A new research has revealed that the low-frequency noises generated by ships might be posing a threat to the endangered southern resident killer whales (SRKW), including orcas, and dolphins. It is a known fact that the underwater low-frequency noises, whose intensity is enhanced by commercial shipping activities, are obstructing the communication and feeding patterns of baleen whales.

However, a new research has now found that the intensity of medium and higher frequency noises is also enhanced by ships, thereby altering the SRKWs best-hearing frequency range. Orcas that are odontocetes or toothed whales, find their food using echolocation. According to authors, odontocete signals are obstructed by the ship noises, particularly in coastal areas where the distance between shipping lanes and shorelines is less than 10 km and the high frequency fails to get completely absorbed.

The population of endangered SRKWs in the Haro Strait off of Washington is nearly 88, but being a major Pacific shipping channel, the strait hosts’ nearly 20 ships daily. According to the study authors, during the summer season, ship noises have an adverse impact on the communication as well as foraging and navigation skills of the endangered SRKWs.

In an environment where SRKWs may already be food-stressed due to reduced populations of their primary prey – Chinook salmon – echolocation masking could have grave population-level consequences,” said the authors.

The authors recommended that equipping the commercial ships with quieting technology, which is used in the military vessels, can prove to be a very successful measure in lessening the noise intensity underwater. In addition, since frequency level and the speed of the ship are linearly related, a reduction in the speed of the ship can also be a prospective mitigation measure. The data reveals that noise level goes down by one decibel, when the speed of the ship decreases by one knot.