Development of an acoustic-based toothed whale depredation detection system for longline fisheries

Depredation on baited hooks and catch of longline fishing gear by toothed whales is a serious source of fishery product loss and increased operating costs. Depredation in tropical waters is dominated by false killer, short fin pilot, and melon headed whales. Depredation is associated with increased acoustic communication, both echolocation and whistles. Longlines take many hours to set and haul over tens of kilometers. Depredation detection would assist operators make decisions to reduce fishery loss. Termination of setting when depredation was occurring on recently set gear, or hauling sections of gear where depredation had not as yet occurred, would help reduce losses. Depredation avoidance would reduce risk of bycatch. Global Detection Systems is developing a depredation proximity detector. A GPS-based and web-enabled buoy will indicate locations of the buoys on the line. Detection is by a sensor array developed for fishing vessels. Detection, irrespective of the toothed whale species involved within a radius of the buoy, will be processed on-board the buoy using an entropy based detection system [Erbe, C., J. Acoust. Soc. Am. 127, 1959 (2010)]. The radius of detection is being determined in fishery trials in Australian and Central Pacific waters. [Work supported by AusIndustry and Commercialisation Australia.]