Baleen Whale Acoustic Activity in the North Pacific: Historical Analysis and Current Occurrence

• Main Author: Stafford, Kathleen M.
• Other Authors: WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
• Format: Text
• Language: English
• Published: 2007
• Subjects: Biological Oceanography; Acoustics; Physical and Dynamic Oceanography; *DETECTION; *DISTRIBUTION; *NORTH PACIFIC OCEAN; *WHALES; *ACOUSTIC DATA; MONITORING; MARINE BIOLOGICAL NOISE; ALASKA GULF; CHLOROPHYLLS; ZOOPLANKTON; PHYTOPLANKTON; SEASONAL VARIATIONS; HYDROPHONES; MIXED LAYER(MARINE); *BLUE WHALES; *ACOUSTIC ACTIVITY; BALAENOPTERA MUSCULUS; EASTERN TROPICAL PACIFIC; PRINCE WILLIAM SOUND; CONCENTRATION; Gulf of Alaska; Pacific; Balaenoptera musculus; baleen whale; baleen whales; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA479320; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA479320

Unclassified historic acoustic data were used to examine long time scale changes in the seasonal and geographic occurrence of large whales in the Pacific and to correlate these changes with oceanographic variables such as sea surface temperature, chlorophyll alpha, etc. Distribution of northeastern Pacific blue whales (as indicated by the numbers of their calls), while insignificantly related to SST, did show a clear seasonal pattern both to chl alpha concentration (negative) and to the mixed layer depth (positive). It was speculated that the negative correlation with chl a might be due to a lag from primary to secondary productivity: as phytoplankton are eaten by zooplankton (which in turn become available to whales), the overall amount of chl alpha decreases. It is recommended that in collaboration with other agencies hydrophones be deployed in the northeastern Gulf of Alaska to provide current information on the occurrence of vocally active whale species, including low-requency baleen whales and higher frequency odontocetes. A likely time might be during the Northern Edge 2008 exercise in Prince William Sound. Meanwhile, a new efficient, low-power, low-cost recorder that can be easily deployed, in an array with other instruments or independently, from a mid-size vessel is being developed. The original document contains color images.