Underwater sound pollution disrupts the communication methods of killer whales and could harm their ability to locate salmon, researchers have found.
Increasing ship traffic is raising the level of underwater pollution and threatening a range of endangered marine species.
The underwater noise, which can be intense, interferes with the way Orcas, one of the world's most powerful predators, and other marine mammals communicate and feed.
"The good news is that by reducing speed, even by as little as one knot, tankers and container ships can cut noise levels and help save numerous threatened species," said marine biologist and lead researcher Dr Scott Veirs, of the Beam Reach Marine Science and Sustainability School in Seattle.
Researchers found underwater sound pollution along the coast of the Pacific disrupts how orca's communication with each other, and interferes with their ability to track and hunt salmon.
They said the 'unprecedented study of ship noise' will help biologist understand the potential effects it has on marine life, and help discover ways to reducing the interference.
The researchers used underwater microphones to measure the noise created by about 1,600 individual ships as they passed through Haro Strait, in Washington state. The two-year study captured the sound made by 12 different types of vessel, including cruise ships, container ships and military vehicles, that passed through the strait about 20 times a day.
The conclusion was that they were harmed by the sounds, regardless of the frequencies. In fact, Washington state has the only population of orcas that are labeled as endangered species. However, the study’s findings concern also toothed whales and dolphins that have their habitat around coastal areas.
In this areas, shallow water make ship noises even louder. The researchers discovered that most of the noise comes from container ships. Apparently, the only ones that are quieter are military vessels. Scientists believe that noise pollution could be easily reduced.