Sonar and quantitative echosounder
Topic outline
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During the training cruise by the Hokkaido University Training Ship Oshoro-Maru in October 2020, we conducted a survey of pelagic fish schools off the coast of Kushiro using sonar and quantitative echosounder. Sonar transmits ultrasonic waves in a lateral direction, allowing the fish schools around the vessel to be observed, while the quantitative echosounder observes the area directly below the vessel. The sonar detects fish schools in the distance, and the fish schools are detected by the quantitative echosounder as they approach the vessel and near the bottom of the vessel. The fish schools detected by these two acoustic devices are caught by the pelagic trawl, and the species and size of the fish seen by the sonar and the quantitative echosounder are confirmed and checked against the acoustic data.
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