A £2,000 reward is being offered to trace the people responsible for the death of a bottlenose dolphin that was allegedly mowed down in a Cornish estuary on Saturday.
It is believed a young calf was killed after a group of boats surrounded a pod of dolphins in the Camel Estuary near Daymer Bay, Padstow, at around 3.30pm.
Faye Archell, trustee of British Divers Marine Life Rescue, said: "Around 25 small vessels were harassing a pod of bottlenose dolphins out of the bay.
"As result of that general harassment a juvenile dolphin was killed.
"It is a criminal offence under the Wildlife and Countryside Act 1981 to harass the animals.
"We are appealing for anyone who has photos or videos of what happened to contact the police."
Ms Archell said incidents such as this have become more common in recent years and she urged boat users to keep a safe distance from the animals to prevent future deaths.
"This probably wasn't malicious – at least we hope it wasn't," she said. "It was probably just a group of people getting carried away enjoying seeing the dolphins.
"There are ways that that can be done safely and guidelines that people should follow that do not ruin the enjoyment but will keep the dolphins safe.
"Unfortunately we are seeing this happen more and more."
The £2,000 reward has been put forward by marine conservation charity Sea Shepherd UK.
A representative from the charity said: "Sea Shepherd UK, together with Bob Archell's Dive Master Insurance, is offering a reward totalling £2,000 for information leading to an arrest and successful conviction of the persons responsible for the suspected killing of a young bottlenose dolphin yesterday."
Bottlenose dolphins have been spotted with increased regularity across the Westcountry in recent days.
Just last week, people were captivated when dolphins were spotted in the River Dart and in several spots off the South Devon coast.
A spokesman from Devon and Cornwall Police said its wildlife crimes officer was looking into the events surrounding the young dolphin's death in the Camel Estuary to determine whether any criminal activity had taken place.
Anyone with information is asked to contact the police on 101.