Long term acoustic recordings available from a fixed hydrophone located 8 km north of Oahu have allowed monitoring of the whale species (blue and fin) which produce low-frequency acoustic calls. This study attempts to quantify those detections to estimate how many calling whales are present.
McDonald, M. A., Fox, C.G., Passive Acoustic Methods for Fin Whale Population Density Estimation, J. Acous. Soc. Am., 105, 2643-2651, 1999. (Online. Opens abstract)
The arcs drawn on the bathymetry map indicate the range bins for which acoustic whale detections were statistically counted. The plus symbols are digital bathymetry data points while the triangles are bathymetry data points from nautical charts. Depths are in meters.