Bioacoustical oceanography at high frequencies

High-frequency acoustical technology is used to measure the spatial distributions of small zooplankton with meter-scale resolution in the vertical, resolutions of hundreds of meters or better in the horizontal, and with temporal resolutions of minutes. Both size and abundance measurements can be made by using sensors in a cast mode from a ship, from undulating towed bodies and by placing instruments on moorings. This presentation includes an overview of some of the technical concepts that are involved, examples of the use of the sensors and systems that have been developed and brief discussions related to the algorithms used to convert acoustical measures to biologically relevant estimates for small zooplankton.