Viability of Inland Fall Chinook Salmon Spawn Containing Overripe Eggs and the Reliability of Egg Viability Estimates

Abstract

Abstract Egg survival to the eyed stage from female inland fall chinook salmon Oncorhynchus tshawytscha that released no apparent overripe eggs was compared with egg survival from the spawn of females with varying percentages of overripe eggs. Use of the estimated number of initially overripe eggs as a predictor of egg survival to the eyed stage was also evaluated. No significant differences in female total length, number of eggs per female, or egg size were observed between the two groups of females. Percent egg survival to the eyed stage of development differed significantly between groups. Females with noticeably overripe eggs produced eggs that had a 30.0% mean survival to the eyed stage versus 50.6% for the eggs from females with no overripe eggs in their spawn. However, visual estimation of the initial number of overripe eggs was not an accurate predictor of egg survival to the eyed stage.