Sounds Under the Surface
Every day we are surrounded by noises – from cars and planes, construction sites, and factories. While for most of us it is an annoyance, in some cases it can be harmful.
But have you ever thought about noises in the ocean? There are natural sounds from storms and waves, but also an increasing number of human-made sounds from boats, oil exploration and production, and military sonar.
There is increasing concern that these noises may affect marine animals, especially whales. Scientists want to know whether noises affect basic behaviors in whales, such as diving and feeding. They are also interested in knowing how different types of noises might affect these behaviors. So, an international team of scientists and underwater sound experts conducted a study at a U.S. Navy listening range to try and figure this all out.
Scientists attached digital acoustic recording tags to the whales while they were at the surface. These tags record every sound the whale makes along with its movement. The study lasted two years and compiled data from beaked whales, pilot whales, and melon headed whales.
With this data, scientists created animations showing the whales behavior before, during, and after being exposed to low levels of a variety of sounds; including sonar. The results showed that beaked whales, which are known for diving to extreme depths, were much more sensitive to sonar than other species. Even low levels of these sounds disrupted their diving, vocal, and likely feeding behaviors.The results are significant for the Navy in terms of planning operations and also for NOAA in developing whale conservation and management tools.