Whales and dolphins stop eating to avoid artificial underwater noise, Scots-led study shows

Research by a group of experts from across Europe shows that underwater noise pollution from human activities is perceived by whales in the same way that they perceive natural predators, which explains why some species are especially sensitive to this kind of interference.

That reportA team of behavioral ecology experts, including study leaders Prof. Patrick Miller and Dr. Saanu Isojunno of the Marine Mammal Research Unit at the University of St. Andrews, found that whales, dolphins and porpoises, known as cetaceans, respond to artificial sounds in a similar way they evolved. to respond to natural predators such as killer whales.

While some creatures may fight or flee from predators when they think they are being attacked, the underwater disturbance created by humans also causes them to stop feeding.

A new study by scientists at the University of St. Andrews shows that whales and dolphins cannot distinguish between artificial underwater noise, such as sonar signals, and sounds made by their natural predators. Photo: Lars Kleivan

The researchers conclude that this may affect their health and make them more vulnerable to threats.

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Polluted and noisy seas ‘a growing danger to whales and dolphins’

Experiments conducted by the research team have shown that marine sonar caused a feeding cessation in all four species of whales they studied – beaked, humpback, sperm whales and long-finned pilot whales – which all rely on acoustic signals to assess danger from predators. and find your food.

“The fact that sonar sounds can negatively impact whales and dolphins has drawn public attention due to high-profile events where large numbers of whales have been stranded due to military sonar activity,” Professor Miller said.

The researchers studied the whales’ behavior in response to recordings of killer whale sounds and marine sonar. Photo: Christian Harbaugh-Hansen

The study examined how mammals tagged with temporary transmitters responded to marine sonar signals and sound recordings made by killer whales, the ocean’s top predator.

It was found that the amount of time spent foraging decreased at about the same rate for each type of noise, although the data differs between species – beaked northern bottlenose dolphins stopped hunting for food completely, and sperm whales halved their foraging time.

“Because human activities affect virtually every animal habitat on the planet, identifying species at risk of disturbance is a priority,” said Professor Miller.

“In our study, the overlapping responses of marine sonar and reproductions of sounds from predatory killer whales show that whales, which are both predator and prey but rely on hearing to find food and detect danger, have not adjusted their threat response by learning to distinguish noise. it poses no risk of predation from what it does.

“Essentially, they have to choose life over dinner when they hear about a potential threat at sea.”

Similar behavior has been reported in response to noise from icebreakers and air guns used in oil and gas exploration.

He says the findings raise concerns for the world’s northernmost cetaceans, as both killer whales and humans are increasingly accessing Arctic waters as sea ice continues to disappear due to climate change.

He added: “Our results indicate that these Arctic marine mammals are facing an impending double whammy due to an increase in true predators as well as perceived threats due to increased underwater human noise.”

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