Sounds generated at low frequency are very important to whales for navigating, hunting and communicating. The sounds are sent back from objects on the seafloor, shorelines, water depth, obstacles and other animals, to the oil filled part of the lower jaw and then sent to the middle ear of the whales. The whales use what is known as echolocation to sense objects. From the information they receive from echolocation the whale can figure out the distance to the object, the size, the shape and the speed to reach the object.
SONAR used by the U.S. Navy is an acronym for Sound Navigation and Ranging. Sonar is necessary to determine the location of submarines and other Navy operations.
In 2000, four different species of whales stranded themselves on beaches in the Bahamas after a US Navy battle group used mid-frequency sonar in the area waters. The government investigated and found the sonar caused the stranding.
Environmentalists sued the Navy in October, 2005, claiming the use of sonar disrupted and killed whales and dolphins. The group wanted the Navy to use harmless passive sonar. In November, 2007, the Federal Appeals Court ordered the US Navy to lessen the harm sonar does to whales. This article is not a political statement, so I will only deal with the affect of sonar on whales.
Sonar acts as a floodlight scanning the ocean at vast distances with intense sound. At 100 miles from the starting system of the sonar, it can cause permanent hearing damage in humans. Whales use hearing like humans use eyes. The noise that is emitted from sonar, greatly affects the ability of whales to function and survive. The sounds have been shown to:
Divert bowhead and gray whales and others from migration paths
Cause the sperm and humpback whales to stop singing
Cause distressed behavior that leads to panic
Confused behavior and beaching
The sonar’s loud noise startles the whales, causing them to surface rapidly. This gives them a gas bubble that produced lesions in organs, including the liver. The whales have physical trauma that included bleeding around the brain, ears and other tissues. These symptoms are similar to a human suffering “the bends.”
Much research has been centered on the beaked whales. These whales were seen in the Hawaiian Islands. Since the incident in the Bahamas Island, the beaked whales have abandoned their habitat or died at sea. Much of their time is spent below 2,200 feet looking for squid. They dive deeper than most marine animals. Their ability to swim at greater depths for longer periods of time makes them more vulnerable to the affect of sonar.
Ken Balcomb, a whale expert from the Center for Whale Research in Puget Sound studied the affects of sonar on a pod of Orcas. They appeared agitated and were moving haphazardly away from the sound. They were trying to put their heads above the water to escape the noise.
The Navy has funded a $6 million project to learn more about the beaked whales and their response to sonar and other loud noises. The goal is to learn about beaked whales by attaching motion detectors and record the timing, depth and angles of their dives and ascents, the study will view the animal reactions when exposed to sound approaching, but not reaching the intensity of sonar signals.
The study is ongoing and will continue for another two years.
