Timing of Landlocked Fall Chinook Salmon Spawning and Egg Survival

Landlocked fall Chinook salmon (Oncorhynchus tshawytscha) in Lake Oahe, South Dakota, USA return to a remote spawning station either already having ovulated (ripe) or with the eggs still retained in the ovary (green). This study documented the ovulation status of female salmon upon arrival at the station and recorded subsequent egg survival to determine the possible impact of different frequencies of spawning operations. The ovulation status of forty-one Chinook salmon was determined upon their arrival at the spawning station in October, 2017. Fish that arrived post-ovulation were spawned as soon as possible, and the resulting eggs maintained discretely until the eyed stage of egg development. Fish that arrived pre-ovulation were held at the station and their ovulation status checked three times per week.