Fauna Journal Entry

Sonar Likely Cause of Whale Stranding (May 11, 2006)

Two years ago, more than 150 melon-headed whales were stranded on beaches in Hawaii's Hanalei Bay. Now, a new report says Navy sonar tests in the area were most likely to blame.

To prevent another disaster, the National Oceanic and Atmospheric Administration (NOAA) recently asked the Navy to reduce the power of sonar waves to be used in exercises this summer around Hawaii. The Navy has agreed to the request. But it still claims its tests were not to blame for the stranding two years ago.

Sonar uses high-energy sound waves to locate underwater objects. Many biologists say the loud sound waves hurt whales by damaging their hearing. It also scares them and makes them rise too quickly through the water, causing dangerous nitrogen bubbles. The whales may also get disoriented or confused by the sonar.

Early in July in 2004, six ships from the United States and Japan were using sonar in drills around the Hawaiian islands of Oahu and Kauai. The next day, the large group of melon-headed whales was spotted in shallow water in Hanalei Bay. Normally, these whales only swim in much deeper waters.

In recent years, sonar has been blamed for other whale strandings in different parts of the world, including the Canary Islands, Alaska, and Japan.

The melon-headed whale gets its name from its rounded, cone-shaped head. The mammal usually travels in large pods that can have between 100 and 1,000 members. The whales are found in tropical waters around the world but are rarely seen because of their preference for deep water.