Researchers find that male humpback whales living around the Ogasawara Islands in Japan reduce or even cease their singing because of shipping noise.
Why is this important?
Underwater Noise Pollution From Ships
Increasing human activity in the water has a great effect on marine creatures. Apart from the plastic and garbage pollution, even noise pollution from the growing marine activity affects them. In fact, previous research even suggested that the average noise, from seismic explosions to military sonars, would increase by 2.5 dB to 3 dB per decade.
Of such noises that affect the waters, the main source is presumed to be shipping noises from commercial ships. In fact, some of the effects of shipping noises on cetaceans are increased stress, changes the feeding behavior, and increases or decreases in sound production.
Humpback Whale Songs Affected
To investigate such effects on whales, a team of researchers from various institutions in Japan used underwater recorders to capture the whale songs of the humpback whales that live around the Ogasawara Islands from February to May of 2017, and examined the effects of a passing ship on their songs.
What they found was that there were fewer humpback whales singing in the area, particularly in the 500 meter area within the shipping lane. Further, the whales within the 1,200 meter area after the ship passed by reduced their songs or even stopped singing altogether. In fact, most of the whales that stopped singing did not sing for at least 30 minutes after the ship had passed.
This suggests that the humpback whales’ singing behavior are at least temporarily affected by shipping noises. For future studies, researchers may explore how prolonged noise exposure might be a potential stressor for the whales.
The study is published in the journal PLOS One.
Why Is This Important?
Whales “sing” to communicate with other whales, to mate, to search for prey, and to navigate. It is an integral part of their lives. As mentioned, shipping noises tend to have negative effects on cetaceans, but it may also vary from one species to another.
For instance, Baleen whales use low frequency calls in communicating, so they are quite sensitive to the low frequency sounds of shipping noise. Since ocean noise caused by human activity continues to increase, it is important to see just how such activities also affect the creatures that actually consider the waters as their only habitat.