Crew on a Greenpeace voyage to Bermuda hope to help expand knowledge of whales and dolphins in the Sargasso Sea by listening to their songs.

As part of its Oceans are Life campaign, members of the organisation are listening out for marine mammals using a specially-designed hydrophone during their journey from the Bahamas.

Kirsten Thompson of the Greenpeace International Science Unit said the hydrophones make a continuous recording across a frequency range used by most whales and dolphins.

“After the ship tour is over and the data is sent to the analyst, we then run it through software which runs semi-automated detectors to identify which species we have passed based on their calls,” Dr Thompson said.

“This species identity, alongside the GPS position, gives us the location of a species that is present at a particular moment in time, essentially a dot on a map of a whale or dolphin.

“For many areas of the high seas, and for some species, we still don't know exactly what the distribution of whales and dolphins are at different times of the year.

“Are there hotspots around particular oceanographic or bathymetric features? How are the whales distributed across their entire range?

“Over time, especially by sharing our data widely on open access repositories we are contributing to the wider knowledge of cetacean distributions and providing data for others to use in answering key conservation questions.”

Rosy Vilela, a radio operator on board the Arctic Sunrise, said that the hydrophones transmit the recorded sounds to software that creates a visual interpretation of what has been captured.

“We can literally see the sounds, which means we don't need to be constantly listening because there is a lot of noise,” she said: “It is hard for human hearing to understand what is going on.

“When you see it, you can see something is happening and listen to it.

“I cannot tell what kind of animals as I am not a scientist, but I can see something there. We are definitely recording something.

“When you know how to read all the data that you see, you can filter it so if you are looking for a specific species, you can set it up to filter and only see that species.

“Right now, our settings are to catch everything because we want to send all the data to the scientists.”

She said the information can be used for a variety of purposes, noting that last year Greenpeace set out to collect data on sea mammals in an area where a deep sea mining company planned to set up shop.

Ms Vilela explained: “A company wanted to go out into an area in the middle of the Pacific which no one has ownership of and we didn’t know what was happening there.

“Deep sea mining includes basically putting down at the bottom of the sea huge machinery that will disturb the environment of whatever is living down there.

“We don’t know what is living there, so the idea was to analyse what is going on and say ‘if you put a big machine here, you are going to disrupt the wildlife there’.

“It’s to collect data so you know what is going on so we can say, maybe you don’t want to do deep sea mining in this area.”

She compared it to a company setting up loud machinery next to a person’s house, forcing them to listen to the noises for years without respite.

“You would go crazy,” Ms Vilela said. “As a human being, you would go crazy.

“So now imagine the animals. That would definitely change the way they live, the way they behave and probably would be very bad for generations of those animals.

“We also don’t know all the animals that live in these areas. It would be a pity to lose flora and fauna that we don’t know is there.”

Briony Venn, a campaign leader, added that little data was collected in the Sargasso Sea, as is true for most areas in the high seas.

“We are trying to gather more of an understanding in a broad sense of what lives out here,” she said.

“It’s complementing the other science work we are doing out here.”

Another scientific project under way on board is environmental DNA testing, in which samples of seawater are collected and screened for trace DNA to determine what animals are in the region.

“Perhaps there will be some correlations between what the hydrophone picks up and what the eDNA analysis shows us,” Ms Venn said. “Migratory birds are also being picked up.

“This is all building a broad picture at a high level of what we have got here.”

Ms Venn added that part of the reason why little research was so far carried out in the region is because it is difficult to access, and Greenpeace is in a unique position to assist scientists to carry out studies.

“There are limited research vessels in the world,” she said. “Development costs money and they are hard to find, so there is a huge ocean and not many vessels to cover ground.

“An expedition out to the high seas takes a long time, and it’s a lot easier to look at the seas closer to home.”