It said the "glamorised" bottlenose dolphins people think of were actually "pretty brutal". The firm believes it could be the best documented case of the behaviour, known as porpicide, ever recorded.

The bottlenose dolphins at the Roatán Institute for Marine Sciences (RIMS), a resort and research institution on an island off the coast of Honduras, are old pros at dolphin performance art.

Dolphins are very social animals that scientists have observed “smiling” while playing with one another. But a solitary bottlenose dolphin, known by the name Delle, has been observed near the ...