Seismic surveys used for oil and gas prospecting on the sea floor are a disturbance for blue whales, the world's biggest animal and one of its rarest species, according to biologists.

The 11-day experiment was conducted during a period when a survey vessel was using a "sparker", a low-to-medium power device that sends an acoustic pulse to the sea floor and picks up the reflected signal to get a picture of the topography.

"On the days when the vessel was operating, the whales called more than two and a half times more frequently than on days when the vessel was not operating," said Joseph Di Iorio.

For humans, "it would be the same as if you were next to a road works hammer and have to shout or repeat what you say," she said.

Dr Di Iorio said further work would show whether blue whales suffered stress or other problems from the acoustic kerfuffle.

"Blue whales are rather solitary whales which swim all the time, are highly dispersed and always travelling, and feeding areas are places where they have the chance to get together in a small range and with a lot of social activity as well.

"Being disturbed during social interactions that don't occur very often could have an influence, perhaps in mating, but we can't really say for sure, or what kind or if it is short term or long term."

One concern is that oil and gas prospecting is venturing out into ever-deeper water, and little is known about the impact this might have on whales' feeding and migratory patterns.