A new paper is available online: Holt, M. M. 2008. Sound exposure and Southern Resident killer whales (Orcinus orca): A review of current knowledge and data gaps. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-89. Summary: This document reviews what is currently known about potential acoustic impacts on endangered Southern Resident killer whales (SRKWs). Killer whales (/Orcinus orca/) use sound for echolocation, social communication, and passive listening. Ambient noise, including that from natural and anthropogenic sources, has the potential to interfere with the reception and use of these important biological sounds. Significant sources of anthropogenic sounds that contribute to ambient background noise in critical habitats of SRKWs include sonar, acoustic harassment devices, vessel traffic, and construction noise. Most measurements of ambient sounds made in SRKW habitat are greatly influenced by vessel traffic that, at close ranges, raises noise levels significantly above ambient levels. In order to address potential acoustic impacts, particularly from anthropogenic sources, this document reviews parameters of sound that are pertinent to the auditory capabilities of killer whales and various studies on noise effects in killer whales and other dolphins. The latter includes auditory ramifications such as auditory masking or hearing loss and behavioral effects such as disruption of foraging events or avoidance of an area. With this information, the document then incorporates information on the soundscape of SRKW habitat and defines zones of audibility, responsiveness, masking, and hearing loss and addresses the likelihood of acoustic impacts on the SRKW population. Lastly, recommendations are made for future work in order to address gaps in information that, if available, would increase confidence in predicting the likelihood of acoustic impacts on SRKWs. PDF online at http://www.nwfsc.noaa.gov/publications/displayinclude.cfm?incfile=technicalm... Best Regards, Marla Holt -- __________________________________ Marla M. Holt, Ph.D. NRC Postdoctoral Associate Marine Mammal Program NOAA NMFS Northwest Fisheries Science Center 2725 Montlake Blvd East Seattle, WA 98112 Phone: 206.860.3261 Fax: 206.860.3400 Web: http://www.nwfsc.noaa.gov/