of marine mammals includes true seals (such as our two species), fur seals, sea lions and walruses, all of which divide their time between land (or ice) and the sea. They also all have thick layers of blubber to insulate them against the cold. All are perfectly adapted to a life spent mostly in cold seas hunting fish or crustaceans.

California Sealions
Californian sealions have clear ear flaps

Sea lions and fur seals are now usually classified as one family and have a few marked differences from their true seal cousins. The most noticeable one is that they move quite differently on land. Whereas true seals drag themselves along by their front flippers, sea lions and fur seals can use all four flippers. This gives them a much more upright stance out of the water. Sea lions and fur seals also have external ear flaps while true seals don’t. No species in this family live in the North Atlantic and so they have not been recorded in the UK. Like all pinnipeds, they faced massive exploitation in the past, in their case for their skins.

Walruses are the last member of the group. Their most obvious features are their long tusks. Both males and females have these tusks, and during feeding they drag them through sediment on the sea floor. This helps them find their shellfish prey. Males also use them for display and fighting. Walruses were once hunted in huge numbers for their tusks until elephant ivory became easier to obtain. Walruses only live in the Northern Hemisphere, both in the Atlantic and Pacific, and are occasionally seen in UK waters. In 2021, a young male spent months touring western Europe, and visited Tenby and the Scillies. Meanwhile, a female animal christened Freya has been touring the North Sea for the last year. This has included stops in Northumberland and Shetland.

Seals Past, Present and Future

Humans living by the coast have been interacting with seals for millennia. Our ancient ancestors hunted them for fur and blubber but would also have noticed the way seals can’t help but be curious about us. It may well be this habit of checking us out that gave rise to the numerous selkie legends that exist in the folklore of multiple cultures, including Scottish, Irish, Faroese and Icelandic. All of the stories concern shapeshifters shedding their seal skins and briefly becoming human on land, often with tragic consequences. Did our ancestors see the seals’ curiosity as confirmation that they were part human, connected in some way?

Grey seals in Howth
These grey seals in Howth harbour, Dublin have been habituated to hand outs

Whether you believe the tales or not, however, our two seal species are magical mammals. Lumbering on land, but champion swimmers underwater, they have faced huge challenges in the past and continue to do so. This means that however many times I see one, I never take it for granted.

Further Reading

The RSPB Spotlight books are great introductions to the UK’s wildlife. This book focuses on our two native seals, highlighting their specific adaptations for a life spent on land and at sea. It is also full of excellent photographs.

This ID guide covers all the marine mammals you are likely to see around the UK as well as further afield. This means it also includes walrus and some of the other seal species that occasionally turn up in our waters, such as bearded seal.

David Thomson grew up listening to stories of the selkies. In the 1950s, he set out to collect the various stories about them from around Scotland and Ireland. The result is a beautiful book exploring folklore alongside the real seals he loves to watch.

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