Maternal Influences on Variation in Egg Sizes in Temperate Marine Fishes

SYNOPSIS. We examine the variation in egg sizes of marine teleostsand evaluate the maternal contribution to this variability.At the species level, egg sizes in 309 North Atlantic fishesrange from 0.3 to 18.0 mm diameter (median = 1.1), size at hatchingvaries directly with egg size, and large adult size is associatedwith large eggs but the relationship is weak. Within populations,egg sizes are distributed normally with a median coefficientof variation of 4% (n = 56 species). Egg size varied among femalesin all cases for which female-level data were found. Estimatesof the variance components of egg size due to females were foundfor three species and, as a percentage of total variance, are71 % for capelin, Mallotus villosus, 46% for winter flounder,Pleuronectes americanus, and 35% for Atlantic cod, Gadus morhua.For cod, which spawn multiple egg batches per year, an additionalbatches-within-females component was estimated to be 26%. Sizeat hatching also differs among sibgroups and is generally directlyrelated to egg size at the individual level. We modelled fishgrowth by allowing individuals to grow at exponential ratesfrom a normal distribution of initial sizes. Comparing sizevariation in model fish to empirical evidence suggests thatvariation in initial sizes, propagated by growth, could accountfor a large fraction of the size variation observed months afterhatching in natural populations. We view size variation in youngmarine fishes to be largely of maternal origin and environmentallymodulated, which if true has special consequences for fisheriesand aquaculture.