Ocean noise harms dolphins, whales
coco
Nov 22, 4:05 AM EST
Report: Ocean noise harms dolphins, whales
By PAUL CHAVEZ
Associated Press Writer
LOS ANGELES (AP) -- Increasing levels of ocean noise generated by
military sonar, shipping, and oil and gas exploration are threatening
dolphins and whales that rely on sound for mating, finding food and
avoiding predators, according to a new report.
The report released Monday by the Natural Resources Defense Council
found that the affects of ocean noise on marine life range from
long-term behavioral change to hearing loss to death.
The report, a follow-up to a 1999 study, included details from
necropsies performed on beached whales suspected of being exposed to
Navy sonar.
Scientists who examined more than a dozen whales that beached in the
Canary Islands in September 2002 found bleeding around the brain and
ears and lesions in the animals' livers and kidneys.
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"It is a set of symptoms that have never before been seen in marine
mammals," said Michael Jasny, the report's principal author. "That
physical evidence has led scientists to understand that the sonar is
injuring the whales in addition to causing them to strand."
Researchers believe that whales are suffering the same type of
decompression sickness that is known as "the bends" in humans. The
leading theory is that sonar either causes whales to panic and surface
too quickly or forces them deeper before they can expel nitrogen,
leading to nitrogen bubbles in the blood.
A federal probe into the mass stranding of 17 whales in the Bahamas in
March 2000 cited the Navy's use of mid-frequency sonar as a
contributing factor.
The Natural Resources Defense Council sued the Navy last month in
federal court in Los Angeles in an attempt to curb its use of
mid-frequency sonar, which is the most common method of detecting enemy
submarines. The environmental group wants limits on sonar during
training exercises, not in war.
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In the new report, the NRDC urged the National Marine Fisheries Service
to better enforce the federal Marine Mammal Protection Act. The service
should also require the Navy to obtain permits for its sonar exercises,
according to the report.
A fisheries service spokeswoman said the agency had not seen the report
and could not comment on it.
Jasny said noises from oil and gas exploration have also been linked to
lower catch rates of halibut, cod and other species of fish.
"It's been shown that some species of fish suffer severe injury to
their inner ears, which can seriously compromise their ability to
survive," he said.
The NRDC recommended year-round restrictions of excessive ocean noise
in critical habitats and seasonal restrictions on migration routes. For
example, the group suggested that oil-and-gas companies avoid seismic
surveys in the winter off the west coast of Africa when baleen whales
are breeding offshore.
It also called on the fisheries service to increase oversight of oil
and gas surveys, which rely on shooting high-intensity air guns at the
ocean's floor.
The true impact of ocean noise remains unknown because strandings
likely represent just a small portion of marine life effected by
excessive noise, Jasny said.
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On the Net:
Natural Resources Defense Council: http://www.nrdc.org