Application of Stationary Hydroacoustic Systems for Studies of Fish Abundance and Behavior

In most applications of hydroacoustic techniques for fish detection and abundance estimation, the data collection procedure involves echo sounding in a down-looking mode from a moving vessel. Stationary systems are virtually unused because of the reduced sampling power; however, in some cases stationary systems may offer several advantages. This study reports on two applications of stationary hydroacoustic systems: one at a coastal power plant intake in Southern California, and the second under the ice near Prudhoe Bay, Alaska. Several advantages of stationary systems were apparent, including more detailed information on fish behavior, capability for detection closer to boundaries, and better signal to noise characteristics.