More on the frequency dependence of target strength of mature herring
Original version
This report is not to be cited without prior reference to the authorsAbstract
The hibernating stock of Norwegian spring-spawning herring has been
acoustically surveyed in a fjord system in northern Norway in December
1992. The survey frequencies are 18, 38, 120, and 200 kHz. When the
corresponding echo sounders were operating, the fundmental measurements of
volume backscattering strength were simultaneous. By comparing integrated
measures of these, the several backscattering cross sections are related.
New results are compared with those obtained from a cruise in the same area
in December 1991, when the same herring stock was observed.