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Enzenhofer, H. J. and G. Cronkite (1998). In-river accessory equipment for fixed-location hydroacoustic systems. Canadian Technical Report of Fisheries and Aquatic Sciences 2250.

This report describes the design, construction and use of the in-river equipment that aids the operation of a fixed-location hydroacoustic system located near the confluence of Qualark Creek with the Fraser River near Yale, British Columbia, Canada. The equipment can be easily deployed by one person and is designed to withstand the forces created by strong current flow. This equipment is essential to the operation of the hydroacoustic system to maintain accurate and defensible enumeration of migrating salmon. Fish migrating in rivers with higher current flow tend to be shore and bottom oriented and require a shore based system aimed close to the river bottom and perpendicular to the flow. Specialised equipment must be used to move fish away from the shore so they can be counted. The operator must be able to aim the transducer precisely to ensure that the beam is close to the river bottom and covers the volume where fish passage occurs. The beam aim must be repeatable after moving the equiment. Since the detection characteristics vary between transducers, the ability to detect should be determined for each transducer in the environment where it is used.