Batch fecundity, the number of eggs released per spawning event, was determined for the first time in pilchard Sardina pilchardus (Walb.) off the Atlantic coast of the Iberian Peninsula. The mean relative fecundity (number of hydrated oocytes per gram of female weight was 416 (standard deviation = 112.9). Different regression models with Portuguese and Spanish data of batch fecundity by weight are presented. A linear model weighted least squares regression is established. The weighted regression presents a homogeneous distribution of the variance, small mean square error of the regression and highest R-squared, according whit this expression: F = -1260.8 + 444.43 W Linear regression of batch fecundity by age for Portugal data is: F = 30811.11 + 3711.88 A