Noise caused by shipping traffic severely affecting critical habitats of orcas
A new study has highlighted about the prevalence and noise caused by ships in the Salish Sea. Noise caused by the shipping traffic is at the same frequency as being used by killer whales to communicate and hunt its prey.
Researchers have undertaken underwater sound measurements in the Strait of Juan de Fuca and Puget Sound. From it, the researchers have found that ships generate high frequency noise that travels much farther than previously thought.
Orcas, which feed majorly on salmons, locate their prey by sending out clicks and listening for the echo, a process, which could be easily disrupted by shipping noise. Study’s lead researcher Scott Veirs of Seattle’s Beam Reach Marine Science and Sustainability School said that they have installed listening devices in the critical habitat of the southern resident orca population adjusted for a wide range of frequencies.
Veirs said that whales are vocal, but their environment is full of ship noise. The researchers have recorded and compared noise from 41 different kinds of ships making 2,809 trips through the Haro Strait. Around 50% of the noises were made by container ships and bulk carriers.
All vessels making significant high frequency noise, but container ships were generally the loudest and military vessels were among the quietest. Container ships were the fastest-moving ships in the study as the faster a ship goes, the louder it is.
The researchers said that critical summertime orca habitat is within a few kilometres of busy shipping lanes and shipping vessels cause significant underwater noise pollution at frequencies likely to interfere with the animals’ communication, foraging and echolocation.
The next step in the research is to better understand how the noise levels documented in the study affect marine life in the Pacific Northwest. “As an endangered species, the killer whales will be at the top of our list. But we also want to look at fish, invertebrates, and the many other marine mammals we have”, affirmed Veirs.
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