The sound of silence
During a period with less traffic during Covid-19, whales quickly started to communicate like they did before marine industrialization. Dr. Michelle Fournet sized the unique possibility to study a temporary calmer ocean.
The Covid-19 slowdown has meant fewer ships on the oceans and therefore less noise under the waves, which has had a dramatic effect on the well-being of many forms of marine life. To further understand the impact that shipping has on marine life, Wallenius Marine decided to support further research through the organization Ocean Alliance, which gave the grant to Dr. Michelle Fournet at Cornell University to study the effects of the pandemic on humpback whales.
“Preliminary analysis indicates that whales contact call more in noisy years, but the call complexity increased during the slowdown. There was more diverse call types when it was quieter.”
To human comparison: if you’re one of the first guests at a house party, the volume is low, and it is easy to express yourself. However, as more arrive and the volume rises, we tend to use a more simplified form of language, often resorting just to sign language. This in effect is what is happening under the water.
Quickly reverts to natural calling
The last silent period occurred directly after 9/11. Scientists studying North Atlantic right whales observed a sharp decrease in stress-related hormones when the traffic stopped, and a return to normal as things picked up again. This was seen as the first evidence that exposure to low-frequency ship noise may be associated with chronic stress in whales.
Dr. Michelle Fournet´s hypothesize is that humpback whales may be able to quickly revert to baseline or “natural” calling behaviour, if humans are willing to turn the noise off.
“We found that the calling behaviour of humpbacks during low noise periods associated with Covid-19 was similar to those recorded by Dr. Roger Payne in Alaska in the 1970s, prior to the onset of major marine industrialization. A larger data set will give us more information, and more of a chance of finding a significant effect of noise on the whales,” she says, hoping that demonstrating a positive impact of quiet oceans may lead policymakers to consider integrating noise management solutions into existing conservation plans.
A fog of sound
There are two types of noise pollution that causes problems for whales – sudden loud noises that can harm them and even cause deafness, and the quieter, ever-present sounds from cargo ships and other boats that can prevent whales from sharing important information with other individuals.
In some areas, ocean noise levels doubled every 10 years between 1960 and 2000. As a result, the “communication space” – the distance over which individual whales can communicate – has been hugely reduced, in the case of blue whales by up to 90 %.
“The worst possible outcome is that due to noise levels post-Covid, combined with climate change and chemical pollution, the quality of the environment could become so poor that the animals can no longer survive in it and slip towards extinction” says Andy Rogan, Sience Manager at Ocean Alliance.
Other species also affected
Whales aren’t the only animals affected. Arctic cod will flee from their usual feeding regions in response to noise. The migratory patterns of apex predators like tuna can be similarly disturbed. Also while seals, squid and even oysters have all been shown to be affected by noise pollution. Whales, however, may be a special case.
“In many ways, humpback whales are indicators of ecological resilience, and lack thereof. When they suffer, it is an indication of a larger problem within the marine ecosystem,” says Dr. Fournet. “We need to understand the context clues given to us by this particularly communicative species in order to interpret the health of marine systems.”
Quiet ships one solution
The wind-powered vessels from the Oceanbird concept can not only reduce air pollution, they will also cut sound pollution in the oceans since there is no or less sounds from a propeller. Besides Oceanbird, Wallenius Marine has taken several other steps to reduce underwater noise, for example increasing energy efficiency as a vital part of ship design and investing in hull cleaning.
“The key to improve underwater life is knowledge. We need to know more about how shipping affects mammals like whales. We strive to leave as small an environmental footprint as possible and have taken measures to reduce air emissions and single-use plastics onboard. Sound pollution is just as serious,” says Niklas Blomqvist, Environment & Quality Manager at Wallenius Marine.