Maternal effects on offspring size: Variation through early development ofchinook salmon

We performed two breeding experiments with chinook salmon (Oncorhynchus tsh awytscha) to explore maternal effects on offspring size. We estimated the m agnitude of maternal effects as the differences between sire-offspring and dam-offspring regression slopes. Early in life, offspring size is largely i nfluenced by maternal size, but this influence decreases through early deve lopment, with the maternal effect becoming negative at intermediate offspri ng ages (corresponding to a period of reduced growth of progeny hatching fr om large eggs) and converging on zero as offspring age. Also, egg size was positively correlated with early survival, but negatively correlated with m aternal fecundity.