LFAS - a clear understanding
Iamdolphinus
20,000 Decibels Under the Sea
A new Navy underwater sonar system threatens whales and dolphins
By Leora Broydo, Utne Reader
Jacques Cousteau 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.
Cousteau's undersea 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
(LFA) sonar 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 use this 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 LFA 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.
"We believe the research program on LFA sonar 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 LFA sonar 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 LFA sonar will
interfere with the natural behavior of many marine species, especially
marine mammals."
In 1999 the Navy released a study of the effects of LFA sonar 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 stopped singing.
The Navy's conclusion, that these changes have "no lasting biological
significance," raised the ire of critics. "These experiments only 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
sonar 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 deaths.
"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 Frantzis.
Most recently, 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 LFA
sonar system.
"The lesson 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
geographic reach."
Nonetheless, the Navy is sticking to its guns and plans to move forward
with deployment.
Where's Jacques Cousteau when you need him?
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