A wildlife expert says he is concerned about a sudden drop in sightings of porpoises on the north Wales coast.

Mick Green, manager of the Bardsey Marine Mammal Project - which monitors the marine mammals around Bardsey Island, Gwynedd - said fisheries and fishing nets could be the reason for the decline.

After using drones for the first time, the project’s recent survey reported a 10% decline in the number of sightings of porpoises per hour.