Use acoustic decoys to divert mammals away from fishing gear
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Decoy devices may be used to divert marine and freshwater mammals away from fishing gear to reduce the risk of entanglement or capture. This may also reduce mammal predation on fish catches thereby reducing human-wildlife conflict.
Supporting evidence from individual studies
A study in 2013 in a pelagic area in the western Gulf of Alaska, USA (Wild et al. 2017) found that increasing the distance between an acoustic decoy device and fishing lines resulted in fewer sperm whales Physeter macrocephalus at the lines, but sperm whale presence and time of arrival did not differ. Deploying acoustic decoy devices at greater distances from fishing lines resulted in fewer sperm whales at the lines during hauls (data reported as statistical model results). However, the distance between the decoy and fishing line did not have a significant effect on sperm whale presence during hauls or the time it took for sperm whales to arrive after hauling commenced. An acoustic decoy device was deployed at various distances (between 1.6 and 12.4 km) from ‘long line’ fishing lines (average 5 km in length) targeting sablefish Anoplopoma fimbria during a total of 14 deployments. The acoustic device (an underwater speaker attached to a buoy, 20 m deep) played recordings of vessel hauling sounds. Acoustic recorders deployed below the decoy and each fishing line at a depth of 100 m recorded sperm whale vocalizations. Fishers recorded sperm whale sightings and evidence of predation during each of the 14 hauls in June–July 2013.Study and other actions tested