Viability of inland fall chinook salmon spawn containing overripe eggs andthe reliability of egg viability estimates

Egg survival to the eyed stage from female inland fall chinook salmon Oncor hynchus tshawytscha that released no apparent overripe eggs was compared wi th egg survival from the spawn of females with varying percentages of overr ipe eggs. Use of the estimated number of initially overripe eggs as a predi ctor of egg survival to the eyed stage was also evaluated. No significant d ifferences in female total length, number of eggs per female, or egg size w ere observed between the two groups of females. Percent egg survival to the eyed stage of development differed significantly between groups. Females w ith noticeably overripe eggs produced eggs that had a 30.0% mean survival t o the eyed stage versus 50.6% for the eggs from females with no overripe eg gs in their spawn, However, visual estimation of the initial number of over ripe eggs was not an accurate predictor of egg survival to the eyed stage.