A Risso's dolphin calf spotted swimming off Bardsey island. Enlarge Image

The Whale and Dolphin Conservation Society said it was the first time such a group had been seen in the area.

Little is known about Risso's dolphins which can be up to 12ft long (3.6m).

Bardsey is one of the few places along the UK coast where they can be seen from the shore.

Simon Keith, from the Whale and Dolphin Conservation Society, said: "The work we do on Bardsey is providing a better understanding of the distribution, numbers and behaviour of Risso's dolphins and harbour porpoises around the island."

'Bearing fruit'

He said the information could be used to develop conservation plans. "This is the first time we have see so many young calves in the same pod, which is incredibly exciting and emphasises the need for ongoing research," he added.

The work is funded by the Countryside Council for Wales (CCW), who say it is important for the long-term future of the dolphins.

CCW's marine mammals ecologist Dr Mandy McMath said:"I am delighted that this project is bearing fruit, and gathering much needed information so that the marine environment is managed in a way that ensures Risso's dolphins long-term conservation."