The Navy got the OK on Monday to experiment with underwater sonar, temporarily allowing them an exemption from federal law that protects marine mammals from incidental injury. The Navy received a five-year exemption from the National Oceanic and Atmospheric Administration’s
The Navy got the OK on Monday to experiment with underwater sonar, temporarily allowing them an exemption from federal law that protects marine mammals from incidental injury.
The Navy received a five-year exemption from the National Oceanic and Atmospheric Administration’s Marine Mammal Protection Act, which protects marine mammals such as whales from incidental injury.
The active part of the system will incorporate a set of low frequency (LF) acoustic transmitting source elements called projectors, suspended from a cable from underneath two ships, according to the National Oceanography and Atmospheric Administration’s Office of Protected Resources Web site.
The part of the system that “listens” is called SURTASS (Surveillance Towed Array Sensor System), which detects the LF echoes using hydrophones towed by the ships.
When complete, the system will be able to detect long-range underwater threats and targets like quiet submarines being developed in non-allied countries, according to the Navy.
The “pings” to be emitted will likely range from 6-100 seconds with 6-15-minute intervals. will reach over 215 decibels, according to information on the Web site for the National Resource Defense Council, one major environmental organization opposed to the experiments.
Hawai’i environmentalists have long expressed concern over ocean noise pollution and the harmful effects that the Navy’s experiments may have on ocean mammals.
The Navy says that sea animals in the region will hear the sounds and possibly react in some way.
Whales that happen to be within the Humpback Whale National Marine Sanctuary may be affected because humpback whale calls are within the range of sound frequencies proposed for the research.
Natural ocean phenomena such as earthquakes and lightning strikes generate powerful low frequency sounds that aren’t necessarily harmful because many whale species also produce loud, low frequency sounds, states the Navy’s SURTASS Web site. Furthermore, these natural noises were part of the environment in which marine mammals evolved.
The Navy says that whales exposed to LFA sonar signals during the Low Frequency Sound Scientific Research Program exhibited less response than the scientific team anticipated.
However, the project has already received harsh reactions from environmentalists who say that LFA is proven to be lethal to whales.
In March 2000, 17 whales and dolphins in the Bahamas were killed after Navy mid-frequency sonar experiments.
The Navy and NOAA said the Bahamas incident involved mid-frequency sonar, which is more harmful under certain unusual circumstances than the low-frequency sonar now permitted.
The Navy initially denied its sonar caused the subsequent deaths of six beaked whales, but later admitted responsibility after tests made possible by the freezing of several dead whales showed the animals had suffered internal injuries from the noise.
“Whales and other marine mammals are particularly vulnerable to noise pollution; they rely on hearing at least as much as we rely on our sight. In the ocean, a deaf whale is a dead whale,” states the NRDC.
This Navy sonar project is somewhat similar to the ongoing ATOC (acoustic thermometry of ocean climate) experiment being run by the Scripps Institute of Oceanography, who in 2001 was granted an extended research permit from the state Department of Land and Natural Resources.
Underwater speakers sit on the seafloor eight miles north of Kaua’i. These “sound sources” emit 260 watts of acoustic power, to be detected by 11 recorders placed around the north Pacific. Sound travels fastest in warm water, so the faster the sound reaches the recorders, the warmer the water must be, as reported in an Aug. 2001 TGI report. Scripps’ research permit extension continues until the end of September.
The SURTASS experiments are granted for a five-year period, to begin in mid-August and continue until 2007.
Web links:
http://www.nmfs.noaa.gov/prot_res/PR2/Acoustics_Program/acoustics.html
http://www.surtass-lfa-eis.com/
http://www.nrdc.org/wildlife/marine/nlfa.asp
TGI Archives:
“Foes want ocean sounds muted,” August 22, 2001
“Comment invited on Navy sonar plan,” March 26 2001
Staff Writer Kendyce Manguchei can be reached at kmanguchei@pulitzer.net or 245-3681 (ext. 252)
