Wild seals at Skomer Marine Conservation Zone
Each month our teams write a blog about the special places they look after. Here, Kate Lock, our Marine Conservation Officer at Skomer, talks about the seals that live in the area and how we work to protect them for the future.
It is not often that we get the chance to enjoy watching wild mammals in their natural environments, which is one reason why seal watching is so magical.
Grey seals, Halichoerus grypus, are Britain’s largest predators with males weighing around 230kg. They are skilful hunters that live in a naturally harsh and tough environment where only the fittest survive.
Grey seals can be spotted along the Pembrokeshire coast year round, but it is in late summer and autumn when large numbers return to the shores to give birth to their pups.
The females, known as cows, give birth to one pup each on quiet beaches or in caves.
Birth to teens in just 3 weeks
The white furry pups spend their first 3 weeks on the shore, feeding and sleeping.
Some can be pretty active and like swimming, even when they’re less than a week old! But most stay on the shores, sleeping and growing.
The cows regularly come ashore to feed their pups who need to treble their birth weight in their first 3 weeks.
By the time the pup is weaned, the mother will have lost up to a third of her body weight.
The pups are then left to fend for themselves, the white coat is shed and a gleaming new ‘adult’ coat is revealed.
Moulted pups leave the beaches, but regularly return to the shore for rest.
Skomer Marine Conservation Zone (MCZ) Grey seal monitoring
At the Skomer MCZ we monitor the grey seals, tracking each seal pup born from birth to fully weaned.
The pups are born on beaches and caves around Skomer island and on the mainland around the Marloes peninsula.
Regular monitoring began at the island sites in 1983 and then on the mainland in 1992. This means we have a huge amount of data that helps us understand more about the seals, and how the population has changed over time.
This information has also helped develop a management plan which helps to minimise disturbance to the seals. This includes speed limits close to shore, and closed zones during the pupping season. Zone maps and a seal watching leaflet are provided to visitors to help them observe seals without causing disturbance.
The good news is that this seems to be working. The Grey seals in this area are doing well, with 345 pups born in Skomer MCZ in 2016 compared to 200 born in 1992.
Grey seal facts
- Grey seals? Colour varies from dark grey to pale cream, often mottled brown to sliver and they can even be ginger. Who called them grey seals?
- They have elongated torpedo bodies encased in blubber to pad outline and round off the corners creating a streamline smooth hydrodynamic shape. Modified legs and arms form stiff webbed paddles that propel them through water. They average 4 mph with quick bursts at greater speeds
- They can dive to over 80m depth and stay submerged for 5-6 minutes at a time
- Their diet is mainly fish with occasional squid and shellfish. Studies estimate that they eat around 5kg per day
- They can sleep in the water and are often seen ‘bottling’, they also rest by hauling out on the rocks at low water
- The cows can lose around 4kg per day when feeding their pup. Many lose up to 50% of their body weight giving birth and feeding their pups. They use about 30,000 kcal/day, to replace that energy they would need to eat 70 cream buns per day
- A 46 year old cow was recorded from Shetland and the oldest bull was 29 from Canada. On average cows reach 30 becoming sexually fertile between 3 and 5 whilst bulls reach 20 and are 10 before they successfully hold position in a breeding group
Seal watching: a guide to observing seals and pups
When: August to December
Where: On beaches of the Marloes Peninsula and Skomer Island, Ramsey and remote parts of the North Pembrokeshire coast.
How: Seals are easily disturbed. Please keep as still, quiet and inconspicuous as possible. Never approach seals close up. If disturbed, mothers will keep away and the pups will miss feeds. Sometimes the mother may become aggressive or may abandon her pup.