Researchers in the US have concluded that sounds emitted by ships threaten the ability of whales and dolphins to communicate, and locate and hunt their prey.
Killer whales are known to emit a frequency which helps them locate a prey. This ability is hindered by the rumbling sounds produced by the passing ships.
Dolphins and porpoises are among other marine creatures that are affected by the sound pollution posed by the ships.
During the two-year study, researchers employed underwater microphones and recorded 12 varieties of sounds created by the 12 vessels on the sea, including cruise ships, container ships and military vehicles that passed through the Haro Strait, in Washington 20 times a day.
It has been observed that the military vehicles are quieter than the civilian ships. However the average intensity of noise next to all the ships was 173 underwater decibels.
The whales, which do not trail alongside the ships, are subjected to 60-90 decibels of sound.
Beamreach researcher Scott Veirs was quoted by the Guardian as saying: "The main concern of this is that even a slight increase in sound may make echolocation more difficult for whales.
"That’s worrying because their prey, Chinook salmon, is already quite scarce.
"Hearing a click off a salmon is probably one of the most challenging things a killer whale does.
"Hearing that subtle click is harder if there’s a lot of noise around you."
Scientists are exploring options to reduce the noise pollution.
The US government, in a bid to protect the endangered species, has protected miles of the Atlantic waters that house the whales.
Veirs was further quoted by the publication as saying: "It should be easy to reduce noise pollution.
"Military ships are quite a bit quieter and there could be straightforward ways of transferring that technology to the commercial fleet.
"Another way to reduce noise is to slow down.
"Decreasing speed by six knots could decrease noise intensity by half."
Image: Two killer whales in action. Photo: courtesy of Robert Pittman.