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Impacts of ocean noise called ill defined

13th February 2003 (ENS) - There is a disturbing lack
of knowledge about the effects of ocean noise on marine
mammals, concludes a new report from the
National Research Council.
The panel that authored the report says a single federal
agency should be put in charge of monitoring and
coordinating research of ocean noise to prevent harm to
whales, dolphins and other sea creatures.

The National Research Council (NRC), an agency of the
National Academy of Sciences, said one agency should
coordinate an investigation of how human generated
sounds may affect marine mammals and other animals.
The government should fund a wide array of research
aimed at increasing the limited data now available to
scientists studying ocean noise, according to the new report.

A beached goosebeak whale somewhere in the Caribbean.
Goosebeaks are among the cetacean species known to be sensitive to loud noises.
(Photo courtesy Laboratorio de Mamíferos Marinos del Caribe)

"Remarkably few details are known about the characteristics of ocean noise, whether it be of human or natural origin, and much less is understood of the impact of noise on the short and long term well being of marine mammals and the ecosystems on which they depend," the report's authors wrote.
Marine researchers are concerned about the lack of knowledge about the effects of noise from the growing number of ships and oil rigs, from marine and coastal development, as well as the increased use of sonar by navies and researchers.

Noise levels from ship traffic have increased some 15 decibels in the last 50 years, but it is difficult to know whether sound levels are continuing to increase, as newer ships may be quieter.

The global shipping fleet increased from 30,000 commercial vessels in 1950 to 87,000 in 1998, but "consequent noise changes cannot be determined because noise data were not collected in a systemic way to allow for scientific comparisons, nor are they being systemically collected at this time," the report states.

"Similar needs exist for every facet of human activity in the oceans," the authors wrote.

Existing information on noise levels is scattered among shipping companies, oil and gas businesses, academic institutions and the military. The report recommends that one agency gather all existing data into one comprehensive database, and initiate a long term program to monitor sound in the sea, targeting important marine mammal habitats such as coastal areas and known migration paths, feeding grounds and breeding areas.

A test of the Navy's Surveillance Towed Array
Sensor System Low Frequency Active sonar
(SURTASS-LFA) (Photo courtesy U.S. Navy)

There is also a need for more investigation into possible links between the use of high energy, midrange sonar and mass strandings of marine animals, according to the report.
Beaked whales in particular have suffered trauma and mass strandings near where naval sonar was being used, the authors said, but they noted that there is not enough data to determine whether the sonar caused the strandings.

"It is important to determine whether there is any connection between sonar use and beachings," they wrote, "and if so, whether this link is peculiar to beaked whales or if other sea species may be affected as well."

A growing body of evidence does correlate naval use of sonar to an array of strandings by beaked whales and other marine life.

In 1996, 12 beaked whales were stranded in Greece during NATO exercises in the Mediterranean Sea using low frequency sonar. And the U.S. Navy and the U.S. National Marine Fisheries Service have acknowledged that the Navy's tactical sonar played a role in the strandings of 17 marine mammals in the Bahamas in 2000.

Ocean going vessels, like this Royal Caribbean vessel
outside the port of Miami, Florida, produce a variety
of noises that may disturb whales and dolphins.
(Photo courtesy Royal Caribbean International)

Military operations are not the only activities receiving criticism for using sonar that may have a harmful affect on marine life. Last fall, National Science Foundation researchers were forced by a court order to halt the use of high decibel air guns for a project to map a fault in the Earth's crust.
Environmentalists filed suit for the court order after the discovery of two dead beaked whales, which stranded themselves on an island in the Gulf of California near where the air gun had been used.

Last month, a federal judge issued a permanent injunction
barring testing of a controversial sonar system designed to
test whether sound pulses could keep migrating gray
whales away from shipping lanes. The judge said the testing
of high frequency sonar pulses, designed by the Woods Hole
Oceanographic Institute, might harm the whales.

Marine mammals are extremely sensitive to noise, which is
one reason why researchers are desperate to better understand
how human generated sounds may be affecting them.

Scientists do not know what effect the noise
and seismic charges used by offshore drilling
platforms might have on marine mammals.
(Photo courtesy Department of Energy)

"Little information exists to describe how marine mammals respond physically and behaviorally to intense sounds and to increases in ambient noise levels," the report finds.
"Marine mammals are unique from you or I because sound is their 'eyes and ears' in the ocean," added Gerald Leape, director of the Marine Conservation Program at the National Environmental Trust. "They use sound to find food, find each other and to talk with each other, in particular between mother and calf.

"The cumulative affects of sonar, seismic testing, oil drilling, shipping and other activities represent a serious threat to marine mammals," Leape said. "We need much more information to fully understand the impact of these threats."

The report concludes that better models to predict the noise levels generated in the ocean by particular human activities are needed. If researchers better understood what kinds of noise ships generate, they could project how much noise will occur in different parts of the ocean based on ship traffic patterns.

National Marine Fisheries officials respond to a pilot whale stranding.
(Photo courtesy NMFS)

Public awareness of the need for increased research and understanding of ocean noise is critical, the report's authors wrote. They urge scientists, as well as other users of sound in the ocean such as the oil and gas industry, to make greater efforts to increase this public awareness.
The report, "Ocean Noise and Marine Mammals," was compiled by the NRC's Ocean Studies Board's Committee on Potential Impacts of Ambient Noise in the Ocean on Marine Mammals at the request of the National Ocean Partnership Program, a federal interagency project.

The report can be read online at: