Oxygen consumption in unfertilized salmonid eggs: an indicator of egg quality?

A negative correlation between oxygen consumption and fertility was observed in both steelhead and chinook salmon eggs. However, this relationship was attributed to bacterial growth. Elimination of samples with bacterial growth resulted in no significant relationship between the rate of oxygen consumption (VO2) and fertility. VO2 of unfertilized eggs of both steelhead and chinook salmon was measured over a storage period of up to 24 days (d). Despite declines in fertility during storage, VO2 did not significantly change throughout storage. The average respiration rate for steelhead eggs was 3.4 nmol O2 per egg per h, and was 4.3 nmol O2 per egg per h for chinook salmon eggs. Treatment of chinook salmon eggs with uncouplers of mitochondrial respiration, 2,4-dinitrophenol (2,4-DNP) and carbonyl cyanide 4-trifluoro-methoxyphenylhydrazone (FCCP), resulted in an increase in VO2 to 12.9 and 11.5 nmol O2 per egg per h, respectively. Treatment with the putative uncoupler, clove oil, resulted in no change in VO2, while KCN, an inhibitor of oxidative phosphorylation, reduced oxygen consumption to zero. Copper caused an increase in oxygen consumption, even in the absence of eggs, suggesting a need for caution in interpreting changes in respiration rates as a result of metal exposure. Thus, unfertilized salmonid eggs demonstrated submaximal VO2, which was not correlated with fertility.