Grey seal population soars in North Wales, new survey shows

Natural Resources Wales (NRW) has completed the first comprehensive aerial census of seals around the entire Welsh coast, revealing a significant increase in the grey seal population in North Wales.

Conducted over three days last August, the survey involved photographing and counting seals at various haul-out sites along the coast and offshore islands, providing an unprecedented estimate of the total seal population in Welsh waters.

The survey, part of a broader study of seal populations in Wales and south-west England, was commissioned by NRW, Natural England, and the Joint Nature Conservation Committee (JNCC).

The Sea Mammal Research Unit, based at the University of St Andrews, carried out the survey in coordination with similar efforts in Scotland and the east coast of England.

Wales is home to three marine Special Areas of Conservation, where Atlantic grey seals (Halichoerus grypus) are protected.

Historically, the population size of these seals has been estimated based on the number of pups born each autumn.

However, grey seals often travel hundreds of kilometres to distant feeding sites outside the pupping season, making it difficult to accurately gauge the total population.

Dr. Thomas Stringell, Lead Specialist Advisor on marine species at NRW, emphasized the importance of this survey: “Grey seals are present around the coast of Wales throughout the year.”

“There is limited information on the grey seal population in many parts of Wales, especially outside of pupping time.”

“Although there is information from pup counts from some of the larger breeding colonies in Wales, there is sparse information for many seal haul-out sites in Wales, with no data since the 1990s for several.”

The aerial survey counted 1,313 grey seals at 58 haul-out sites across Wales.

Notably, 70% of these seals were concentrated along the North Wales coast, with the remainder found primarily along the Pembrokeshire coast.

Based on the assumption that only about 25% of seals are hauled out and visible at any given time, researchers estimate a total population of at least 5,300 grey seals in Welsh waters.

The data also revealed a significant increase in the grey seal population in North Wales, with numbers rising by approximately 65% over the past 20 years.

Dr. Stringell highlighted the potential impact of these findings: “The results from the aerial photographs and counts are now being further analysed by experts on seals, and we are hopeful it will lead to a much better understanding of the population of seals we have in Wales.”

Dr. Dave Thompson, a seal biologist at the Sea Mammal Research Unit who led the survey, underscored the challenges of surveying the Welsh coast, which has historically been underrepresented in nationwide seal surveys.

“The coasts of Wales are notoriously difficult to survey for seals and are not usually covered in our regular nationwide aerial surveys, so there is very little historical haul-out data from Wales. This survey will help us to build a picture of seal abundance across Wales and south-west England,” he said.

Grey seals, the larger of the two seal species found in the UK, spend most of their time at sea feeding on fish but return to land to rest, moult, and pup.

The information gathered from this survey is expected to play a crucial role in future conservation efforts, ensuring that these iconic marine mammals continue to thrive along the Welsh coast.