a systematic gathering of information on fish availability and abundance using underwater sound.
a well-logging method in which sound impulses are generated and transmitted into the formations opposite the wellbore. The time it takes for the sound impulses to travel through the rock is measured and recorded. Subsequent interpretation of the record (log) permits an estimation of the rock's porosity and fluid content to be made. The process is also called sonic logging. See sonic logging. ...
a systematic gathering of information on fish availability and abundance using underwater sound.