International Seal Day

Seals are one of the most curious and endearing creatures found in the UK’s waters. Spotting one bobbing in the ocean, or hauled out on the rocks, is always a treat. 

But although the public perception of seals is that they’re very cute, they are actually one of the UK’s apex ocean predators. This doesn’t stop people calling them the puppies of the sea though!

Here in the UK we have two seal species: grey seals and common (or harbour) seals. Despite their name, there are more grey seals than common seals along the UK’s coast. 

Back in December, Cal visited St Abb’s Head National Nature Reserve and had a wonderful conversation with Ciaran Hatsell from the National Trust for Scotland on the Our Ocean Podcast. 

Grey seal numbers in this region have made a remarkable recovery after the colony was culled in the 1960s and ‘70s due to conflicts with fishermen. 

Cal was there for a very special reason: December is in the heart of pupping season for the grey seals that form colonies around St Abb’s. As well as observing the colony from a safe distance with Ciaran, Cal also learned some incredible facts about the seals we find along our coastline.

Here are five of our favourites:

Every adult grey seal has its own individual fur markings that act like a fingerprint. This means we can ID individual seals from photos taken in different locations, allowing us to get a better idea of how far they travel. 

Ciaran and his team are creating a photo ID catalogue to help track seals between colonies and locations. 

Once a seal pup is born, it spends its first three weeks suckling from its mother. Seal milk is around 60% fat, which helps the pup bulk up and develop the layer of blubber it needs to survive in the open sea. A seal pup can put on approximately 2kg per day during this period.

As Ciaran said, “It’s survival of the fattest.”

But at the same time, the cows (the name for female seals) lose a lot of weight as they aren’t feeding. Just before she gives birth, a seal cow can weigh up to 200kg, but she’ll spend the next three weeks transferring that weight and energy to her new-born pup.

As adults, grey seals are nomadic and they travel staggering distances. Ciaran shared that one seal that has been seen breeding in St Abb’s has also been spotted off the German coast! 

They can also dive to depths of up to 200m when they’re hunting! They’re able to do this not because they have big lungs, but because their bodies are adapted to store oxygen in their muscle tissue. This allows them to not only dive to incredible depths, but also to stay underwater for long periods.

During breeding season, the biggest male seals – known as bulls – will fight for control of groups of female seals. These huge bulls rampage around chasing off any newcomer who attempts to take over their patch. 

For the bull seal, this is worth the energy because it ensures they’re the one who mates with the females once their pups are weaned. 

This is an incredible biological adaptation called “delayed implantation”. What it means in practice is that a female seal can mate with the dominant bull on her beach right after her pup has weaned. 

However, at this point she is too weak to sustain a pregnancy. So, she can keep the fertilised embryo in what’s called the “blastocyst” stage until she has fed enough and recouped her energy. Only then will her body allow the pregnancy to progress.

Usually she has about three months of feeding before her next pregnancy begins. Then the gestation period for grey seals is nine months.

It’s really important to give seals space if you see them, especially when they’re hauled out on land. During pupping season, the females and pups need to conserve their energy. This means any unnecessary movement could affect their chances of survival. 

If you see a seal – or a colony of seals – always keep a respectful distance and don’t disturb them. If you have a dog with you, keep it on a leash and under close control. 

When a seal that’s resting on land looks at you, it’s a sign you’ve come too close. Even if they don’t move, your presence will cause a spike in cortisol due to stress, so back away and leave them to it. 

If you see a seal pup without its mother, leave it where it is and give it space. The mothers will often take dips in the sea to cool off while they’re feeding their pups. 

But if you are genuinely worried for its welfare, such as if the pup looks injured, thin or distressed, call the British Divers Marine Life Rescue (BDMLR). 

You can listen to Cal’s whole conversation with Ciaran on the Our Ocean Podcast.

Photo credit: Gabe Hearnshaw