The difference-frequency band of the Kongsberg TOPAS PS18 parametric sub-bottom profiling sonar, nominally 1–6 kHz, is being used to observe Atlantic herring. Representative TOPAS echograms of herring layers and schools observed in situ in December 2008 and November 2009 are presented. These agree well with echograms of volume backscattering strength derived simultaneously with the narrowband Simrad EK60/18- and 38-kHz scientific echo sounder, also giving insight into herring avoidance behavior in relation to survey vessel passage. Progress in rendering the TOPAS echograms quantitative is described.
Foote, Kenneth G.; Hanlon, Roger T.; Iampietro, Pat J.; Kvitek, Rikk G.(Acoustical Society of America, 2006-02)
The squid Loligo opalescens is a key species in the nearshore pelagic community of California, supporting the most valuable state marine fishery, yet the stock biomass is unknown. In southern Monterey Bay, extensive beds ...
Zimmer, Walter M. X.; Harwood, John; Tyack, Peter L.; Johnson, Mark P.; Madsen, Peter T.(Acoustical Society of America, 2008-11)
Beaked whales can remain submerged for an hour or more and are difficult to sight when they come to the surface to breathe. Passive acoustic detection (PAD) not only complements traditional visual-based methods for detecting ...
Foote, Kenneth G.; Chu, Dezhang; Hammar, Terence R.; Baldwin, Kenneth C.; Mayer, Larry A.; Hufnagle, Lawrence C.; Jech, J. Michael(Acoustical Society of America, 2005-04)
Development of protocols for calibrating multibeam sonar by means of the standard-target method is documented. Particular systems used in the development work included three that provide the water-column signals, namely ...
