Use an electric current to deter mammals from fishing gear
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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.
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