BIOACOUSTICAL OCEANOGRAPHY AT HIGH-FREQUENCIES

High-frequency acoustical technology is used to measure the spatial di stributions of small zooplankton with meter-scale resolution in the ve rtical, resolutions of hundreds of meters or better in the horizontal, and with temporal resolutions of minutes. Both size and abundance mea surements can be made by using sensors in a cast mode from a ship, fro m undulating towed bodies and by placing instruments on moorings. This presentation includes an overview of some of the technical concepts t hat are involved, examples of the use of the sensors and systems that have been developed and brief discussions related to the algorithms us ed to convert acoustical measures to biologically relevant estimates f or small zooplankton. (C) 1995 International Council for the Explorati on of the Sea