Oceans are becoming increasingly noisy. People don’t usually think about noise pollution in that way but it is damaging ecosystems around the world. While ships can be causing some noise as well, the biggest source of noise is oil and gas exploration. Now an international team of scientists have found that humpback whales are tremendously affected by noise levels in the ocean.
Oil and gas exploration is noisy because geologists use large loud acoustic air guns to probe the structure of the ocean floor in search of fossil fuels. Ships are towing arrays with a number of sensors that help detecting places suitable for exploration looking for fossil fuels. While it is still necessary for the worldwide economy, scientists suspected that these noises may be affecting migration of humpback whales. It was not clear how whales react to firing air guns and what factors matter the most. How far do whales get disturbed by these noses if they do at all? Scientists set out to answer these questions.
Scientists analysed reactions of migrating whales to strings of repetitively firing air guns as they were towed for an hour across the path of these animals. Whales were monitored at three points in time – before air guns went off, while they were firing and one hour after. They also performed a series of control experiments to see how whales react to the vessel itself. That was interesting in itself, because these ships are quite common nowadays, but no one knows if they are still disturbing animals just by floating by.
Scientists installed small suction-cup acoustic tags on a few of the whales to see what kind of impact they receive. Soon they realized that both distance and airgun level are equally important factors in determining the response. The received signal is not as important. Dr Rebecca Dunlop, one of the authors of the study, said: “Within a certain distance, they did not show a clear avoidance reaction to the vessel alone, suggesting it was the air guns that triggered this reaction”. Whales don’t like these noises and typically avoid them, swimming to the opposite direction. But does this study have any practical implications?
Researchers believe it does. There is an on-going movement to protect whales from human activities and environmental regulations are constantly getting more and stricter. And so scientists hope that the results of this study will be taken into account when prevention measures will be discussed.
Source: University of Queensland
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