Acoustic studies investigating the distribution and abundance of krill in critical blue whale habitat in the Monterey Bay submarine canyon

• Published in: The Journal of the Acoustical Society of America 2006-11, Vol.120 (5_Supplement), p.3108-3108
• Main Authors: McGarry, Louise P., Greene, Charles H., Wiebe, Peter H., Croll, Donald A.
• Format: Article
• Language: English
• Subjects: Cetacea; Marine
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4787583

Blue whales, the largest animal on the planet, are frequently found in concentrations at the ocean surface in areas over thick sound-scattering layers of krill. In this study, the dive behavior of a blue whale was investigated in the context of zooplankton acoustic backscatter data concurrently collected in the Monterey Bay submarine canyon. The whale dive behavior revealed that the whale spent greater than 50 percent of its time in the region of the most intense backscatter, suggesting threshold foraging behavior. In order to describe the prey field within the canyon, additional day and night acoustic surveys with MOCNESS net tows in the canyon and along its perimeter were collected. Here, a three-dimensional characterization of the prey field is developed using the acoustic data. Further work will be undertaken to estimate the relative biomass of the zooplankton taxa generating the acoustic backscatter within and without the intense sound-scattering layer, and to model the acoustic backscatter that would be expected to be generated from the zooplankton specimens collected: the forward problem. [This work is supported by the ONR.]