For millennia, vast expanses of the Arctic Ocean have been untouched by humans, an ocean where narwhals and other marine mammals lived undisturbed. Now that climate change is melting sea ice, there has been a slight increase in human activity in the Arctic. This has resulted in a significant increase in noise from a range of human sources including seismic surveys, mine blasts, port projects and cruise ships.
While the noise is not violently loud when it comes from far enough away, for narwhals the noise is disturbing and causes stress – even from miles away. These are the results of unique experiments conducted with the iconic whale. The University of Copenhagen assisted the Greenland Institute of Natural Resources (Pinngortitaleriffik) in analyzing the data collected during the research.
Narwhals are notoriously difficult to study as they only live in the hard-to-reach High Arctic, which is often covered in ice. But the research team managed to tag a herd of narwhals in the Scoresby Sound fjord system of east Greenland using various measuring equipment. They then positioned a ship in the fjord, which exposed the animals to noise – both from the ship’s engine and from a seismic air cannon used for oil exploration.
“The reactions of narwhals indicate that they are frightened and stressed. They stop making the click sounds they need for food, they stop diving deeply, and they swim close to shore, a behavior they usually display only when they feel threatened by killer whales. This behavior means that they have no chance of finding food as long as the noise persists, ”says marine biologist Outi Tervo of the Greenland Natural Resources Institute, who is one of the original researchers. of the study.
Researchers may also find that whales perform an unusual number of tail flicks when fleeing a ship. This can be dangerous for them as it significantly depletes their energy reserves. Consistent conservation of energy is important for narwhals because they need plenty of oxygen to dive several hundred feet below the surface for food and to come back to the surface to breathe.
Everything in a narwhal’s life is healthy
Narwhals spend much of their time in darkness – partly because the arctic is dark for half the year, and partly because these sea unicorns hunt at depths down to 1800 meters, where there is no light. So everything in a narwhal’s life is based on sound. And like bats, they orient themselves by echolocation, which includes making clicks when they hunt.
“Our data shows that narwhals respond to noise 20-30 kilometers from a noise source by completely stopping their clicking sounds. And in one case, we were able to measure this from a source 40 kilometers away. It is quite surprising that we can measure how something so far away can influence the behavior of whales, ”says Professor Susanne Ditlevsen from the Department of Mathematical Sciences at the University of Copenhagen.
Professor Ditlevsen was responsible for the statistical analyzes of the huge and extremely complex data sets that emerged from the experiments, where the data was collected via an underwater microphone, a GPS, an accelerometer (a device that measures movement in three directions ) and heart rate monitors. She keeps :
“Even when the sound of a ship is lower than the background noise in the ocean and we can no longer hear it with our advanced equipment, whales can hear it and distinguish it from other sounds that are in the ocean. their breast. And so, to some extent, their behavior is clearly affected. This shows how incredibly sensitive narwhals are.
After a week of sonic testing, the researchers observed that the whales’ behavior was returning to normal.
“But if they are exposed to noise for a long time – for example, if a port is built nearby which leads to regular sea traffic, the success of whales in hunting might be affected for a longer period, which could become quite serious for them. In this case, we fear that it could have physiological consequences for them and alter their physical form ”, explains Outi Tervo.
Appeal to the authorities
The researchers hope is that the authorities and other decision-makers ensure better management of activities that create noise pollution in narwhal habitats.
“For the most part, narwhals live around Greenland, Canada and Svalbard in Norway. As such, these countries have the primary responsibility for looking after them. Because narwhals are so well adapted to the arctic environment, they can’t just choose to go to the Caribbean instead. It is under pressure from both the warming of the water temperature and, in some places, the catch of fish. Now noise is part of the equation, ”explains Susanne Ditlevsen.
Outi Tervo adds, “Changes are happening so quickly in the Arctic that we fear narwhals may not be able to adapt unless more effort is made to protect them. Some areas are so important to narwhals that it could be argued that human disturbance should not be allowed there at all. Elsewhere, it may be possible to set rules regarding, for example, how fast you can navigate, or that you can only navigate with much quieter electric motors. The technology offers excellent opportunities to reduce noise ”.
