Jacobs Journal of Aquaculture and Research

Mortality of Landlocked Fall Chinook Salmon Broodstock After Electrofishing or Ascending a Fish Ladder

*Michael E. Barnes
Department Of Game, Mc Nenny State Fish Hatchery, Fish And Parks, McNenny State Fish Hatchery, South Dakota,USA , United States

*Corresponding Author:
Michael E. Barnes
Department Of Game, Mc Nenny State Fish Hatchery, Fish And Parks, McNenny State Fish Hatchery, South Dakota,USA , United States
Email:mike.barnes@state.sd.us

Published on: 2019-05-17

Abstract

Landlocked fall Chinook salmon (Oncorhynchus tshawytscha) broodstock can be obtained either passively after broodfish ascend a fish ladder, or actively through electrofishing. This study examined the mortality of broodstock Chinook salmon obtained by either method in Lake Oahe, South Dakota, USA in 2017. Overall, 10% of the 594 salmon that ascended the ladder died prior to spawning, which was significantly less than the 19% of the 344 salmon that died after electrofishing. More importantly, only 4% of the female broodstock that ascended the ladder died, which was also significantly less than the 12% mortality of females that were electrofished. Mortality of the ladder-run males was also significantly lower than that of males obtained by electrofishing. The salmon broodstock that ascended the ladder survived for a slightly longer duration. These results strongly suggest a negative effect of electrofishing on landlocked fall Chinook salmon broodstock survival. The use of electrofishing to obtain landlocked Chinook salmon broodstock is only recommended if the number of fish ascending a fish ladder cannot provide the desired number of broodstock.

Keywords

Chinook salmon; Oncorhynchus tshawytscha; Spawning; Broodstock ;Mortality.

Introduction

Feral broodfish collection is a common practice for many fisheries management agencies. Active capture methods, such as electrofishing, are used for broodstock collection, as are passive methods such as fish ladders or weirs [1, 2]. Typically, broodstock must remain alive for days after such capture to allow for ovulation or to maximize artificial spawning operational efficiencies. However, mortality rates may vary with broodstock collection methods [3].