Towards a simpler assessment of the environmental impact of hydrographic echosounders

Conducting seafloor-mapping surveys often implies preliminary authorization requests based on the prediction of the field radiated by the sonars to be operated, compared to acceptable thresholds established for concerned marine animals and different risk levels. Applied to multibeam echosounders, risk assessment studies show very moderate risk levels, for objective reasons that are presented here together with some modelling results. Such systematic risk evaluations are redundant since they always concern the same sonars and animal species. It is suggested that regulatory authorities explicitly consider the case of seafloor-mapping echosounders, confirm their limited impact according to current methodologies and standards and, when appropriate, exonerate them from preliminary risk assessment.