Use acoustic decoys to divert mammals away from fishing gear

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

37%
Certainty

30%
Harms

0%

Calculating overall effectiveness category

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.

Study locations

Key messages

One study evaluated the effects on marine mammals of using acoustic decoys to divert mammals away from fishing gear. The study was in the Gulf of Alaska (USA).

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (1 STUDY)

Behaviour change (1 study): One study in the Gulf of Alaska found that increasing the distance between an acoustic decoy device and fishing lines resulted in fewer sperm whales at the lines, but sperm whale presence and time of arrival did not differ.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

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
Referenced paper
Wild L., Thode A., Straley J., Rhoads S., Falvey D. & Liddle J. (2017) Field trials of an acoustic decoy to attract sperm whales away from commercial longline fishing vessels in western Gulf of Alaska. Fisheries Research, 196, 141-150.

Please cite as:

Berthinussen, A., Smith, R.K. and Sutherland, W.J. (2021) Marine and Freshwater Mammal Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation

Related Actions

Actions	Effectiveness	Studies	Category
Install exclusion and/or escape devices for mammals on fishing nets Action Link	Likely to be beneficial	7	Synopsis Link
Establish handling and release protocols for mammals captured by fisheries Action Link	Unknown effectiveness (limited evidence)	1	Synopsis Link
Introduce legislation to prohibit or restrict the use of fishing gear types or methods that are harmful to mammals Action Link	No evidence found (no assessment)	0	Synopsis Link