A rare incident of "porpicide" has been captured in Cardigan Bay, where conservationists spotted a lone harbour porpoise being attacked by a pod of seven bottlenose dolphins.

The Wildlife Trust Cardigan Bay Marine Wildlife Centre marine team were on a four hour dolphin survey last weekend when they witnessed the attack, the reason for which remains a mystery.

This isn't the first time this kind of behaviour has been observed in Cardigan Bay. In 2014 it was spotted by Wildlife Trust observers on four separate occasions.

"For decades we have known that bottlenose dolphins attack harbour porpoises," said Sarah Perry, Wildlife Trust Living Seas Science Officer.

"This is an act known as porpicide, a behaviour that has been documented around the world, however the reasons for these attacks remains poorly understood.

"Various theories have been proposed including prey competition, object-orientated play, practicing infanticide and heightened aggression in male bottlenose dolphins."

The dolphins involved in the most recent encounter were a mixed group of males and females with two young, one under a year old.

"Although slightly distressing, observing aggressive behaviour such as this is fascinating to both members of the public and researchers alike," said Sarah.

"Most days I am left in awe of the dolphin's power and stealth like hunting abilities. Their behaviours and social systems are complex and encounters with these animals never fail to amaze me.

"Encounters such as this demonstrate we have much still to learn about these enigmatic creatures and it's vitally important that we all make efforts to conserve our seas and the marine environment for future generations to enjoy and be inspired by."

For further information on vital research work carried out by The Wildlife Trust of South and West Wales or Cardigan Bay Marine Wildlife Centre visit www.welshwildlife.org or www.cbmwc.org