Population size and fishing mortality rate and their variances were estimated for the Spanish sardineSardinella auritaalong the southern Fujian coast, China, in 1971–1983 and 1986–1989 by Jones's length-based cohort analysis. Population abundance and biomass varied among different periods, whereas exploitation patterns were consistent within periods from 1971 to 1983 but differed significantly from those in 1986–1989. The approximate variance estimators for this method were developed in general form by the delta method. Errors in the estimates caused by the input parameters were examined, and we conclude that correlation between the estimates of asymptotic lengthL∞and the growth coefficientKtends to reduce errors in the population estimates from length-based cohort analysis. Risk of misestimating population size increases when length-based cohort analysis is used for stocks with high natural mortality. A comparison of the population biology and fisheries of the Spanish sardine around the world shows that the population along the southern Fujian coast is much smaller than that off northwestern Africa.