HM Coastguard's Coleraine team were tasked on Sunday morning, 17th March, after receiving a report of a dolphin washed ashore in Lough Foyle.
The team rushed to the scene of the incident, however despite their best efforts, the dolphin had to be put down.
A spokesperson for Coleraine Coastguard team commented:
"The Coleraine team was tasked this morning to a report of a dolphin washed ashore at Bellarena in Lough Foyle. Members of the Ulster Gliding Centre had helped to keep the animal alive."
The spokesperson continued:
"With advice from British Divers Marine Life Rescue and the assistance of the Ulster Gliding Centre and a local vet, team members attempted to return the animal to the sea.
"Unfortunately, despite the best efforts by all, the dolphin had to be put down."
For emergencies along the coast, dial 999 COASTGUARD.