In acoustic resource surveys using a quantitative echosounder, noise measurement is important to ensure the quality of the data obtained. It is relatively easy to measure the overall background noise of a quantitative echosounder installed on a research vessel in passive mode with the transmission of the quantitative echosounder stopped. However, incorporating noise measurements during actual surveys is rarely done due to survey time constraints. In “The multidisciplinary ecosystem survey in the eastern Indian sector of the Southern Ocean (80–150°E) by the Japanese research vessel Kaiyo-maru in the 2018–19 austral summer,” we took advantage of the frequent oceanographic observations by CTD during the survey to incorporate noise measurement in a format that does not significantly affect ship time. The time loss due to the method adopted this time was estimated to be about 20 min, and it was considered that the impact on the time of the entire survey was not large. In addition, noise measurement can be carried out smoothly if it is incorporated into the survey plan in advance and a thorough meeting is held with the navigation officer.
Abe et al. (Wed,) studied this question.