Stock assessment of Alaska red king crab, Paralithodes camtschaticus, can be improved by incorporating embryo production, which requires an understanding of the size-fecundity relationship and an understanding of interannual and seasonal variability in fecundity. We collected red king crab egg clutches from Bristol Bay, AK, during summer 2007 to 2010 and autumn 2007 to 2009 and estimated individual fecundity using dry weight methods. Fecundity increased with female size up to 138 mm carapace length (CL), at which point the slope decreased by 40%, suggesting senescence. Fecundity varied significantly but slightly (maximum, 5%) among years. Fecundity was consistently lower in autumn than spring, suggesting brood loss, with a 6% decrease between seasons in females smaller than 138 mm CL and a 10% decrease in larger females. When incorporating embryo production in stock assessments, differences in the size-fecundity relationship should be accounted for and rates of brood loss can be used to predict larval output more effectively if fecundity cannot be measured shortly before hatching. To include potential environmental effects on the relationship, time series of fecundity and female size should be extended over a wider range of future temperature conditions.