Locomotory activity and depth distribution of adult great barracuda (Sphyraena barracuda) in Bahamian coastal habitats determined using acceleration and pressure biotelemetry transmitters

Abstract

Documenting free-swimming fish in their natural environment using acoustic transmitters equipped with acceleration and pressure sensors may contribute to knowledge of locomotory behaviour for a variety of aquatic species. Previously, collection of acceleration data has been limited to archival loggers, necessitating retrieval of the devices; however, recent advances in biotelemetry have allowed for acceleration data to be transmitted to a remote receiver. To illustrate the application of this technology, relative locomotory activity and depth utilisation of adult great barracuda (Sphyraena barracuda) were monitored across habitat types and diel periods using acoustic transmitters equipped with tri-axial acceleration and pressure sensors within an acoustic telemetry array (n = 53 receivers) deployed in The Bahamas. Although there were no differences in acceleration or depth use across habitats or diel periods, there was evidence of movement into shelf habitat during mid-day where they occupied depths >10 m. Given both the method of calculating the accelerometer output, and that the transmitters were unable to store and transmit large quantities of data, we suggest choosing transmitter settings with a short average delay and high transmission frequency to optimise data quality and resolution. This paper represents one of the first reports of the use of telemetered acceleration values from free-swimming fish.