**************This research will be one of several topics presented in a webcast news briefing at 10:30 a.m. (CDT; 11:30 a.m. EDT) on Tuesday, Oct. 23. Reporters may register for the webcast here: www.aipwebcasting.com**************
Newswise — Concern is growing that human-generated noise in the ocean disrupts marine animals that rely on sound for communication and navigation. In the modern ocean, the background noise can be ten times louder than it was just 50 years ago. But new modeling based on recently published data suggests that 200 years ago – prior to the industrial whaling era -- the ocean was even louder than today due to the various sounds whales make.
California researchers Michael Stocker and Tom Reuterdahl of Ocean Conservation Research in Lagunitas, Calif., present their findings at the 164th meeting of the Acoustical Society of America (ASA), held Oct. 22 – 26 in Kansas City, Missouri. Using historic population estimates, the researchers assigned “sound generation values” to the species for which they had good vocalization data. "In one example, 350,000 fin whales in the North Atlantic may have contributed 126 decibels – about as loud as a rock concert – to the ocean ambient sound level in the early 19th century," Stocker notes. This noise would have been emitted at a frequency from 18 – 22 hertz.
According to the researchers, use of whaling records to determine just how many whales were harvested from the ocean over the course of industrialized whaling is difficult because the captains were taxed on their catch and therefore had an incentive to “fudge” the numbers. Some captains kept two sets of books. After the collapse of the Soviet Union, some of the real reports began surfacing. In one example the Soviets initially reported taking approximately 2,710 humpback whales from the late 1950s to the mid-1960s. The newer data reveal the actual number was closer to 48,000.
This more accurate data was supported by population estimates using mitochondrial DNA, which does not change through female lines of a species. Thus the current diversity in DNA can serve as a proxy for historic population numbers.
While their estimates suggest there was a whole lot of whale racket a couple centuries ago, Stocker says "we can assume that animals have adapted to biological noise over the eons, which may not be the case with anthropogenic noise. Anthropogenic noise is often broader band and differently textured than natural noise, so the impacts are likely different as well. Investigating these differences and their impact on marine life is the topic of intense research.”
MORE INFORMATION ABOUT THE 164th ASA MEETING
The Kansas City Marriott Downtown Hotel is located at 200 West 12th Street, Kansas City, Missouri, 64105. The hotel main numbers are: 816-421-6800; fax: 816-855-4418.
USEFUL LINKSMain meeting website: http://acousticalsociety.org/meetings/kansas_cityMeeting Abstract Database: http://asa.aip.org/asasearch.htmlHotel site: https://resweb.passkey.com/Resweb.do?mode=welcome_ei_new&eventID=8120158
WORLD WIDE PRESS ROOMASA's World Wide Press Room (www.acoustics.org/press) contains additional tips about newsworthy stories and with lay-language papers, which are 300-1200 word summaries of presentations written by scientists for a general audience and accompanied by photos, audio, and video.
PRESS REGISTRATIONASA will grant free registration to credentialed full-time journalists and professional freelance journalists working on assignment for major news outlets. If you are a reporter and would like to attend, contact Charles E. Blue (email@example.com, 301-209-3091), who can also help with setting up interviews and obtaining images, sound clips, or background information.
****************************This news release was prepared for the Acoustical Society of America (ASA) by the American Institute of Physics (AIP).
ABOUT THE ACOUSTICAL SOCIETY OF AMERICAThe Acoustical Society of America (ASA) is the premier international scientific society in acoustics devoted to the science and technology of sound. Its 7,000 members worldwide represent a broad spectrum of the study of acoustics. ASA publications include The Journal of the Acoustical Society of America (the world's leading journal on acoustics), Acoustics Today magazine, ECHOES newsletter, books, and standards on acoustics. The Society also holds two major scientific meetings each year. For more information about ASA, visit our website at http://www.acousticalsociety.org.