can't talk on a cell phone when you're on an airplane. Your phone
and the pilot's navigation system use the same frequency, and the
signals could interfere with each other. The U.S. military and whales
off the Pacific coast are having a similar conflict, and it's not
clear who will come out on top.
the late 1990s, the U.S. military has been experimenting with the
use of sonar to detect super-quiet submarines. The U.S. Navy says
this technology could be helpful in detecting submarines and underwater
threats from other nations. But the new sonar, called low-frequency
active (LFA) sonar, employs the same frequency whales use to navigate
and communicate with each other. A study commissioned by the U.S.
Navy concluded that the whales were affected while the sonar was
in use, but that their patterns returned to normal after the sonar
was turned off. Environmentalists and whale watchers say the study
doesn't answer questions of whether the whales suffer hearing loss
or other permanent damage from the sound waves, which are very loud
and can be carried through the water for hundreds of miles.
conflict highlights two related dilemmas that have become more prominent
in the wake of September 11th: Balancing environmental concerns
with a desire to protect national security, and controlling underwater
noise pollution, caused by warships, cruise liners, and exploration,
that can disrupt communication and navigation systems of whales
officials will soon decide whether to use LFA sonar. The U.S.
Navy says the whales are safe, but activists worry about long-term
May 4 and 18
Why do things sound different under water? How to bats navigate?
Check out our spring webcasts as the kids from the Aim High program
make echos, investigate the workings of their ears, and visit
with a real live bat!
does sonar work?
See how reflected sound waves help a whale find its food --
or an officer find a submarine.
does the Navy's sonar sound like?
A biologist at Cornell University has been studying whale songs
and asking whether the Navy's sonar affects them. You can listen
to the whales and to their calls amidst the LFA sonar blips.
is louder under water. Try this!
This simple experiment you can do at home will show you that water
is a very effective carrier of sound.
do animals navigate?
Sonar is one of several tricks animals use to find their way around
the world. Aside from eyes and ears, some species -- including
whales -- use small magnets in their bodies!
environmental impact statement
Documents from 1999 and before describe how LFA sonar will be
used, how it relates to whale sonar, research on how LFA might
affect people diving in the area, and other information.
Environmental groups, like the National Resources Defense Council,
say FLA sonar has a lasting and detrimental effect on whales.
The issue of sonar and whales is sure to stay in the headlines.
Check our links page for headlines and background news articles.