Timing of Landlocked Fall Chinook Salmon Spawning and Egg Survival

Nathan Huysman, Jill M Voorhees, Hilary Meyer, Eric Krebs and Michael E Barnes*

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. After ovulation was observed, these fish were spawned as soon as possible as well. There was no significant difference in survival between the eggs of fish that arrived either pre- or post-ovulation at the station, nor from those that were spawned the same day as they returned to the station compared to those that had to wait up to nine days before spawning. There was also no significant difference in egg survival between those fish that were spawned the same day as they were determined to have ovulated, versus those that were spawned up to seven days after ovulation. There was no significant correlation between egg survival and the number of days a female was held post-ovulation, nor between egg survival and the number of days that a female with unknown ovulation timing was held prior to spawning. These results suggest that spawning landlocked fall Chinook salmon in Lake Oahe more than once-per-week is not necessary and will not positively affect egg survival.

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Published on: Feb 22, 2019 Pages: 1-4

Full Text PDF Full Text HTML DOI: 10.17352/2455-8400.000044
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