Autonomous Acoustic Receiver Deployment and Mooring Techniques for Use in Large Rivers and Estuaries

Acoustic telemetry receivers are used across a range of aquatic habitats to study a diversity of aquatic species. The Juvenile Salmon Acoustic Telemetry System autonomous acoustic receiver system was deployed and moored in the Columbia River and its estuary. A high receiver loss rate during 2005 in the Columbia River estuary, an area with high water velocities and unstable substrates, prompted improvements to the receiver mooring system, and in 2006 the mooring system was redesigned. This change included elimination of surface buoys, a cable bridle, and an anchor tagline (for anchor recovery). The new mooring configuration, consisting of an acoustic receiver, acoustic release, and mooring line sections that were anchored to the riverbed, improved receiver recovery rates and crew safety. Additionally, a reward program was implemented to provide an incentive for people to return found receivers. The mooring design presented here performed well compared with previous acoustic receiver mooring methods used in the Columbia River system and should be useful for similar applications in large rivers and estuaries with high water velocities and shifting substrates.