Evol Ecol Res 10: 1187-1199 (2008) Full PDF if your library subscribes.
Why are salmon eggs red? Egg carotenoids and early life survival of Chinook salmon (Oncorhynchus tshawytscha)
Selene T. Tyndale1*, Robert J. Letcher1#, John W. Heath2 and Daniel D. Heath1
1Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 and 2Yellow Island Aquaculture Ltd., Campbell River, British Columbia V9W 6K9, Canada
Correspondence: D. Heath, Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada.
Background: The characteristic red colour of salmon eggs is due to provisioning of carotenoids at the cost of the mother.
Hypothesis: Carotenoid-based pigmentation of salmon eggs provides increased offspring survival during incubation and elevated disease resistance upon seawater entry.
Organism: Chinook salmon (Oncorhynchus tshawytscha, Walbaum); Quinsam River, Chehalis River, and domestic stocks.
Methods: We tested for correlations of egg carotenoid levels measured in Chinook salmon eggs reared as maternal families with (1) incubation survival and (2) specific disease (vibriosis) challenge resistance.
Conclusions: Egg carotenoids were primarily astaxanthin and declined throughout larval development. Incubation survival and disease resistance were significantly and positively correlated with mean family carotenoid concentration measured in eggs. A 1.0 µg · g−1 increase in egg carotenoid concentration confers an approximately 10% survival benefit. However, the incubation–survival relationship was asymptotic, indicating a threshold effect of carotenoids on incubation survival. Egg carotenoid concentration was also positively correlated with specific disease resistance 7 months later in life.
Keywords: carotenoid, Chinook salmon, disease resistance, eggs, fitness, immune function, incubation survival, trade-off.
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