Lack of Correlation between Chinook Salmon Spawn Survival and the Number of Overripe Eggs as Determined by Digital Imagery

Abstract

AbstractThe number of overripe eggs in spawn of landlocked fall Chinook salmon Oncorhynchus tshawytscha was determined quantitatively from digital images recorded prior to fertilization. The percentage of overripe eggs recorded from the digital images was not significantly correlated with survival at egg eye‐up, fry hatch, or swim‐up but was significantly correlated with the visually estimated number of overripe eggs (r 2 = 0.914, P < 0.001). There was also no significant difference between the percentages of overripe eggs determined by the two methods. Neither the digital image nor visual‐estimation techniques for assessing overripe eggs are reliable predictors of egg survival, but the digital imagery validated the use of visual estimates.