Use an electric current to deter mammals from fishing gear

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

Effectiveness

50%
Certainty

30%
Harms

20%

Calculating overall effectiveness category

Background information and definitions

Low-voltage electric currents may be used to deter marine and freshwater mammals from fishing gear. This may reduce the risk of mammals becoming entangled or captured in gear, as well as human-wildlife conflict resulting from mammal predation on fish catches. However, caution is required to ensure that mammals that have contact with the gear are not injured. There may also be safety risks for fishers operating electrified gear.

Study locations

Key messages

One study evaluated the effects of using an electric current to deter mammals from fishing gear. The study was in the Fraser River (Canada).

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (0 STUDIES)

OTHER (1 STUDY)

Human-wildlife conflict (1 study): One controlled study in the Fraser River found that using an electric current on a fishing net reduced Pacific harbour seal predation on salmon catches.

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 controlled study in 2007 at a site in the Fraser River, Canada (Forrest et al. 2009) found that using an electric current on a fishing net reduced Pacific harbour seal Phoca vitulina richardsi predation on catches of salmon Oncorhynchus spp. A section of fishing net treated with an electric current had higher catch rates of salmon (4 fish/km/minute) than an untreated section without an electric current (1 fish/km/minute). Seals were observed avoiding the electric section of the net (numbers not reported). An experimental nylon gill net (diagonal mesh size 133 mm, 60 meshes deep) was divided into two 91-m sections. One section was treated with a pulsed low-voltage electric current (produced by two horizontal wire electrodes spaced 2 m apart). The other section had no treatment. The net was deployed for 20 minutes three times/day on 22 days in August–September 2007. The electric treatment was alternated between the two sections of net. An observer on board the fishing vessel recorded salmon catches during a total of 67 net deployments.
Study and other actions tested
Referenced paper
Forrest K.W., Cave J.D., Michielsens C.G.J., Haulena M. & Smith D.V. (2009) Evaluation of an electric gradient to deter seal predation on salmon caught in gill-net test fisheries. North American Journal of Fisheries Management, 29, 885-894.

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

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This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation

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Install exclusion and/or escape devices for mammals on fishing nets Action Link	Likely to be beneficial	7	Synopsis Link