Establishing a Method for Electrical Immobilization of Whitefish on Board Fishing Vessels

A downscaled version of an electrical dry stunner used in aquaculture has been adapted for use on fishing vessels to immobilize the catch (cod, haddock and saithe) shortly after capture to facilitate immediate and easy catch handling, and to minimize downgrading due to poor bleed-out. Possible effects of electrical stimulation of white muscle (blood lactate, initial pH and twitch ability) were determined. Eye roll, respiration, equilibrium, swim ability and noxious stimuli were assessed after stunning and fillets were examined with respect to color shade, possible blood spots and discolorations. Suitable voltages, exposure times to electricity, and rows of electrodes were 40 and 70 V, 4 to 6 s, and 3 to 5 rows of electrodes, respectively. Cod and haddock can be immobilized without skeletal damages and occurrence of blood spots and discolorations. In contrast, 11% of the saithe had fractured spine usually accompanied by a single large blood spot.