Underwater noises produced by research vessels (some comments on acoustic sampling protocol for the Area 48 synoptic survey

The underwater vessel noise levels perceived by the echosounder EK-500 transducers of three Russian research vessels have been presented. These data have been compared to the estimate of the underwater noise level, produced by the Icelandic R/V B.Saemundsson..
Underwater noise level perceived by the echosounder transducer versus its operation frequency and vessel speed has been analyzed. It has been shown that the level of underwater noise produced by vessel is an important technical property to be taken into account in assessment of such parameters of Acoustic Sampling Protocol as TS and Sv thresholds and vessel’s speed . The interrelation between choice of TS and Sv thresholds and vessel speed when echosurveying has been emphasized.
It has been shown that a difference between the underwater noise levels of vessels participating in multiple-ship survey, cannot provide for the choice of desirable speed of the vessels with the unique given level of TS and Sv thresholds used by all vessels. The importance of the research vessel underwater noise level has been discussed when standardizing acoustic data collection from multiple-ships like during a multinational effort to synoptical survey the Area 48 .