Ship Noise May Injure Endangered Killer Whales and Their Ability to Hunt
It turns out that ship noise may also cause issues for killer whales. Scientists have found that ship noise extends to frequencies used by endangered killer whales to communicate and find food.
One of the threats faced by marine mammals and other ocean-dwelling creatures is noise pollution from ships. The growth in commercial shipping has actually raised the intensity of low-frequency noise almost 10-fold since the 1960s. Because this noise occurs at the low frequencies used by baleen whales, there's growing evidence that it may impact their ability to communicate and, thus, to survive. However, researchers weren't sure whether this noise extended to higher frequencies.
Salmon-eating orcas use mid- and high-frequencies to communicate and find their prey. That's why researchers measured a wide range of frequencies to see whether they may also be impacted by ship noise.
So what did they find? It turns out that ships are responsible for elevated background noise levels not only at low frequencies, but also at medium and higher frequencies, including the 20,000 Hz, where killer whales hear best.
So what can be done about this? Overall, container ships exhibit the highest median source levels while military vessels have some of the lowest levels. This suggests that transfer of quieting technology to the commercial sector could be a successful noise mitigation strategy. In addition, the ships could just slow down in order to reduce noise pollution.
The findings show that killer whales may be impacted by shipping noise. This is especially important to note for conservation purposes in the future.
The findings are published in the journal PeerJ.
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