AcousticEcology.org Spotlight Report
International Whaling Commission
June 23-27, 2008
Scientific Committee on the web [GO THERE]
Download AEI edit of SOCER and Annex K noise sections [DOWNLOAD(pdf)]
See previous AEI Spotlight Reports on IWC considerations of noise (note: 2004 and 2006 included special focus sessions on noise issues) [GO THERE]
WDCS daily coverage of IWC 2008 meeting [GO THERE]
This year, as in 2007, noise was not a major focus of the work of the Scientific Committee. There were no special workshops of in-depth focus sessions on noise topics, so this year's AEI report consists simply of editing together the two sections of formal Scientific Committee publications that summarize new research that took place since the 2007 meeting. The result is an 8-page pdf, which can be downloaded at the link above.
The first document we excerpt is the State of the Cetacean Environment Report (SOCER), which summarizes recent research on a wide array of topics, including noise. Each year’s SOCER focuses on a particular region (in 2008, the North Atlantic), and also has a section on key research from other parts of the globe. The sections of the 2008 SOCER addressing noise impacts are reproduced below.
The second section included in AEI's report came from Annex K of the Scientific Committee Report. Annex K is the report of the Standing Working Group on Environmental Concerns; here, we find a brief summary of the SOCER, as well as summaries of other papers submitted to the IWC Scientific Committee by members of the committee. Several pages of Annex K that include the sections on SOCER and noise impacts are reproduced after the SOCER noise sections in AEI's report.
Download AEI edit of 2008 SOCER and Annex K noise sections [DOWNLOAD(pdf)]
Among the more interesting new studies summarized in SOCER, Annex K, and the AEI Spotlight Report are the following:
- Right whales changing their call frequency, perhaps to compensate for increased background noise
- Possible evidence of whales gathering together and decreasing vocalizing and diving when near a seismic survey
- Evidence that harbour porpoises, with less intense echolocation clicks than bottlenose dolphins, may find it hard to find prey in noisy environments
- A major effort to develop noise exposure criteria for cetaceans finds that while injury takes place only at relatively high sound levels (230dB), behavioral change often occur at much lower levels, though with much variation among species and individuals (harbour porpoises being "quite sensitive" to sounds as low as 90-120dB, with "profound and sustained avoidance" at 140dB; many species showed reactions at 120-160dB, with some others also sensitive to sounds down to 90dB).
- Studies of 3 of 19 deep-diving whales stranded in the summer of 2005 on Taiwan showed gas emboli tissue damage, generally considered consistent with sonar-induced injury. Both China and the US had engaged in sonar exercises during this period, though the US exercises were 400 miles away.
- Two reviews of seismic survey mitigation guidelines found a wide range of safety measures being used: safety zones range from .5km to 3km, with sound level safety thresholds ranging from 160-190dB. The authors state that “a single standard [exclusion zone] value [i.e., radius of impact] for all seismic surveys regardless of airgun volume or water depth is inappropriate”. One critical observation is that “relatively few aspects of current mitigation have a firm scientific basis and proven efficacy in the field”.
- A report on a series of unusual strandings of about 60 individuals of several deep-diving whale species on the west coast of the United Kingdom last winter, with passing note that France also saw an unusual spike in strandings.
- Detailed discussion of studies looking at bowhead whale distribution and call patterns during seismic surveys off Alaska's north slope. It appears that when feeding, whales tolerate higher sound levels than when migrating; in addition, there was evidence of decreased calling during surveys, which could corelate to decreased foraging activity.
- Another detailed discussion addressed increasing offshore wind and other renewable energy development, especially noise impacts of pile driving.