Effects of Varying Voltage and Pulse Pattern during Electrical Immobilization of Adult Chum Salmon on Egg Survival to the Eyed Egg Stage

Abstract

Abstract Electrical shock is becoming widely used to immobilize adult salmon before gamete removal. Working with immobilized fish reduces repetitive motion injuries among workers and decreases staff requirements, but survival rates of eggs obtained from adults immobilized by electrical currents have varied. Eleven DC wave forms and voltage combinations were used to immobilize adult chum salmon Oncorhynchus keta, and survival rates of eggs taken from shocked fish were compared with survival rates from fish immobilized with carbon dioxide. Egg survival rates increased as voltage and pulse pattern intensity decreased. Similar egg survival rates were recorded for those obtained from the carbon dioxide controls (98%) and those obtained at the lower voltage and pulse patterns (96-98%), thus validating the use of electrical immobilization on adult chum salmon before gamete removal.