The Relationship Between Digital Egg Coloration and Egg Survival in Landlocked Fall Chinook

Digital color values were collected from the eggs of 128 spawns from individual landlocked fall Chinook salmon Oncorhynchus tshawytscha females from Lake Oahe, South Dakota, USA, in 2008, 2009, 2015 and 2016. For all spawns, the mean (SE) a* value, a measure of red-green chromaticness, was 10.99 (0.27), and ranged from 3.98 to 18.71. Mean (SE) b* (yellow-green) was 20.27 (0.32), and ranged from 9.28 to 28.50. Mean (SE) L* (white-black) was 20.73 (0.48), and ranged from 3.98 to 18.71. Egg total color index also showed considerable variation, with a mean (SE) of 23.05 (0.37) and range from 11.70 to 31.64. Egg survival to the eyed-stage was weakly, but significantly, correlated to b* (r = 0.206), L* (r = 0.185), Chroma (r = 0.211), and Entire Color Index (r = 0.211). Spawns with no egg survival had eggs with significantly lower a* values compared to spawns where at least some of the eggs survived to the eyed stage. L*, a*, b*, Chroma, and Entire Color Index varied significantly among the years, but Hue and egg survival to the eyed stage did not. The results of this study indicate a possible link between egg color and landlocked fall Chinook salmon egg survival, possibly due to differences in the diets of feral broodstock females or their ability to deposit bodily carotenoids in the developing eggs.