Use of an Electrified Test-Fishing Gill Net for Deterrence of Pacific Harbor Seal Predation on Salmon in the Fraser River, B.C

An electrical deterrent system was installed and tested as an effective and safe method to deter Pacific harbour seals Phoca vitulina richardsi and their predation on sockeye Oncorhynchus nerka and pink salmon Oncorhynchus gorbuscha caught in a Fraser River gillnet test fishery.  Seals were deterred from foraging from a test fishing gillnet in the Fraser River by using a pulsed, low-voltage DC electrical gradient.  Salmon catch-per-unit-effort (CPUE) was significantly greater for the treated (electric) section of a gillnet compared to the non-treated (non-electric) section (electric section marginal mean CPUE = 4.0•(10³m•min^-1)^-1 versus non-electric section marginal mean CPUE = 1.0•(10³m•min^-1)^-1) and there was no overlap between the 95% confident intervals for the two treatments.  There were no apparent injuries to any animals during the study.  This previously undocumented non-lethal technology demonstrates the potential to reduce pinniped predation on salmon, with meaningful implications for fisheries management agencies that rely on gillnet test fisheries in freshwater rivers frequented by pinnipeds.