Electrofishing of Landlocked Fall Chinook Salmon Broodstock Negatively Impacts Egg Survival

Abstract

AbstractElectrofishing is frequently used to collect landlocked fall Chinook Salmon Oncorhynchus tshawytscha broodstock. This experiment compared reproductive parameters, including egg survival, from female salmon that had either been obtained by electrofishing or passively captured after ascending a fish ladder. Mean ± SE percent survival to the eyed stage of development was significantly lower for eggs spawned from females that had been electroshocked (16.66 ± 4.68%) compared to those from females obtained at the fish ladder (31.53 ± 3.55%). There were no significant differences in spawning female TL, postspawn weight, egg size, or fecundity between the two groups. A significant correlation was observed between the survival of eggs from electroshocked females and the frequency of female handling; no such correlation was observed in eggs from ladder‐run females. Although electrofishing may be useful in gathering landlocked fall Chinook Salmon broodstock, lower egg survival can be expected. This may be mitigated, however, by decreasing the number of handling events to which fish are subjected prior to spawning.