A floating device for stationary hydroacoustic sampling in shallow waters

A floating device was designed for use in stationary hydroacoustic studies of fish movements and current-speed measurements (Acoustic Doppler Current Profiler, ADCP) in the shallow inter- and subtidal zone of mangrove waters (3-10 m depth). The floating device was a stable platform for the hydroacoustic equipment. It features adjustable depth of the transducer below the water surface and adjustable beam direction (horizontal, vertical) of the echosounder. The design is simple, robust, and rapidly bolted together. The results of the ADCP measurements in the mangrove channel at the end of the wet season were unusable even at weak neap tides because bedload transport of fine muddy substrate led to missing bottom echoes that are required for the current-velocity calculation.