MARINE scientists are delving into the secret world of an elusive dolphin species by examining their unique sounds for the first time.

Unlike the better-known common and bottlenose dolphins, the Atlantic white-sided dolphin prefers the deep ocean to coastal waters and is rarely seen by humans. The species is so poorly understood in science that there are no accurate estimates on population size, although the dolphin is hunted in the Faroe Islands.

Now scientists at the Scottish Association for Marine Science (SAMS) in Oban plan to examine recordings of Atlantic white-sided dolphins to describe their vocal behaviour – or acoustic repertoire. By documenting the dolphin’s unique sounds, the team will provide a crucial baseline for further studies to learn more about this secretive cetacean. Their project, funded by the Royal Society of Edinburgh, will document sounds such as the dolphins’ echolocation clicks and the duration and pitch of their whistles.

SAMS fellow and marine mammal expert Susannah Calderan recently compiled a report on the species that concluded there were no reliable population estimates available for the species, leaving them potentially vulnerable.

She said: “For Atlantic white-sided dolphins, it can be a case of ‘out of sight, out of mind’. It is more straightforward to study bottlenose dolphins because they are a coastal species; we have more of an idea where they are going to be. White-sided dolphins are usually on the continental shelf or further out in the ocean. When we do find them, they don’t often ‘play’ with the boats and, because of their speed, are very hard to photograph. We have recordings of white-sided dolphins – they have an unusual whistle that sounds like a space alien – but no-one has documented the acoustic repertoire in detail before.”

The SAMS team collated recordings from various sources from the eastern and western North Atlantic.