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Noise pollution, although not as deadly to us as other types of pollution we usually generate, might have some devastating effects on other life forms. Some marine creatures use sound to be able to navigate and communicate with each other and as it turns out, killer whales are sound blocked by ship noises.
Orcas and ships in Washington State
As you may or may not know, Southern Resident killer whales are an endangered type of orca living in Washington State’s Haro Strait. This is the core critical habitat for the aquatic mammals, allowing the salmon eating creatures to thrive, all the while bringing millions of dollars to Canadian and Pacific Northwestern ecotourism.
Unfortunately for them, they share their habitat not only with their favorite food source, the Chinook salmon, but also with thousands of ships which pass through the strait all the time. This might not be such a good thing for the creatures, mostly because of the noises all the ships make.
When hunting, swimming, or just communicating with other members of their species, killer whales use sonar and echolocation. By attuning to mid and high frequencies, the animals can hunt, navigate, and swim better.
Since the 1960s, the levels of noise pollution in the oceans have risen ten-fold due to the rise of commercial shipping. The fact that the frequencies emitted by the ships were affecting baleen whales was already known, but the team of scientists wanted to see if it also affects toothed whales.
Noise pollution for all frequencies
In order to make sure that they cover all of the frequencies that can be picked up by the marine mammals, the researchers measured a very wide range of frequencies, from 10Hz all the way up to 40,000 Hz.
What they found didn’t really work to boost their morale.
As it turns out, not only do most ships generate very high levels of background noise at low frequencies, but they also reach medium and very high frequencies. This includes the 20,000 Hz frequency which killer wales use to hear the best.
This means that their entire core habitat, the costal environment teeming with salmon and shipping lanes for kilometer on end, is filled with noise disruptions that are interfering with the animals’ echolocation. These are some bad news for the region’s orcas, as they risk getting hurt quite a lot because of the noise interferences.
The team did find, however, two solutions for reducing the levels of noise pollution in the oceans – equipping commercial ships with military level noise cancelling technology, or just slowing down, since every knot reduces the noise levels by one decibel.
Image source: Wikimedia
