Yes, the whales sleep too. But less and less. And it’s not a sleep disorder. This is the whale watching business. Companies want to offer their customers the best possible experience. They place their boats as close as possible to the whales. This leads to the whales being disturbed by a change in their behavior. A team from the University of Aarhus in Denmark investigated how our noise changes whales.
Unusual behaviors
The noise changes them. They dive, change course, swim faster, breathe more often. They disperse and can make other sounds than usual. Apparently there is an explanation: the engines of the boats are too loud. “Unlike humans, the dominant sense of whales is not seeing, but hearing. A whale cannot see a observation boat 100 meters away. But they listen to it,” explains Australian Kate R. Sprogis, a biologist at Aarhus University. “So it makes sense to take this into account when setting guidelines for whale watching,” he adds.
Underwater speakers and cameras were used on drones. The aim was to determine the noise level of the boats by which humpback whales change their behavior. The results were published this week in the eLife magazine. The article is called V.Essel noise levels control humpback whale behavioral responses that affect whale watching. A short name.
The experiments were carried out in the Gulf of Exmouth on the west coast of Australia. It has the largest population of humpback whales in the world. The researchers looked at a mother and her baby. They emitted engine noise from various levels from a boat 100 meters away. They completed a total of 42 experiments on controlled noise pollution.
Reduce the noise!
At 172 decibels, which is a loud boat, the mother’s rest time was reduced by 30%. Her breathing rate doubled and her swimming speed increased by 37%. They returned to a state of rest when the noise of the boat drove away.
Repeated shocks can have long-term consequences for whales. Mothers use a lot of energy to react negatively to underwater noise. So they have less energy to feed their young or avoid predators.
Young don’t get enough milk. Soon they will have to grow and become strong enough to cope with the migration to colder regions.
The researchers concluded that the noise level of a boat engine should be kept below 150 decibels. Knowing how our noise changes whales will help introduce this noise emission standard. Otherwise we will continue to interrupt the whales’ sleep. And harm your daily life.
