Bull. Jpn. Soc. Fish. Oceanogr. 74(sp), Page 4-18, 2010   Influence of spatio-temporal changes in stock reproductive potential on the recruitment levels of fish Yutaka Kurita Tohoku National Fisheries Research Institute, Fisheries Research Agency, 3-27-5 Shinhama, Shiogama, Miyagi 985-0001, Japan e-mail: kurita@affrc.go.jp Mechanisms of changes in reproductive traits both at an individual level and a population level, and the hypothesized mechanisms of the effects of variation in stock reproductive potential on recruitment were reviewed. Large/old fish spawn relatively more eggs per body weight for a longer duration with a wider range of temporal and spatial distributions, and they likely contribute proportionally more to recruitment compared with small/young fish. Thus, the existence of a sufficient biomass of large/old females and/or the occurrence of a sufficient proportion of large/old females in spawners are hypothesized to be necessary to assure a large recruitment with a low variability under a stochastically variable environment during the early life stages. An appropriate stock management and future researches in relation to this topic are discussed. Key words: stock reproductive potential, temporal variation, spatial variation, maternal effect, recruitment