Mooring scientific instruments on the seabed – Design, deployment protocol and performance of a recoverable frame for acoustic receivers

Acoustic telemetry is increasingly used to observe and monitor animal movements in aquatic environments. Practical deployment mechanisms are needed to sustain consistent data flows in challenging environments. A tripod frame was developed to facilitate the deployment of acoustic receivers on the seabed, allowing for the recovery of all equipment with an acoustic release system. The procedures of deployment and recovery proved to be practical and efficient during a field trial in the North Sea. Compared to a common cabled design, the tripod frame realized a significantly higher detection probability and performed consistently better at greater distance and louder ambient noise. In the context of ocean observation in challenging environments, the tripod frame is a useful tool for temporary and continuous monitoring of tagged fish presence, potentially fitted with additional instruments.