Methodic recommendations for measuring underwater noise of research and commercial vessels

Recommendations for measuring underwater noise from vessels intended for fisheries researches and monitoring of bioresources are compiled based on current technical regulations and standards. Key terms and tools for the measurement are described, requirements for conditions of the measuring are determined, potential uncertainties of the data and procedures of the data recording and postprocessing are explained. The principles of placement, operation, and interaction are established for the main components of the hydroacoustic measurement system and the object of measurement. The sound pressure levels of noise emitted by vessel in the frequency range of 10–25,000 Hz in narrow and 1/3-octave frequency bands is measured. Parameters of the vessel movement along the track and distance to the registration point are monitored during the testing; the noise level is measured in the far acoustic field of the vessel and then normalized to a distance of 1 m. The sound pressure levels of noise are presented in dB relative to the reference sound pressure of 1 μPa. The measured noise levels are compared with the thresholds recommended by the International Council for the Exploration of the Sea (ICES). These thresholds represent the levels below which the effect of fish avoiding the vessel can be ignored. Frequency ranges and levels of the noise exceeding these limits are identified. These recommendations will be used as a component of the acceptance testing program for new research fishing vessels of Project 17050, as well as for acoustic certification of other vessels engaged in researches conducted by the Russian Research Institute of Fisheries and Oceanography (VNIRO) and its branches.