LONDON - A common dolphin juvenile has been killed by four bottlenose dolphins in an attack that could become more common as the oceans warm, a cetacean expert has warned.
People on a dolphin spotting trip from New Quay, Ceredigion, were left "hysterical" by the incident last Thursday at 18:10 BST in Cardigan Bay, where the juvenile was thrown out of the water.
Climate change means common dolphin numbers are increasing in the area, where resident bottlenose dolphins will hunt them as a form of "play", said Matthew Westfield from the UK Cetacean Strandings Investigation Programme (CSIP).
It recovered the juvenile - estimated to be two years old - to perform an autopsy.
"Across the UK we are seeing more attacks where a bottlenose dolphin attacks a common dolphin juvenile," he said.
A boat owned by Dolphin Spotting Boat Trips and carrying 12 passengers spotted what they initially thought was a porpicide - the name given to the deliberate killing of a harbour porpoise by bottlenose dolphins.
The group included Ghost, a favourite with dolphin spotters.
"Ghost and another dolphin she was with all of a sudden started speeding towards this larger group of dolphins," said passenger Holly Williams, 35.
"They started jumping out the water and we thought they were just playing."
They saw something being flung out of the water by the dolphins and initially thought it was a salmon.
"My daughter was hysterical," said Ms Williams.
"She loves animals and is very sensitive."
The company's photographer Sarah Michelle Wyre, 30, said: "It was an incredibly rare encounter where a pod of bottlenose dolphin attacked and killed a common dolphin calf.
"I've never seen that behaviour before. It's very common for bottlenose dolphins to attack porpoise bit not a common dolphin calf."
Dylan Coundley-Hughes, 22, is a researcher for the SeaWatch Foundation caught the attack on camera.
"These kind of attacks are so rare to see in person. We know they happen in the wild but it's rare they're ever seen," he said.
Mr Westfield said the increasing number of common dolphins in the area mean more interactions with the resident population of about 250 bottle nose dolphins.
"Its not that clear why they do it," he said.
The food the two types of dolphins eat only "slightly" overlap, he explained. (BBC/ Sarah Michelle Photography)
