20,000 Decibels Under the Sea
A new Navy underwater sonar system threatens whales
By Leora Broydo, Utne Reader
took us to the bottom of the ocean and back in his
acclaimed 1953 book, Le Monde du Silence (The Silent World). His
documentary film bearing the same title won an Oscar in 1957. Today,
Cousteau might have chosen a different name for his works, perhaps
20,000 Decibels Under the Sea.
world is getting to be a noisy place. You may not
have heard the sounds of supertankers, cargo ships, military testing,
or oil drilling on your Songs of the Humpback Whales CD, but they're
out there in force. Environmentalists say the ever-increasing racket
poses a serious threat to marine animals and that steps should be
taken to protect them. At least one perpetrator of underwater noise,
the U.S. Navy, is hearing the message loud and clear.
The Navy is drawing
fire over its use of a new low-frequency active
sonar (LFAS) system, which their experts say is essential for detecting
superquiet enemy submarines developed for the post Cold War seascape.
It works by generating
blasts of sound at upwards of 230 decibels (a jet engine is about 120
decibels at the source) from massive transmitters that ships drag through
the water; technicians then interpret the echoes. The Navy wants to
technology in 80 percent of the world's oceans.
Herein lies the
rub: Some marine mammals also use low-frequency sound to communicate,
feed, and navigate. "Bottlenose dolphins can
distinguish between a cube and a sphere of similar size just by
listening to their echoes," writes Chris Clarke in Earth Island
Journal (Summer 2000).
The question is,
will the new sonar system harm these sound-sensitive
creatures? The Navy claims its research shows LFAS poses no
significant threat to marine life. But an unusual coalition of animal
activists,environmentalists, scientists, and politicians say the Navy
doesn't have enough proof.
the research program on LFAS conducted by the Navy has been inadequate,"
states a letter signed by 26 members of the U.S. House of Representatives
to Secretary of Defense William Cohen. "Because sound produced
by the LFAS system is designed to travel over vast distances,
and because the
sound produced by the system is so powerful, there is
a growing scientific concern that the use of LFAS will interfere
with the natural behavior of many marine species, especially marine
In 1999 the Navy
released a study of the effects of LFAS exposure on
whales off the coasts of California and the Hawaiian Islands.
Independent scientists working in conjunction with the Navy found the
sound blasts did
have an impact:
Vocalizations of fin and blue whales decreased, gray
whales deviated from their migration paths (the louder the sound, the
greater the deviation), and about one-third of the humpback whales
The Navy's conclusion,
that these changes have "no lasting biological
significance," raised the ire of critics. "These experiments
tested immediate observable changes in behavior to an exposure level
of around 150 decibels, a sound well below the 240 decibel level at
which the technology will be deployed," writes marine researcher
Leigh Calvez in The Ecologist (June 2000).
Indeed, it's what
the report doesn't say that opponents find so
compelling. During the tests off Hawaii, notes Earth Island Journal,
members of the Hawai'i Ocean Mammal Institute found two abandoned
whale calves and a baby
dolphin in the
test area. "We have never heard of anyone observing an
abandoned calf in our nine years of research off the Hawaiian
Islands," OMI's Marsha Green told Earth Island Journal. "The
tests may cause disorientation so the mother and calf become
separated and then cannot find each other."
In May 1996, 12
Cuvier's beaked whales beached themselves and died on the Kyparissiakos
Gulf coastline in Greece. The whales, a breed that rarely gets beached,
were healthy and young and had no external signs of injury or disease.
Writing in the journal Nature, A. Frantzis of the Department of Biology
at the University of Athens, Greece, noted that a NATO vessel was conducting
low-frequency sonar tests in the gulf at the same time as the whale
"We know that
LFAS was used in the Kyparissiakos Gulf. We also know that no other
LFAS tests or mass strandings have occurred in the
Greek Ionian Sea since 1981. Taking the past 16.5 years into account,
the probability of a mass stranding occurring for other reasons during
the period of the LFAS tests is less than 0.07 percent," wrote
in March 2000, 17 marine mammals of various species
stranded at several locations in the Northern Bahamas islands; seven
died, while others were pushed back into the sea. A report from the
National Oceanic and Atmospheric Administration, a government agency,
concludes that "injuries to the six beaked whale heads were all
consistent with an intense acoustic or pressure event . . . in particular
all had some hemorrhages in or around the ears." The strandings
occurred the same day five Navy ships were
in the area using mid-frequency active sonar, which is far less powerful
than their LFAS system.
to be taken is be precautionary," says Michael Jasny, a
policy consultant for the Natural Resources Defense Council. "There
are too many uncertainties and risks to deploy a system of such wide
Navy is sticking to its guns and plans to move
forward with deployment.
Cousteau when you need him?