A review and inventory of fixed autonomous recorders for passive acoustic monitoring of marine mammals: 2013 state-of-the-industry

Fixed autonomous acoustic recording devices(autonomous recorders [ARs]) are defined as any electronic recording system that acquires and stores acoustic data internally (i.e., without a cable or radio link to transmit data to a receiving station), is deployed semi-permanently underwater (via a mooring, buoy, or attached to the sea floor), and must be retrieved to access the data. More than 40 ARs were reviewed. They varied greatly in capabilities and costs, from small, hand-deployable units for detecting dolphin and porpoise clicks in shallow water to larger units that can be deployed in deep water and can record at high-frequency bandwidths for over a year. The capabilities and limitations of the systems reviewed herein are discussed in terms of their effectiveness in monitoring and studying marine mammals.